Liquid discharge head, control device, and liquid discharge device

Abstract

To provide a liquid discharge head, a control device, and a liquid discharge device capable of suppressing image disturbance.SOLUTION: A liquid discharge head according to an embodiment includes an actuator and a drive unit. The actuator varies the volume of a pressure chamber. The drive unit drives the actuator. The drive unit performs a discharge operation of driving the actuator based on discharge signals with multiple gradation levels, and drives the actuator using a precursor signal that causes pressure oscillation without liquid discharge during the non-discharge period in accordance with the gradation level in the discharge operation when a non-discharge period equal to or longer than a predetermined time exists immediately before the discharge operation.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a liquid ejection head, a control device, and a liquid ejection device. [Background technology]

[0002] Inkjet heads mounted on inkjet printers are known as liquid ejection devices. Inkjet printers eject ink droplets from the inkjet head to form images or the like on the surface of a recording medium. Inkjet heads eject ink droplets from nozzles that communicate with pressure chambers by changing the volume of the pressure chambers with a piezoelectric actuator. The operation of the actuator is controlled by a drive waveform input to the actuator.

[0003] In such liquid ejection devices, image distortion can be suppressed by performing a precursor operation in which a vibration waveform that does not eject liquid is applied before the ejection waveform, but it is difficult to suppress image distortion in the high frequency range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-212661 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a liquid ejection head, a control device, and a liquid ejection device that are capable of suppressing image disturbance. [Means for solving the problem]

[0006] A liquid ejection head according to an embodiment includes an actuator and a driving unit. The actuator changes the volume of a pressure chamber. The driving unit drives the actuator. The driving unit performs an ejection operation by driving the actuator with an ejection signal of multiple gradations, and when there is a non-ejection time of a predetermined period or more immediately before the ejection operation, the driving unit drives the actuator with a precursor signal that causes pressure vibration without ejecting liquid during the non-ejection time in accordance with the gradation of the ejection operation. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of a liquid ejection device according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view showing the configuration of the liquid ejection head. [Diagram 3] FIG. 2 is a cross-sectional view showing a part of the configuration of the liquid ejection head. [Figure 4] FIG. 4 is an explanatory diagram showing the correspondence between pixels and waveform patterns in Example 1, Example 2, and a comparative example. [Diagram 5] FIG. 4 is an explanatory diagram showing printing characteristics of Example 1, Example 2, and a comparative example. [Figure 6] FIG. 1 is an explanatory diagram illustrating a configuration of a liquid ejection device according to a first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A liquid ejection head 10 and a liquid ejection device 100 according to the first embodiment will be described below with reference to Figs. 1 to 5. Fig. 1 is a block diagram showing the configuration of the liquid ejection device 100 according to the first embodiment. Fig. 2 is a perspective view showing the configuration of the liquid ejection head, and Fig. 3 is a cross-sectional view showing the configuration of an actuator of the liquid ejection head. Fig. 4 is an explanatory diagram showing the correspondence between pixels and waveform patterns in Example 1, Example 2, and Comparative Example. Fig. 5 is an explanatory diagram showing the printing characteristics of Example 1, Example 2, and Comparative Example. Fig. 6 is an explanatory diagram showing the configuration of the liquid ejection device 100. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for the purpose of explanation.

[0009] As shown in FIG. 1, the liquid ejection device 100 includes a liquid ejection head 10, a liquid supply unit 21, a transport unit 22, an operation unit 25, a display unit 26, and a control unit 30.

[0010] As shown in FIG. 6, the liquid ejection device 100 is an inkjet printer that performs an image formation process on a medium such as paper by ejecting liquid such as ink from the liquid ejection head 10 while transporting the medium, which is the ejection target, along a predetermined transport path that passes through a printing position opposite the liquid ejection head 10.

[0011] The liquid ejection head 10 is, for example, a share-mode shared-wall type inkjet head. The liquid ejection head 10 may be a non-circulation type head that does not circulate ink, or may be a circulation type head that circulates ink. In this embodiment, the liquid ejection head 10 will be described using an example of a non-circulation type head.

[0012] For example, the liquid ejection head 10 includes an actuator 11 having a plurality of piezoelectric elements that communicate with the nozzles, and a drive circuit 12 as a drive section that drives the actuator 11.

[0013] For example, the liquid ejection head 10 has a plurality of nozzles 111 that eject liquid, a plurality of pressure chambers 112 that communicate with the nozzles, and a flow path that includes a common chamber that communicates with the plurality of pressure chambers 112. The flow path of the liquid ejection head 10 is connected to a liquid supply unit 21, and ink is supplied to the flow path of the liquid ejection head 10 from the liquid supply unit.

[0014] The actuator 11 is, for example, an actuator plate made of a piezoelectric member in a plate shape, and includes a plurality of piezoelectric elements 115 and electrodes 116 formed on the piezoelectric elements 115. For example, groove-shaped pressure chambers 112 are formed between the plurality of piezoelectric elements 115. The actuator 11 increases or decreases the volume of the pressure chambers 112 by applying a voltage to the electrodes 116 of the piezoelectric elements 115 provided corresponding to each pressure chamber 112, causing the piezoelectric elements 115 to deform, thereby causing ink to be ejected from the nozzles 111.

[0015] The drive circuit 12 drives the actuator 11 by applying a drive voltage to the electrodes of the piezoelectric body. The drive circuit 12 generates a control signal and a drive signal for operating the piezoelectric element 115. The drive circuit 12 generates a control signal for control such as selecting the timing of ejecting liquid and the piezoelectric element 115 that ejects liquid, according to an image signal input from the control unit 30 of the liquid ejection device 100. The drive circuit 12 also generates a voltage to be applied to the electrode 116 of the piezoelectric element 115, i.e., a drive signal (electrical signal), according to the control signal. When the drive circuit 12 applies the drive signal to the piezoelectric element 115, the piezoelectric element 115 is driven to change the volume of the pressure chamber 112. That is, the actuator 11 is configured to be drive-controllable by the control of the control unit 30.

[0016] As shown in FIG. 1, the driving circuit 12 includes a data buffer 13, a decoder 14, and a driver 15. The data buffer 13 is an example of a memory that stores information necessary for driving control. The data buffer 13 stores print data and image data. As an example, the data buffer 13 stores print data for each piezoelectric element of the actuator 11 in chronological order. For example, the data buffer 13 stores various information, including gradation values ​​of multiple pixels and formation timing for driving the actuator to form each pixel on a recording medium, as print data and image data. The decoder 14 controls the driver 15 for each piezoelectric element based on the print data stored in the data buffer 13. The driver 15 outputs a drive signal that operates each piezoelectric element 115 based on the control of the decoder 14. The drive signal is a voltage applied to the electrode 116 of each piezoelectric element 115.

[0017] In this embodiment, the drive circuit 12 generates and outputs a predetermined waveform pattern to each piezoelectric element based on an image signal input from the control unit 30. That is, the drive circuit 12 drives each of the multiple drive elements corresponding to each nozzle 111 of the liquid ejection unit with the predetermined waveform pattern. For example, the drive circuit 12 drives the liquid ejection unit with multiple multi-waveform patterns that combine multiple drop waveforms.

[0018] For example, the drive circuit 12 outputs a discharge signal for discharging liquid in accordance with the gradation value of the discharge target pixel at the timing of forming the discharge target pixel accompanied by liquid discharge. For example, the drive circuit 12 performs a discharge operation by driving the piezoelectric element 115 with a multi-level discharge signal.

[0019] Furthermore, when the timing for forming a non-ejection target pixel without liquid ejection is reached and the target pixels that will be formed at a specific gradation value within a specified number of pixels immediately after the timing, the drive circuit 12 outputs a vibration signal without ejection according to the gradation of the ejection target pixel. In the present embodiment, as an example, when the specified number is 2 cycles or more, or 2 pixels or more, and the specific gradation value is 2 gradations or more, the drive circuit 12 outputs a precursor vibration signal.

[0020] In other words, at the timing of formation of a pixel that does not involve ink ejection and includes a pixel that involves ink ejection among pixels whose formation timing arrives at a specific gradation within a specified number of pixels immediately after the pixel, a vibration signal for vibrating the nozzle without ink ejection is output according to the gradation value of the pixel with ink ejection. That is, in a drive waveform for driving a piezoelectric element 115 forming a certain pressure chamber 112, if there are non-ejection pixels not accompanied by ejection more than a specified number of pixels immediately before an ejection operation in which an ejection signal of a specific gradation or higher is applied, a precursor signal for causing pressure vibration without ejection of liquid is applied at the timing of forming the non-ejection pixel before the ejection signal according to the gradation in the ejection operation, and the piezoelectric element 115 is precursor-driven. In other words, in a drive waveform for driving a piezoelectric element 115 forming a certain pressure chamber 112, if there is a non-ejection time not accompanied by ejection for a predetermined time or more immediately before an ejection operation in which an ejection signal of a specific gradation or higher is applied, a precursor signal for causing pressure vibration without ejection of liquid is applied in the non-ejection time before the ejection signal according to the gradation in the ejection operation, and the piezoelectric element 115 is precursor-driven.

[0021] As a specific example, in multi-drop driving of up to four gradations, if there are two or more cycles of a non-ejection waveform of 1 gradation (0 drop) immediately before an ejection waveform of 3 gradations (2 drops) or an ejection waveform of 4 gradations (3 drops), the drive circuit 12 places a precursor waveform, which is an oscillation waveform that does not involve ejection, at the position of the non-ejection waveform of 1 gradation. On the other hand, if there are two or more cycles of 1 gradation before the ejection waveform of 2 gradations (1 drop), the drive circuit 12 does not place a precursor waveform and leaves it as a non-ejection waveform.

[0022] The liquid supply unit 21 is connected to the primary side of the flow path of the liquid ejection head 10, and supplies liquid to the flow path of the liquid ejection head 10. For example, the liquid supply unit 21 includes a tank for storing liquid, a connection flow path that connects the tank and the flow path of the liquid ejection head 10, and a liquid delivery pump that delivers the liquid from the tank to the liquid ejection head 10.

[0023] The transport unit 22 transports a medium such as paper along a predetermined transport path and supplies it to a printing position. The transport unit 22 includes, for example, a plurality of transport rollers and transport guides arranged along the transport path. The transport unit 22 supports the medium so that it can move relative to the liquid ejection head 10.

[0024] The operation unit 25 includes function keys such as a power key, a paper feed key, and an error reset key.

[0025] The display unit 26 has a display capable of displaying various states of the image printing device.

[0026] The control unit 30 is, for example, a control board, and includes a processor 31, a Read Only Memory (ROM) 32, a Random Access Memory (RAM) 33, an image memory 34, and an I / O port 35 which is an input / output port.

[0027] The processor 31 is a processing circuit such as a CPU (Central Processing Unit) that is a controller. The processor 31 corresponds to the central part of a computer. The processor 31 controls each part to realize various functions as a printer according to an operating system and an application program. For example, the processor 31 controls the operation of the liquid ejection head 10, the liquid supply unit 21, and the transport unit 22 provided in the liquid ejection device 100. In addition, the processor 31 transmits the print data stored in the image memory 34 to the drive circuit 12 in the drawing order during printing.

[0028] The ROM 32 corresponds to a read-only main memory portion of the computer. The ROM 32 stores the operating system and application programs. The ROM 32 may also store data necessary for the processor 31 to execute processes for controlling each unit.

[0029] The RAM 33 corresponds to a rewritable main memory portion of the computer. The RAM 33 stores data necessary for the processor 31 to execute processing. The RAM 33 is also used as a work area where information is appropriately rewritten by the processor 31. The work area may include an image memory where print data is expanded.

[0030] The image memory 34 stores, for example, print data from the external device 200 .

[0031] The I / O port 35 is an interface unit that inputs data from the external device 200 and outputs data to the outside. Print data from the external device 200 is sent to the control unit 30 through the I / O port 35 and stored in the image memory 34.

[0032] In the liquid ejection device 100 configured as described above, when the control unit 30 inputs a signal to the liquid ejection head 10, the drive circuit 12 applies a drive voltage to the plurality of piezoelectric elements 115 in response to the signal from the control unit 30, thereby generating a potential difference in the plurality of piezoelectric elements 115 and selectively deforming them, thereby increasing or decreasing the volume of the pressure chamber 112, thereby ejecting liquid from the nozzle 111. For example, when a voltage that serves as an expansion element is applied, the piezoelectric element 115 deforms, the volume of the corresponding pressure chamber 112 increases, the pressure decreases, and ink from the common chamber flows into the pressure chamber 112. Then, when a drive voltage of a reverse potential is applied to the electrode 116 of the piezoelectric element 115 while the volume of the pressure chamber 112 is increased, the piezoelectric element 115 deforms, the volume of the pressure chamber 112 decreases, and the pressure increases. As a result, the ink in the pressure chamber 112 is pressurized and ejected from the nozzle 111.

[0033] Waveform data of the drive waveforms is stored, for example, in a memory in the drive circuit 12. A driver IC of the drive circuit 12 selects which drive waveform to input to the actuator 11 based on grayscale data sent from the control board.

[0034] For example, the drive waveform generated by the drive circuit 12 is a multi-drop waveform that repeats a drop waveform for ejecting liquid according to the gradation to form one dot. As an example, the number of ejections within one drive cycle is set to up to three drops, and an example is shown in which ink is driven with gradation numbers from 1 to 4 within one drive cycle. Each drop waveform is an ejection waveform that includes an expansion pulse (expansion element) and a contraction pulse (contraction element).

[0035] 4 is an explanatory diagram showing drive patterns corresponding to each pixel in four image areas (a) to (d) for Example 1, Example 2, and Comparative Example. For example, an image area in which a plurality of pixels are arranged vertically and horizontally in a matrix is ​​shown.

[0036] For example, in this embodiment, the driving waveform is a multi-drop drive having up to three drop waveforms (elements) in one printing cycle for each pixel, and an example is given of an image with four gradations (0, 1 drop, 2 drop, 3 drop), where the specified number is 2 pixels and the specific gradations are 2 drop and 3 drop.

[0037] In this embodiment, one printing cycle has three cycles for three drops, and the periodic length of each drop waveform is equal. Each of these driving waveforms is composed of a combination of multiple gradation ejection waveform sections PA and PD, a non-ejection waveform section PB that does not eject liquid, and a precursor waveform section PC that vibrates without ejecting liquid. Note that the driving waveform for each gradation may be a combination of multiple same drop waveforms, or a combination of multiple different drop waveforms.

[0038] In this embodiment, when the print data is non-ejected for a specified time or more immediately before an ejection waveform section PA having a drop waveform of a specified gradation or more, the drive circuit 12 performs precursor driving immediately before the ejection of the specified gradation or more. That is, when a non-ejection waveform immediately precedes a 2-drop or 3-drop waveform, a vibration waveform without ejection is applied at a specified timing before applying the waveform for ejecting 2 or 3 drops. In other words, the drive circuit 12 generates a drive waveform that applies vibration without ejection prior to the ejection timing when an ejection timing of a specified gradation or more comes after a specified non-ejection timing according to the print pattern.

[0039] An example of a drive pattern according to this embodiment will be described with reference to Fig. 4. Fig. 4 shows cells corresponding to pixels in a certain image area, with the vertical and horizontal cells corresponding to, for example, each pixel. Fig. 4 corresponds to image formation timing when the vertical axis is time. That is, five or five vertical lines arranged in each of the image areas in Fig. 4 indicate waveform arrangement patterns with time in the vertical direction.

[0040] In the first embodiment, for example, cells of the second ejection waveform section PA driven by an ejection waveform of three or four gradations, margin cells of the non-ejection waveform section PB of one gradation, and cells of the precursor waveform section PC that performs precursor driving are arranged in a predetermined pattern.

[0041] That is, the image area of ​​the first embodiment has a second ejection waveform section PA, which is an ejection waveform with a reference gradation of 2 or more. Also, the drive waveform of the first embodiment has a non-ejection waveform section PB, for example, 2 or more, as a prescribed number, before the second ejection waveform section PA of the reference gradation. And, among these consecutive non-ejection waveform sections (non-ejection waveform cells) PB, a precursor waveform section PC is arranged in the cell immediately before the drop waveform section PA.

[0042] That is, when printing rectangular images from top to bottom in FIG. 4, if the pixels are formed in 3-4 gradations and there are two consecutive blank pixels, the drive circuit 12 performs control so that a precursor operation is performed one pixel before the pixel formed in 3-4 gradations.

[0043] For example, in the comparative example, cells of the first ejection waveform section PD driven in two gradations and blank cells corresponding to the non-ejection waveform section PB of one gradation are arranged in a predetermined pattern. In the comparative example, precursor driving is not performed.

[0044] In the second embodiment, for example, cells of the second ejection waveform section PA driven by an ejection waveform of 3 or 4 gradations, cells of the non-ejection waveform section PB of 1 gradation, and cells of the precursor waveform section PC performing precursor drive are arranged in a predetermined pattern.

[0045] That is, the driving waveform of Example 2 has a drop waveform section PA that is an ejection waveform with a reference gradation of 3 or more. The driving waveform of Example 2 also has a prescribed number of non-ejection waveform sections PB, for example, 2 or more, before the drop waveform section PA of the reference gradation. Among the cells of the consecutive non-ejection waveform sections PB, the precursor waveform section PC is disposed in the cell two cells before the second ejection waveform section PA.

[0046] That is, when printing rectangular images from top to bottom in FIG. 4, in the second embodiment, if a pixel is formed at 3.4 gradation and there are two consecutive blank pixels, the drive circuit 12 performs control so that a precursor operation is performed two pixels before the pixel formed at 3.4 gradation.

[0047] In other words, these controls are multi-drop waveforms that eject liquid with multiple ejection waveforms, and when there are two or more non-ejection timings before the ejection timing of 3 or 4 gradations, the precursor waveform is placed at the timing one or two before that. That is, the drive waveform of Example 1 and the drive waveform of Example 2 have an ejection waveform section PA that accompanies the ejection of liquid, a non-ejection waveform section PB that is a waveform that does not eject liquid, and a precursor waveform section PC that is a vibration waveform that does not eject liquid.

[0048] That is, in this embodiment, when the print data includes an ejection waveform section PA of three or more gradations and there are two or more consecutive blanks, i.e., non-ejection waveform sections PB of one gradation, within a specified number immediately before the ejection waveform section PA of three or more gradations, the drive circuit 12, which is an example of a drive device, outputs a precursor waveform section PC that performs precursor drive immediately before or two before the ejection waveform section PA in the blanks. That is, the liquid ejection head 10 executes a precursor one pixel before when there are two or more rows of blanks with three or four gradations, or executes a precursor two pixels before when there are two or more rows of blanks with three or four gradations.

[0049] As an example, the ejection waveform section PA is a multi-drop waveform that repeats a reference ejection drop waveform 0 to 3 times depending on the gradation. For example, the ejection drop waveform is a waveform that includes a first expansion pulse that expands the pressure chamber 112 and a first contraction pulse that contracts the pressure chamber 112. In the first expansion pulse, the voltage is lowered from a first voltage, which is an intermediate voltage, to a second voltage that is lower than the intermediate voltage, and the second voltage is maintained for a predetermined time, and then the voltage is returned to the first voltage. Then, after the first voltage is maintained for a predetermined time, a third voltage that is higher than the first voltage is applied as a first contraction pulse for a predetermined time, and the voltage is returned to the first voltage. The ejection drop waveform is a waveform that ejects with an expansion pulse and suppresses vibration with a contraction pulse.

[0050] When the second voltage is applied for a predetermined time by the first expansion pulse as an ejection operation by the ejection waveform section PA, an electric field is generated in a predetermined direction of the piezoelectric element 115, and the piezoelectric element 115 is deformed. The volume of the pressure chamber 112 expands due to this deformation of the piezoelectric element 115, and the ink pressure inside decreases, and the meniscus at the opening of the nozzle 111 is largely drawn toward the pressure chamber 112. Then, the ink pressure inside the pressure chamber 112 (ink chamber) starts to oscillate, and the ink flow velocity oscillates with a phase shift of 90 degrees.

[0051] After expansion by the expansion pulse, when the voltage is returned to the first voltage, the pressure chamber 112 returns to its original shape. Then, when the first voltage is maintained for a predetermined time, the meniscus advances and ink ejection begins. Then, after the first voltage is maintained for a predetermined time, a contraction pulse voltage is further applied to again deform the piezoelectric element 115 of the actuator 11, contracting the volume of the pressure chamber 112 and increasing the ink pressure, thereby suppressing the vibration of the pressure and flow rate within the pressure chamber 112. By repeating this ejection waveform n times, n drops of ink are ejected.

[0052] For example, the precursor waveform section PC is a waveform that has a longer expansion pulse or a smaller potential difference than the ejection waveform, and applies vibration without ejecting liquid. In other words, compared to the ejection waveform section PA, the precursor waveform section PC is a vibration waveform that does not eject liquid when ink flow velocity vibration occurs. Note that, for example, the precursor waveform section PC may be a waveform with only a contraction element, or a waveform that has an expansion element and a contraction element in sequence. For example, it may be a waveform that does not eject liquid by lengthening each expansion time.

[0053] Fig. 5 is an explanatory diagram showing the printing state by the waveform of Example 1, the waveform of Example 2, and the waveform of the comparative example without precursor operation. Fig. 5 shows that the comparative example causes image distortion especially in the high frequency band, and the printing state of the waveform of Example 1 or Example 2 can suppress image distortion.

[0054] According to the liquid ejection head 10 and the liquid ejection device 100 of the present embodiment, the precursor operation is performed at a required gradation, thereby reducing the power load and suppressing image disturbance in the printing range. That is, by performing the precursor operation only at a specific gradation, the power load can be reduced and the amount of heat generated by the actuator can be suppressed. Also, as shown in FIG. 5, even at frequencies exceeding 20 kHz, the pressure vibration can be stabilized, image disturbance can be suppressed, and good printing performance can be achieved. Also, according to the above embodiment, the drive circuit 12 provided in the liquid ejection head 10 generates a drive signal for performing the precursor operation, so that the liquid ejection head 10 itself can complete the control involving the precursor operation.

[0055] The embodiment of the present invention is not limited to the above-mentioned configuration.

[0056] For example, in the above embodiment, an example was shown in which the driving circuit 12 having a driver IC provided in the liquid ejection head 10 functions as a driving unit that generates a driving signal for performing a precursor operation, but the present invention is not limited to this. For example, precursor control may be performed in a control device such as the control unit 30 or an external terminal connected to the liquid ejection head 10. That is, when there is a non-ejection timing immediately before an ejection waveform of print data with a specified gradation or higher, precursor control may be performed on the control device side, whereby vibration that does not involve ejection of liquid is applied at the non-ejection timing according to the gradation. In addition, in each embodiment shown in FIG. 4, the cells driven by the discharge waveform section PA of 3rd and 4th gradations are arranged in a predetermined pattern in a predetermined image area, and in the comparative example, the cells driven by the discharge waveform section PD of 2nd gradation are arranged in a predetermined pattern, but this is not limited to this. For example, the discharge waveform section PA of 3rd and 4th gradations and the discharge waveform section PD of 2nd gradation may be mixed in one image area. In this case, the precursor waveform is applied at the timing of the non-discharge waveform section PB of 1 pixel or 2 pixels before the discharge waveform section PA of 3rd and 4th gradations, and even if there are two consecutive non-discharge cells immediately before the discharge waveform section PD of 2nd gradation, the precursor drive is not performed before the discharge waveform section PD, and the non-discharge waveform is driven as it is. In addition, in a case where the drive cycle is divided into 3 parts and driven, even if the precursor waveform is applied at a specific gradation or higher, pixels that drive the precursor waveform only in a certain cycle pattern may be arranged. In addition, an example has been shown in which each cell corresponds to a pixel and is driven for each pixel, but this is not limited to this. For example, driving may be performed in units different from pixels. For example, for each period of the ejection waveform that drives the piezoelectric element 115 to be ejected at a specific gradation or higher, if the immediately preceding two periods are non-ejection periods, the precursor may be driven at the timing one period or two periods before.

[0057] For example, the above embodiment has been described using a drive waveform for ejecting three drops, but the present invention is not limited to this and may be a drive waveform for ejecting four or more drops. The drop waveform is not limited to one type, and multiple types or more may be combined. It is also possible to vary the ejection volume by changing the pulse width and voltage value of each element.

[0058] Furthermore, the voltage value applied to each piezoelectric element 115 can be adjusted as appropriate according to various conditions. For example, a potential difference may be generated by grounding one of adjacent piezoelectric elements 115 and applying a voltage to the other, or a potential difference may be generated by applying a voltage to both of them.

[0059] The drive waveform is not limited to a pull-shooting waveform, but may be a push-shooting waveform or a push-pull-shooting waveform. For example, the configuration of the liquid ejection head 10 is not limited to the above example, and may be used in other types of heads. For example, it may be a structure in which ink is ejected by deforming a vibration plate using static electricity, or a heat element type structure in which ink is ejected from a nozzle using thermal energy from a heater or the like. In these cases, the vibration plate or heater serves as an actuator for applying pressure vibration to the inside of the pressure chamber 112.

[0060] The liquid ejection device 100 is exemplified as an inkjet printer that forms a two-dimensional image with ink on an image formation medium, but is not limited to this and may be, for example, a 3D printer, an industrial manufacturing machine, a medical machine, etc. The liquid ejection device may be a 3D printer, an industrial manufacturing machine, a medical machine, etc., and may form a three-dimensional object by ejecting, for example, a material substance or a binder for solidifying the material from an inkjet head.

[0061] According to at least one of the embodiments described above, by performing a precursor operation at a required gradation, it is possible to reduce the power load and suppress image disturbance in the print range.

[0062] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0063] 10...liquid ejection head, 11...actuator, 12...drive circuit, 13...data buffer, 14...decoder, 15...driver, 21...liquid supply section, 22...transport section, 25...operation section, 26...display section, 30...control section, 31...processor, 32...ROM, 33...RAM, 34...image memory, 35...I / O port, 100...liquid ejection device, 111...nozzle, 112...pressure chamber, 115...piezoelectric element, 116...electrode, 200...external connection device

Claims

1. An actuator that changes the volume of a pressure chamber; A drive unit that drives the actuator, The drive unit performs an ejection operation by driving the actuator with an ejection signal of multiple gradations, and if there is a non-ejection period of a predetermined period or longer immediately before the ejection operation, drives the actuator with a precursor signal that causes pressure vibration without ejecting liquid during the non-ejection period, in accordance with the gradation of the ejection operation.

2. The driving unit inputs a discharge signal corresponding to the number of gradations of the pixel to be discharged at a timing when the pixel to be discharged is formed by discharging liquid, and 2. A liquid ejection head as described in claim 1, wherein when two or more consecutive pixels that are not to be ejected occur immediately before the formation timing of a pixel to be ejected that is driven by an ejection signal of a specified gradation or higher, the actuator is driven by the precursor signal at the formation timing of a pixel two pixels or one pixel before the pixel to be ejected.

3. The liquid ejection head according to claim 1 , wherein the frequency of the ejection signal is greater than 20 kHz.

4. A drive unit that drives an actuator that changes the volume of the pressure chamber, The drive unit outputs a discharge signal for discharging liquid at a timing for forming a discharge target pixel accompanied by liquid discharge, in accordance with a gradation value of the discharge target pixel, and A control device that outputs a precursor signal that does not involve ejection according to a gradation value of a non-ejection target pixel when a target pixel that involves ejection of liquid is included among a specified number of target pixels immediately following the formation of a non-ejection target pixel that does not involve liquid ejection.

5. A liquid ejection apparatus comprising the liquid ejection head according to claim 1 .

Images