Liquid ejection head, control device, and liquid ejection apparatus

Abstract

The invention provides a liquid ejection head capable of suppressing image disorder, a control device, and a liquid ejection device. A liquid ejection head according to an embodiment includes an actuator and a drive unit. The actuator varies the volume of the pressure chamber. The drive unit drives the actuator. The drive unit performs an ejection operation for driving the actuator on the basis of ejection signals of a plurality of gradation levels, and when there is a non-ejection time equal to or greater than a predetermined time immediately before the ejection operation, the drive unit drives the actuator in accordance with the gradation level in the ejection operation. During the non-ejection time, the actuator is driven by a precursor signal that causes the actuator to perform pressure vibration without the ejection of the liquid.

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head, a control device, and a liquid ejection device. Background Art

[0002] As a liquid ejection device, an inkjet head mounted on an inkjet printer is known. The inkjet printer ejects ink droplets from the inkjet head to form an image or the like on the surface of a recording medium. The inkjet head ejects ink droplets from a nozzle connected to the pressure chamber by changing the volume of the pressure chamber using a piezoelectric actuator. The operation of the actuator is controlled by a drive waveform input to the actuator.

[0003] In such a liquid ejection device, image disturbance may be suppressed by performing a precursor operation of providing a vibration waveform that does not eject liquid before the ejection waveform. However, it is difficult to suppress image disturbance in a high frequency band. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a liquid ejection head, a control device and a liquid ejection device capable of suppressing image disturbance.

[0005] The liquid ejection head according to the 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 drives the ejection action of the actuator according to ejection signals of multiple gray levels, and, when there is a non-ejection time of more than a predetermined time immediately before the ejection action, the actuator is driven by a pioneer signal that causes the actuator to perform pressure vibrations without ejecting liquid during the non-ejection time, corresponding to the gray level in the ejection action. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is an explanatory diagram showing the structure of the liquid ejecting device according to the first embodiment.

[0007] Figure 2 It is a perspective view showing the structure of the liquid ejecting head.

[0008] Figure 3 It is a cross-sectional view showing a part of the structure of the liquid ejecting head.

[0009] Figure 4 It is an explanatory diagram showing the correspondence between pixels and waveform patterns in Example 1, Example 2, and Comparative Example.

[0010] Figure 5 It is an explanatory diagram showing the printing characteristics of Example 1, Example 2 and the comparative example.

[0011] Figure 6 It is an explanatory diagram showing the structure of the liquid ejecting device according to the first embodiment.

[0012] Description of Reference Numerals

[0013] 10: liquid ejection head; 11: actuator; 12: drive circuit; 13: data buffer; 14: decoder; 15: driver; 21: liquid supply unit; 22: conveying unit; 25: operation unit; 26: display unit; 30: control unit; 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. DETAILED DESCRIPTION

[0014] Refer to the following Figures 1 to 5 A liquid ejection head 10 and a liquid ejection device 100 according to the first embodiment will be described. Figure 1 It is a block diagram showing the structure of the liquid ejection device 100 according to the first embodiment. Figure 2 2 is a perspective view showing the structure of a liquid ejection head. Figure 3 It is a cross-sectional view showing the structure of an actuator of a liquid ejection head. Figure 4 It is an explanatory diagram showing the correspondence between pixels and waveform patterns in Example 1, Example 2, and Comparative Example. Figure 5 It is an explanatory diagram showing the printing characteristics of Example 1, Example 2 and the comparative example. Figure 6 1 and 2 are explanatory diagrams showing the structure of the liquid ejection device 100. It should be noted that, in order to facilitate the explanation, the structure is appropriately shown in each figure in an enlarged, reduced or omitted manner.

[0015] like Figure 1 As shown, 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 .

[0016] like Figure 6 As shown, the liquid ejection device 100 is an inkjet printer that performs image formation processing on a medium such as paper by transporting a medium such as paper as a ejection object along a predetermined conveying path passing through a printing position relative to the liquid ejection head 10, while ejecting a liquid such as ink from the liquid ejection head 10.

[0017] The liquid ejection head 10 is, for example, a shared-mode shared-wall inkjet head. The liquid ejection head 10 may be a non-circulating head that does not circulate ink, or a circulating head that circulates ink. In this embodiment, the liquid ejection head 10 is described using an example of a non-circulating head.

[0018] For example, the liquid ejection head 10 includes an actuator 11 having a plurality of piezoelectric elements communicating with nozzles, and a drive circuit 12 as a drive unit that drives the actuator 11 .

[0019] For example, the liquid ejection head 10 has a plurality of nozzles 111 for ejecting liquid, a plurality of pressure chambers 112 communicating with the nozzles, and a flow path including a common chamber communicating with the plurality of pressure chambers 112. The flow path of the liquid ejection head 10 is connected to the liquid supply unit 21, and ink is supplied to the flow path of the liquid ejection head 10 from the liquid supply unit.

[0020] The actuator 11 is, for example, an actuator plate formed of a piezoelectric component 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 piezoelectric elements 115 are deformed by applying voltage to the electrodes 116 of the piezoelectric elements 115 provided corresponding to the respective pressure chambers 112, whereby the actuator 11 increases or decreases the volume of the pressure chambers 112 to eject ink from the nozzles 111.

[0021] The driving circuit 12 drives the actuator 11 by applying a driving voltage to the electrodes of the piezoelectric body. The driving circuit 12 generates a control signal and a driving signal for operating the piezoelectric element 115. The driving circuit 12 generates a control signal for selecting the timing for ejecting the liquid and controlling the piezoelectric element 115 for ejecting the liquid, etc., based on an image signal input from the control unit 30 of the liquid ejecting device 100. In addition, the driving circuit 12 generates a voltage, i.e., a driving signal (electrical signal), to be applied to the electrode 116 of the piezoelectric element 115 based on the control signal. After the driving circuit 12 applies the driving 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-controlled by the control of the control unit 30.

[0022] like Figure 1 As shown, 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 required for driving control. The data buffer 13 stores print data and image data. As an example, the data buffer 13 stores print data in a time series for each piezoelectric element of the actuator 11. For example, the data buffer 13 stores various information as print data and image data, and the various information includes grayscale values ​​of multiple pixels and formation timing of driving the actuator to form each pixel on the recording medium. For each piezoelectric element, the decoder 14 controls the driver 15 based on the print data stored in the data buffer 13. Based on the control of the decoder 14, the driver 15 outputs a drive signal for causing each piezoelectric element 115 to operate. The drive signal is a voltage applied to the electrode 116 of each piezoelectric element 115.

[0023] In the present embodiment, the driving 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 driving circuit 12 drives a plurality of driving elements corresponding to each nozzle 111 of the liquid ejection unit according to the predetermined waveform pattern. For example, the driving circuit 12 drives the liquid ejection unit according to a plurality of multi-waveform patterns obtained by combining a plurality of droplet waveforms.

[0024] For example, the driving circuit 12 outputs a discharge signal for discharging liquid according to the grayscale value of the discharge target pixel at the formation timing of the discharge target pixel accompanying the liquid discharge. For example, the driving circuit 12 drives the piezoelectric element 115 to discharge according to the discharge signal of multiple grayscales.

[0025] In addition, when the formation timing of the non-ejection target pixel not accompanied by liquid ejection is included in the target pixels with a specific grayscale value as the formation timing within the prescribed number immediately thereafter, the driving circuit 12 outputs a vibration signal not accompanied by ejection corresponding to the grayscale of the ejection target pixel. In this embodiment, as an example, when the prescribed number is more than two cycles or more than two pixels and the specific grayscale value is more than 2 grayscales, the pioneer vibration signal is output.

[0026] That is, the formation timing of the pixel that is not accompanied by ink ejection is included in the pixels that are formed without ink ejection and whose formation timing arrives at a specific grayscale within a prescribed number immediately after the pixel, and a vibration signal corresponding to the grayscale value of the pixel that is accompanied by the ink ejection is output to make the nozzle vibrate without ink ejection.

[0027] That is, in the driving waveform for driving the piezoelectric element 115 forming a certain pressure chamber 112, when there are non-ejection pixels not accompanied by ejection for a predetermined number of pixels or more immediately before the ejection action to which an ejection signal of a certain grayscale or more is applied, a pioneer signal for causing pressure vibrations not accompanied by liquid ejection is applied at the formation timing of the non-ejection pixels before the ejection signal according to the grayscale in the ejection action, and the piezoelectric element 115 is pioneer-driven. In other words, in the driving waveform for driving the piezoelectric element 115 forming a certain pressure chamber 112, when there is a non-ejection time not accompanied by ejection for a predetermined time or more immediately before the ejection action to which an ejection signal of a certain grayscale or more is applied, a pioneer signal for causing pressure vibrations not accompanied by liquid ejection is applied during the non-ejection time before the ejection signal according to the grayscale in the ejection action, and the piezoelectric element 115 is pioneer-driven.

[0028] As a specific example, in the multi-droplet drive up to 4 gray levels, for example, when there is a non-ejection waveform of 1 gray level (0 droplets) for two or more cycles immediately before the ejection waveform of 3 gray levels (2 droplets) or the ejection waveform of 4 gray levels (3 droplets), the drive circuit 12 arranges a pioneer waveform as a vibration waveform not accompanied by ejection at the position of the non-ejection waveform of 1 gray level. On the other hand, when there is a 1 gray level for two or more cycles before the ejection waveform of 2 gray levels (1 droplet), the drive circuit 12 does not arrange a pioneer waveform and keeps the non-ejection waveform as it is.

[0029] The liquid supply unit 21 is connected to one 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 connecting flow path connecting the tank and the flow path of the liquid ejection head 10, and a liquid delivery pump for delivering the liquid in the tank to the liquid ejection head 10.

[0030] The conveying unit 22 conveys a medium such as paper along a predetermined conveying path and supplies the medium to a printing position. The conveying unit 22 includes, for example, a plurality of conveying rollers and conveying guides arranged along the conveying path. The conveying unit 22 supports the medium so as to be movable relative to the liquid ejection head 10 .

[0031] The operation unit 25 includes function keys such as a power key, a paper feed key, and an error cancel key.

[0032] The display unit 26 includes a display capable of displaying various states of the image printing apparatus.

[0033] The control unit 30 is, for example, a control substrate, and includes a processor 31 , a ROM (Read Only Memory) 32 , a RAM (Random Access Memory) 33 , an image memory 34 , and an I / O port 35 as an input / output port.

[0034] The processor 31 is a processing circuit such as a CPU (Central Processing Unit) as a controller. The processor 31 is equivalent to the central part of the computer. The processor 31 controls each part that should realize various functions as a printer according to the operating system and application program. For example, the processor 31 controls the operation of the liquid ejection head 10, the liquid supply unit 21, and the conveying unit 22 provided in the liquid ejection device 100. In addition, the processor 31 sends the print data stored in the image memory 34 to the drive circuit 12 in the drawing order during printing.

[0035] The ROM 32 corresponds to the main storage unit for reading 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 processing for controlling each unit.

[0036] RAM 33 is equivalent to the freely rewritable main storage part of the above-mentioned computer. RAM 33 stores data required for the processor 31 to execute the process. In addition, RAM 33 can also be used as a work area for the processor 31 to rewrite information as appropriate. The work area can also include an image memory for developing print data.

[0037] The image memory 34 stores, for example, print data from the externally connected device 200 .

[0038] The I / O port 35 is an interface unit for inputting data from the externally connected device 200 and outputting data to the outside. Print data from the externally connected device 200 is sent to the control unit 30 through the I / O port 35 and is stored in the image memory 34.

[0039] In the liquid ejection device 100 thus configured, 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 according to the signal from the control unit 30, thereby causing a potential difference to be generated in the plurality of piezoelectric elements 115, and selectively deforming the piezoelectric elements 115, and causing the liquid to be ejected from the nozzle 111 by increasing or decreasing the volume of the pressure chamber 112. For example, when a voltage as an expansion element is applied, the piezoelectric element 115 is deformed, thereby increasing the volume of the corresponding pressure chamber 112 and reducing the pressure, and the ink in the common chamber flows into the pressure chamber 112. Then, when a reverse potential drive voltage is applied to the electrode 116 of the piezoelectric element 115 after the volume of the pressure chamber 112 has increased, the piezoelectric element 115 is deformed, thereby reducing the volume of the pressure chamber 112 and increasing the pressure. As a result, the ink in the pressure chamber 112 is pressurized and ejected from the nozzle 111.

[0040] The waveform data of the driving waveform is stored in, for example, a memory in the driving circuit 12. Which driving waveform is input to the actuator 11 is selected by the driver IC of the driving circuit 12 based on the grayscale data sent from the control substrate.

[0041] For example, the driving waveform generated by the driving circuit 12 is a multi-droplet waveform, which is a droplet waveform of the ejected liquid that repeatedly forms one dot corresponding to the grayscale. As an example, the number of ejections in one cycle of the driving cycle is up to 3 drops, for example, the ink is driven at 1 to 4 grayscales in one cycle of the driving cycle. Each droplet waveform is an ejection waveform including an expansion pulse (expansion element) and a contraction pulse (contraction element).

[0042] For example, Figure 4 This is an explanatory diagram showing the driving patterns corresponding to the pixels in the image areas of the four patterns (a) to (d) for Example 1, Example 2, and Comparative Example. For example, an image area is shown in which a plurality of pixels are arranged vertically and horizontally in a matrix.

[0043] For example, the present embodiment illustrates a driving waveform of a multi-droplet drive having a maximum of three droplet waveforms (elements) within one printing cycle of each pixel, wherein the specified number is 2 pixels in an image of 4 gray levels (0, 1 drop, 2 drop, 3 drop), and the specific gray levels are 2 drop and 3 drop.

[0044] In this embodiment, there are three cycles in one printing cycle as the printing cycle corresponding to three droplets, and the cycle lengths of the droplet waveforms are equal. These driving waveforms are composed of a combination of ejection waveform parts PA and PD of multiple grayscales, a non-ejection waveform part PB that does not eject liquid, and a pioneer waveform part PC that vibrates without ejecting liquid. It should be noted that the driving waveform in each grayscale can combine multiple identical droplet waveforms, or can also combine multiple different droplet waveforms.

[0045] In this embodiment, in the print data, when there is a non-ejection for a predetermined time or longer immediately before the ejection waveform portion PA of the droplet waveform having a predetermined grayscale or higher, the drive circuit 12 performs a pioneer drive immediately before the ejection at the predetermined grayscale or higher. That is, when there is a non-ejection waveform immediately before the 2-droplet waveform and the 3-droplet waveform, a vibration waveform without ejection is applied at a predetermined timing before the waveform for ejection of 2 or 3 drops is applied. In other words, in the corresponding print pattern, when the ejection timing of the predetermined grayscale or higher arrives after the predetermined non-ejection timing, the drive circuit 12 generates a drive waveform that does not eject and gives vibration before the ejection timing.

[0046] Reference Figure 4 An example of a driving pattern according to this embodiment will be described. Figure 4 The cells corresponding to the pixels in a certain image area are shown. For example, the vertical and horizontal cells correspond to the pixels respectively. Figure 4 The image formation timing corresponding to the vertical axis is taken as time. That is, Figure 4 The vertical lines arranged in 4 or 5 columns in the image area represent the arrangement pattern of the waveform when taking time vertically.

[0047] In Example 1, for example, cells of the second ejection waveform portion PA driven with a 3-grayscale or 4-grayscale ejection waveform, blank cells of the 1-grayscale non-ejection waveform portion PB, and cells of the pioneer waveform portion PC for pioneer driving are arranged in a predetermined pattern.

[0048] That is, the image area of ​​the first embodiment has an ejection waveform of more than 2 gray levels as the reference gray level, that is, the second ejection waveform portion PA. In addition, the driving waveform of the first embodiment has a predetermined number of, for example, two or more non-ejection waveform portions PB before the second ejection waveform portion PA of the reference gray level. In addition, a precursor waveform portion PC is arranged in a unit preceding the second ejection waveform portion (liquid drop waveform portion) PA in the continuous non-ejection waveform portion (non-ejection waveform unit) PB.

[0049] That is, when the drive circuit 12 is Figure 4 When printing rectangular images from top to bottom, when pixels are formed with 3 or 4 grayscales and two pixels are connected by a blank, manipulation such as a pioneer action is performed at the pixel before the pixel formed based on 3 or 4 grayscales.

[0050] For example, in the comparative example, the cells of the first discharge waveform portion PD driven at 2 gray levels and the cells of the blank corresponding to the non-discharge waveform portion PB at 1 gray level are arranged in a predetermined pattern. In the comparative example, the pioneer drive is not performed.

[0051] In Embodiment 2, for example, the units of the second ejection waveform portion PA driven with a 3-gradation or 4-gradation ejection waveform, the units of the 1-gradation non-ejection waveform portion PB, and the units of the pioneer waveform portion PC for pioneer driving are arranged in a predetermined pattern.

[0052] That is, the driving waveform of the second embodiment has a discharge waveform of 3 grayscales or more as a reference grayscale, that is, the second discharge waveform portion (liquid drop waveform portion) PA. In addition, the driving waveform of the second embodiment has a predetermined number of, for example, 2 or more, non-discharge waveform portions PB before the second discharge waveform portion (liquid drop waveform portion) PA of the reference grayscale. In addition, the pioneer waveform portion PC is arranged at the first two units of the second discharge waveform portion PA in the unit of the continuous non-discharge waveform portion PB.

[0053] That is, when the drive circuit 12 is Figure 4 When printing rectangular images from top to bottom, in Example 2, when pixels are formed with 3 or 4 grayscales and two pixels are connected by a blank, manipulation such as a pioneer action is performed at two pixels before the pixels formed based on 3 or 4 grayscales.

[0054] That is, these controls are controls for allocating a precursor waveform to the preceding one or two timings when a multi-droplet waveform is used to eject liquid by multiple ejection waveforms and there are two or more non-ejection timings before the ejection timing of 3 or 4 grayscales. That is, the driving waveform of Example 1 and the driving waveform of Example 2 have an ejection waveform portion PA accompanying the ejection of liquid, a non-ejection waveform portion PB as a waveform that does not eject liquid, and a precursor waveform portion PC as a vibration waveform that does not eject liquid.

[0055] That is, in the present embodiment, when there is a discharge waveform part PA of 3 grayscales or more as print data in the driving circuit 12 as an example of a driving device, and when two or more blanks, that is, non-discharge waveform parts PB of 1 grayscale are continuous within a specified number immediately before the discharge waveform part PA of 3 grayscales or more, the driving circuit 12 outputs a pioneer waveform part PC for performing a pioneer drive immediately before or two timings before the discharge waveform part PA in the blank. That is, the liquid ejection head 10 performs a pioneer at the previous pixel when the blank is 2 columns or more and is 3 or 4 grayscales, or performs a pioneer at the previous 2 pixels when the blank is 2 columns or more and is 3 or 4 grayscales.

[0056] As an example, the ejection waveform portion PA is a multi-droplet waveform that is a reference droplet ejection waveform that is repeated any number of times from 0 to 3 times according to the grayscale. For example, the droplet ejection waveform is a waveform having 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 reduced from a first voltage that is an intermediate voltage to a second voltage that is lower than the intermediate voltage, and after the second voltage is continued for a predetermined time, it is returned to the first voltage. Then, after the first voltage is continued 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 first voltage is returned. The droplet ejection waveform is a waveform that ejects by an expansion pulse and suppresses vibration by a contraction pulse.

[0057] As the ejection action realized by the ejection waveform PA, when the second voltage is applied for a predetermined time by the first expansion pulse, 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 is expanded due to the deformation of the piezoelectric element 115, the internal ink pressure is reduced, and the meniscus of the opening of the nozzle 111 is greatly pulled toward the pressure chamber 112. Then, the ink pressure in the pressure chamber 112 (ink chamber) starts to vibrate, and the ink flow rate vibrates with a phase shift of 90 degrees.

[0058] When the pressure chamber 112 returns to the original shape after being expanded by the expansion pulse and returns to the first voltage, the pressure chamber 112 returns to the 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, by further applying the voltage of the contraction pulse, the piezoelectric element 115 of the actuator 11 is deformed again and the volume of the pressure chamber 112 is contracted to increase the ink pressure, thereby suppressing the pressure and flow velocity vibrations in the pressure chamber 112. By repeating this ejection waveform n times, n droplets of ink are ejected.

[0059] For example, the precursor waveform PC is a waveform that has a longer expansion pulse or a smaller potential difference than the ejection waveform and imparts vibration without ejecting liquid. That is, compared with the ejection waveform PA, the pioneer waveform PC is a vibration waveform that does not eject liquid when the flow velocity of the ink vibrates. It should be noted that, for example, the pioneer waveform PC can be a waveform having only a contraction element, or a waveform having an expansion element and a contraction element in sequence. For example, it can also be a waveform that does not eject liquid by extending each expansion time.

[0060] Figure 5 This is an explanatory diagram showing the printing state achieved by the waveform of Example 1, the waveform of Example 2, and the waveform of the comparative example without the pioneer action. Figure 5 It can be seen that in the comparative example, image disturbance occurs particularly in the high frequency band, but the printing states of the waveforms of Examples 1 and 2 can suppress image disturbance.

[0061] According to the liquid ejection head 10 and the liquid ejection device 100 of the present embodiment, by performing a pilot action at a desired grayscale, it is possible to reduce the power load and suppress image disturbance within the printing range. That is, by setting the pilot action to be performed only at a specific grayscale, it is possible to reduce the power load and suppress the heat generation of the actuator. In addition, Figure 5 As shown, even at a frequency exceeding 20kHz, the pressure vibration can be stabilized, image disturbance can be suppressed, and good printing performance can be achieved. In addition, according to the above-mentioned embodiment, in order to generate a driving signal for performing a pioneer action by the driving circuit 12 provided in the liquid ejection head 10, the control accompanying the pioneer action can be completed by the liquid ejection head 10 itself.

[0062] It should be noted that the embodiments of the present invention are not limited to the above-mentioned configurations.

[0063] For example, in the above-mentioned embodiment, the driving circuit 12 having the driver IC provided in the liquid ejection head 10 is shown as an example in which the driving unit functions as a driving signal for generating a pioneer action, but the present invention is not limited thereto. For example, the pioneer control may also 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, in the case where there is a non-ejection timing immediately before the ejection waveform above the prescribed grayscale of the print data, the pioneer control is performed on the control device side according to the grayscale, in which control is performed to impart vibration without the ejection of the liquid at the non-ejection timing.

[0064] In addition, Figure 4 In each of the embodiments shown, an example is shown in which the unit driven by the ejection waveform part PA of 3 or 4 gray levels is arranged in a predetermined pattern in a predetermined image area, and in the comparative example, an example is shown in which the unit driven by the ejection waveform part PD of 2 gray levels is arranged in a predetermined pattern, but it is not limited to this. For example, the ejection waveform part PA of 3 or 4 gray levels and the ejection waveform part PD of 2 gray levels can be mixed in one image area. In this case, even if the pioneer waveform is applied at the timing of the non-ejection waveform part PB of the previous pixel or two pixels immediately before the ejection waveform part PA of 3 or 4 gray levels, there are two consecutive non-ejection units of pixels immediately before the ejection waveform part PD of 2 gray levels, and the pioneer drive is not performed before the ejection waveform part PD, and it will become a drive that keeps the non-ejection waveform unchanged. In addition, in the case of driving by dividing the driving cycle into three parts, even if the pioneer waveform is applied at a specific gray level or more, the pixels with the pioneer waveform having only a specific periodic pattern can be allocated to drive. In addition, although an example is shown in which each unit corresponds to a pixel and is driven according to the pixel, it is not limited to this. For example, the drive may be performed in units different from pixels. For example, when the two cycles immediately before each cycle of the ejection waveform of the piezoelectric element 115 that is driven to eject at a specific grayscale or above are non-ejecting, the pioneer drive may be performed at the timing of the previous cycle or the previous two cycles.

[0065] For example, the above embodiment is described using a driving waveform for ejecting three droplets, but the present invention is not limited thereto. For example, a driving waveform for ejecting four or more droplets may be used. The droplet waveform is not limited to one type, and may be combined with more than one type. The ejection volume may also be different depending on the pulse width and voltage value of each element.

[0066] The voltage value applied to each piezoelectric element 115 can be appropriately adjusted 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 by applying voltages to both.

[0067] The driving waveform is not limited to pull, and may also be a push or push-pull waveform.

[0068] For example, the structure of the liquid ejection head 10 is not limited to the above example, and can also be used for other types of heads. For example, it can also be a structure in which a vibration plate is deformed by static electricity to eject ink, or a heating element type structure such as a heater that uses thermal energy to eject ink from a nozzle. In these cases, the vibration plate or the heater becomes an actuator for applying pressure vibration to the inside of the pressure chamber 112.

[0069] Regarding the liquid ejection device 100, an inkjet printer that forms a two-dimensional image formed by ink on an image forming medium is exemplified, but the invention is not limited thereto, and may be, for example, a 3D printer, an industrial manufacturing machine, or a medical machine, etc. The liquid ejection device may also be a 3D printer, an industrial manufacturing machine, or a medical machine, etc., and may be, for example, a device that forms a three-dimensional object by ejecting a material as a raw material or an adhesive for fixing the raw material from an inkjet head.

[0070] According to at least one of the above-described embodiments, by performing a pioneer operation at a necessary grayscale, it is possible to reduce power load and suppress image disturbance within the printing range.

[0071] Although several embodiments of the present invention have been described, these embodiments are only presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the purpose of the invention. These embodiments and their variations are included in the scope and purpose of the invention, and are also included in the invention described in the claims and their equivalents.

Claims

1. A liquid ejection head, comprising: an actuator to change the volume of the pressure chamber; and a driving unit, driving the actuator, The driving unit drives the ejection action of the actuator according to ejection signals of multiple gray levels, and when there is a non-ejection time of more than a predetermined time immediately before the ejection action, the actuator is driven by a pioneer signal that causes the actuator to perform pressure vibrations without ejecting liquid during the non-ejection time, corresponding to the gray levels in the ejection action.

2. The liquid ejection head according to claim 1, wherein: The driving unit inputs a discharge signal corresponding to the grayscale number of the discharge target pixel at a formation timing of the discharge target pixel accompanying the discharge of the liquid, and When there are two or more consecutive non-ejecting pixels immediately before the formation timing of an ejection target pixel driven by an ejection signal above a specified grayscale, the actuator is driven according to the pioneer signal at the formation timing of a pixel two pixels before or one pixel before the ejection target pixel.

3. The liquid ejection head according to claim 1, wherein: The number of the actuator and the number of the driving unit are plural.

4. The liquid ejection head according to claim 1, wherein: The actuator is a plate-shaped actuator plate, comprising: a plurality of piezoelectric elements; and an electrode formed on the piezoelectric element, The pressure chamber is formed between the plurality of piezoelectric elements and is deformed by the driving unit applying a voltage to the electrode.

5. The liquid ejection head according to claim 1, wherein The driving unit includes a memory for storing information including a grayscale value of the ejection target pixel and a formation timing of the ejection target pixel for each piezoelectric element of the actuator.

6. The liquid ejection head according to claim 1, wherein The liquid ejection head is a non-circulation type head that does not circulate liquid.

7. The liquid ejection head according to claim 1, wherein The liquid ejection head is a circulation type head that circulates liquid.

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

9. A control device comprising: a driving unit that drives an actuator to change the volume of the pressure chamber, The driving unit outputs a discharge signal for discharging liquid in accordance with the grayscale value of the discharge target pixel at a formation timing of the discharge target pixel accompanying the discharge of the liquid, and When a non-ejection target pixel not accompanied by liquid ejection is formed at a timing where an ejection target pixel accompanied by liquid ejection is included in a prescribed number of target pixels immediately thereafter, a pioneer signal not accompanied by ejection is outputted corresponding to the grayscale value of the ejection target pixel.

10. A liquid ejection device comprising: The liquid ejection head according to any one of claims 1 to 8.

Images