JP7392431B2 - Liquid ejection device, head drive control device - Google Patents

Description

The present invention relates to a liquid ejecting device and a head drive control device.

Due to manufacturing variations in liquid ejection heads, variations occur in the ejection speed and amount of liquid between heads or between nozzles.

Conventionally, there has been known a common drive waveform in which a trimming range in a period from an expansion waveform element (falling waveform element) that expands a pressure chamber to a holding waveform element is adjusted (Patent Document 1).

Special table 2018-509320 publication

However, the configuration disclosed in Patent Document 1 has a problem in that it is not possible to sufficiently suppress variations in ejection speed and ejection amount (ejection characteristics) between nozzles.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce variations in ejection characteristics.

In order to solve the above problems, a device for discharging liquid according to claim 1 of the present invention includes:
a drive waveform generation unit that generates and outputs a common drive waveform including a drive pulse that causes liquid to be ejected from a nozzle of the liquid ejection head;
Selection means for selecting a waveform portion of the drive pulse applied to the pressure generating element of the liquid ejection head from the common drive waveform;
means for outputting a selection signal specifying a waveform portion to be selected by the selection means,
The driving pulse includes at least an expansion waveform element that expands the pressure chamber of the liquid ejection head, a holding waveform element that maintains the expanded state by the expansion waveform element, and the pressure chamber held by the holding waveform element. a contraction waveform element that causes the liquid to be discharged by contracting the liquid;
The selection signal includes a signal for non-selecting a waveform portion extending from the middle of the holding waveform element to at least a part of the contraction waveform element of the drive pulse.

According to the present invention, variations in ejection characteristics can be reduced.

1 is a schematic explanatory diagram of a printing device as a device for ejecting liquid according to a first embodiment of the present invention. FIG. 2 is an explanatory plan view of a discharge unit of the printing apparatus. FIG. 3 is an explanatory cross-sectional view of an example of the head in a direction perpendicular to the nozzle arrangement direction. FIG. 4 is a cross-sectional explanatory diagram similarly taken along the nozzle arrangement direction. FIG. 2 is a block diagram illustrating a portion related to a head drive control device of the printing apparatus. FIG. 3 is an explanatory diagram for explaining common drive waveforms and selection signals in the first embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an applied waveform applied to a pressure generating element in the same embodiment. FIG. 3 is an explanatory diagram for explaining the operation of the embodiment. FIG. 7 is an explanatory diagram for explaining the ejection speed before and after correction. FIG. 7 is an explanatory diagram for explaining a common drive waveform and a selection signal in a second embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an applied waveform applied to a pressure generating element in the same embodiment. FIG. 7 is an explanatory diagram for explaining a common drive waveform and a selection signal in a third embodiment of the present invention. FIG. 6 is an explanatory diagram illustrating an applied waveform applied to a pressure generating element in the same embodiment. FIG. 3 is an explanatory diagram for explaining the operation of the embodiment. It is a schematic explanatory view of a printing device as a device which discharges liquid concerning an 8th embodiment of the present invention. FIG. 2 is an explanatory diagram of a discharge unit of the printing apparatus. It is an exploded perspective view of an example of a head module in the same embodiment. It is an exploded perspective explanatory view of the same head module seen from the nozzle surface side. FIG. 2 is an explanatory perspective view of the external appearance of an example of the head in the same embodiment as seen from the nozzle surface side. FIG. 4 is a perspective explanatory view of the external appearance seen from the side opposite to the nozzle surface. It is also an exploded perspective explanatory view. FIG. 4 is an exploded perspective view of the flow path forming member. 23 is an enlarged perspective explanatory view of the main part of FIG. 22. FIG. FIG. 4 is a cross-sectional perspective view of the flow path portion.

Embodiments of the present invention will be described below with reference to the accompanying drawings. DESCRIPTION OF THE PREFERRED EMBODIMENTS A printing apparatus as a liquid ejecting apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic explanatory diagram of the same printing apparatus, and FIG. 2 is a plan explanatory diagram of a discharge unit of the same printing apparatus.

The printing apparatus 1 includes a carry-in section 10 for carrying in the sheet material P, a pre-processing section 20, a printing section 30, a drying section 40, and a carry-out section 50. The printing apparatus 1 applies (applies) a pretreatment liquid as necessary to the sheet material P carried in (supplied) from the carry-in section 10 in a pretreatment section 20 serving as a pretreatment means, and applies (applies) a pretreatment liquid as necessary to the sheet material P carried in (supplied) from a carry-in section 10 . is applied to perform the required printing, and after drying the liquid adhering to the sheet material P in the drying section 40, the sheet material P is discharged to the carry-out section 50.

The carry-in section 10 includes a carry-in tray 11 (lower carry-in tray 11A, upper carry-in tray 11B) that accommodates a plurality of sheet materials P, and a feeding device 12 (12A) that separates sheet materials P from the carry-in tray 11 one by one and sends them out. , 12B), and supplies the sheet material P to the preprocessing section 20.

The pre-processing section 20 includes a coating section 21 that is a processing liquid applying means that applies a processing liquid having the effect of coagulating ink and preventing show-through to the printing surface of the sheet material P, for example.

The printing section 30 includes a drum 31 that is a supporting member (rotating member) that rotates while supporting the sheet material P on its circumferential surface, and a liquid discharge section 32 that discharges liquid toward the sheet material P supported on the drum 31. We are prepared.

The printing section 30 also includes a transfer cylinder 34 that receives the sheet material P fed from the preprocessing section 20 and passes the sheet material P to and from the drum 31, and a transfer cylinder 34 that receives the sheet material P conveyed by the drum 31 and inverts the sheet material P. A delivery cylinder 35 for delivering to a mechanism section 36 is provided.

The leading end of the sheet material P conveyed from the pre-processing section 20 to the printing section 30 is gripped by a gripping means (sheet gripper) provided on the transfer cylinder 34, and is conveyed as the transfer cylinder 34 rotates. The sheet material P conveyed by the transfer drum 34 is delivered to the drum 31 at a position facing the drum 31.

A gripping means (sheet gripper) is also provided on the surface of the drum 31, and the leading end of the sheet material P is gripped by the gripping means (sheet gripper). A plurality of suction holes are formed in a distributed manner on the surface of the drum 31, and suction means generates a suction airflow directed inward from the required suction holes of the drum 31.

The sheet material P transferred from the transfer drum 34 to the drum 31 is gripped at the leading end by a sheet gripper, is suctioned and supported on the drum 31 by the suction airflow by the suction means, and is conveyed as the drum 31 rotates. be done.

The liquid discharge section 32 includes a discharge unit 33 (33A to 33D) which is a liquid discharge means. For example, the ejection unit 33A emits cyan (C) liquid, the ejection unit 33B emits magenta (M) liquid, the ejection unit 33C emits yellow (Y) liquid, and the ejection unit 33D emits black (K) liquid. Discharge each. In addition, it is also possible to use a discharge unit that discharges a special liquid such as white or gold (silver).

For example, as shown in FIG. 2, the ejection unit 33 includes a plurality of liquid ejection heads (hereinafter simply referred to as "heads") 1 having a plurality of nozzle rows in which a plurality of nozzles 11 are arranged in a staggered manner on a base member 331. It is a full-line type head located in the

The ejection operation of each ejection unit 33 of the liquid ejection section 32 is controlled by a drive signal according to print information. When the sheet material P carried by the drum 31 passes through an area facing the liquid ejection section 32, liquids of each color are ejected from the ejection unit 33, and an image corresponding to the print information is printed.

The reversing mechanism section 36 is a mechanism that reverses the sheet material P in a switchback manner when double-sided printing is performed on the sheet material P passed from the delivery cylinder 35, and the reversed sheet material P is transferred to the printing section. 30 through the transport path 360 to the upstream side of the transfer cylinder 34.

The drying section 40 dries the liquid deposited on the sheet material P in the printing section 30. As a result, liquid components such as water in the liquid evaporate, the colorant contained in the liquid is fixed on the sheet material P, and curling of the sheet material P is suppressed.

The carry-out section 50 includes a carry-out tray 51 on which a plurality of sheet materials P are loaded. The sheet materials P conveyed from the drying section 40 are sequentially stacked and held on a carry-out tray 51.

Although this embodiment is explained using an example in which the sheet material is a cut sheet material, it is also possible to use a device that uses a continuous body (web) such as continuous paper or roll paper, and a device that uses sheet material such as wallpaper. The present invention can also be applied to the following.

Next, an example of the head will be described with reference to FIGS. 3 and 4. FIG. 3 is an explanatory cross-sectional view of the same head in a direction perpendicular to the nozzle arrangement direction, and FIG. 4 is a cross-sectional explanatory view similarly taken along the nozzle arrangement direction.

The head 1 of this embodiment has a nozzle plate 10, a channel plate 20, and a diaphragm member 30 as a wall member that are laminated and bonded. A piezoelectric actuator 40 that displaces a vibration region (diaphragm region, diaphragm) 31 of a diaphragm member 30 and a common flow path member 50 that also serves as a frame member of the head 1 are provided.

The nozzle plate 10 has a nozzle row in which a plurality of nozzles 11 are arranged.

The channel plate 20 includes a plurality of pressure chambers 21 communicating with the plurality of nozzles 11, an individual supply channel 22 which also serves as a fluid resistance section and communicating with each pressure chamber 21, and one or more channels communicating with the one or more individual supply channels 22. An intermediate supply channel 23 is formed. Adjacent pressure chambers 21, 21 are separated by a partition wall 28.

The diaphragm member 30 has a plurality of movable vibration regions 31 that form the walls of the pressure chambers 21 of the channel plate 20 . Here, the diaphragm member 30 has a two-layer structure (not limited thereto), and is composed of a first layer 30a forming a thin wall portion and a second layer 30b forming a thick wall portion from the channel plate 20 side.

A deformable vibration region 31 is formed in a portion of the first layer 30a, which is a thin wall portion, corresponding to the pressure chamber 21. In the vibration region 31, an island-shaped convex portion 31a, which is a thick portion that is joined to the piezoelectric actuator 40 in the second layer 30b, is formed. Furthermore, a joint portion 38, which is a thick portion, is formed in the second layer 30b at a portion of the diaphragm member 30 that corresponds to the pressure chamber partition wall 28.

A piezoelectric actuator 40 including an electromechanical transducer as a pressure generating element (driving means, actuator means) for deforming the vibration region 31 of the diaphragm member 30 is arranged on the opposite side of the diaphragm member 30 from the pressure chamber 21. are doing.

This piezoelectric actuator 40 is manufactured by forming grooves in a piezoelectric member 41 bonded to a base member 44 by half-cut dicing, and combing a required number of columnar piezoelectric elements 42 and pillars 43 at predetermined intervals in the nozzle arrangement direction. It is tooth-shaped.

The piezoelectric element 42 is a piezoelectric element that displaces the vibration region 31 by applying a driving voltage. The support column 43 is a piezoelectric element that supports the partition wall 28 between the pressure chambers 21, 21 without applying a driving voltage.

The piezoelectric element 42 is bonded to an island-shaped convex portion 31a, which is a thick wall portion, formed in the vibration region 31 of the diaphragm member 30 with an adhesive. On the other hand, the strut portion 43 is bonded to a joint portion 38, which is a thick portion, provided at a portion of the diaphragm member 30 corresponding to the partition wall 28 using an adhesive.

The piezoelectric member 41 is made by alternately laminating piezoelectric layers and internal electrodes, and the internal electrodes are each drawn out to an end face and connected to an external electrode (end face electrode), and a flexible wiring member 45 is connected to the external electrode. .

The common flow path member 50 forms a common supply flow path 51. The common supply channel 51 communicates with the intermediate supply channel 23 via a filter section 39 provided in the diaphragm member 30 .

In this head 1, for example, by lowering the piezoelectric element 42 from a reference potential (intermediate potential), the piezoelectric element 42 contracts, the vibration region 31 of the diaphragm member 30 is pulled, and the volume of the pressure chamber 21 expands. , liquid flows into the pressure chamber 21.

Thereafter, the voltage applied to the piezoelectric element 42 is increased to extend the piezoelectric element 42 in the stacking direction, and the vibration region 31 of the diaphragm member 30 is deformed in the direction toward the nozzle 11, thereby contracting the volume of the pressure chamber 21. , the liquid in the pressure chamber 21 is pressurized, and the liquid is discharged from the nozzle 11.

Next, parts related to the head drive control device that drives and controls the head will be explained with reference to the block diagram of FIG. 5.

The head drive control device 400 includes a head control section 401, a drive waveform generation section 402 and a waveform data storage section 403 that constitute drive waveform generation means, a head driver 410, and an ejection timing generation section 404 for generating ejection timing. It is equipped with

When the head control unit 401 receives the ejection timing pulse stb, it outputs an ejection synchronization signal LINE, which serves as a trigger for generation of a common drive waveform, to the drive waveform generation unit 402. Further, the head control unit 401 outputs an ejection timing signal CHANGE corresponding to the amount of delay from the ejection synchronization signal LINE to the drive waveform generation unit 402.

The drive waveform generation unit 402 generates and outputs a common drive waveform Vcom at a timing based on the ejection synchronization signal LINE and the ejection timing signal CHANGE.

The head control unit 401 also serves as means for outputting a selection signal that specifies a waveform portion to be selected by a selection means constituted by an analog switch AS of the head driver 410.

The head control unit 401 receives image data, and based on this image data, controls common driving for each nozzle 11 according to the size of liquid to be ejected from each nozzle 11 of the head 1 and variations in characteristics of the nozzle 11. A selection signal MN for selecting a predetermined required waveform portion of the waveform Vcom is generated. Therefore, the number of selection signals MN equal to the number of nozzles 11 is output. Further, the selection signal MN is a signal whose timing is synchronized with the ejection timing signal CHANGE.

Then, the head control unit 401 transfers the image data SD, the synchronization clock signal SCK, the latch signal LT that commands latching of the image data, and the generated selection signal MN to the head driver 410.

The head driver 410 is a selection unit that selects a waveform portion of the common drive waveform Vcom to be applied to each pressure generating element (piezoelectric element 42) of the liquid ejection head 1 based on various signals from the head control unit 401.

This head driver 410 includes a shift register 411, a latch circuit 412, a gradation decoder 413, a level shifter 414, and an analog switch array 415.

The shift register 411 receives the image data SD transferred from the head control unit 401 and the synchronization clock signal SCK. The latch circuit 412 latches each register value of the shift register 411 using a latch signal LT transferred from the head control unit 401.

The gradation decoder 413 decodes the value latched by the latch circuit 412 (image data SD) and the selection signal MN for each nozzle 11, and outputs the result. The level shifter 414 level-converts the logic level voltage signal of the gradation decoder 413 to a level at which the analog switch AS of the analog switch array 415 can operate.

The analog switch AS of the analog switch array 415 is a switch that is turned on/off by the output of the gradation decoder 413 provided via the level shifter 414, and is means for passing/not passing (blocking) the common drive waveform Vcom.

This analog switch AS is provided for each nozzle 11 included in the head 1, and is connected to an individual electrode of a piezoelectric element 42 corresponding to each nozzle 11. Further, the common drive waveform Vcom from the drive waveform generation section 402 is input to the analog switch AS. Further, as described above, the timing of the selection signal MN is synchronized with the timing of the common drive waveform Vcom.

Therefore, by switching the analog switch AS on and off at appropriate timing according to the output of the gradation decoder 413 provided via the level shifter 414, the piezoelectric element 42 corresponding to each nozzle 11 is transferred from the common drive waveform Vcom. A portion of the waveform to be applied is selected. As a result, the size of the droplet ejected from the nozzle 11 is controlled.

The discharge timing generation unit 404 generates and outputs a discharge timing pulse stb every time the sheet material P is moved by a predetermined amount, based on the detection result of the rotary encoder 405 that detects the amount of rotation of the drum 31. The rotary encoder 405 includes an encoder wheel that rotates together with the drum 31 and an encoder sensor that reads a slit in the encoder wheel.

Next, drive waveforms in the first embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is an explanatory diagram for explaining the common drive waveform and selection signal in the same embodiment, and FIG. 7 is an explanatory diagram for explaining the applied waveform applied to the pressure generating element in the same embodiment.

As shown in FIG. 6A, the drive waveform Vcom of this embodiment includes a drive pulse P as an ejection pulse that pressurizes the pressure chamber 21 and ejects the liquid. The drive pulse P is, for example, a pulse for ejecting small droplets (droplets).

The drive pulse P includes an expansion waveform element a that expands the pressure chamber 21, a holding waveform element b that maintains the state expanded by the expansion waveform element a, and a holding waveform element b that holds the pressure chamber 21 from the state held by the holding waveform element b. and a contraction waveform element c that is contracted to eject liquid.

The expansion waveform element a is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V1 (V1<Vm).

The holding waveform element b is a waveform that holds the potential V1, which is the terminal potential of the expansion waveform element a.

In the present embodiment, the contraction waveform element c is a waveform that performs two-stage contraction, rising from the held potential V1 to the potential V2 (Vm>V2>V1), holding the potential V2 for a predetermined time, and then rising to the intermediate potential. Stand up to Vm.

In this embodiment, the contraction waveform element c includes a first stage contraction waveform element c1 that rises from potential V1 to potential V2, an intermediate hold waveform element c2 that holds potential V2, and a second stage contraction waveform element c2 that rises from potential V2 to intermediate potential Vm. It is composed of a contraction waveform element c3.

On the other hand, the selection signal MN for selecting the drive pulse P output from the head control unit 401 includes multiple types (here, three) of selection signals A, B, and C, as shown in FIG. 6(b). There is. The head control unit 401 outputs one of the selection signals A, B, and C predetermined for each nozzle 11 as the selection signal MN.

In this embodiment, when the selection signals A, B, and C are "L", the common drive waveform Vcom passes through the analog switch AS, and when the selection signals A, B, and C are "H", the common drive waveform It is assumed that Vcom does not pass through the analog switch AS. That is, by turning on the selection signals A to C, the waveform portion to be selected by the analog switch AS (selection means) is designated.

The selection signal A transitions from "H" to "L" in the middle (time t0) of the intermediate potential holding waveform element d, which is a waveform element before the falling start (starting end) of the expansion waveform element a. Then, the selection signal A transitions from "L" to "H" in the middle (time t4) of the intermediate potential holding waveform element e, which is a waveform element after the contraction waveform element c ends and rises to the intermediate potential Vm. .

Therefore, when the selection signal A is output, all of the drive pulses P pass through, as shown by the solid line in FIG. 6(c). As a result, the applied waveform PA shown in FIG. 7(a) is applied to the piezoelectric element 42. Note that the "applied waveform" is a drive waveform applied to the piezoelectric element 42.

The selection signal B transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0), and from "L" to "H" in the middle of the holding waveform element b (time t1). , transitions from "H" to "L" again in the middle of the contraction/holding waveform element c2 (time t2). Then, the selection signal B transitions from "L" to "H" in the middle of the intermediate potential holding waveform element e (time t4).

In this way, when the selection signal B transitions from "L" to "H" in the middle of the holding waveform element b, and the common drive waveform Vcom does not pass, the voltage applied to the piezoelectric element 42 changes to the holding potential at that time. It is held at V1. Then, when the selection signal B transitions from "H" to "L", it rises from the holding potential V1 to the potential of the contraction waveform element c at the time of the transition.

Therefore, when the selection signal B is output, as shown by the dashed line in FIG. 6(c), the waveform portion of the drive pulse P up to time t1 passes, and the potential V1 is held between time t1 and t2. At time t2, the potential of the intermediate holding waveform element c2 of the contraction waveform element c rises to the potential V2. As a result, an applied waveform PB shown in FIG. 7(b) is applied to the piezoelectric element 42.

The selection signal C transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0), and from "L" to "H" in the middle of the holding waveform element b (time t1). , transitions from "L" to "H" at the end of the second stage contraction waveform element c3 (time t3). Then, the selection signal C transitions from "L" to "H" in the middle of the intermediate potential holding waveform element e (time t4).

Therefore, when the selection signal C is output in the same manner as the selection signal B, as shown by the two-dot chain line in FIG. The potential V1 is held between t1 and t3, and rises to the intermediate potential Vm at time t3. As a result, the applied waveform PC shown in FIG. 7(c) is applied to the piezoelectric element 42.

That is, in this embodiment, the selection signals B and C are both signals that unselect the waveform portion extending from the middle of the holding waveform element b of the drive pulse P to at least part of the contraction waveform element c. In this embodiment, the selection signal for unselecting a waveform portion extending from the middle of the holding waveform element b to at least a part of the contraction waveform element c of the drive pulse P includes two waveform portions for unselecting different waveform portions. Selection signals B and C are included.

As shown in FIG. 7, the applied waveforms PA to PC have a relationship of PwA<PwB<PwC, where the time of the holding waveform element b is the pulse width PwA to PwC.

Therefore, by applying selection signals A to C according to the ejection characteristics of the nozzle 11 to the piezoelectric element 42 of the nozzle 11, the ejection speed (droplet speed) of the liquid (droplet) ejected from the nozzle 11 can be adjusted. Variations can be suppressed.

Next, an example of the operation of this embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is an explanatory diagram illustrating an example of the relationship between the three nozzles, selection signals, and applied waveforms, and FIG. 9 is an explanatory diagram illustrating the ejection speed before and after correction.

Here, as shown in FIG. 9, it is assumed that droplets D1 to D3 are ejected from three nozzles n1 to n3, respectively. When all of the drive pulses P (applied waveform PA) are applied to three nozzles n1 to n3, as shown in FIG. The droplet D2 of the nozzle n3 is delayed in the order of the droplet D3 of the nozzle n3.

Further, the pulse width PwC of the applied waveform PC is set to a time that can most efficiently increase the discharge speed to the pressure chamber 21.

Therefore, as shown in FIG. 8, selection signals A to C are assigned to each nozzle n1 to n3. The application waveform PA is applied to the nozzle n1 having the characteristic of the fastest ejection speed, and the application waveform PB is applied to the nozzle n2 having the characteristic of the second fastest ejection speed. Then, the application waveform PC is applied to the nozzle n3 having the characteristic of the slowest ejection speed.

As a result, as shown in FIG. 9(b), the variation in the ejection speed of the droplets D1 to D3 ejected from each nozzle n1 to n3 is reduced, and the ejection speeds are almost the same (including the same). It can be adjusted (corrected) to

In this case, since three types of applied waveforms are extracted using the same common drive waveform Vcom, variations in ejection characteristics can be reduced without increasing the waveform length. Further, there is no need to provide a drive waveform generation circuit for each nozzle. Note that the number of selection signals is not limited to three types, but can be two, or four or more types.

Next, a second embodiment of the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is an explanatory diagram for explaining the common drive waveform and selection signal in the same embodiment, and FIG. 11 is an explanatory diagram for explaining the applied waveform applied to the pressure generating element in the same embodiment.

As shown in FIG. 10A, the drive waveform Vcom of this embodiment includes a drive pulse P as an ejection pulse that pressurizes the pressure chamber 21 and ejects the liquid. The drive pulse P is, for example, a pulse for ejecting small droplets (droplets).

The drive pulse P includes an expansion waveform element a that expands the pressure chamber 21, a holding waveform element b that maintains the state expanded by the expansion waveform element a, and a holding waveform element b that holds the pressure chamber 21 from the state held by the holding waveform element b. and a contraction waveform element c that is contracted to eject liquid.

The expansion waveform element a is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V1 (V1<Vm). The holding waveform element b is a waveform that holds the potential V1, which is the terminal potential of the expansion waveform element a. In this embodiment, the contraction waveform element c is a waveform that performs one-step contraction, and rises from the held potential V1 to the intermediate potential Vm.

On the other hand, as shown in FIG. 10(b), the selection signal MN for selecting the drive pulse P output from the head control unit 401 includes multiple types (four in this case) of selection signals A, B, C, and D. Contains. The head control unit 401 outputs any one of the selection signals A, B, C, and D predetermined for each nozzle 11 as the selection signal MN.

In this embodiment, when the selection signals A, B, C, and D are "L", the common drive waveform Vcom passes through the analog switch AS, and when the selection signals A, B, C, and D are "H", the common drive waveform Vcom passes through the analog switch AS. , the common drive waveform Vcom does not pass through the analog switch AS (does not pass).

The selection signal A transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0) before the expansion waveform element a starts falling, and after the contraction waveform element c ends, the intermediate potential Vm is reached. In the middle of the intermediate potential holding waveform element e after rising to 1 (time t5), it transitions from "L" to "H".

Therefore, when the selection signal A is output, the entire drive pulse P passes through, as shown by the solid line in FIG. 10(c). As a result, the applied waveform PA shown in FIG. 11(a) is applied to the piezoelectric element 42.

The selection signal B transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0), and from "L" to "H" in the middle of the holding waveform element b (time t1). , transitions from "H" to "L" again in the middle of contraction waveform element c (time t2). Then, in the middle of the intermediate potential holding waveform element e (time t5), it transitions from "L" to "H".

Therefore, when the selection signal B is output, as shown by the dashed line in FIG. 10(c), the waveform portion of the drive pulse P up to time t1 passes, and the potential V1 is held between time t1 and t2. It rises to the potential of contraction waveform element c at time t2. As a result, an applied waveform PB shown in FIG. 11(b) is applied to the piezoelectric element 42.

The selection signal C transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0), and from "L" to "H" in the middle of the holding waveform element b (time t1). , transitions from "L" to "H" at the end of contraction waveform element c (time t3). Then, in the middle of the intermediate potential holding waveform element e (time t5), it transitions from "L" to "H".

Therefore, when the selection signal C is output, as shown by the two-dot chain line in FIG. 10(c), the waveform portion of the drive pulse P up to time t1 passes, and the potential V1 is held between time t1 and t3. , rises to the potential of contraction waveform element c at time t3. As a result, the applied waveform PC shown in FIG. 11(c) is applied to the piezoelectric element 42.

The selection signal D transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0), and from "L" to "H" in the middle of the holding waveform element b (time t1). , transitions from "L" to "H" at the end of contraction waveform element c (time t4). Then, in the middle of the intermediate potential holding waveform element e (time t5), it transitions from "L" to "H".

Therefore, when the selection signal D is output, as shown by the broken line in FIG. It rises to the potential of contraction waveform element c at t4. As a result, the applied waveform PD shown in FIG. 11(d) is applied to the piezoelectric element 42.

That is, in this embodiment, the selection signals B, C, and D are all signals that unselect the waveform portion extending from the middle of the holding waveform element b of the drive pulse P to at least a part of the contraction waveform element c. . In the present embodiment, the selection signal for unselecting a waveform portion extending from the middle of the holding waveform element b to at least part of the contraction waveform element c of the driving pulse P includes three waveform portions for unselecting different waveform portions. Selection signals B, C, and D are included.

Here, for example, the plurality of nozzles 11 are divided into four groups based on the ejection speed, and selection signals A, B, C, and D are assigned in descending order of the ejection speed.

Since the voltage change of the contraction waveform element c becomes steeper in the order of the applied waveforms PA to PD, the applied waveform PA can correct the ejection speed relatively slowest, and the applied waveform PD can correct the ejection speed relatively faster.

In this way, by dividing the plurality of nozzles 11 into groups and allocating selection signals to them, variations in ejection speed can be reduced.

Note that grouping can be performed in the same manner in the first embodiment as well.

Next, a third embodiment of the present invention will be described with reference to FIGS. 12 to 14. FIG. 12 is an explanatory diagram for explaining the common drive waveform and selection signal in the same embodiment, and FIG. 13 is an explanatory diagram for explaining the applied waveform applied to the pressure generating element in the same embodiment. FIG. 14 is an explanatory diagram for explaining the operation of the embodiment.

As shown in FIG. 12A, the drive waveform Vcom of this embodiment includes a drive pulse P as an ejection pulse that pressurizes the pressure chamber 21 and ejects the liquid. The drive pulse P is, for example, a pulse for ejecting small droplets (droplets).

The drive pulse P is composed of a first pulse (first waveform portion) P1 that causes liquid to be ejected, and a second pulse (second waveform portion) P2 that does not cause liquid to be ejected.

The first pulse P1 of the drive pulse P is an expansion waveform element a that expands the pressure chamber 21, a holding waveform element b that maintains the state expanded by the expansion waveform element a, and a state held by the holding waveform element b. and a contraction waveform element c that contracts the pressure chamber 21 and discharges liquid.

The expansion waveform element a is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V1 (V1<Vm). The holding waveform element b is a waveform that holds the potential V1, which is the terminal potential of the expansion waveform element a. In this embodiment, the contraction waveform element c is a waveform that performs one-step contraction, and is a waveform that rises from the held potential V1 to the intermediate potential Vm.

The second pulse P2 of the drive pulse P is an expansion waveform element f that expands the pressure chamber 21, a holding waveform element g that maintains the state expanded by the expansion waveform element f, and a state held by the holding waveform element g. , and a contraction waveform element h that contracts the pressure chamber 21 (does not eject liquid).

The expansion waveform element f is a waveform that falls from the intermediate potential (or reference potential) Vm to the potential V3 (V1<V3<Vm). The holding waveform element g is a waveform that holds the potential V3, which is the terminal potential of the expansion waveform element f. The contraction waveform element g is a waveform that rises from the held potential V3 to the intermediate potential Vm.

The terminal end of the contraction waveform element c of the first pulse P1 and the start end of the expansion waveform element f of the second pulse P2 are connected by a bridging waveform element i that holds the terminal potential of the contraction waveform element c. Note that the potential held by the bridging waveform element i is the intermediate potential Vm in this embodiment, but it is the terminal potential of the contraction waveform element c of the first pulse P1 (the final potential when two-step contraction is performed). It is also possible to set the potential to be higher than the intermediate potential Vm and hold the potential.

On the other hand, the selection signal MN for selecting the drive pulse P output from the head control unit 401 includes multiple types (four in this case) of selection signals A, B, and C, as shown in FIG. 12(b). There is. The head control unit 401 outputs one of the selection signals A, B, and C predetermined for each nozzle 11 as the selection signal MN.

In this embodiment, when the selection signals A, B, and C are "L", the common drive waveform Vcom passes through the analog switch AS, and when the selection signals A, B, and C are "H", the common drive waveform It is assumed that Vcom does not pass through the analog switch AS.

The selection signal A transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time t0) before the start of the fall of the expansion waveform element a, and then transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d before the start of the fall of the expansion waveform element a. In the middle of the intermediate potential holding waveform element e after rising to the potential Vm (time t3), it transitions from "L" to "H".

Therefore, when the selection signal A is output, the applied waveform PA shown in FIG. 13(a) is applied to the piezoelectric element 42.

The selection signal B transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time point t0), and transitions from "H" to "L" in the middle of the bridging waveform element i between the first pulse P1 and the second pulse P2 (time point t0). At t1), there is a transition from "L" to "H". Then, the selection signal B transitions from "H" to "L" in the middle of the holding waveform element g of the second pulse P2 (time t2), and after the contraction waveform element h ends and rises to the intermediate potential Vm. In the middle of the intermediate potential holding waveform element e (time t3), it transitions from "L" to "H".

Therefore, when the selection signal B is output, the applied waveform PB shown in FIG. 13(b) is applied to the piezoelectric element 42.

The selection signal C transitions from "H" to "L" in the middle of the intermediate potential holding waveform element d (time point t0), and transitions from "H" to "L" in the middle of the bridging waveform element i between the first pulse P1 and the second pulse P2 (time point t0). At t1), there is a transition from "L" to "H".

Therefore, when the selection signal C is output, the applied waveform PC shown in FIG. 13(c) is applied to the piezoelectric element 42.

That is, in the present embodiment, the selection signals B and C are both in the middle of the bridging waveform element i after the first contraction waveform element c of the first pulse P1 of the drive pulse P (the first contraction waveform element c of the second pulse P2). This is a signal that deselects a waveform portion extending from (before the start of the second expansion waveform element g) to at least a portion of the second pulse P2. In the present embodiment, the selection signal for unselecting a waveform portion extending from the middle of the bridging waveform element i of the drive pulse P to at least a part of the second pulse P2 includes two waveform portions for unselecting different waveform portions. Selection signals B and C are included.

As shown in FIG. 13, the applied waveforms PA to PC have the relationship TwA<TwB<TwC=0, where the time interval of the bridging waveform element i between the first pulse P1 and the second pulse P2 is Tw. become.

Here, the second pulse P2 in this embodiment expands the pressure chamber 21 with the expansion waveform element g when the liquid is being ejected by the first pulse P1, so that the ejected droplet (liquid column extending from the nozzle 11) ) can be pulled back into the pressure chamber 21, thereby reducing the discharge amount.

Furthermore, the shorter the interval Tw between the first pulse P1 and the second pulse P2 (the period of the bridging waveform element i), the smaller the ejection amount.If the interval Tw is sufficiently long, or if there is no second pulse P (TwC= 0), the ejection amount increases.

Therefore, the ejection amount of application waveform A is the smallest, the ejection amount of application waveform C is the largest, and the ejection amount of application waveform B is intermediate.

Here, as shown in FIG. 14, when applying the applied waveform A, the ejection amount of the nozzle group of group 1 is large, the ejection amount of the nozzle group of group 2 is medium, and the ejection amount of the nozzle group of group 3 is small. Suppose that

Therefore, selection signal A is assigned to the nozzles in group 1 and applied waveform A is applied, selection signal B is assigned to the nozzles in group 2 and applied waveform B is applied, and selection signal C is applied to the nozzles in group 3. is assigned to give the applied waveform C. This makes it possible to reduce variations in the amount of ejection between the nozzles.

Further, in this embodiment, the second pulse P2 is a pulse that does not eject liquid, but it can also be a pulse that causes liquid to be ejected.

In this embodiment as well, since three types of applied waveforms are extracted using the same common drive waveform Vcom, variations in ejection characteristics can be reduced without increasing the waveform length. Further, there is no need to provide a drive waveform generation circuit for each nozzle. Note that the number of selection signals is not limited to three types, but can be two, or four or more types.

In each of the above embodiments, the selection signal MN includes two or more types of signals (selection signals A to D, etc.), but one type of selection signal MN can specify multiple waveform parts. It may be possible to do so.

Next, a printing device as a device for ejecting liquid according to an eighth embodiment of the present invention will be described with reference to FIGS. 15 and 16. FIG. 15 is a schematic explanatory diagram of the printing apparatus, and FIG. 16 is an explanatory diagram of a discharge unit of the printing apparatus.

The printing device 500 includes a carry-in section 510 that carries in sheet material P such as a continuous body, a roll paper, a web, etc., a guide conveyance section 570 that guides and conveys the sheet material P carried in from the carry-in section 510 to the printing section 530, and a sheet It includes a printing section 530 that prints by discharging liquid onto the material P, a drying section 540 that dries the sheet material P, and a delivery section 550 that transports the sheet material P.

The sheet material P is sent out from the original winding roller 591 of the carry-in section 510, guided and conveyed by each roller of the carry-in section 510, the guide conveyance section 570, the drying section 540, and the carry-out section 550, and then taken up by the winding roller 592 of the carry-out section 550. It is wound up.

This sheet material P is conveyed in a printing section 530 facing a discharge unit 533, and an image is printed on the sheet material P using liquid discharged from the discharge unit 533.

Here, the discharge unit 533 includes two head modules 100A and 100B on the common base member 113.

When the direction in which the heads 1 are lined up in the direction perpendicular to the transport direction of the head module 100 is defined as the head arrangement direction, the head rows 1A1 and 1A2 of the head module 100A eject liquid of the same color. Similarly, the head rows 1B1 and 1B2 of the head module 100A are set as a set, the head rows 1C1 and 1C2 of the head module 100B are set as a set, and the head rows 1D1 and 1D2 are set as a set, and liquid of a desired color is ejected, respectively.

Next, an example of the head module in this embodiment will be described with reference to FIGS. 17 and 18. FIG. 17 is an exploded perspective view of the head module, and FIG. 18 is an exploded perspective view of the head module viewed from the nozzle surface side.

The head module 100 includes a plurality of heads 1 that are liquid ejection heads that eject liquid, and a base member 103 that holds the plurality of heads 1.

The head module 100 also includes a heat dissipation member 104, a manifold 105 forming a flow path for supplying liquid to the plurality of heads 1, a printed circuit board (PCB) 106 connected to the flexible wiring member 101, and a module. A case 107 is provided.

Next, an example of the head in this embodiment will be described with reference to FIGS. 19 to 24. FIG. 19 is an explanatory perspective view of the external appearance of the same head as seen from the nozzle surface side, FIG. 20 is an explanatory perspective view of the external appearance of the same head as seen from the side opposite to the nozzle surface, FIG. 21 is an exploded perspective explanatory view of the head, and FIG. 22 is the same flow path configuration. 23 is an enlarged perspective view of the main part of FIG. 22, and FIG. 24 is a cross-sectional perspective view of the flow path portion.

The liquid ejection head 1 includes a nozzle plate 10 , a flow path plate (individual flow path member) 20 , a diaphragm member 30 , a common flow path member 50 , a damper member 60 , a common flow path member 70 , and a frame member 80 , a wiring member (flexible wiring board) 45, and the like. A head driver (driver IC) 410 is mounted on the wiring member 45 .

The nozzle plate 10 has a plurality of nozzles 11 that eject liquid. The plurality of nozzles 11 are arranged in a two-dimensional matrix.

The individual flow path member 20 includes a plurality of pressure chambers (individual liquid chambers) 21 each communicating with the plurality of nozzles 11 , a plurality of individual supply flow paths 22 communicating with the plurality of pressure chambers 21 , and a plurality of pressure chambers 21 . A plurality of individual recovery channels 23 are formed, each of which communicates with the other. One pressure chamber 21 and the individual supply flow path 22 and individual recovery flow path 23 communicating therewith are collectively referred to as an individual flow path 25.

The diaphragm member 30 forms a diaphragm 31 that is a deformable wall surface of the pressure chamber 21, and the diaphragm 31 is integrally provided with a piezoelectric element 42. Further, the diaphragm member 30 is formed with a supply side opening 32 communicating with the individual supply channel 22 and a recovery side opening 33 communicating with the individual recovery channel 23. The piezoelectric element 42 is a pressure generating means that deforms the diaphragm 31 and pressurizes the liquid in the pressure chamber 21.

Note that the individual flow path member 20 and the diaphragm member 30 are not limited to being separate members. For example, the individual flow path member 20 and the diaphragm member 30 can be integrally formed from the same member using an SOI (Silicon on Insulator) substrate. That is, an SOI substrate in which a silicon oxide film, a silicon layer, and a silicon oxide film are formed in this order on a silicon substrate is used, and the silicon substrate is used as the individual flow path member 20, and the silicon oxide film, the silicon layer, and the silicon oxide film are formed on the silicon substrate. The diaphragm 31 can be formed using the above. In this configuration, the layered structure of the silicon oxide film, the silicon layer, and the silicon oxide film of the SOI substrate becomes the diaphragm member 30. In this way, the diaphragm member 30 includes one made of a material formed into a film on the surface of the individual channel member 20.

The common channel member 50 is a common channel tributary member, and includes a plurality of common supply channel tributaries 52 communicating with two or more individual supply channels 22 and a plurality of common recovery channels communicating with two or more individual recovery channels 23. The tributaries 53 are formed adjacent to each other alternately.

The common channel member 50 includes a through hole that serves as a supply port 54 that communicates with the supply side opening 32 of the individual supply channel 22 and the common supply channel tributary 52, and a through hole that connects the recovery side opening 33 of the individual recovery channel 23 with the common recovery channel. A through hole is formed to serve as a recovery port 55 through which the tributary stream 53 passes.

In addition, the common flow path member 50 includes a portion 56a of one or more common supply flow path main streams 56 that communicate with the plurality of common supply flow path tributaries 52, and one or more common flow path members 56a that communicate with the plurality of common recovery flow path tributaries 53. It forms a part 57a of the main stream 57 of the recovery channel.

The damper member 60 includes a supply side damper 62 that faces (opposes) the supply port 54 of the common supply channel tributary 52 and a recovery side damper 63 that faces (opposes) the recovery port 55 of the common recovery channel tributary 53. have.

Here, the common supply channel tributary 52 and the common recovery channel tributary 53 have grooves arranged alternately in the common channel member 50, which is the same member, sealed with a damper member 60 forming a deformable wall surface. It consists of

The common flow path member 70 is a common flow path main stream member, and includes a common supply flow path main flow 56 communicating with a plurality of common supply flow path tributaries 52 and a common recovery flow path main flow 57 communicating with a plurality of common recovery flow path tributaries 53. Form.

A part 56b of the main stream 56 of the supply channel and a part 57b of the main stream 57 of the common recovery channel are formed in the frame member 80. A portion 56b of the common main supply channel 56 communicates with a supply port 81 provided in the frame member 80, and a portion 57b of the common recovery channel main stream 57 communicates with a recovery port 82 provided in the frame member 80.

In this head 1, the liquid passes from the common supply channel main stream 56 to the common supply channel branch 52, is supplied from the supply port 54 to the pressure chamber 21, and is discharged from the nozzle 11. The liquid that is not discharged from the nozzle 11 passes through the common recovery channel tributary 53 from the recovery port 55, flows into the common recovery channel main stream 57, passes through the recovery port 82, an external circulation device, and passes through the supply port 81, and then returns to the common supply stream. is supplied to the main stream 56.

In this way, even when the nozzles 11 include the heads 1 arranged in a two-dimensional matrix, the head drive control according to the first to fourth embodiments can be applied.

In the present application, the liquid to be ejected may have a viscosity and surface tension that can be ejected from the head, and is not particularly limited, but the viscosity becomes 30 mPa・s or less at room temperature and normal pressure, or by heating or cooling. Preferably. More specifically, solvents such as water and organic solvents, coloring agents such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , edible materials such as natural pigments, etc., and these include, for example, inkjet inks, surface treatment liquids, constituent elements of electronic devices and light emitting devices, and formation of electronic circuit resist patterns. It can be used for purposes such as a liquid for use in liquids, a material liquid for three-dimensional modeling, and the like.

Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators using electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a diaphragm and opposing electrodes are used as energy sources for discharging liquid. Includes things that do.

Furthermore, "devices that eject liquid" include not only devices that can eject liquid onto objects to which liquid can adhere, but also devices that eject liquid into the air or into liquid. .

The "device for discharging liquid" may include means for feeding, transporting, and discharging objects to which liquid can adhere, as well as pre-processing devices, post-processing devices, and the like.

For example, an image forming device is a device that ejects ink to form an image on paper as a “device that ejects liquid,” and an image forming device that forms layers of powder to form three-dimensional objects (three-dimensional objects). There is a three-dimensional modeling device (three-dimensional modeling device) that discharges a modeling liquid onto a powder layer.

Further, the "device for ejecting liquid" is not limited to a device that can visualize significant images such as characters and figures using ejected liquid. For example, it includes those that form patterns that have no meaning in themselves, and those that form three-dimensional images.

The above-mentioned "something to which a liquid can adhere" refers to something to which a liquid can adhere at least temporarily, such as something that adheres and sticks, something that adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic boards, piezoelectric elements, powder layers, organ models, and test cells. Unless otherwise specified, it includes everything to which liquid adheres.

The material for the above-mentioned "material to which liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere thereto, even temporarily.

Further, the "device for discharging liquid" includes a device in which a liquid discharging head and an object to which liquid can be attached move relative to each other, but the present invention is not limited to this. Specific examples include a serial type device that moves a liquid ejection head, a line type device that does not move a liquid ejection head, and the like.

In addition, the "device for discharging a liquid" includes a processing liquid coating device that discharges a processing liquid onto paper in order to apply the processing liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulation device that granulates fine particles of the raw material by spraying a composition liquid in which the raw material is dispersed in a solution through a nozzle.

In addition, in the terms of this application, image formation, recording, printing, imprinting, printing, modeling, etc. are all synonymous.

1 Printing device 10 Carrying-in section 20 Pre-processing section 30 Printing section 40 Drying section 50 Carrying-out section 21 Application section 33 Discharge unit 100 Liquid discharge head (head)
106 Pressure chamber 112 Piezoelectric element 400 Head drive control device 401 Head control section 402 Drive waveform generation section 403 Waveform data storage section 410 Head driver

Claims (8)

a drive waveform generation unit that generates and outputs a common drive waveform including a drive pulse that causes liquid to be ejected from a nozzle of the liquid ejection head;
Selection means for selecting a waveform portion of the drive pulse applied to the pressure generating element of the liquid ejection head from the common drive waveform;
means for outputting a selection signal specifying a waveform portion to be selected by the selection means,
The driving pulse includes at least an expansion waveform element that expands the pressure chamber of the liquid ejection head, a holding waveform element that maintains the expanded state by the expansion waveform element, and the pressure chamber held by the holding waveform element. a contraction waveform element that causes the liquid to be discharged by contracting the liquid;
An apparatus for ejecting liquid, wherein the selection signal includes a signal for unselecting a waveform portion extending from the middle of the holding waveform element to at least a part of the contraction waveform element of the drive pulse. a drive waveform generation unit that generates and outputs a common drive waveform including a drive pulse that causes liquid to be ejected from a nozzle of the liquid ejection head;
Selection means for selecting a waveform portion of the drive pulse applied to each pressure generating element of the liquid ejection head from the common drive waveform;
means for outputting a selection signal specifying a waveform portion to be selected by the selection means,
The drive pulse includes a continuous first pulse and a second pulse,
The first pulse is a pulse that causes the liquid to be ejected,
The second pulse includes an expansion waveform element that expands the pressure chamber of the liquid ejection head , a holding waveform element that maintains the expanded state by the expansion waveform element, and a holding waveform element that maintains the pressure chamber held by the holding waveform element. a contraction waveform element to be contracted;
The end of the first pulse and the start of the second pulse are connected by a bridging waveform element that holds the end potential of the first pulse,
An apparatus for discharging a liquid, wherein the selection signal includes a signal for non-selecting a waveform portion extending from the middle of the bridging waveform element of the drive pulse to at least a part of the second pulse. 3. The device for ejecting liquid according to claim 2, wherein the selection signal includes a signal that deselects all of the second pulses of the drive pulses. 4. The device for ejecting liquid according to claim 1, wherein the selection signal includes a signal for selecting all of the drive pulses. 5. The selection signal includes a plurality of signals that unselect some waveform portions of the drive pulse, and the waveform portions to be unselected are different. A device for discharging the liquid described in . An applied waveform applied to the pressure generating element of the nozzle whose ejection speed or ejection amount of the liquid exceeds a predetermined amount, and an applied waveform applied to the pressure generating element of the nozzle whose ejection speed of the liquid is equal to or less than a predetermined amount. 6. The device for discharging a liquid according to claim 1, wherein the liquid discharging device has different values. a drive waveform generation unit that generates and outputs a common drive waveform including a drive pulse that causes liquid to be ejected from a nozzle of the liquid ejection head;
Selection means for selecting a waveform portion of the drive pulse applied to the pressure generating element of the liquid ejection head from the common drive waveform;
means for outputting a selection signal specifying a waveform portion to be selected by the selection means,
The driving pulse includes at least a first expansion waveform element that expands the pressure chamber of the liquid ejection head, a first holding waveform element that maintains the expanded state by the first expansion waveform element, and the first holding waveform. a first contraction waveform element that causes the pressure chamber held by the element to contract and discharge the liquid;
The head drive control device is characterized in that the selection signal includes a signal for unselecting a waveform portion of the drive pulse that extends from the middle of the first holding waveform element to at least a part of the first contraction waveform element. . a drive waveform generation unit that generates and outputs a common drive waveform including a drive pulse that causes liquid to be ejected from a nozzle of the liquid ejection head;
Selection means for selecting a waveform portion of the drive pulse applied to the pressure generating element of the liquid ejection head from the common drive waveform;
means for outputting a selection signal specifying a waveform portion to be selected by the selection means,
The drive pulse includes a continuous first pulse and a second pulse,
The first pulse is a pulse that causes liquid to be ejected,
The second pulse includes an expansion waveform element that expands the pressure chamber of the liquid ejection head , a holding waveform element that maintains the expanded state by the expansion waveform element, and a holding waveform element that maintains the pressure chamber held by the holding waveform element. a contraction waveform element to be contracted;
The end of the first pulse and the start of the second pulse are connected by a bridging waveform element that holds the end potential of the first pulse,
The head drive control device is characterized in that the selection signal includes a signal for non-selecting a waveform portion extending from the middle of the bridging waveform element of the drive pulse to at least a part of the second pulse.

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