Liquid discharge device, and liquid discharge device driving method

Abstract

To provide a liquid discharge device that improves a degree-of-freedom of a design and enables correction of a discharge rate, and a liquid discharge device driving method.SOLUTION: A liquid discharge device comprises: a liquid discharge head comprising a first discharge part including a first nozzle for discharging a liquid, a first pressure chamber communicating with the first nozzle, and a first driving element which is so driven as to change a volume of the first pressure chamber; a first drive signal generating circuit which generates a first drive signal having a first pulse supplied to the first driving element when droplets of a first quantity are discharged from the first nozzle; and a second drive signal generating circuit which generates a second drive signal having a second pulse that is supplied to the first driving element and is different from the first pulse. The first drive signal has a first start potential holding element which maintains a first potential from start of one driving period to start of the first pulse, the second drive signal has a second start potential holding element which maintains a second potential from start of one driving period to start of the second pulse, and the first potential and the second potential are different from each other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection device and a method for driving the liquid ejection device. [Background technology]

[0002] 2. Description of the Related Art Liquid ejection devices that eject liquid such as ink onto a medium such as printing paper have been proposed.

[0003] The liquid ejection device described in Patent Document 1 includes a drive signal generation unit that generates a drive signal, a drive pulse selection unit that selectively combines multiple drive pulses included in the drive signal, and a drive element that ejects droplets from the nozzles based on the selected drive pulse. The device selects a pulse corresponding to the image to be printed from multiple types of pulses included in the drive signal, and switches the amount of droplets ejected from the nozzles.

[0004] liquid discharge device [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-88582 Summary of the Invention [Problem to be solved by the invention]

[0006] The drive signal maintains a common potential during periods other than the pulse period. When designing the pulse shape to satisfy the required ejection volume and ejection speed for the pulse included in the drive signal while fixing the common potential, the degree of freedom in design is limited. As a result, for example, it is difficult to achieve the desired droplet ejection volume, and the ejection volume cannot be adequately corrected. [Means for solving the problem]

[0007] A liquid ejection device according to one aspect of the present disclosure comprises a liquid ejection head having a first ejection section including a first nozzle that ejects liquid, a first pressure chamber communicating with the first nozzle, and a first drive element that is driven to change the volume of the first pressure chamber in accordance with a drive signal; a first drive signal generation circuit that generates a first drive signal having a first pulse that is supplied to the first drive element when ejecting a first amount of droplets from the first nozzle; and a second drive signal generation circuit that generates a second drive signal that is supplied to the first drive element and has a second pulse that is different from the first pulse, wherein the first drive signal has a first starting potential holding element that maintains a first potential from the start of one drive cycle to the start of the first pulse, and the second drive signal has a second starting potential holding element that maintains a second potential from the start of one drive cycle to the start of the second pulse, and the first potential and the second potential are different.

[0008] A driving method for a liquid ejection device according to one aspect of the present disclosure is a driving method for a liquid ejection device having a liquid ejection head with a first ejection section including a first nozzle that ejects liquid, a first pressure chamber communicating with the first nozzle, and a first drive element that is driven to change the volume of the first pressure chamber in accordance with a drive signal, wherein when ejecting a first amount of droplets from the first nozzle, a first drive signal having a first pulse that is supplied to the first drive element is generated, and a second drive signal having a second pulse that is supplied to the first drive element and is different from the first pulse is generated, and when generating the first drive signal and the second drive signal, a first potential of a first start potential holding element from the start of one drive cycle of the first drive signal to the start of the first pulse is set to be different from a second potential of a second start potential holding element from the start of one drive cycle of the second drive signal to the start of the second pulse. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a liquid ejection device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the electrical configuration of the liquid ejection device according to the first embodiment. [Figure 3]FIG. 3 is a bottom view of the liquid ejection head shown in FIG. [Figure 4] 4 is a cross section showing a part of the head chip shown in FIG. 3. [Figure 5] 4 is a diagram for explaining a drive signal supplied to the first nozzle row shown in FIG. 3. FIG. [Figure 6] 4 is a diagram for explaining a drive signal supplied to a second nozzle row shown in FIG. 3. FIG. [Figure 7] 4 is a diagram for explaining a drive signal supplied to a third nozzle row shown in FIG. 3. FIG. [Figure 8] FIG. 10 is a diagram illustrating an example in which the driving cycles are continuous. [Figure 9] FIG. 4 is a diagram for explaining supply of a drive signal. [Figure 10] FIG. 4 is a diagram for explaining supply of a drive signal. [Figure 11] FIG. 10 is a diagram illustrating conventional drive signal correction. [Figure 12] FIG. 10 is a diagram showing the relationship between the drive period and the liquid ejection amount in a conventional drive signal. [Figure 13] FIG. 10 is a diagram showing the relationship between the peak value and the liquid ejection amount for each frequency in a conventional drive signal. [Figure 14] FIG. 10 is a diagram illustrating frequency characteristics. [Figure 15] FIG. 10 is a diagram for explaining the influence of frequency characteristics on the ejection amount. [Figure 16] 10A and 10B are diagrams for explaining correction of large dot drive signals according to the present embodiment. [Figure 17] 10A and 10B are diagrams showing the relationship between the drive period and the liquid ejection amount in the correction of the large dot drive signal of the present embodiment. [Figure 18] 10A and 10B are diagrams illustrating the ejection speed when the intermediate potential is changed during the connection of the driving period. [Figure 19] 10A and 10B are diagrams illustrating the ejection speed when the width of the potential change during connection is changed. [Figure 20] FIG. 10 is a diagram showing the impact deviation when the width of the potential change is changed at a transport speed of 80 m / min. [Figure 21] FIG. 10 is a diagram showing impact deviation when the width of potential change is changed at a transport speed of 40 m / min. [Figure 22] FIG. 10 is a diagram showing a drive signal in a first modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0011] The following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the Y1 and Y2 directions are opposite directions along the Y-axis. The Z1 and Z2 directions are opposite directions along the Z-axis. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Furthermore, the X-axis, Y-axis, and Z-axis are typically perpendicular to each other, but this is not a limitation. For example, they may intersect at an angle between 80° and 100°. In this specification, "equal" refers not only to strict equality but also to manufacturing and assembly errors.

[0012] A: First embodiment A1: Overall configuration of the liquid ejection device 100 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects liquid such as ink as droplets onto a medium M. The medium M is, for example, printing paper. Note that the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0013] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, and a liquid ejection head 50.

[0014] The liquid container 10 stores liquid. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped liquid pack made of flexible film, and a liquid tank that can be refilled with liquid. The type of liquid that can be stored in the liquid container 10 is arbitrary.

[0015] The control unit 20 controls the operation of each element of the liquid ejection device 100. The control unit 20 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory.

[0016] The transport mechanism 30 transports the medium M in the Y1 direction under the control of the control unit 20. The transport mechanism 30 includes, for example, a long transport roller along the X axis and a motor that rotates the transport roller. Note that the transport mechanism 30 is not limited to a configuration using a transport roller, and may be configured, for example, to use a drum or endless belt that transports the medium M while adsorbed to its outer peripheral surface by electrostatic force or the like.

[0017] The multiple liquid ejection heads 50 are housed in a carriage 501. The multiple liquid ejection heads 50 are arranged so as to be distributed over the entire range of the medium M in the direction along the X axis. Each liquid ejection head 50 ejects liquid supplied from a liquid container 10 from each of multiple nozzles onto the medium M under the control of a control unit 20 based on image data Img. This ejection is performed in parallel with the transport of the medium M by a transport mechanism 30, so that an image corresponding to the image data Img is formed on the surface of the medium M using droplets.

[0018] A2: Electrical configuration of the liquid ejection device 100 2 is a diagram showing the electrical configuration of the liquid ejection device 100 according to the first embodiment. As shown in FIG.

[0019] In this embodiment, six head chips 51 are provided as the plurality of head chips 51. Specifically, two first head chips 51a, two second head chips 51b, and two third head chips 51c are provided.

[0020] Each head chip 51 has a plurality of ejection units 510. Specifically, each first head chip 51a has a plurality of first ejection units 510a. Each first ejection unit 510a has a first drive element Ea. Each second head chip 51b has a plurality of second ejection units 510b. Each second ejection unit 510b has a second drive element Eb. Each third head chip 51c has a plurality of third ejection units 510c. Each third ejection unit 510c has a third drive element Ec. Furthermore, each ejection unit 510 has a nozzle N that ejects liquid, as will be described later.

[0021] Under the control of the control unit 20, the drive control unit 52 switches whether or not to supply the drive signal Com output from the control unit 20 as the supply signal Vin to each of the multiple discharge units 510 of the head chip 51. In addition, the drive control unit 52 acquires discharge amount information InA relating to the amount of droplets discharged from the nozzle N from each head chip 51 and transmits it to the control unit 20.

[0022] The control unit 20 includes a control circuit 21 , a memory circuit 22 , a power supply circuit 23 , a drive signal generating circuit 24 , and a discharge amount information acquiring section 25 .

[0023] The control circuit 21 has a function to control the operation of each part of the liquid ejection device 100 and a function to process various data. The control circuit 21 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the control circuit 21 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU. Furthermore, when the control circuit 21 is made up of multiple processors, the multiple processors may be mounted on different boards or the like.

[0024] In addition, by executing the program, the control circuit 21 generates a control signal Sk1, a print data signal SI, a waveform designation signal dCom, a latch signal LAT, a change signal CNG, and a clock signal CLK as signals for controlling the operation of each part of the liquid ejection device 100.

[0025] The control signal Sk1 is a signal for controlling the driving of the transport mechanism 30. The print data signal SI is a digital signal for specifying the operating state of the drive element E. The latch signal LAT is used in conjunction with the print data signal SI and is a timing signal that determines the timing of liquid ejection from each nozzle N of the head chip 51.

[0026] The control circuit 21 has a control unit 210. The control unit 210 generates drive signal information InB that specifies the waveform of the drive signal Com based on the ejection amount information InA, and transmits the drive signal information InB to the drive signal generation circuit 24.

[0027] The memory circuitry 22 stores various programs executed by the control circuitry 21 and various data such as image data Img processed by the control circuitry 21. The memory circuitry 22 includes, for example, one or both of semiconductor memories: a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). The image data Img is supplied from an external device 200 such as a personal computer or a digital camera. The memory circuitry 22 may be configured as a part of the control circuitry 21.

[0028] The power supply circuit 23 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid ejection device 100 as appropriate. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head 50. The power supply potential VHV is also supplied to the drive signal generation circuit 24.

[0029] The drive signal generation circuit 24 is a circuit that repeatedly generates a drive signal Com for driving each drive element E included in each ejection section 510. Specifically, the drive signal generation circuit 24 has, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 24, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal. The amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 23, thereby generating the drive signal Com. Of the waveforms included in the drive signal Com, the signal with the waveform that is actually supplied to the drive element E is the aforementioned supply signal Vin. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com.

[0030] The drive signal generation circuit 24 includes, for example, a first drive signal generation circuit 241 that generates the first drive signal ComAa, a second drive signal generation circuit 242 that generates the second drive signal ComC, and a third drive signal generation circuit 243 that generates the third drive signal ComAb. The drive signal generation circuit 24 also includes a drive signal generation circuit that generates the fourth drive signal ComAc, a drive signal generation circuit that generates the fifth drive signal ComBa, a drive signal generation circuit that generates the sixth drive signal ComBb, and a drive signal generation circuit that generates the seventh drive signal ComBc (not shown). The first drive signal ComAa, the second drive signal ComC, the third drive signal ComAb, the fourth drive signal ComAc, the fifth drive signal ComBa, the sixth drive signal ComBb, and the seventh drive signal ComBc will be described later.

[0031] A3: Arrangement of multiple head chips 51 Fig. 3 is a bottom view of the liquid ejection head 50 shown in Fig. 2. As described above, the liquid ejection head 50 has six spaced-apart head chips 51. Each head chip 51 is elongated and extends along the α-axis that intersects the X-axis and Y-axis when viewed in the Z1 direction.

[0032] In this embodiment, of the six head chips 51, the two head chips 51 located on the left side in FIG. 3 are referred to as "first head chips 51a." The two head chips 51 located in the center in FIG. 3 are referred to as "second head chips 51b." The two head chips 51 located on the right side in FIG. 3 are referred to as "third head chips 51c."

[0033] The first head chip 51a has a plurality of first nozzles Na. The plurality of first nozzles Na are divided into two first nozzle rows La, which are aligned along the longitudinal direction of the first head chip 51a. Similarly, the second head chip 51b has a plurality of second nozzles Nb. The plurality of second nozzles Nb are divided into two second nozzle rows Lb, which are aligned along the longitudinal direction of the second head chip 51b. The third head chip 51c has a plurality of third nozzles Nc. The plurality of third nozzles Nc are divided into two third nozzle rows Lc, which are aligned along the longitudinal direction of the third head chip 51c. Each nozzle row L is a collection of a plurality of nozzles N arranged linearly, intersecting the X-axis and Y-axis.

[0034] The nozzles N are each formed to have the same opening area as one another, and are arranged at equal intervals along the β axis, which is perpendicular to the α axis.

[0035] A4: Partial configuration of each head chip 51 Fig. 4 is a cross-section showing a portion of the head chip 51 shown in Fig. 3. As shown in Fig. 4, the head chip 51 has a nozzle plate 11, a vibration absorber 12, a flow path substrate 13, a pressure chamber substrate 14, a diaphragm 15, a wiring substrate 16, a housing unit 17, and a drive circuit 18. The nozzle plate 11, the vibration absorber 12, the flow path substrate 13, the pressure chamber substrate 14, the diaphragm 15, the wiring substrate 16, and the housing unit 17 are each a plate-like member that is elongated in the direction along the Y axis. The nozzle plate 11, the flow path substrate 13, the pressure chamber substrate 14, the diaphragm 15, and the wiring substrate 16 are arranged in this order in the Z1 direction.

[0036] The nozzle plate 11 is a plate-like member in which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through-hole that allows a liquid to pass through. The nozzles N eject the liquid by vibration of the vibration plate 15. The nozzle plate 11 is bonded to the flow path substrate 13 with, for example, an adhesive.

[0037] The flow path substrate 13 is formed with flow paths for supplying liquid to the multiple nozzles N. Specifically, the flow path substrate 13 is formed with a space Ra, multiple supply flow paths 131, multiple communication flow paths 132, and a supply liquid chamber 133. The space Ra is an elongated opening extending in a direction along the α-axis in a plan view seen along the Z-axis. Each of the supply flow path 131 and the communication flow path 132 is a through-hole formed for each nozzle N. The supply liquid chamber 133 is an elongated space extending in a direction along the α-axis across the multiple nozzles N, and connects the space Ra and the multiple supply flow paths 131 to each other. Each of the multiple communication flow paths 132 overlaps with one nozzle N corresponding to that communication flow path 132 in a plan view. A pressure chamber substrate 14 is bonded to the flow path substrate 13 with, for example, an adhesive.

[0038] A plurality of pressure chambers C are provided in the pressure chamber substrate 14. Each pressure chamber C is formed for each nozzle N and is an elongated space extending in a direction along the β-axis in a plan view. The plurality of pressure chambers C are arranged in a direction along the α-axis. The pressure chamber C is a space located between the flow path substrate 13 and the vibration plate 15. The pressure chamber C communicates with the nozzle N via a communication flow path 132, and also communicates with the space Ra via a supply flow path 131 and a supply liquid chamber 133.

[0039] The nozzle plate 11, the flow path substrate 13, and the pressure chamber substrate 14 are each manufactured by processing a silicon single crystal substrate using, for example, dry etching, wet etching, etc. However, other known methods may also be used as appropriate to manufacture the nozzle plate 11, the flow path substrate 13, and the pressure chamber substrate 14.

[0040] A diaphragm 15 is disposed on the surface facing the Z1 direction of the pressure chamber substrate 14. The diaphragm 15 is a plate-like member that can vibrate elastically.

[0041] A plurality of drive elements E corresponding to the nozzles N are arranged on the surface of the vibration plate 15 facing the Z1 direction. Each drive element E has an elongated shape extending in a direction along the β axis in a plan view. The plurality of drive elements E correspond to a plurality of pressure chambers C and are arranged in a direction along the α axis. The drive elements E are driven to change the volume of the pressure chambers C in accordance with the supply signal Vin generated from the drive signal Com. In other words, the drive elements E are deformed by the application of a voltage. When the vibration plate 15 vibrates in conjunction with this deformation, the pressure in the pressure chambers C fluctuates, causing liquid to be ejected from the nozzles N.

[0042] The housing 17 is a case for storing the liquid to be supplied to the multiple pressure chambers C. As shown in FIG. 4, a space Rb is formed in the housing 17. The space Rb in the housing 17 and the space Ra in the flow path substrate 13 are connected to each other. The space formed by the spaces Ra and Rb functions as a liquid storage chamber R, which is a reservoir that stores the liquid to be supplied to the multiple pressure chambers C. The liquid is supplied to the liquid storage chamber R via an inlet 171 formed in the housing 17. The liquid in the liquid storage chamber R is supplied to the pressure chambers C via the supply liquid chamber 133 and each supply flow path 131.

[0043] The vibration absorber 12 is a flexible film that forms the wall surface of the liquid storage chamber R. The vibration absorber 12 is a compliant substrate that absorbs pressure fluctuations of the liquid within the liquid storage chamber R.

[0044] The wiring board 16 is a plate-like member on which wiring is formed for electrically connecting the drive circuit 18 and the multiple drive elements E. The wiring board 16 is, for example, a rigid board. The wiring board 16 has wiring formed thereon that electrically connects the drive circuit 18 mounted on the surface facing the Z1 direction with the multiple bumps 16B required for driving each drive element E on the surface facing the Z2 direction. The drive circuit 18 constitutes part of the drive control unit 52 described above and has an IC (Integrated Circuit) chip that outputs a supply signal Vin and an offset potential VBS based on a drive signal Com for driving each drive element E. In addition, a flexible wiring board (not shown) that is connected to the control unit 20 is connected to the wiring board 16.

[0045] The wiring board 16 may be a flexible board such as an FFC (Flexible Flat Cable), or may be an FPC (Flexible Printed Circuits) or a COF (Chip On Film) on which the drive circuit 18 is mounted.

[0046] In the head chip 51, each of the aforementioned ejection sections 510 includes a nozzle N, a pressure chamber C, and a driving element E. In this embodiment, one ejection section 510 is configured by the nozzle N, the pressure chamber C, the supply flow path 131, the communication flow path 132, and the portion of the diaphragm 15 that corresponds to the driving element E.

[0047] Furthermore, the pressure chamber C and drive element E of the first discharge section 510a of the first nozzle row La are referred to as the "first pressure chamber Ca" and the "first drive element Ea." The pressure chamber C and drive element E of the second discharge section 510b of the second nozzle row Lb are referred to as the "second pressure chamber Cb" and the "second drive element Eb." The pressure chamber C and drive element E of the third discharge section 510c of the third nozzle row Lc are referred to as the "third pressure chamber Cc" and the "third drive element Ec."

[0048] The configuration of each head chip 51 is not limited to the example shown in Fig. 4. Each head chip 51 may have, for example, a circulation flow path for circulating a liquid.

[0049] A5: Drive signal Com Fig. 5 is a diagram illustrating the drive signal Com for generating the supply signal Vin supplied to the first nozzle row La shown in Fig. 3. Fig. 6 is a diagram illustrating the drive signal Com for generating the supply signal Vin supplied to the second nozzle row Lb shown in Fig. 3. Fig. 7 is a diagram illustrating the drive signal Com for generating the supply signal Vin supplied to the third nozzle row Lc shown in Fig. 3.

[0050] The latch signal LAT shown in Figures 5 to 7 includes a pulse PlsL for defining a drive period Tu. The drive period Tu corresponds to a printing period for forming dots on a medium M using droplets from the nozzles N. The drive period Tu is defined as, for example, the period from the rising edge of a pulse PlsL to the rising edge of the next pulse PlsL. The specific length or period of the drive period Tu is not particularly limited.

[0051] 2 generates the drive signal Com. The drive signal Com includes, for example, the first drive signal ComAa, the third drive signal ComAb, the fourth drive signal ComAc, the fifth drive signal ComBa, the sixth drive signal ComBb, the seventh drive signal ComBc, and the second drive signal ComC.

[0052] As shown in FIG. 5, one of the first drive signal ComAa, the fifth drive signal ComBa, and the second drive signal ComC is supplied as a supply signal Vin from the drive control unit 52 to one electrode of each first drive element Ea belonging to the first nozzle row La during one drive period Tu. An offset potential VBS is supplied to the other electrode of each first drive element Ea. Although not shown in detail, the drive control unit 52 in FIG. 2 includes a switching circuit 701. Although not shown in detail, the switching circuit 701 is connected to a signal line transmitting the first drive signal ComAa, a signal line transmitting the fifth drive signal ComBa, a signal line transmitting the second drive signal ComC, a signal line transmitting a print data signal SI1 corresponding to the first nozzle row La, a signal line transmitting a clock signal CLK, and a signal line transmitting a latch signal LAT. The switching circuit 701 selects one of the first drive signal ComAa, the fifth drive signal ComBa, and the second drive signal ComC based on the clock signal SCK, the print data signal SI1, and the latch signal LAT, generates a supply signal Vin corresponding to each first drive element Ea, and outputs it to wiring connected to one electrode of each of the multiple first drive elements Ea.

[0053] As shown in FIG. 6, one of the third drive signal ComAb, the sixth drive signal ComBb, and the second drive signal ComC is supplied as a supply signal Vin from the drive control unit 52 to one electrode of each second drive element Eb belonging to the second nozzle row Lb during one drive period Tu. An offset potential VBS is supplied to the other electrode of each second drive element Eb. Although not shown in detail, the drive control unit 52 in FIG. 2 includes a switching circuit 702. Although not shown in detail, the switching circuit 702 is connected to a signal line transmitting the third drive signal ComAb, a signal line transmitting the sixth drive signal ComBb, a signal line transmitting the second drive signal ComC, a signal line transmitting the print data signal SI2 corresponding to the second nozzle row Lb, a signal line transmitting the clock signal CLK, and a signal line transmitting the latch signal LAT. The switching circuit 702 selects one of the third drive signal ComAb, the sixth drive signal ComBb, and the second drive signal ComC based on the clock signal SCK, the print data signal SI2, and the latch signal LAT, generates a supply signal Vin corresponding to each second drive element Eb, and outputs it to wiring connected to one electrode of each of the multiple second drive elements Eb.

[0054] As shown in FIG. 7, one of the fourth drive signal ComAc, the seventh drive signal ComBc, and the second drive signal ComC is supplied as a supply signal Vin from the drive control unit 52 to one electrode of each third drive element Ec belonging to the third nozzle row Lc during one drive period Tu. An offset potential VBS is supplied to the other electrode of each third drive element Ec. Although not shown in detail, the drive control unit 52 in FIG. 2 includes a switching circuit 703. Although not shown in detail, the switching circuit 703 is connected to a signal line transmitting the fourth drive signal ComAc, a signal line transmitting the seventh drive signal ComBc, a signal line transmitting the second drive signal ComC, a signal line transmitting the print data signal SI3 corresponding to the third nozzle row Lc, a signal line transmitting the clock signal CLK, and a signal line transmitting the latch signal LAT. The switching circuit 703 selects one of the fourth drive signal ComAc, the seventh drive signal ComBc, and the second drive signal ComC based on the clock signal SCK, the print data signal SI3, and the latch signal LAT, generates a supply signal Vin corresponding to each third drive element Ec, and outputs it to wiring connected to one electrode of each of the multiple third drive elements Ec.

[0055] The first drive signal ComAa in Fig. 5, the third drive signal ComAb in Fig. 6, and the fourth drive signal ComAc in Fig. 7 are all signals for forming large dots, which are "droplets of a first amount." Even when multiple head chips 51 attempt to eject the same droplets using the same drive signal Com, slight differences will occur in the amount of droplets ejected from the nozzles N of each head chip 51 due to manufacturing and assembly errors. To reduce these differences, the drive signals Com supplied to each head chip 51, particularly the signals for large dots, are adjusted.

[0056] For example, the first drive signal ComAa is generated according to the average ejection rate of the two first head chips 51a. Similarly, the third drive signal ComAb is generated according to the average ejection rate of the two second head chips 51b. The fourth drive signal ComAc is generated according to the average ejection rate of the two third head chips 51c. Furthermore, the first drive signal ComAa, the third drive signal ComAb, and the fourth drive signal ComAc are generated so as to reduce the difference in ejection rate among the first head chip 51a, the second head chip 51b, and the third head chip 51c.

[0057] The fifth drive signal ComBa, the sixth drive signal ComBb, and the seventh drive signal ComBc are signals for ejecting small dots that are smaller than large dots. As described above, the fifth drive signal ComBa is generated according to the average ejection rate of the two first head chips 51a. Similarly, the sixth drive signal ComBb is generated according to the average ejection rate of the two second head chips 51b. The seventh drive signal ComBc is generated according to the average ejection rate of the two third head chips 51c. The fifth drive signal ComBa, the sixth drive signal ComBb, and the seventh drive signal ComBc are generated so as to reduce the difference in ejection rate between the first head chip 51a, the second head chip 51b, and the third head chip 51c. Furthermore, the second drive signal ComC is a signal for driving the drive element E to slightly vibrate the meniscus MN of the nozzle N to the extent that liquid is not ejected from the nozzle N, in order to prevent the liquid in the nozzle N from thickening, etc. The second drive signal ComC is not a signal for ejecting liquid, and therefore does not cause differences in the ejection amount. For this reason, the second drive signal ComC is common to each head chip 51.

[0058] 5, the first drive signal ComAa has a first start potential holding element a1, a first pulse PAa, and a first end potential holding element a7. The first drive signal generation circuit 241 shown in Fig. 2 generates the first drive signal ComAa having the first pulse PAa that is supplied to the first drive element Ea when a large dot is ejected from the first nozzle Na.

[0059] 5, the first start potential holding element a1 is an element that maintains a first potential E1a from the start of one drive period Tu to the start of the first pulse PAa. In this embodiment, the first potential E1a is an intermediate potential of the first pulse PAa and is a potential different from the reference potential E0. The reference potential E0 is, for example, a potential higher than the offset potential VBS.

[0060] The first end potential holding element a7 is an element that maintains the first potential E1a from the end of the first pulse PAa to the end of one drive period Tu. In this embodiment, the first end potential holding element a7 maintains the first potential E1a, but may also maintain a potential other than the first potential E1a, such as the reference potential E0. Therefore, in this embodiment, the potentials of the first start potential holding element a1 and the first end potential holding element a7 are the same, but may also be different from each other.

[0061] The first pulse PAa has an expansion element a2, a sustain element a3, an ejection element a4, a sustain element a5, and a return element a6, in this order. The expansion element a2 is an element that drives the first drive element Ea to expand the volume of the first pressure chamber Ca by changing the potential. The expansion element a2 changes the potential from the first potential E1a to the minimum potential Ex of the first pulse PAa. The sustain element a3 is an element that maintains the minimum potential Ex. The ejection element a4 is an element that drives the first drive element Ea to contract the volume of the expanded first pressure chamber Ca by changing the potential after the expansion element a2, thereby ejecting a large dot, which is a "first amount of droplet," from the first nozzle Na. The ejection element a4 changes the potential from the minimum potential Ex to the maximum potential E2a of the first pulse PAa. The sustain element a5 is an element that maintains the maximum potential E2a. The return element a6 is an element that returns from the maximum potential E2a to the first potential E1a.

[0062] 6, the third drive signal ComAb has a third start potential holding element b1, a third pulse PAb, and a third end potential holding element b7. The third drive signal generation circuit 243 shown in FIG. 2 generates the third drive signal ComAb having the third pulse PAb that is supplied to the second drive element Eb when a large dot is ejected from the second nozzle Nb.

[0063] The third start potential holding element b1 is an element that maintains the third potential E1b from the start of one drive period Tu to the start of the third pulse PAb. The third potential E1b is an intermediate potential of the third pulse PAb, and is equal to the reference potential E0 in this embodiment. The third potential E1b is also a potential different from the first potential E1a.

[0064] The third end potential holding element b7 is an element that maintains the third potential E1b from the end of the third pulse PAb to the end of one drive period Tu. Note that in this embodiment, the third end potential holding element b7 may maintain a potential other than the third potential E1b. Therefore, in this embodiment, the potentials of the third start potential holding element b1 and the third end potential holding element b7 are the same, but may also be different.

[0065] The third pulse PAb has an expansion element b2, a sustain element b3, an ejection element b4, a sustain element b5, and a return element b6, in this order. The expansion element b2 is an element that drives the second drive element Eb to expand the volume of the second pressure chamber Cb by changing its potential. The expansion element b2 changes its potential from the third potential E1b to the minimum potential Ex of the third pulse PAb. The sustain element b3 is an element that maintains the minimum potential Ex. This minimum potential Ex is the same as the minimum potential Ex of the first pulse PAa described above, but may be different. The ejection element b4 is an element that drives the second drive element Eb by changing its potential after the expansion element b2 to contract the volume of the expanded second pressure chamber Cb, thereby ejecting a large dot, which is a "first amount of droplet," from the second nozzle Nb. The ejection element b4 changes its potential from the minimum potential Ex to the maximum potential Ey of the third pulse PAb. The sustain element b5 is an element that maintains the maximum potential Ey. The maximum potential Ey is lower than the maximum potential E2a of the first pulse PAa. The return element b6 is an element that returns from the maximum potential Ey to the third potential E1b.

[0066] 7, the fourth drive signal ComAc has a fourth start potential holding element c1, a fourth pulse PAc, and a fourth end potential holding element c7. The drive signal generation circuit 24 shown in FIG. 2 generates the fourth drive signal ComAc having the fourth pulse PAc that is supplied to the third drive element Ec when a large dot is ejected from the third nozzle Nc.

[0067] The fourth start potential holding element c1 is an element that maintains the fourth potential E1c from the start of one drive period Tu to the start of the fourth pulse PAc. The fourth potential E1c is an intermediate potential of the fourth pulse PAc. In this embodiment, the fourth potential E1c is a potential different from the first potential E1a and the reference potential E0.

[0068] The fourth end potential holding element c7 is an element that maintains the fourth potential E1c from the end of the fourth pulse PAc to the end of one drive period Tu. Note that in this embodiment, the fourth end potential holding element c7 may maintain a potential other than the fourth potential E1c, for example, the reference potential E0. Therefore, in this embodiment, the potentials of the fourth start potential holding element c1 and the fourth end potential holding element c7 are the same, but may also be different from each other.

[0069] The fourth pulse PAc has an expansion element c2, a sustain element c3, an ejection element c4, a sustain element c5, and a return element c6, in this order. The expansion element c2 is an element that drives the third drive element Ec to expand the volume of the third pressure chamber Cc by changing its potential. The expansion element c2 changes its potential from the fourth potential E1c to the minimum potential Ex of the fourth pulse PAc. The sustain element c3 is an element that maintains the minimum potential Ex. This minimum potential Ex is the same as the minimum potential Ex of the first pulse PAa described above, but may be different. The ejection element c4 is an element that drives the third drive element Ec by changing its potential after the expansion element c2 to contract the volume of the expanded third pressure chamber Cc, thereby ejecting a large dot, which is a "first amount of droplet," from the third nozzle Nc. The ejection element c4 changes its potential from the minimum potential Ex to the maximum potential E2c of the fourth pulse PAc. The sustain element c5 is an element that maintains the maximum potential E2c. The maximum potential E2c is lower than the maximum potential E2a of the first pulse PAa and the maximum potential Ey of the third pulse PAb. The return element c6 is an element for returning from the maximum potential E2c to the fourth potential E1c.

[0070] The fifth drive signal ComBa shown in Fig. 5 includes a fifth start potential holding element d1, a fifth pulse PBa, and a fifth end potential holding element d2. The drive signal generation circuit 24 shown in Fig. 2 generates the fifth drive signal ComBa having the fifth pulse PBa to be supplied to the first drive element Ea when ejecting a small dot from the first nozzle Na.

[0071] The fifth start potential holding element d1 is an element that maintains the first potential E1a from the start of one drive period Tu to the start of the fifth pulse PBa. The fifth end potential holding element d2 is an element that maintains the first potential E1a from the end of the fifth pulse PBa to the end of one drive period Tu. Note that the potentials of the fifth start potential holding element d1 and the fifth end potential holding element d2 are the same, but may be different from each other. Furthermore, the potentials of the fifth start potential holding element d1 and the fifth end potential holding element d2 may be potentials other than the first potential E1a.

[0072] The fifth pulse PB drops from the first potential E1a to a potential lower than the first potential E1a, maintains this potential, then rises to a potential higher than the first potential E1a, maintains this potential, then drops to a potential lower than the first potential E1a and maintains this potential.The fifth pulse PBa maintains this low potential, then rises to a potential higher than the first potential E1a, maintains this potential, and then returns to the first potential E1a.

[0073] The second drive signal ComC shown in FIGS. 5 to 7 includes a second start potential holding element e1, a second pulse PC, and a second end potential holding element e5. The second drive signal generation circuit 242 in FIG. 2 generates the second drive signal ComC having a second pulse PC that is different from the first pulse PAa described above. The second pulse PC is a slight vibration pulse supplied to the first drive element Ea when vibrating the first nozzle Na to prevent the liquid from being ejected. The second pulse PC is a slight vibration pulse supplied to the second drive element Eb when vibrating the second nozzle Nb to prevent the liquid from being ejected. The second pulse PC is a slight vibration pulse supplied to the third drive element Ec when vibrating the third nozzle Nc to prevent the liquid from being ejected.

[0074] The second start potential holding element e1 is an element that maintains the second potential E3 from the start of one drive period Tu to the start of the second pulse PC. The second end potential holding element e5 is an element that maintains the second potential E3 from the end of the second pulse PC to the end of one drive period Tu. In this embodiment, the second potential E3 is equal to the reference potential E0. Note that the potentials of the second start potential holding element e1 and the second end potential holding element e5 are the same, but may be different from each other. Furthermore, the potentials of the second start potential holding element e1 and the second end potential holding element e5 may be potentials other than the reference potential E0.

[0075] The second pulse PC is a trapezoidal wave and has an expansion element e2, a sustain element e3, and a contraction element e4 in this order. The expansion element e2 changes potential from the second potential E3 to the minimum potential Ez of the second pulse PC. The sustain element e3 is an element that maintains the minimum potential Ez. The contraction element e4 is an element that returns from the minimum potential Ez to the second potential E3.

[0076] The sixth drive signal ComBb shown in FIG. 6 includes a sixth start potential holding element f1, a sixth pulse PBb, and a sixth end potential holding element f2. The drive signal generation circuit 24 shown in FIG. 2 generates the sixth drive signal ComBb having the sixth pulse PBb supplied to the second drive element Eb when ejecting a small dot from the second nozzle Nb. The sixth start potential holding element f1 and the sixth end potential holding element f2 maintain the third potential E1b. The sixth pulse PBb is similar to the fifth pulse PBa, but the potentials and potential change rates are set so that a small dot is ejected from the second nozzle Nb.

[0077] The seventh drive signal ComBc shown in FIG. 7 includes a seventh start potential holding element g1, a seventh pulse PBc, and a seventh end potential holding element g2. The drive signal generation circuit 24 shown in FIG. 2 generates the seventh drive signal ComBc having the seventh pulse PBc supplied to the third drive element Ec when ejecting a small dot from the third nozzle Nc. The seventh start potential holding element g1 and the seventh end potential holding element g2 maintain the fourth potential E1c. The seventh pulse PBc is similar to the fifth pulse PBa, but the potentials and potential change rates are set so that a small dot is ejected from the third nozzle Nc.

[0078] FIG. 8 is a diagram showing an example in which drive cycles Tu are consecutive. In FIG. 8, for example, in the first drive cycle Tu, each of the multiple discharge units 510 performs discharge driving to form large dots, which are "droplets of a first amount." In the second drive cycle Tu, each of the multiple discharge units 510 performs micro-vibration driving. In the third drive cycle Tu, each of the multiple discharge units 510 performs discharge driving to form large dots. In the fourth drive cycle Tu, each of the multiple discharge units 510 performs discharge driving to form large dots.

[0079] Figure 8(a) shows the drive waveform of the supply signal Vin supplied to the first drive element Ea of the first head chip 51a. Figure 8(b) shows the drive waveform of the supply signal Vin supplied to the second drive element Eb of the second head chip 51b. Figure 8(c) shows the drive waveform of the supply signal Vin supplied to the third drive element Ec of the third head chip 51c.

[0080] 8(a), in the first head chip 51a, the first drive signal ComAa is supplied to each first drive element Ea during the third and fourth drive periods Tu. The first end potential holding element a7 of the first drive signal ComAa during the third drive period Tu and the first start potential holding element a1 of the first drive signal ComAa during the fourth drive period Tu are both at the first potential E1a, and the first potential E1a continues at the connection portion between the two drive periods Tu.

[0081] In the first head chip 51a, the first drive signal ComAa is supplied to each of the first drive elements Ea during the first drive period Tu, and the second drive signal ComC is supplied to each of the first drive elements Ea during the second drive period Tu. The first end potential holding element a7 of the first drive signal ComAa during the first drive period Tu and the second start potential holding element e1 of the second drive signal ComC during the second drive period Tu have different potentials.

[0082] 8(b), in the second head chip 51b, the third drive signal ComAb is supplied to each second drive element Eb during the third and fourth drive periods Tu. The third end potential holding element b7 of the third drive signal ComAb during the third drive period Tu and the third start potential holding element b1 of the third drive signal ComAb during the fourth drive period Tu are both at the third potential E1b, and the third potential E1b continues at the connection portion between the two drive periods Tu.

[0083] In the second head chip 51b, the third drive signal ComAb is supplied to each of the second drive elements Eb during the first drive period Tu, and the second drive signal ComC is supplied to each of the second drive elements Eb during the second drive period Tu. The third end potential holding element b7 of the third drive signal ComAb during the first drive period Tu and the second start potential holding element e1 of the second drive signal ComC during the second drive period Tu have the same potential, and the reference potential E0 continues at the connection portion between the two drive periods Tu.

[0084] 8(c), in the third head chip 51c, the fourth drive signal ComAc is supplied to each of the third drive elements Ec during the third and fourth drive periods Tu. The fourth end potential holding element c7 of the fourth drive signal ComAc during the third drive period Tu and the fourth start potential holding element c1 of the fourth drive signal ComAc during the fourth drive period Tu are both at the fourth potential E1c, and the fourth potential E1c continues at the connection portion between the two drive periods Tu.

[0085] In the third head chip 51c, the fourth drive signal ComAc is supplied to each of the third drive elements Ec during the first drive period Tu, and the second drive signal ComC is supplied to each of the third drive elements Ec during the second drive period Tu. The fourth end potential holding element c7 of the fourth drive signal ComAc during the first drive period Tu and the second start potential holding element e1 of the second drive signal ComC during the second drive period Tu have different potentials.

[0086] 9 and 10 are diagrams for explaining the supply of the drive signal Com. In this embodiment, as shown in FIG. 9, the same drive signal Com related to the ejection of liquid is supplied to the head chips 51 arranged in the Y1 direction, which is the transport direction of the medium M. Specifically, the first drive signal ComAa and the fifth drive signal ComBa are supplied to the two first head chips 51a. The third drive signal ComAb and the sixth drive signal ComBb are supplied to the two second head chips 51b. The fourth drive signal ComAc and the seventh drive signal ComBc are supplied to the two third head chips 51c.

[0087] 10, the second drive signal ComC, which is not related to the ejection of liquid from the nozzles N, is common to the head chips 51 arranged in the X1 direction, which intersects with the transport direction of the medium M. Specifically, the same second drive signal ComC is supplied to one first head chip 51a, one second head chip 51b, and one third head chip 51c located in the upper row of FIG. 10. The same second drive signal ComC is also supplied to one first head chip 51a, one second head chip 51b, and one third head chip 51c located in the lower row of FIG. The drive signal generation circuit 24 may generate two second drive signals ComC: a second drive signal ComC having a second pulse PC supplied to the drive elements E of one first head chip 51a, one second head chip 51b, and one third head chip 51c located in the upper row of Fig. 10, and a second drive signal ComC having a second pulse PC supplied to the drive elements E of one first head chip 51a, one second head chip 51b, and one third head chip 51c located in the lower row of Fig. 10. Alternatively, the drive signal generation circuit 24 may generate one second drive signal ComC and supply the same second drive signal ComC to all of the first head chip 51a to third head chip 51c.

[0088] In this embodiment, the second drive signal ComC is the same for all head chips 51, but the second drive signal ComC having different waveforms may be supplied between the upper and lower parts of FIG.

[0089] In this way, the signal supply paths may be different for signals related to the ejection of liquid and signals not related to the ejection of liquid. Note that both the signals related to the ejection of liquid and the signals not related to the ejection of liquid may be supplied to each of the head chips 51 arranged in the Y1 direction, which is the transport direction of the medium M, for example.

[0090] FIG. 11 is a diagram illustrating conventional correction of the drive signal ComAx. As shown in FIG. 11, conventionally, the peak value Vh is corrected without changing the intermediate potential of the drive signal ComAx so as to adjust the liquid ejection amount to the desired ejection amount. Specifically, for example, when the ejection amount is insufficient based on the drive signal ComAx shown in FIG. 11(a), the peak value Vh is increased, and the drive signal ComAx shown in FIG. 11(a) is corrected to the drive signal ComAx shown in FIG. 11(b). However, in this case, even if the peak value Vh is increased or decreased, it may not be possible to adjust the liquid ejection amount to the desired amount. Specifically, it is more difficult to adjust the liquid ejection amount to the desired amount with high-frequency driving than with low-frequency driving.

[0091] Fig. 12 is a diagram showing the relationship between the drive period Tu and the liquid ejection amount Iw in a conventional drive signal ComAx. Fig. 12 shows the cases where the ratio of the intermediate potential to the peak value Vh is 40% and 50%. When the intermediate potential is not changed, the peak value Vh is larger when the ratio of the intermediate potential to the peak value Vh is 40% than when it is 50%.

[0092] As shown in Figure 12, by changing the ratio of the intermediate potential to the peak value Vh from 50% to 40%, i.e., by increasing the peak value Vh, the liquid ejection volume Iw increases at 40 μs or longer. However, when the drive period Tu is small, i.e., when the frequency is high, the change in the ejection volume is smaller than when the drive period Tu is large, i.e., when the frequency is low. In other words, the change in the ejection volume per volt of peak value Vh decreases as the drive frequency increases.

[0093] FIG. 13 shows the relationship between the peak value Vh and the liquid ejection volume Iw for each frequency of the conventional drive signal ComAx. FIG. 13 illustrates the relationship between the peak value Vh and the ejection volume Iw at 5.0 kHz, 31.5 kHz, and 63.0 kHz. As shown in FIG. 13, the ejection volume Iw changes less when the peak value Vh is changed at 63.0 kHz than when it is changed at 5.0 kHz and 31.5 kHz. In other words, the amount of change in the ejection volume per volt of the peak value Vh is smaller when driven at high frequency than when driven at low frequency. Therefore, if the correction amount of the peak value Vh is further increased to ensure the ejection volume during high frequency driving, the droplet ejection speed during low frequency driving will be excessively faster than the desired speed. This may result in misalignment of the droplets.

[0094] FIG. 14 is a diagram illustrating frequency characteristics. The frequency characteristics shown in FIG. 14(a) are determined by the sum of the relationship between the drive frequency and the ejection amount Iw due to the influence of the Tm vibration, which is the vibration of the meniscus MN of the nozzle N shown in FIG. 14(b), and the relationship between the drive frequency and the ejection amount Iw due to the influence of the Tc vibration, which is the vibration in the flow path of the ejection unit 510 shown in FIG. 14(c). The influence of the Tm vibration is particularly large in high-frequency drive. Therefore, in low-frequency drive, the influence of the residual vibration, which is the Tc vibration after the ejection of droplets, and the influence of the refill, which is the Tm vibration after the ejection of liquid, are smaller than in high-frequency drive. In low-frequency drive, the next drive signal Com is applied after the meniscus MN has returned to its non-driven state. On the other hand, in high-frequency drive, the ejection amount is easily affected by the Tm vibration of the meniscus MN of the nozzle N and the Tc vibration in the flow path of the ejection unit 510.

[0095] FIG. 15 is a diagram illustrating the effect of frequency characteristics on the ejection amount. FIG. 15 shows the change in ejection amount Iw according to the drive frequency when the ratio of the intermediate potential to the peak value Vh is 50% and 40%, and illustrates the difference in the amount of change in the ejection amount Iw in the high-frequency range. The vertical axis of FIG. 15 represents the fluctuation rate [%] of the ejection amount when the ejection amount Iw is 100% in the low-frequency range where the ratio is 50% and 40%. As shown in FIG. 15, when the ratio of the intermediate potential to the peak value Vh is 40%, the fluctuation rate of the ejection amount is lower than when it is 50%. In other words, with high-frequency driving, even if the correction amount of the peak value Vh is increased without changing the intermediate potential, it is difficult to increase the ejection amount Iw. Therefore, with the conventional correction method that changes only the peak value Vh, it becomes more difficult to increase the liquid ejection amount Iw as the driving frequency increases.

[0096] 16 is a diagram for explaining the correction of the large dot drive signal ComA in this embodiment. As shown in FIG. 16, in this embodiment, the intermediate potential is corrected in addition to the correction of the peak value Vh.

[0097] Specifically, for example, if the large dot drive signal ComA shown in Fig. 16(a) is supplied to the drive element E of the head chip 51 and the amount of droplets ejected from the nozzle N is insufficient for a large dot, the large dot drive signal ComA shown in Fig. 16(b) is corrected by increasing the peak value Vh and the intermediate potential. The large dot drive signal ComA in Fig. 16(a) is the same as the third drive signal ComAb shown in Fig. 6 described above. The large dot drive signal ComA in Fig. 16(b) is the same as the first drive signal ComAa shown in Fig. 5 described above.

[0098] Furthermore, for example, if the large dot drive signal ComA shown in Fig. 16(a) is supplied to the drive element E of the head chip 51 and the amount of droplets ejected from the nozzle N is excessive for a large dot, the peak value Vh is reduced and the intermediate potential is lowered to correct to the large dot drive signal ComA shown in Fig. 16(c). The large dot drive signal ComA in Fig. 16(c) is the same as the fourth drive signal ComAc shown in Fig. 7 described above.

[0099] In this way, in this embodiment, the intermediate potential is corrected along with the correction of the peak value Vh, so that the ejection volume can be increased while suppressing the peak value Vh even in high frequency driving, compared to when only the peak value Vh is corrected.

[0100] FIG. 17 shows the relationship between the drive period Tu and the liquid ejection amount Iw when correcting the large-dot drive signal ComA of this embodiment. FIG. 17 shows the relationship between the drive period Tu and the liquid ejection amount Iw when the first drive signal ComAa and the third drive signal ComAb are supplied to the drive elements E of a given head chip 51. The potential change width D2a, which is the peak value Vh of the first drive signal ComAa, is greater than the potential change width D2b, which is the peak value Vh of the third drive signal ComAb. Additionally, the first potential E1a of the first start potential holding element a1, which is the intermediate potential of the first drive signal ComAa, is greater than the third potential E1b (reference potential E0) of the third start potential holding element b1, which is the intermediate potential of the third drive signal ComAb. Therefore, the ratio of the intermediate potential to the peak value Vh of the first drive signal ComAa and the third drive signal ComAb is the same, 50%.

[0101] As shown in FIG. 17, the first drive signal ComAa has a larger ejection volume regardless of frequency than the third drive signal ComAb. In this embodiment, the first drive signal ComAa has a larger ejection volume in the high-frequency range as well as the low-frequency range compared to the third drive signal ComAb. In other words, by supplying a drive signal ComA having the waveform of the first drive signal ComAa to a head chip 51 that ejects a smaller volume than the volume corresponding to a large dot, the ejection volume can be increased. Therefore, in this embodiment, the change in the ejection volume per 1V due to frequency is reduced compared to the conventional art.

[0102] The same can be said about the fourth drive signal ComAc.

[0103] Furthermore, as described above, the first potential E1a of the first start potential holding element a1 of the first drive signal ComAa is different from the second potential E3 of the second start potential holding element e1 of the second drive signal ComC. In this way, the different potentials of the first start potential holding element a1 of the first drive signal ComAa and the second start potential holding element e1 of the second drive signal ComC allow for greater design flexibility than when these potentials are the same. For example, as described above, adjusting the first potential E1a in addition to the peak value Vh makes it easier to adjust the ejection volume and ejection speed to the desired volume and speed. As described above, correcting the intermediate potential in addition to correcting the peak value Vh makes the ejection volume and ejection speed less susceptible to changes in the frequency characteristics, making it easier to adjust the ejection volume and ejection speed to the desired volume and speed.

[0104] Furthermore, as described above, the reference potential E0 serving as the "third potential" of the third start potential holding element b1 of the third drive signal ComAb is different from the first potential E1a of the first start potential holding element a1 of the first drive signal ComAa. This ensures flexibility in the design of the first drive signal ComAa and the third drive signal ComAb. Therefore, when the first nozzle Na and the second nozzle Nb eject the same large dot, the different potentials of the first start potential holding element a1 and the third start potential holding element b1 allow for more accurate alignment of the ejection volume compared to when the potentials are the same. In other words, the difference in ejection volume can be reduced.

[0105] 5 and 6, the potential change width D1a of the expansion element a2 of the first pulse PAa is different from the potential change width D1b of the ejection element b4 of the third pulse PAb, and the potential change width D2a of the ejection element a4 of the first pulse PAa is different from the potential change width D2b of the ejection element b4 of the third pulse PAb. In this way, the potential change widths D1a and D1b are different, and the potential change widths D2a and D2b are also different, due to the difference in the potential of the first start potential holding element a1 and the third start potential holding element b1. This reduces the effect of frequency characteristics, as described above, and therefore reduces the difference in the ejection volume of large dots, which are the same droplets, between the first nozzle Na and the second nozzle Nb.

[0106] Furthermore, the first drive signal ComAa is supplied to the first drive element Ea without being supplied to the second drive element Eb. The third drive signal ComAb is supplied to the second drive element Eb without being supplied to the first drive element Ea. The second drive signal ComC, which includes a second pulse PC, which is a micro-vibration pulse, is supplied to the first drive element Ea and the second drive element Eb. In other words, the first drive signal ComAa is a dedicated ejection drive signal for ejecting large dots from the first nozzle Na, and the third drive signal ComAb is a dedicated ejection drive signal for ejecting large dots from the second nozzle Nb. On the other hand, the second drive signal ComC is not a signal related to ejection, but a micro-vibration drive signal that only vibrates the meniscus MN. By sharing this micro-vibration drive signal among multiple drive elements E, the drive signal generation circuit 24 can be prevented from becoming complicated.

[0107] The second potential E3 of the second start potential holding element e1 is a potential within a range from the first potential E1a of the first start potential holding element a1 to the third potential E1b of the third start potential holding element b1. In this embodiment, the second potential E3 and the third potential E1b are the same.

[0108] By keeping the second potential E3 within this range, compared to when it is outside this range, even when the first pulse PAa and the second pulse PC are consecutive, as shown in the first and second drive periods Tu in FIG. 8(a), the potential difference at the connection between the drive period Tu in which the first pulse PAa is supplied and the drive period Tu in which the second pulse PC is supplied is prevented from becoming excessively large. This allows for stable ejection and micro-vibration driving. This prevents unintended ejection of droplets during micro-vibration driving and unstable ejection volume and ejection speed during ejection of large dots.

[0109] Furthermore, the first end potential holding element a7 of the first drive signal ComAa maintains the same first potential E1a as the first start potential holding element a1. Therefore, when the first pulse PAa is continuously ejected as shown in the third and fourth drive periods Tu in FIG. 8(a), a potential difference is prevented from occurring when the two drive periods Tu are connected. This allows for stable ejection.

[0110] Similarly, the third end potential holding element b7 of the third drive signal ComAb maintains the same third potential E1b as the third start potential holding element b1. Therefore, when the third pulse PAb is continuously ejected as shown in the third and fourth drive periods Tu in FIG. 8(b), a potential difference is prevented from occurring at the connection between the two drive periods Tu. This allows for stable ejection.

[0111] Furthermore, the maximum ejection frequency of the first drive signal ComAa and the third drive signal ComAb is preferably 10 kHz or higher. In the high frequency range of 10 kHz or higher, the first potential E1a is different from the third potential E1b, and the above-mentioned effect is significantly exhibited.

[0112] It should be noted that the maximum ejection frequency by the first drive signal ComAa and the third drive signal ComAb is, for example, about 150 kHz or less, taking ejection stability into consideration.

[0113] 2, the control unit 20 includes a discharge amount information acquisition unit 25 and a control unit 210. The discharge amount information acquisition unit 25 acquires first discharge amount information InAa relating to the amount of droplets discharged from the first nozzle Na. The control unit 210 generates first drive signal information InBa that specifies the waveform of the first drive signal ComAa based on the first discharge amount information InAa and transmits the first drive signal information InBa to the first drive signal generation circuit 241. The control unit 210 changes at least one of the potential change width D1a of the expansion element a2 of the first pulse PAa, the potential change width D2a of the discharge element a4 of the first pulse PAa, and the first potential E1a based on the first discharge amount information InAa.

[0114] For example, when using the liquid ejection head 50, the ejection amount may change due to changes over time in the shape of the components that make up the liquid ejection head 50, the temperature of the place where the head is used, and other factors. Even in such cases, the control unit 20, which is equipped with the ejection amount information acquisition section 25 and the control section 210, can adjust the ejection amount to a desired amount depending on the changes over time and the temperature of the place where the head is used. Furthermore, it is possible to reduce differences in the ejection amount between multiple nozzles N that eject droplets of the same size.

[0115] Furthermore, the discharge volume information acquisition unit 25 acquires second discharge volume information InAb relating to the volume of droplets discharged from the second nozzle Nb. Furthermore, the control unit 210 generates second drive signal information InBb that specifies the waveform of the third drive signal ComAb based on the second discharge volume information InAb, and sends the second drive signal information InBb to the second drive signal generation circuit 242. Based on the second discharge volume information InAb, the control unit 210 changes at least one of the potential change width D1b of the expansion component b2 of the third pulse PAb, the potential change width D2b of the discharge component b4 of the third pulse PAb, and the third potential E1b.

[0116] By providing the discharge amount information acquisition unit 25 and the control unit 210, when the same large dot is discharged from the first nozzle Na and the second nozzle Nb, differences in discharge amount between the first nozzle Na and the second nozzle Nb can be reduced due to the aforementioned changes over time and the temperature of the place of use. Note that the discharge amount information acquisition unit 25 and the control unit 210 also correct the potential change width and intermediate potential of other pulses in the same manner as above. This makes it possible to reduce differences in discharge amount between multiple nozzles N that discharge droplets of the same size.

[0117] FIG. 18 shows the droplet ejection speed Vm when a large dot is ejected in the latter drive period Tu when the intermediate potential is changed when two drive periods Tu are connected. LL1 in FIG. 18 shows the state of the droplet ejection speed Vm when a large dot is ejected in the latter drive period Tu when the intermediate potential is not changed when two drive periods Tu are connected. LL2 in FIG. 18 shows the state of the droplet ejection speed Vm when a large dot is ejected in the latter drive period Tu when two drive periods Tu are connected and the intermediate potential of the latter drive period Tu is +2 V different from the intermediate potential of the former drive period Tu. LL3 in FIG. 18 shows the state of the droplet ejection speed Vm when a large dot is ejected in the latter drive period Tu when two drive periods Tu are connected and the intermediate potential of the latter drive period Tu is -2 V different from the intermediate potential of the former drive period Tu. In the example shown in FIG. 18, when the drive period changes, the period from the start of the drive period to the start of the ejection pulse changes.

[0118] 18, if the intermediate potential is changed when the drive period Tu is connected, the change in potential drives the drive element E, causing pressure vibrations in the liquid in the pressure chamber C and nozzle N. If an ejection pulse is applied at a timing that resonates or does not resonate with this pressure vibration, the ejection characteristics change significantly. For this reason, it is preferable to use the length of the first start potential holding element a1 within a range in which the effect of the potential difference of the intermediate potential when the drive period Tu is connected is minimal on the ejection speed.

[0119] Specifically, it is preferable that the period tx from the start of the first start potential holding element a1 to the middle position of the expansion element a2 of the first pulse PAa shown in FIG. 5 satisfies the following formula. 0.25×TC+n≦tx≦0.75×TC+n The above TC is the natural vibration period of the first discharge part 510a, and n is a natural number.

[0120] When the period tx satisfies the above formula, the stability of ejection can be improved compared to when the formula is not satisfied, even if the intermediate potential is changed when the drive cycle Tu is connected.

[0121] Furthermore, it is preferable that the period tx satisfies the following formula: tx=0.5×Tc+n When the period tx satisfies the above formula, the ejection stability can be particularly improved compared to when the period tx does not satisfy the formula.

[0122] Similarly, it is preferable that the period tx from the start of the third start potential holding element b1 to the middle position of the expansion element b2 of the third pulse PAb shown in FIG. 6 satisfies the following formula. 0.25×TC+n≦tx≦0.75×TC+n The above TC is the natural vibration period of the second discharge part 510b, and n is a natural number.

[0123] When the period tx satisfies the above formula, the stability of ejection can be improved compared to when the formula is not satisfied, even if the intermediate potential is changed when the drive cycle Tu is connected.

[0124] Furthermore, it is preferable that the period tx satisfies the following formula: tx=0.5×Tc+n When the period tx satisfies the above formula, the ejection stability can be particularly improved compared to when the period tx does not satisfy the formula.

[0125] 19 is a diagram showing the ejection speed Vm when the potential change width Vx at the connection of the drive cycles Tu is changed. In other words, the potential change width Vx indicates the difference between the intermediate potential of the first drive cycle Tu and the intermediate potential of the second drive cycle Tu between two consecutive drive cycles Tu. As shown in FIG. 19, the larger the absolute value of the potential change width Vx at the connection of the drive cycles Tu, the greater the impact on the ejection speed Vm.

[0126] The potential change width Vx during connection is preferably 4.0 V or less. Therefore, the difference between the first potential E1a and the second potential E3 is preferably 4.0 V or less. When the difference is 4.0 V or less, the ejection stability can be improved compared to when the difference exceeds 4.0 V.

[0127] Similarly, the difference between the second potential E3 and the third potential E1b is preferably 4.0 V or less. When the difference is 4.0 V or less, the ejection stability can be improved compared to when the difference exceeds 4.0 V.

[0128] FIG. 20 shows the impact deviation when the potential change width Vx is changed at a transport speed of 80 m / min. FIG. 21 shows the impact deviation when the potential change width Vx is changed at a transport speed of 40 m / min. As shown in FIGS. 20 and 21, the larger the potential change width Vx, the more unstable the ejection becomes, and the greater the impact deviation. Furthermore, the higher the transport speed, the greater the impact of the potential change width Vx. Considering such impact deviation, it is preferable that the potential change width Vx be 4.0 V or less.

[0129] As described above, in the driving method of the liquid ejection device 100, the first potential E1a of the first start potential holding element a1 of the first drive signal ComAa is set to be different from the second potential E3 of the second start potential holding element e1 of the second drive signal ComC. By setting the potentials of the first start potential holding element a1 of the first drive signal ComAa and the second start potential holding element e1 of the second drive signal ComC to be different in this way, design flexibility can be increased compared to when the potentials are the same. Therefore, for example, as described above, adjusting the first potential E1a in addition to the peak value Vh makes it easier to bring the ejection amount and ejection speed closer to the desired amount and speed. Therefore, the driving method of the liquid ejection device 100 of this embodiment enables sufficient correction of the ejection amount and ejection speed.

[0130] B: Modified example The above-described embodiments can be modified in various ways. Specific modifications that can be applied to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be combined as appropriate within the scope of not mutually contradictory.

[0131] B1. First variant FIG. 22 is a diagram showing the first drive signal ComAa of the first modified example. In the above-described embodiment, the potential change from the reference potential E0 to the first potential E1a was steep, but as in the first modified example of FIG. 22, the change may be gradual. This makes it possible to prevent the ejection from becoming unstable due to changes in the potential change width Vx during connection as described above. The same applies to drive signals Com other than the first drive signal ComAa.

[0132] B2. Other Modifications In the above-described embodiment, each head chip 51 has two nozzle rows L, but the number of nozzle rows included in each head chip 51 may be one, or three or more.

[0133] The "first amount of droplets" is not limited to large dots, but may be medium or small dots. Note that the "first amount of droplets" indicates the size of such droplets, and does not take into account differences in the discharge amount due to manufacturing errors and assembly errors of the nozzles N.

[0134] In the above-described embodiment, the intermediate potential of the fifth drive signal ComBa is the first potential E1a, which is the intermediate potential of the first drive signal ComAa. However, this is not limited to this. The intermediate potential of the fifth drive signal ComBa may be set to a potential different from the first potential E1a, which is the intermediate potential of the first drive signal ComAa. This further improves the design flexibility of the ejection pulse. In this case, it is preferable that the difference between the intermediate potential of the fifth drive signal ComBa and the first potential E1a, which is the intermediate potential of the first drive signal ComAa, be set to the same value as the above-described potential change width Vx. Furthermore, it is preferable that the duration of the fifth start potential holding element d1 be set to the same value as the period tx from the start of the first start potential holding element a1 to the middle position of the expansion element a2 of the first pulse PAa. In this configuration, the fifth drive signal ComBa may correspond to a "second drive signal." In this case, the fifth pulse PBa of the fifth drive signal ComBa corresponds to a "second pulse," and the start potential of one drive cycle of the fifth drive signal ComBa corresponds to a "second potential." Similarly, the intermediate potential of the sixth drive signal ComBb may be set to a potential different from the third potential E1b, which is the intermediate potential of the third drive signal ComAb, and the intermediate potential of the seventh drive signal ComBc may be set to a potential different from the fourth potential E1c, which is the intermediate potential of the fourth drive signal ComAc.

[0135] In the above-described embodiment, the second head chip 51b may correspond to the "first head chip," and the first head chip 51a or the third head chip 51c may correspond to the "second head chip." In this case, the second nozzle Nb, the second pressure chamber Cb, the second driving element Eb, and the second ejection unit 510b correspond to the "first nozzle," "first pressure chamber," "first driving element," and "first ejection unit." The first nozzle Na, the first pressure chamber Ca, the first driving element Ea, and the first ejection unit 510a, or the third nozzle Nc, the third pressure chamber Cc, the third driving element Ec, and the third ejection unit 510c correspond to the "second nozzle," "second pressure chamber," "second driving element," and "second ejection unit." Similarly, the third head chip 51c may correspond to the "first head chip," and the first head chip 51a or the second head chip 51b may correspond to the "second head chip." In this case, the third nozzle Nc, the third pressure chamber Cc, the third drive element Ec, and the third discharge unit 510c correspond to the "first nozzle," "first pressure chamber," "first drive element," and "first discharge unit." The first nozzle Na, the first pressure chamber Ca, the first drive element Ea, and the first discharge unit 510a, or the second nozzle Nb, the second pressure chamber Cb, the second drive element Eb, and the second discharge unit 510b correspond to the "second nozzle," "second pressure chamber," "second drive element," and "second discharge unit."

[0136] In the above-described embodiment, the liquid ejection device 100 was a line type in which multiple nozzles N were distributed across the entire width of the medium M, but the present disclosure can also be applied to a serial type liquid ejection device in which a carriage 501 carrying a liquid ejection head 50 is moved back and forth.

[0137] The liquid ejection device 100 exemplified in the above embodiment may be employed in various devices such as facsimile machines and copiers, in addition to devices dedicated to printing, and the applications of the present disclosure are not particularly limited. However, the applications of the liquid ejection device are not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device for manufacturing biochips, for example.

[0138] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the above-described embodiments. Furthermore, the configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as the above-described embodiments, and any configuration can be added. [Explanation of symbols]

[0139] 24...drive signal generation circuit, 25...discharge amount information acquisition unit, 50...liquid discharge head, 51a...first head chip, 51b...second head chip, 51c...third head chip, 52...drive control unit, 100...liquid discharge device, 210...control unit, 241...first drive signal generation circuit, 242...second drive signal generation circuit, 243...third drive signal generation circuit, 510a...first discharge unit, 510b...second discharge unit, 51 Oc...third ejection section, Ca...first pressure chamber, Cb...second pressure chamber, Cc...third pressure chamber, ComAa...first drive signal, ComAb...third drive signal, ComC...second drive signal, D1a...potential change width, D1b...potential change width, D2a...potential change width, D2b...potential change width, E1a...first potential, E1b...third potential, E3...second potential, Ea...first drive element, Eb...second drive element, Ec...third drive element , InAa...first ejection amount information, InAb...second ejection amount information, InBa...first drive signal information, InBb...second drive signal information, La...first nozzle row, Lb...second nozzle row, Lc...third nozzle row, Na...first nozzle, Nb...second nozzle, Nc...third nozzle, PAa...first pulse, PAb...third pulse, PC...second pulse, Tu...drive period, Vx...potential change width, a1...first start potential holding element, a2...expansion element, a3...sustain element, a4...ejection element, a5...sustain element, a6...return element, a7...first end potential holding element, b1...third start potential holding element, b2...expansion element, b3...sustain element, b4...ejection element, b6...return element, b7...third end potential holding element, e1...second start potential holding element, e2...expansion element, e3...sustain element, e4...contraction element, e5...second end potential holding element, tx...period.

Claims

1. a liquid ejection head including a first ejection unit including a first nozzle that ejects liquid, a first pressure chamber that communicates with the first nozzle, and a first drive element that is driven to change the volume of the first pressure chamber in response to a drive signal; a first drive signal generating circuit that generates a first drive signal having a first pulse to be supplied to the first drive element when a first amount of droplets is ejected from the first nozzle; a second drive signal generating circuit configured to generate a second drive signal that is supplied to the first drive element and has a second pulse different from the first pulse; Equipped with the first drive signal has a first start potential holding element that maintains a first potential from the start of one drive cycle to the start of the first pulse; the second drive signal has a second start potential holding element that maintains a second potential from the start of one drive cycle to the start of the second pulse; the first potential and the second potential are different; A liquid ejection device characterized by:

2. the first pulse has an expansion element that drives the first drive element so as to expand the volume of the first pressure chamber by changing the potential, and an ejection element that drives the first drive element so as to contract the expanded volume of the first pressure chamber by changing the potential after the expansion element, thereby ejecting a first amount of droplets from the first nozzle, A period tx from the start of the first start potential holding element to the middle position of the expansion element of the first pulse satisfies the following formula: 0.25×TC+n≦tx≦0.75×TC+n TC is the natural vibration period of the first ejection unit, and n is a natural number. The liquid ejection device according to claim 1 .

3. A period tx from the start of the first start potential holding element to the middle position of the expansion element of the first pulse satisfies the following formula: tx=0.5×Tc+n TC is the natural vibration period of the first ejection unit, and n is a natural number. The liquid ejection device according to claim 1 .

4. the first drive signal has a first final potential holding element that maintains the first potential from the end of the first pulse to the end of one drive cycle; The liquid ejection device according to claim 1 .

5. a difference between the first potential and the second potential is 4.0 V or less; The liquid ejection device according to claim 1 .

6. the maximum ejection frequency of the first drive signal and the second drive signal is 10 kHz or more; The liquid ejection device according to claim 1 .

7. a discharge amount information acquisition unit that acquires first discharge amount information relating to the amount of droplets discharged from the first nozzle; a control unit configured to generate first drive signal information that specifies a waveform of the first drive signal based on the first ejection amount information, and to transmit the first drive signal information to the first drive signal generation circuit; Furthermore, the first pulse has an expansion element that drives the first drive element so as to expand the volume of the first pressure chamber by changing the potential, and an ejection element that drives the first drive element so as to contract the expanded volume of the first pressure chamber by changing the potential after the expansion element, thereby ejecting a first amount of droplets from the first nozzle, the control unit changes at least one of a potential change width of an expansion element of the first pulse, a potential change width of an ejection element of the first pulse, and the first potential based on the first ejection amount information. The liquid ejection device according to claim 1 .

8. the liquid ejection head further comprises a second ejection unit including a second nozzle that ejects liquid, a second pressure chamber that communicates with the second nozzle, and a second drive element that is driven to change the volume of the second pressure chamber in response to a drive signal; a third drive signal generating circuit that generates a third drive signal having a third pulse to be supplied to the second drive element when a first amount of droplets is ejected from the second nozzle; the third drive signal has a third start potential holding element that maintains a third potential from the start of one drive cycle to the start of the third pulse; the third potential is different from at least the first potential; The liquid ejection device according to claim 1 .

9. the second pulse is a minute vibration pulse that is supplied to the first driving element when vibrating the first nozzle so as not to eject the liquid, and that is supplied to the second driving element when vibrating the second nozzle so as not to eject the liquid, the first drive signal is supplied to the first drive element without being supplied to the second drive element; the third drive signal is supplied to the second drive element without being supplied to the first drive element, the second drive signal is supplied to the first drive element and the second drive element; The liquid ejection device according to claim 8 .

10. the first pulse has an expansion element that drives the first drive element to expand the volume of the first pressure chamber by changing the potential, and an ejection element that contracts the expanded volume of the pressure chamber by changing the potential after the expansion element, thereby ejecting a first amount of droplets from the first nozzle; the third pulse has an expansion element that drives the second drive element to expand the volume of the second pressure chamber by changing the potential, and an ejection element that contracts the expanded volume of the second pressure chamber by changing the potential after the expansion element, thereby ejecting a first amount of droplet from the second nozzle, a potential change width of the expansion component of the first pulse and a potential change width of the expansion component of the third pulse are different, a potential change width of the ejection element of the first pulse is different from a potential change width of the ejection element of the third pulse; The liquid ejection device according to claim 8 .

11. A period tx from the start of the first start potential holding element to the intermediate position of the ejection element of the first pulse and a period tx from the start of the third start potential holding element to the intermediate position of the ejection element of the third pulse satisfy the following formula: 0.25×TC+n≦tx≦0.75×TC+n TC is the natural vibration period of the second ejection portion, and n is a natural number. The liquid ejection device according to claim 8 .

12. A period tx from the start of the first start potential holding element to the intermediate position of the ejection element of the first pulse, and a period tx from the start of the third start potential holding element to the intermediate position of the ejection element of the third pulse, satisfy the following formula: tx=0.5×Tc+n TC is the natural vibration period of the second ejection portion, and n is a natural number. The liquid ejection device according to claim 8 .

13. the first drive signal has a first final potential holding element that maintains the first potential from the end of the first pulse to the end of one drive cycle; the third drive signal has a third final potential holding element that maintains the third potential from the end of the third pulse to the end of one drive cycle. The liquid ejection device according to claim 8 .

14. a difference between the first potential and the second potential is 4.0 V or less; a difference between the second potential and the third potential is 4.0 V or less; The liquid ejection device according to claim 8 .

15. the second potential is a potential within a range from the first potential to the third potential; The liquid ejection device according to claim 8 .

16. a discharge amount information acquisition unit that acquires first discharge amount information relating to the amount of droplets discharged from the first nozzle and second discharge amount information relating to the amount of droplets discharged from the second nozzle; a control unit configured to generate first drive signal information that specifies a waveform of the first drive signal based on the first ejection amount information and second drive signal information that specifies a waveform of the second drive signal based on the second ejection amount information, and to transmit the first drive signal information to the first drive signal generation circuit and the second drive signal information to the third drive signal generation circuit; Furthermore, the first pulse has an expansion element that drives the first drive element to expand the volume of the first pressure chamber by changing the potential, and an ejection element that contracts the expanded volume of the first pressure chamber by changing the potential, thereby ejecting a droplet from the first nozzle; the third pulse has an expansion element that drives the second drive element to expand the volume of the second pressure chamber by changing the potential, and an ejection element that contracts the expanded volume of the second pressure chamber by changing the potential, thereby ejecting a droplet from the second nozzle; the control unit changes a potential change width of the expansion element of the first pulse, a potential change width of the expansion element of the first pulse, and the first potential based on the first discharge amount information; the control unit changes a potential change width of an expansion element of the third pulse, a potential change width of an ejection element of the third pulse, and the third potential based on the second ejection amount information. The liquid ejection device according to claim 8 .

17. A method for driving a liquid ejection device including a liquid ejection head having a first ejection section including a first nozzle that ejects liquid, a first pressure chamber that communicates with the first nozzle, and a first drive element that is driven to change the volume of the first pressure chamber in response to a drive signal, the method comprising: generating a first drive signal having a first pulse to be supplied to the first drive element when ejecting a first amount of droplets from the first nozzle; generating a second drive signal supplied to the first drive element, the second drive signal having a second pulse different from the first pulse; When generating the first drive signal and the second drive signal, a first potential of a first start potential holding element from the start of one drive cycle of the first drive signal to the start of the first pulse is set to be different from a second potential of a second start potential holding element from the start of one drive cycle of the second drive signal to the start of the second pulse. A method for driving a liquid ejection device.

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