Droplet discharge apparatus and droplet discharge apparatus driving method

Abstract

A droplet discharge device (1) is provided with: an acquisition unit that acquires a distance (L) between a recording medium (M) and a droplet discharge head (23); an adjustment unit that widens or narrows the pulse width of the common drive waveform P00 on the basis of the distance L; a determination unit that selects one or more drive pulses corresponding to the size of the droplet from the common drive waveform P01 adjusted by the adjustment unit and determines a discharge drive pulse; and a discharge control unit that discharges droplets of a plurality of sizes from the nozzle 21 on the basis of the plurality of discharge drive pulses determined by the determination unit.

Description

Technical Field

[0001] This invention relates to a droplet ejection device and a driving method for the droplet ejection device. Background Technology

[0002] Previously, droplet ejection devices were known for recording images by ejecting droplets onto the recording surface of a recording medium. In these droplet ejection devices, droplets are ejected from the nozzle of a droplet ejection head at appropriate timing based on image data.

[0003] As such a droplet ejection device, Patent Document 1 describes an invention that aligns the droplet positions of droplets of different sizes ejected in response to multiple drive pulses.

[0004] Existing technical documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-144659 Summary of the Invention

[0006] However, droplets of different sizes exhibit varying ejection velocities due to differences in air resistance. Consequently, as the media spacing widens, the droplet position deviates based on this difference in ejection velocity. Patent Document 1 lacks any description or instruction regarding maintaining a consistent droplet position when the media spacing changes.

[0007] The present invention was made in view of the following circumstances. Its object is to provide a droplet ejection device and a method for driving the droplet ejection device that can make the droplet positions of droplets of different sizes consistent even when the medium spacing changes.

[0008] To address the above-mentioned problems, technical solution 1 describes a droplet ejection device comprising a droplet ejection head. This droplet ejection head uses a common drive waveform containing multiple drive pulses present in a drive cycle to eject droplets of multiple sizes from a nozzle to perform a recording operation on a recording medium. The droplet ejection device comprises:

[0009] The acquisition unit acquires the distance between the recording medium and the droplet ejection head;

[0010] The adjustment unit widens or narrows the pulse width of the common driving waveform based on the distance.

[0011] The decision unit selects one or more drive pulses corresponding to the droplet size from the common drive waveform adjusted by the adjustment unit to determine the ejection drive pulse; and

[0012] The ejection control unit causes multiple droplets of various sizes to be ejected from the nozzle based on multiple ejection drive pulses determined by the determination unit.

[0013] The invention described in technical solution 2 is based on the droplet ejection device described in technical solution 1.

[0014] The droplet ejection device also includes a selection unit that selects the waveform level based on a table that maps the distance to the waveform level.

[0015] The adjustment unit widens or narrows the pulse width of the common driving waveform based on the waveform level.

[0016] The invention described in technical solution 3 is based on the droplet ejection device described in technical solution 2.

[0017] The adjustment unit widens or narrows the amplitude of the common driving waveform based on the waveform level.

[0018] The invention described in technical solution 4 is based on the droplet ejection device described in technical solution 3.

[0019] The adjustment unit causes the plurality of driving pulses to be widened or narrowed in equal proportions.

[0020] The invention described in technical solution 5 is based on any of the droplet ejection devices described in technical solutions 1 to 4.

[0021] Regarding the common driving waveform, the amplitude of the waveform for switching droplets of different sizes is at least 18V / μs.

[0022] The invention described in technical solution 6 is in any of the droplet ejection devices described in technical solutions 1 to 4.

[0023] The ejection drive pulse includes at least four drive pulses.

[0024] Technical solution 7 describes a driving method for a droplet ejection device, the droplet ejection device comprising a droplet ejection head, the droplet ejection head using a common driving waveform including multiple driving pulses present in a driving cycle to eject droplets of multiple sizes from a nozzle to perform a recording operation on a recording medium, wherein the driving method includes:

[0025] The step involves obtaining the distance between the recording medium and the droplet ejection head.

[0026] The adjustment step involves widening or narrowing the pulse width of the common driving waveform based on the distance.

[0027] The decision step involves selecting one or more drive pulses corresponding to the droplet size from among multiple drive pulses within the common drive waveform adjusted by the adjustment step to determine the ejection drive pulse; and

[0028] The ejection control step, based on a plurality of ejection drive pulses determined by the decision step, causes droplets of a plurality of sizes to be ejected from the nozzle.

[0029] According to the present invention, even if the medium spacing changes, the droplet positions of droplets of different sizes can be made consistent. Attached Figure Description

[0030] Figure 1 It is a three-dimensional diagram of an inkjet recording device.

[0031] Figure 2 This is a block diagram of an inkjet recording device.

[0032] Figure 3 This is a schematic diagram of the pressure chamber and nozzle viewed along the nozzle's axial direction, showing the change in pressure chamber corresponding to the drive pulse.

[0033] Figure 4 This is a flowchart illustrating a driving method for an inkjet recording apparatus related to this embodiment.

[0034] Figure 5 This is a diagram showing the spacing between the media.

[0035] Figure 6 This is a diagram showing the correspondence between media spacing and length grades.

[0036] Figure 7A This is a diagram showing a common drive waveform before the adjustment control is executed.

[0037] Figure 7B This is a diagram showing multiple common drive waveforms that have performed adjustment control corresponding to the length level.

[0038] Figure 8A This is a graph showing the droplet ejection velocity when the waveform of switching between droplets of different sizes has an amplitude of 12V / μs.

[0039] Figure 8B This is a graph showing the droplet ejection velocity when the waveform of switching between droplets of different sizes has an amplitude of 14V / μs.

[0040] Figure 8C This is a graph showing the droplet ejection velocity when the waveform of switching between droplets of different sizes has an amplitude of 18V / μs.

[0041] Figure 8D It is a graph showing the waveform of switching between droplets of different sizes, and the difference in ejection velocity between small and large droplets.

[0042] Figure 9AIt is a graph showing the droplet ejection velocity when using 3 drive pulses for ejection from a single point.

[0043] Figure 9B It is a graph showing the droplet ejection velocity when using 4 drive pulses for ejection from a single point.

[0044] Figure 9C It is a graph showing the difference in ejection velocity between small and medium droplets, based on the number of driving pulses used for each point of ejection.

[0045] Figure 10 This is a diagram showing multiple common drive waveforms that have undergone adjustment control corresponding to the amplifier level. Detailed Implementation

[0046] One embodiment of the present invention will now be described with reference to the accompanying drawings. The following description is merely illustrative of one embodiment and is not intended to limit the scope of the invention.

[0047] [Overall structure of the inkjet recording device]

[0048] First, as a droplet ejection device related to this embodiment, a structural example of an inkjet recording device 1 having an inkjet head 23 as a droplet ejection head is disclosed.

[0049] Figure 1 This is a perspective view of the inkjet recording device 1. Furthermore, Figure 2 This is a block diagram showing the functional structure of the inkjet recording device 1. The inkjet recording device 1 includes, for example, a conveying unit 10, a recording action unit 20, a cleaning unit 30, a control unit 40, a storage unit 50, a communication unit 60, an operation receiving unit 70, a display unit 80, and a power supply unit 90.

[0050] (Transportation Department)

[0051] The conveying unit 10 moves the recording medium M, which is the object of image recording. The recording medium M is not particularly limited. For example, a continuous piece of cloth or multiple sheets of paper in the conveying direction can be used as the recording medium M. The conveying unit 10 aligns the recording medium M with the recording range of the recording action unit 20.

[0052] The conveying section 10 includes a drive roller 11, a conveyor belt 12, a driven roller 13, a conveying motor 14, a pressing roller 15, and a peeling roller 16.

[0053] The conveyor belt 12 is annular and is positioned between the drive roller 11 and the driven roller 13. The conveyor belt 12 rotates as the drive roller 11 rotates. Through the rotation of the conveyor belt 12, the recording medium M, placed on the conveyor surface, moves along... Figure 1 It moves in the direction of transport.

[0054] The driven roller 13 rotates as the conveyor belt 12 moves. The conveyor motor 14 drives the drive roller 11 to rotate at a speed corresponding to the control signal from the control unit 40. The pressing roller 15 removes wrinkles and other protrusions from the mounting surface. Specifically, the pressing roller 15 presses the recording medium M against the mounting surface of the conveyor belt 12. The peeling roller 16 peels the recording medium M from the conveyor surface and transfers it to the post-processing device. Specifically, the peeling roller 16 pulls the recording medium M from the conveyor belt 12 with a predetermined pressure.

[0055] (Recording Action Department)

[0056] The recording action unit 20 ejects ink droplets onto the recording medium M to record an image. The recording action unit 20 has a plurality of head units 20a arranged along the transport direction of the recording medium M. Furthermore, the head unit 20a is composed of a plurality of inkjet heads 23 arranged in a predetermined pattern and ejecting ink droplets from their openings. The inkjet heads 23 include nozzles 21 and piezoelectric elements 22, etc.

[0057] Furthermore, the recording motion unit 20 includes a head drive unit 24. Based on the control of the control unit 40, the head drive unit 24 outputs drive pulses that cause each piezoelectric element 22 to expand or contract. For example... Figure 3 As shown, the piezoelectric element 22 deforms the ink flow path (pressure chamber) 25 that supplies ink to the nozzle 21 due to the deformation caused by the drive pulse. The ink in the ink flow path 25 is subjected to pressure fluctuations due to this deformation and is ejected from the nozzle 21.

[0058] (Cleaning Department)

[0059] The nozzles 21 openings in the 30 pairs of inkjet heads 23 are arranged on the nozzle surface N (reference). Figure 5 The cleaning unit 30 includes a wiping component 32 for wiping ink and its solidified residue, such as ink adhering to the nozzle surface N, and a drive unit 31 for actuating the wiping component 32. The wiping component 32 is not particularly limited, and may be, for example, a non-woven fabric that absorbs ink, a resin component on a scraper that removes solids, etc.

[0060] (Control Department)

[0061] The control unit 40 is a processor that performs overall control of the operation of the inkjet recording device 1. The control unit 40 may include, for example, a CPU 41 (Central Processing Unit) and RAM 42 (Random Access Memory). The CPU 41 performs arithmetic operations to execute various control processes of the inkjet recording device 1. The RAM 42 provides working memory space to the CPU 41 and stores temporary data. The control unit 40 functions as an adjustment unit, a decision-making unit, and an output control unit by executing predetermined programs.

[0062] Furthermore, the control unit 40 acts as an adjustment unit to adjust the common drive waveform P00 (reference). Figure 7A The waveform of the common drive waveform P00 and the adjustment control are described later.

[0063] Furthermore, the control unit 40, acting as a decision-making unit, generates a waveform selection signal. The waveform selection signal is derived from the common drive waveform P01 (reference). Figure 7B Select the drive pulse corresponding to the dot size in the ) and determine the ejection drive pulse that makes the ink ejected from the nozzle 21.

[0064] Specifically, the waveform selection signal is a negative logic pulse signal. When the control unit 40 takes the logic sum of the negative logic pulse signal and the common drive waveform P01, drive pulses other than the selected drive pulse are removed, and the output drive pulse is determined.

[0065] Furthermore, the control unit 40 acts as the dispensing control unit, and the control head drive unit 24 outputs the determined dispensing drive pulse to the piezoelectric element 22. Then, the control unit 40 causes ink to be dispensed from the nozzle 21.

[0066] (Storage Department)

[0067] The storage unit 50 stores image data and processing data of the recording object, other setting data, and programs. Image data may be temporarily stored, for example, in DRAM (Dynamic Random Access Memory), which is capable of large-capacity storage and high-speed output. Furthermore, setting data and programs are stored in non-volatile memory such as flash memory and / or HDD (Hard Disk Drive). By employing this structure, setting data can be stored even when the power supply to the inkjet recording device 1 is interrupted.

[0068] Furthermore, the storage unit 50 stores the common drive waveform P00 before the control unit 40 performs adjustment control and the common drive waveform P01 after the adjustment control is performed. Additionally, the storage unit 50 stores a correspondence table T (reference) of the medium spacing and length levels (waveform levels) required for the control unit 40 to perform adjustment control. Figure 6 ).

[0069] (Ministry of Communications)

[0070] The communication unit 60 controls the transmission and reception of data with external devices according to a predetermined communication standard, such as TCP / IP (Transmission Control Protocol / Internet Protocol). The communication unit 60 can also be connected to a LAN (Local Area Network) and can connect to the external Internet via a router. Furthermore, the communication unit 60 can also be directly connected to peripheral devices via a USB cable connected to a USB (Universal Serial Bus) terminal.

[0071] (Operations and Acceptance Department)

[0072] The operation receiving unit 70 accepts user input operations and outputs the accepted content as an input signal to the control unit 40. The operation receiving unit 70 may include, for example, a touch panel and a push-button switch. When the operation receiving unit 70 is a touch panel, it may also be located at a position overlapping the display screen of the display unit 80, and the operation content may be determined synchronously with the display content shown on the display screen.

[0073] (Display Department)

[0074] The display unit 80 displays the status and selection menu to the user. The display unit 80 may include, for example, a display screen and an indicator (lamp). For example, an indicator may be used to indicate the presence or absence of power supply or the presence or absence of malfunction using an LED (Light Emitting Diode) lamp. Furthermore, the display unit 80 may include, for example, a liquid crystal display (LCD) capable of displaying various text and graphics in a dot-matrix format on the display screen.

[0075] (Electricity Supply Department)

[0076] The power supply unit 90 supplies power from the power source to the inkjet recording device 1.

[0077] [Record the driving process in the action]

[0078] Next, based on Figure 4 The driving process of the inkjet head 23 during the recording operation will be explained. For example, the control unit 40 of the inkjet recording device 1 performs the driving process of the inkjet head 23 based on the user's operation receiving unit 70 to obtain a printing instruction.

[0079] (Steps for obtaining the medium gap)

[0080] First, the control unit 40 obtains the medium gap (step S1). The medium gap refers to, for example,... Figure 5 The distance L shown is from the nozzle surface N of the inkjet head 23 to the image forming surface of the recording medium M.

[0081] Specifically, for example, the media spacing for each recording medium M is pre-stored in the storage unit 50. Therefore, the control unit 40 obtains the media spacing based on the type of recording medium M included in the printing instruction. Alternatively, a device (distance sensor) capable of measuring the media spacing based on the recording medium M may be installed at a position upstream of the inkjet head 23 in the transport direction. The control unit 40 then obtains the media spacing based on the measurement data from this device. Through the control described above, the control unit 40 functions as a unit for obtaining the distance L between the recording medium M and the droplet ejector head 23.

[0082] (Steps for selecting length level)

[0083] Next, the control unit 40 selects the length level (step S2).

[0084] As described above, the storage unit 50 stores a correspondence table T between media intervals and length grades. Therefore, the control unit 40 selects the corresponding length grade based on the media interval obtained in step S1. Through this control, the control unit 40 functions as a selection unit that selects the waveform grade based on the media interval.

[0085] Figure 6 An example corresponding to table T is shown. For example... Figure 6 As shown in Table T, the length level decreases as the medium interval increases. Therefore, in the adjustment control described later, the adjustment is performed in a way that the pulse width widens as the medium interval increases.

[0086] Furthermore, for example, it is possible to create a corresponding table T by ejecting droplets of different sizes while varying the medium spacing and length grades, and recording the medium spacing and length grades at the same ejection position.

[0087] (Common drive waveform adjustment steps)

[0088] After selecting the length level, the control unit 40 performs adjustment control to adjust the waveform of the common drive waveform P00 according to the length level (step S3).

[0089] Specifically, such as Figure 7A and Figure 7B As shown, the control unit 40 maintains the drive frequency according to the length level and widens or narrows the pulse width of each drive waveform of the common drive waveform P00 in the time direction with equal scaling rates. Thus, the control unit 40 adjusts the common drive waveform P00 into the common drive waveform P01. Furthermore, in Figure 7A and Figure 7B In the case of length level 12, the common drive waveform P01 does not change from the common drive waveform P00, but this case is also considered as performing adjustment control.

[0090] The subsequent operations are the same as those of the conventional inkjet recording device 1. That is, the control unit 40 generates a waveform selection signal for forming dots of the desired size (step S4). Then, the control unit 40 determines the ejection drive pulse by taking the logical sum of the common drive waveform P01 and the waveform selection signal, and selecting one or more drive pulses from a group of drive pulses for ejecting ink (step S5).

[0091] Specifically, for example, like Figure 7B As shown, when the length level is 8 and small droplets are ejected, the control unit 40 takes the logical sum of the common drive waveform P01 within the range indicated by arrow A1. Furthermore, when ejecting medium droplets, the control unit 40 takes the logical sum of the common drive waveform P01 within, for example, the range indicated by arrow A2. Furthermore, when ejecting large droplets, the control unit 40 takes the logical sum of the common drive waveform P01 within, for example, the range indicated by arrow A3.

[0092] Then, the control unit 40 applies the selected drive pulse to the piezoelectric element 22 via the head drive unit 24, thereby ejecting ink from the nozzle 21 (step S6). Then, the control unit 40 repeats steps S4 to S6 until the image associated with the obtained printing instruction is formed.

[0093] Example

[0094] Next, regarding the present invention, the results obtained from evaluating the preferred structure will be described. Furthermore, although the present invention will be specifically described below based on embodiments, the present invention is not limited to the specific examples described below. In addition, in the following embodiments, droplets smaller than 10 pL are defined as small droplets, droplets larger than 10 pL but less than 20 pL are defined as medium droplets, and droplets larger than 20 pL are defined as large droplets.

[0095] [Example 1. Relationship between the slope of the waveform of droplet size switching and droplet ejection velocity]

[0096] The amplitude of the waveform for switching between droplets of different sizes in the common drive waveform P01 is appropriately set by the control unit 40. Furthermore, in this inkjet recording apparatus 1, the droplet ejection speed is measured while varying the length for each droplet size.

[0097] Figure 8A This is a graph showing the relationship between the length of the droplet and the droplet ejection velocity when the amplitude of the waveform switching between different droplet sizes is set to 12V / μs. Furthermore, Figure 8BThis is a graph showing the relationship between the length levels and the droplet ejection velocity when the amplitude of the waveform switching between different droplet sizes is set to 14V / μs. Furthermore, Figure 8C This is a graph showing the relationship between the length of the droplet and the droplet ejection velocity when the amplitude of the waveform switching between different droplet sizes is set to 18V / μs. Figures 8A to 8C In the diagram, the horizontal axis represents the length level, and the vertical axis represents the droplet ejection velocity. Furthermore, Figure 8D It shows based on Figures 8A to 8C A graph showing the difference in ejection velocity between small and large droplets at each length level under various amplitudes. Figure 8D In the diagram, the horizontal axis represents the length grade, and the vertical axis represents the droplet ejection velocity difference.

[0098] from Figure 8A as well as Figure 8B and Figure 8C Comparison, or Figure 8D It can be seen that when the amplitude of the waveform switching between droplets of different sizes is above 18V / μs, the difference in droplet velocity is generated when droplets of different sizes are ejected.

[0099] [Example 2. Relationship between the number of driving pulses in droplet ejection at a single point and the ejection velocity per droplet size]

[0100] Under the control of the control unit 40, the inkjet recording device 1 is configured to eject a single droplet based on three drive pulses. Furthermore, in this inkjet recording device 1, the droplet ejection speed is measured while varying the length for each droplet size. Similarly, the inkjet recording device 1 is configured to eject a single droplet based on four drive pulses. Again, the droplet ejection speed is measured while varying the length for each droplet size.

[0101] Figure 9A This is a graph showing the droplet ejection velocity when a single droplet is ejected using three driving pulses. Furthermore, Figure 9B This is a graph showing the droplet ejection velocity based on the scenario where a single droplet is ejected using four driving pulses. Figure 9A and Figure 9B In the diagram, the horizontal axis represents the length level, and the vertical axis represents the droplet ejection velocity. Furthermore, Figure 9C It shows based on Figure 9A and Figure 9B A graph showing the difference in droplet ejection velocity between small and medium droplets at each length level under various driving pulse numbers. Figure 9C In the diagram, the horizontal axis represents the length grade, and the vertical axis represents the droplet ejection velocity difference.

[0102] from Figure 9A and Figure 9B Comparison, or Figure 9C It can be seen that when a droplet is ejected from a single point based on four or more driving pulses, the difference in droplet velocity is generated when ejecting droplets of different sizes.

[0103] [Summarize]

[0104] As in Examples 1 and 2, when the amplitude of the waveform switching between droplets of different sizes is 18V / μs or more as described above, and when a single droplet is ejected based on four or more drive pulses, a difference in ejection speed occurs between different droplet sizes. Therefore, droplet deviation is easily generated. However, according to the inkjet recording apparatus 1 of this embodiment, the problem of such a difference in ejection speed between droplet sizes can be solved by selecting the length grade.

[0105] [Effects of the Implementation Method]

[0106] As described above, the inkjet recording apparatus 1 associated with this embodiment includes a unit for acquiring the distance L between the recording medium M and the inkjet head 23. Furthermore, the inkjet recording apparatus 1 includes an adjustment unit for widening or narrowing the pulse width of the common drive waveform P00 based on the distance L. Additionally, the inkjet recording apparatus 1 includes a determination unit for selecting one or more drive pulses corresponding to the droplet size from the adjusted common drive waveform P01 to determine the ejection drive pulse. Furthermore, the inkjet recording apparatus 1 includes an ejection control unit for ejecting droplets of multiple sizes from the nozzle 21 based on the multiple ejection drive pulses determined by the determination unit. Thus, even if the media spacing of the recording medium M changes, the inkjet recording apparatus 1 adjusts the common drive waveform P00 accordingly. Therefore, according to the inkjet recording apparatus 1 associated with this embodiment, even if the media spacing of the recording medium M changes, the droplet positions of droplets of different sizes can be made consistent.

[0107] Furthermore, in the inkjet recording apparatus 1 related to this embodiment, the adjustment unit widens or narrows multiple drive pulses by equal proportions. Additionally, the determination unit determines the ejection drive pulses for ejecting droplets of multiple sizes based on a single common drive waveform. With this structure, the adjustment unit can precisely adjust the pulse width and amplitude of the common drive waveform P00.

[0108] Furthermore, in the inkjet recording apparatus 1 related to this embodiment, regarding the common drive waveform P00, the amplitude of the waveform for switching between droplets of different sizes is at least 18V / μs. Furthermore, in the inkjet recording apparatus 1 related to this embodiment, the ejection drive pulse includes at least four drive pulses. As described above, although the difference in ejection velocity for each droplet size further increases with this structure, the inkjet recording apparatus 1 related to this embodiment can ensure consistent droplet positions.

[0109] [Other structures]

[0110] The above description is based on embodiments related to the present invention, but the present invention is not limited to the embodiments described above. It is obvious that the present invention can be modified in various ways to include the scope of the invention as set forth in the claims and its equivalents.

[0111] The above illustrates a structure for adjusting the droplet position by varying only the pulse width of the common driving waveform P00, but it is not limited to this. For example, as Figure 10 As shown, the dripping position can also be adjusted by changing the amplitude (driving voltage value) of the common driving waveform P00.

[0112] This change is based on the amplifier level (waveform level) corresponding to the dielectric spacing. However, the change in drop position caused by changing the amplitude is small. Therefore, it is preferable to configure the structure as follows: after changing the pulse width of the common drive waveform P00, the drive voltage value is changed if fine-tuning is required.

[0113] Furthermore, the above example illustrates the case of adjusting the droplet position in a single inkjet head 23, but it can also be applied to an inkjet recording device 1 equipped with multiple inkjet heads 23. Additionally, in this structure, the multiple inkjet heads 23 can each be configured with different correspondence tables T according to their individual differences.

[0114] Furthermore, the droplet ejection rate also varies depending on the physical properties of the ejected ink, such as viscosity, surface tension, and density. For example, in the case of ink containing large particles with low specific gravity, the ejection rate decreases more significantly due to the low density. Therefore, a corresponding table T can be set for each physical property of the ejected ink.

[0115] Furthermore, the above-described configuration involves the control unit 40 adjusting the common drive waveform P00 based on the length level obtained according to the medium spacing by referring to the correspondence table T, but it is not limited to this. For example, the control unit 40 may also adjust the common drive waveform P00 based on the medium spacing according to a predetermined function.

[0116] Furthermore, the above example illustrates the structure by which the control unit 40 automatically acquires the media spacing and length grade, but it is not limited to this. For example, it can also accept inputs of the media spacing, droplet size range, and length grade based on user operations on the operation receiving unit 70.

[0117] In addition, Figure 7B The diagram illustrates a case where the control unit 40 takes a logical sum of the waveform selection signal from the rear end of the time direction of the common driving waveform P01 based on the droplet size, but it is not limited to this. For example, the control unit 40 may also take a logical sum of the waveform selection signal from the front end of the time direction of the common driving waveform P01 based on the droplet size. Alternatively, the control unit 40 may take a logical sum of the waveform selection signal without using an arbitrary position of the common driving waveform P01 as a reference.

[0118] Furthermore, while the droplet ejection device is described above as inkjet recording device 1, the droplets ejected by the droplet ejection device are not limited to ink droplets. It can be a droplet ejection device that ejects droplets of various functional liquids, such as pretreatment agents.

[0119] Industrial availability

[0120] The present invention can be used for a droplet ejection device and a method for driving the droplet ejection device to ensure that droplets of different sizes fall at the same position even when the medium spacing changes.

[0121] Explanation of symbols

[0122] 1: Inkjet recording device (droplet ejection device); 21: Nozzle; 23: Inkjet head (droplet ejection head); 40: Control unit (acquisition unit, selection unit, adjustment unit, decision unit, ejection control unit); L: Distance (media interval, distance between recording medium and droplet ejection head); M: Recording medium; T: Correspondence table (table); P00: Common drive waveform; P01: Common drive waveform (adjusted common drive waveform).

Claims

1. A droplet ejection device comprising a droplet ejection head, the droplet ejection head using a common drive waveform including multiple drive pulses present in a drive cycle to eject droplets of multiple sizes from a nozzle to perform a recording operation on a recording medium, wherein, The droplet ejection device includes: The acquisition unit acquires the distance between the recording medium and the droplet ejection head; The adjustment unit widens or narrows the pulse width of the common driving waveform based on the distance. The decision unit selects one or more drive pulses corresponding to the size of the droplet from the common drive waveform adjusted by the adjustment unit to determine the ejection drive pulse; as well as The ejection control unit causes multiple droplets of various sizes to be ejected from the nozzle based on multiple ejection drive pulses determined by the determination unit.

2. The droplet ejection device according to claim 1, wherein, The droplet ejection device also includes a selection unit that selects the waveform level based on a table that maps the distance to the waveform level. The adjustment unit widens or narrows the pulse width of the common driving waveform based on the waveform level.

3. The droplet ejection device according to claim 2, wherein, The adjustment unit widens or narrows the amplitude of the common driving waveform based on the waveform level.

4. The droplet ejection device according to claim 3, wherein, The adjustment unit causes the plurality of driving pulses to be widened or narrowed in equal proportions.

5. The droplet ejection device according to any one of claims 1 to 4, wherein, Regarding the common driving waveform, the amplitude of the waveform for switching droplets of different sizes is at least 18V / μs.

6. The droplet ejection device according to any one of claims 1 to 4, wherein, The ejection drive pulse includes at least four drive pulses.

7. A driving method for a droplet ejection device, the droplet ejection device comprising a droplet ejection head, the droplet ejection head using a common driving waveform including multiple driving pulses present in a driving cycle to eject droplets of multiple sizes from a nozzle to perform a recording operation on a recording medium, wherein... The driving method includes: The step involves obtaining the distance between the recording medium and the droplet ejection head. The adjustment step involves widening or narrowing the pulse width of the common driving waveform based on the distance. The decision step involves selecting one or more drive pulses corresponding to the droplet size from among multiple drive pulses within the common drive waveform adjusted by the adjustment step to determine the ejection drive pulse; and The ejection control step, based on a plurality of ejection drive pulses determined by the decision step, causes droplets of a plurality of sizes to be ejected from the nozzle.

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