Liquid ejection device, head drive control device

Abstract

To reduce variation in discharge characteristics.SOLUTION: A liquid discharging device comprises an analog switch AS which selects passage and non-passage of a drive waveform Vcom that drives a piezoelectric element 140 of a head 100, and a head control section 410 which outputs a selective signal for controlling passage and non-passage of the drive waveform Vcom by the analogue switch AS. The drive waveform Vcom includes a falling waveform element a23 that becomes an expanding waveform element for expanding a pressure chamber 121 of the head 100, and selectively outputs a first selective signal A1 for controlling the analogue switch AS so that a waveform, which changes from a first potential V1 to a third potential which becomes a start potential of the expanding waveform element, is applied to the piezoelectric element 140, and a second selective signal A2 for controlling the analogue switch AS so that a waveform, which changes from a second potential V2 different from the first potential V1 to the third potential, is applied to the piezoelectric element 140.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a liquid ejecting device and a head drive control device. [Background technology]

[0002] Due to manufacturing variations and the like, liquid ejection heads have variations in the ejection speed and ejection amount of liquid between heads or between nozzles.

[0003] Conventionally, there is known a technique for adjusting the trimming range in the period from an expansion waveform element (falling waveform element) in a common drive waveform that expands a pressure chamber to a holding waveform element that holds the expanded state (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2018-509320 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration disclosed in Patent Document 1, when a common drive pulse is used for ejecting different droplet types, for example, large and small droplets, the same trimming is performed regardless of the droplet type. Therefore, if the variation differs between the droplet types, it is difficult to simultaneously correct both droplet types, and there is a problem that the ejection characteristics vary depending on the droplet type.

[0006] The present invention has been made in consideration of the above problems, and has an object to reduce the variation in ejection characteristics. [Means for solving the problem]

[0007] In order to solve the above problems, a liquid ejection device according to the present invention comprises: A head having a plurality of nozzles for ejecting liquid; a selection means for selecting whether or not to pass a drive waveform for driving a piezoelectric element of the head; a means for outputting a selection signal for controlling the selection means to select whether to pass or not pass the driving waveform; the drive waveform includes an expansion waveform element that expands a pressure chamber of the head, The output means includes at least a first selection signal for controlling the selection means so that a waveform that changes from a first potential to a start potential of the expansion waveform element is applied to the piezoelectric element; a second selection signal for controlling the selection means so that a waveform that changes from a second potential different from the first potential to a start potential of the expansion waveform element is applied to the piezoelectric element, among the driving waveforms. The composition was as follows.

[0008] According to the present invention, the variation in ejection characteristics can be reduced. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic explanatory diagram of a printing apparatus as a liquid ejecting apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view illustrating a discharge unit of the printing apparatus. [Diagram 3] FIG. 2 is an explanatory external perspective view of an example of a head of a discharge unit, as viewed from the nozzle surface side. [Figure 4] FIG. 13 is an explanatory perspective view of the exterior of the inkjet head as viewed from the opposite side to the nozzle surface. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 7 is an enlarged perspective view of a main part of FIG. 6. [Figure 8] FIG. [Figure 9] FIG. 2 is a block diagram illustrating a portion relating to a head drive control device. [Figure 10]11 is an explanatory diagram of an example of a portion that selects a common drive waveform of a head driver. FIG. [Figure 11] 3A to 3C are explanatory diagrams illustrating a common drive waveform, a selection signal, and a trimming waveform in the first embodiment of the present invention. [Figure 12] 10A to 10C are explanatory diagrams illustrating an example of a common drive waveform, a selection signal, and a trimming waveform in Comparative Example 1. [Figure 13] 5A to 5C are explanatory diagrams illustrating an example of droplet speeds using a common drive waveform and a trimming waveform corrected by a selection signal, illustrating the effects of the first embodiment of the present invention. [Figure 14] 13 is an explanatory diagram illustrating a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in a second embodiment of the present invention. FIG. [Figure 15] 13 is an explanatory diagram illustrating a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in a third embodiment of the present invention. FIG. [Figure 16] 11 is an explanatory diagram illustrating an example of correction for two nozzles with different droplet velocities; FIG. [Figure 17] 13 is an explanatory diagram illustrating a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in a fourth embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. A printing apparatus as a liquid ejecting apparatus according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic explanatory diagram of the printing apparatus, and Figure 2 is a plan explanatory diagram of an ejection unit of the printing apparatus.

[0011] The printing device 1 is a device that ejects liquid, and includes an input section 10 for inputting a sheet material P, a pre-processing section 20, a printing section 30, a drying section 40, a reversing mechanism section 60, and an output section 50.

[0012] The printing device 1 applies (coats) a pretreatment liquid to the sheet material P transported (supplied) from the loading section 10 as necessary in the pretreatment section 20, which is a pretreatment means, applies liquid in the printing section 30 to perform the required printing, dries the liquid adhering to the sheet material P in the drying section 40, and then discharges the sheet material P to the unloading section 50.

[0013] The loading section 10 includes an input tray 11 (lower input tray 11A, upper input tray 11B) that stores multiple sheet materials P, and a feeding device 12 (12A, 12B) that separates and sends out the sheet materials P one by one from the input tray 11, and supplies the sheet materials P to the pre-processing section 20.

[0014] The pre-treatment section 20 includes an application section 21 which is a treatment liquid application means for applying a treatment liquid to the printing surface of the sheet material P, the treatment liquid having the effect of, for example, agglomerating ink and preventing show-through.

[0015] The printing unit 30 includes a drum 31 which is a support member (rotating member) that supports the sheet material P on its circumferential surface and rotates, and a liquid ejection unit 32 which ejects liquid toward the sheet material P supported by the drum 31.

[0016] The printing section 30 also includes a transfer cylinder 34 that receives the sheet material P sent from the pre-processing section 20 and transfers the sheet material P between the drum 31, and a transfer cylinder 35 that receives the sheet material P transported by the drum 31 and transfers it to the drying section 40.

[0017] The sheet material P transported from the pre-processing section 20 to the printing section 30 has its leading edge gripped by a gripping means (sheet gripper) provided on the transfer cylinder 34, and is transported as the transfer cylinder 34 rotates. The sheet material P transported by the transfer cylinder 34 is delivered to the drum 31 at a position opposite to the drum 31.

[0018] 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 dispersed manner on the surface of the drum 31, and the suction means generates a suction airflow that flows inward from the required suction holes of the drum 31.

[0019] Then, the sheet material P transferred from the transfer cylinder 34 to the drum 31 has its leading edge gripped by the sheet gripper, and is adsorbed and supported on the drum 31 by the suction airflow of the suction means, and is transported as the drum 31 rotates.

[0020] The liquid discharge section 32 includes discharge units 33 (33A to 33D) which are liquid discharge means. For example, the discharge unit 33A discharges cyan (C) liquid, the discharge unit 33B discharges magenta (M) liquid, the discharge unit 33C discharges yellow (Y) liquid, and the discharge unit 33D discharges black (K) liquid. In addition, discharge units that discharge special liquids such as white, gold (silver), etc. can also be used.

[0021] The discharge unit 33 is, for example, a full-line type head in which a plurality of liquid discharge heads (heads) 100, each having a plurality of nozzles 111 arranged in a two-dimensional matrix, are arranged in a staggered pattern on a base member 331, as shown in FIG.

[0022] The discharge operation of each discharge unit 33 of the liquid discharge section 32 is controlled by a drive signal corresponding to the printing information. When the sheet material P supported on the drum 31 passes through an area facing the liquid discharge section 32, liquid of each color is discharged from the discharge unit 33, and an image corresponding to the printing information is printed.

[0023] The sheet material P to which the liquid has been applied by the liquid discharge unit 32 is delivered from the drum 31 to a delivery cylinder 35 , and then delivered by the delivery cylinder 35 to a transport mechanism unit 41 that transports the sheet material P to a drying unit 40 .

[0024] The drying section 40 uses a heating means 42 to heat the sheet material P conveyed by the conveying mechanism section 41, and dries the liquid adhering to the sheet material P. This causes the liquid content, such as moisture, in the liquid to evaporate, the colorant contained in the liquid to be fixed on the sheet material P, and curling of the sheet material P is suppressed.

[0025] The reversing mechanism 60 is a mechanism that reverses the sheet material P using a switchback method when performing double-sided printing on the sheet material P that has passed through the drying section 40, and the reversed sheet material P is sent back upstream of the transfer drum 34 through the double-sided conveying path 61.

[0026] The discharge section 50 includes a discharge tray 51 on which a plurality of sheet materials P are stacked. The sheet materials P conveyed from the drying section 40 via the reversing mechanism section 60 are sequentially stacked and held on the discharge tray 51.

[0027] Next, an example of a head of a discharge unit will be described with reference to Figures 3 to 8. Figure 3 is an explanatory perspective view of the liquid discharge head as viewed from the nozzle surface side, Figure 4 is an explanatory perspective view of the same as viewed from the opposite side to the nozzle surface, Figure 5 is an exploded perspective view of the same, Figure 6 is an exploded perspective view of the flow path components of the same, Figure 7 is an enlarged perspective view of the main parts of Figure 6, and Figure 8 is a cross-sectional perspective view of the flow path portion of the same.

[0028] The head 100 is a circulation type liquid ejection head, and includes a nozzle plate 110, a flow path plate (individual flow path member) 120, a vibration plate member 130, a common flow path tributary member 150, a damper member 160, a common flow path mainstream member 170, a frame member 180, and a wiring member (flexible wiring board) 145. A head driver (driver IC) 146 is mounted on the wiring member 145. In this embodiment, the individual flow path member 120 and the vibration plate member 130 form an actuator substrate 102.

[0029] The nozzle plate 110 has a plurality of nozzles 111 for ejecting liquid. The plurality of nozzles 111 are arranged in a two-dimensional matrix.

[0030] The individual flow path member 120 forms a plurality of pressure chambers (individual liquid chambers) 121 each communicating with the plurality of nozzles 111, a plurality of individual supply flow paths 122 each communicating with the plurality of pressure chambers 121, and a plurality of individual recovery flow paths 123 each communicating with the plurality of pressure chambers 121.

[0031] The vibration plate member 130 forms a vibration plate 131 which is a deformable wall surface of the pressure chamber 121, and a piezoelectric element 140 is integrally provided on the vibration plate 131. Further, the vibration plate member 130 is formed with a supply side opening 132 which communicates with the individual supply flow path 122, and a recovery side opening 133 which communicates with the individual recovery flow path 123. The piezoelectric element 140 is a pressure generating means which deforms the vibration plate 131 to pressurize the liquid in the pressure chamber 121.

[0032] The common flow path branch member 150 forms a plurality of common supply flow path branches 152 communicating with two or more individual supply flow paths 122 and a plurality of common recovery flow path branches 153 communicating with two or more individual recovery flow paths 123, which are alternately adjacent to each other.

[0033] The common flow path tributary member 150 is formed with a through hole which serves as a supply port 154 communicating between the supply side opening 132 of the individual supply flow path 122 and the common supply flow path tributary 152, and a through hole which serves as a recovery port 155 communicating between the recovery side opening 133 of the individual recovery flow path 123 and the common recovery flow path tributary 153.

[0034] In addition, the common flow path tributary member 150 forms a portion 156a of one or more common supply flow path main streams 156 that communicate with multiple common supply flow path tributaries 152, and a portion 157a of one or more common return flow path main streams 157 that communicate with multiple common return flow path tributaries 153.

[0035] The damper member 160 has a supply side damper facing (opposing) the supply port 154 of the common supply flow path branch 152 and a recovery side damper facing (opposing) the recovery port 155 of the common recovery flow path branch 153.

[0036] Here, the common supply flow path tributary 152 and the common return flow path tributary 153 are formed by sealing grooves arranged alternately in the common flow path tributary member 150, which is the same member, with a damper member 160 that forms a deformable wall surface.

[0037] The common flow passage main member 170 forms a common supply flow passage main 156 that communicates with the multiple common supply flow passage tributaries 152 and a common return flow passage main 157 that communicates with the multiple common return flow passage tributaries 153 .

[0038] A portion 156b of the main supply flow channel 156 and a portion 157b of the main common return flow channel 157 are formed in the frame member 180. The portion 156b of the main common supply flow channel 156 communicates with a supply port 181 provided in the frame member 180, and the portion 157b of the main common return flow channel 157 communicates with a return port 182 provided in the frame member 180.

[0039] In this head 100 , when a drive pulse is applied to the piezoelectric element 140 , the piezoelectric element 140 is deflected and deformed, pressurizing the liquid in the pressure chamber 121 , causing the liquid to be ejected from the nozzle 111 in the form of droplets.

[0040] Furthermore, when the head 100 is not ejecting liquid, or when the liquid is not ejected from the nozzles 111, it circulates via a circulation path to which the recovery port 182 and the supply port 181 are connected.

[0041] Next, the section relating to the head drive control device that controls the drive of the head will be described with reference to the block diagram of FIG.

[0042] The head drive control device 400 comprises a head control section 401, a drive waveform generating section 402 and a waveform data storage section 403 which constitute a drive waveform generating means, a head driver 410, and an ejection timing generating section 404 for generating ejection timing.

[0043] 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 generating a common drive waveform, to the drive waveform generation unit 402. In addition, the head control unit 401 outputs an ejection timing signal CHANGE, which corresponds to the amount of delay from the ejection synchronization signal LINE, to the drive waveform generation unit 402.

[0044] The drive waveform generating 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.

[0045] The head control unit 401 also functions as a means for outputting a selection signal that specifies the waveform portion to be selected by a selection means constituted by an analog switch AS of the head driver 410 .

[0046] The head control unit 401 also serves as an adjustment means, receiving image data and generating a selection signal MN for each nozzle 111 based on this image data, for selecting a predetermined required waveform portion of the common drive waveform Vcom for each nozzle 111, depending on the size of the liquid to be ejected from each nozzle 111 of the head 100 and the characteristic variations of the nozzles 111. Therefore, the selection signal MN is output in number to the number of nozzles 111. Also, the selection signal MN is a signal whose timing is synchronized with the ejection timing signal CHANGE.

[0047] Then, the head control unit 401 transfers to the head driver 410 the image data SD, the synchronous clock signal SCK, the latch signal LT that commands the latching of the image data, and the generated selection signal MN.

[0048] The head driver 410 is a selection unit that selects a waveform portion of the common driving waveform Vcom to be applied to each pressure generating element (piezoelectric element 140 ) of the head 100 based on various signals from the head control unit 401 .

[0049] The 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 .

[0050] The shift register 411 receives the image data SD and the synchronous clock signal SCK transferred from the head control unit 401. The latch circuit 412 latches each register value of the shift register 411 by a latch signal LT transferred from the head control unit 401.

[0051] The gradation decoder 413 decodes the value (image data SD) latched by the latch circuit 412 and the selection signal MN for each nozzle 111, and outputs the result. The level shifter 414 converts the level of 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.

[0052] The analog switch AS of the analog switch array 415 is a switching means which is turned on / off by the output of the gradation decoder 413 given via the level shifter 414, and is a means for passing / non-passing (blocking) the common drive waveform Vcom.

[0053] This analog switch AS is provided for each nozzle 111 that the head 100 has, and is connected to an individual electrode of the piezoelectric element 140 corresponding to each nozzle 111. In addition, a common drive waveform Vcom is input to the analog switch AS from the drive waveform generating unit 402. Also, as described above, the timing of the selection signal MN is synchronized with the timing of the common drive waveform Vcom.

[0054] Therefore, the analog switch AS is switched on / off at an appropriate timing according to the output of the gradation decoder 413 provided via the level shifter 414, thereby selecting a waveform portion to be applied to the piezoelectric element 140 corresponding to each nozzle 111 from the common drive waveform Vcom. As a result, the size of the droplet ejected from the nozzle 111, etc. are controlled.

[0055] An ejection timing generation unit 404 generates and outputs an ejection timing pulse stb every time the sheet material P is moved by a predetermined amount based on the detection result of a rotary encoder 405 that detects the amount of rotation of the drum 31. The rotary encoder 405 is composed of an encoder wheel that rotates together with the drum 31, and an encoder sensor that reads the slits of the encoder wheel.

[0056] Next, an example of a section for selecting a common drive waveform of the head driver will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram of a switch section of the head driver.

[0057] 10(a), a drive waveform is applied to the piezoelectric element 140 via a selection switch Sa (Sa1, Sa2,...), which is a switching means serving as a selection means for inputting a common drive waveform Vcom. The selection switch Sa corresponds to an analog switch AS.

[0058] By turning on and off the selection switch Sa by a selection signal MN, a required waveform portion of the common drive waveform Vcom is extracted (trimmed) and applied to the piezoelectric element 140 as a trimmed waveform (applied waveform) Vt.

[0059] Here, when the selection switch Sa is in the ON state, the common drive waveform Vcom passes, and when the selection switch Sa is in the OFF state, the common drive waveform Vcom does not pass. When the selection switch Sa is in the OFF state, the common drive waveform Vcom does not pass, and due to the characteristics of the piezoelectric element 140, which is a capacitive element, the potential of the piezoelectric element 140 (the potential of the trimming waveform Vt) is held at the potential when the selection switch Sa was in the OFF state.

[0060] In the second example of FIG. 10(a), a drive waveform is applied to piezoelectric element 140 via a parallel circuit of droplet amount switches Sb (Sb1, Sb2...) and trimming selection switches Sc (Sc1, Sc2...) that input a common drive waveform Vcom.

[0061] The droplet amount switch Sb is turned on / off according to the droplet amount (large, medium, small).

[0062] By turning the trimming selection switch Sc on and off by a selection signal MN, a required waveform portion of the common drive waveform Vcom is extracted (trimmed) and applied to the piezoelectric element 140 as a trimmed waveform (applied waveform) Vt.

[0063] Here too, when the trimming selection switch Sc is in the ON state, the common drive waveform Vcom passes, and when the trimming selection switch Sc is in the OFF state, the common drive waveform Vcom does not pass. When the trimming selection switch Sc is in the OFF state, the common drive waveform Vcom does not pass, and due to the characteristics of the piezoelectric element 140, which is a capacitive element, the potential of the piezoelectric element 140 (the potential of the trimming waveform Vt) is held at the potential when the trimming selection switch Sc was in the OFF state.

[0064] Next, the drive waveforms and selection signals in the first embodiment of the present invention will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram for explaining a common drive waveform, selection signal, and trimming waveform (applied waveform) in the same embodiment.

[0065] 11(a), the common drive waveform Vcom of this embodiment includes a hold waveform portion d1 where the first potential V1 is held, an inter-pulse hold waveform portion d2 where a second potential V2 different from the first potential V1 is held, and drive pulses P1 and P2. When ejecting a small droplet, the drive pulse P2 is selected, and when ejecting a large droplet, the drive pulses P1 and P2 are selected.

[0066] In this embodiment, the first potential V1 and the second potential V2 are both predetermined potentials. The first potential V1 is set as a reference potential (intermediate potential) of the common driving waveform Vcom. The driving pulses P1 and P2 are ejection pulses that pressurize the pressure chamber 121 to eject liquid.

[0067] The driving pulse P1 includes a falling waveform element a11, a falling hold waveform element a12, a falling waveform element a13, a hold waveform element b1, and a rising waveform element c1.

[0068] The falling waveform element a11 falls from the first potential V1 held in the hold waveform portion d1 to a fifth potential V5, expanding the pressure chamber 121. The falling hold waveform element a12 is a waveform element that holds the fifth potential V5, which is the end potential of the falling waveform element a11. This falling hold waveform element a12 becomes the waveform portion that performs trimming, and the period of the hold waveform element a12 is set as the trimming period TL1. The falling waveform element a13 is an expansion waveform element that falls from the fifth potential V5 to a sixth potential V6, expanding the pressure chamber 121.

[0069] In this embodiment, the falling waveform element a11 is also a waveform element that expands the pressure chamber 121, and the drive pulse P1 expands the pressure chamber 121 in two stages, but the falling waveform element a13, which is primarily responsible for expanding the pressure chamber 121, is referred to as the "expansion waveform element" (the same applies to the drive pulses and embodiments that follow).

[0070] The hold waveform element b1 holds the sixth potential V6 which is the end potential of the falling waveform element a13. The rising waveform element c1 is a contraction waveform element which rises from the sixth potential V6 held in the hold waveform element b1 to the second potential V2 of the inter-pulse hold waveform portion d2, contracting the pressure chamber 121 to eject liquid.

[0071] The driving pulse P2 includes a falling waveform element a21, a falling hold waveform element a22, a falling waveform element a23, a hold waveform element b2, and a rising waveform element c2.

[0072] The falling waveform element a21 falls from the second potential V2 held in the inter-pulse hold waveform portion d2 to the third potential V3, expanding the pressure chamber 121. The falling hold waveform element a22 is a waveform element that holds the third potential V3, which is the end potential of the falling waveform element a21. This falling hold waveform element a22 becomes the waveform portion that performs trimming, and the period of the falling hold waveform element a22 is set as the trimming period TL2. The falling waveform element a23 is an expansion waveform element that falls from the third potential V3 held in the falling hold waveform element a22 to the fourth potential V4, expanding the pressure chamber 121.

[0073] The hold waveform element b2 holds the fourth potential V4 which is the end potential of the falling waveform element a23. The rising waveform element c2 is a contraction waveform element which rises from the fourth potential V4 held in the hold waveform element a22 to the first potential V1, contracting the pressure chamber 121 to eject liquid.

[0074] In this embodiment, the relationship between the first potential V1 to the sixth potential V6 is set as V2>V1>V5>V3>V6>V4. Also, the signs "V1" to "V6" of the first potential V1 to the sixth potential V6 are specific to each embodiment, and do not mean that the potentials are the same between different embodiments.

[0075] On the other hand, the selection signal MN for selecting the driving pulses P1, P2 output from the head control unit 401, which is an output means, includes a first selection signal A1 and a second selection signal A2, as shown in FIGS. 11(b1) and (b2).

[0076] The head control unit 401 selectively outputs a first selection signal A1 or a second selection signal A2 depending on the size of the droplet to be ejected. In this embodiment, the head control unit 401 outputs the first selection signal A1 when ejecting a small droplet, and outputs the second selection signal A2 when ejecting a large droplet.

[0077] In this embodiment, when the first selection signal A1 and the second selection signal A2 are "ON", the analog switch AS is in the "ON" state, and the common drive waveform Vcom passes through the analog switch AS. When the first selection signal A1 and the second selection signal A2 are "OFF", the analog switch AS is in the "OFF" state, and the common drive waveform Vcom does not pass through (is non-passing) the analog switch AS.

[0078] In other words, the first selection signal A1 and the second selection signal A2 can control whether the common drive waveform Vcom is passed or not through the analog switch AS, which serves as the selection means. Note that the first selection signal A1 and the second selection signal A2 are binary signals that are "ON" when "H" and "OFF" when "L", for example, but are represented in Figure 11 as the "ON" and "OFF" of the analog switch AS.

[0079] 11(b1), the first selection signal A1 goes to the ON state before time t0, and goes to the OFF state at time t1 in the middle of the held waveform portion d1 before the start of the falling waveform element a11 of the drive pulse P1. By the first selection signal A1 going to the OFF state, the first potential V1 is held until it goes to the ON state again. After that, the first selection signal A1 goes to the ON state at time t4 within the trimming period TL2 of the falling hold waveform element a22 of the drive pulse P2.

[0080] As a result, as shown in Figure 11 (c1), the trimming waveform Vt1 for small droplets is maintained at the first potential V1 from time t0 to time t4, and at time t4 falls from the first potential V1 to a third potential V3, which is the start potential of the falling waveform element a23, which is an expansion waveform element of the drive pulse P2.

[0081] Thereafter, the trimming waveform Vt1 for small droplets becomes similar to the common drive waveform Vcom, and becomes a waveform including the portion of the falling hold waveform element a22 of the drive pulse P2 after time t4, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0082] In other words, the first selection signal A1 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the first potential V1 to the start potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0083] 11(b2), the second selection signal A2 goes to the ON state before time t0, and goes to the OFF state at time t1 in the middle of the held waveform portion d1 before the start of the falling waveform element a11 of the drive pulse P1. By the second selection signal A2 going to the OFF state, the first potential V1 is held until it goes to the ON state again. After that, the second selection signal A2 goes to the ON state at time t2 within the trimming period TL1 of the falling hold waveform element a12 of the drive pulse P1.

[0084] Furthermore, the second selection signal A2 turns to the OFF state at time t3 in the middle of the inter-pulse hold waveform portion d2 before the start of the falling waveform element a21 of the drive pulse P2. By the second selection signal A2 turning to the OFF state, the second potential V2 is held until the second selection signal A2 turns to the ON state again. After that, the second selection signal A2 turns to the ON state at time t4 within the trimming period TL2 of the falling hold waveform element a22 of the drive pulse P2.

[0085] As a result, as shown in Figure 11 (c2), the trimming waveform Vt2 for large droplets is held at the first potential V1 from time t0 to time t2, and at time t2 falls from the first potential V1 to a fifth potential V5, which is the holding potential of the falling holding waveform element a22 of the drive pulse P1.

[0086] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom from time t2 to time t3, and becomes a waveform that includes the portion of the falling hold waveform element a12 of the drive pulse P1 after time t2, the falling waveform element a13, the hold waveform element b1, and the rising waveform element c1.

[0087] Furthermore, the large droplet trimming waveform Vt2 is held at the second potential V2 until time t4, at which time it falls from the second potential V2 to the third potential V3, which is the start potential of the falling waveform element a13, which is an expansion waveform element of the drive pulse P2.

[0088] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom, and becomes a waveform including the portion of the falling hold waveform element a22 of the drive pulse P2 after time t4, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0089] In other words, the second selection signal A2 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the second potential V2 to the starting potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0090] Here, the timing (times t2 and t4 in this embodiment) at which the analog switch AS, which is the selection means, is switched from non-selection (OFF state) to selection (ON state) by the first selection signal A1 and the second selection signal A2 is made to differ according to the ejection characteristics of each nozzle 111. In other words, the timing at which the analog switch AS, which is the selection means, is switched from non-selection (OFF state) to selection (ON state) differs between at least two nozzles 111.

[0091] As a result, a trimming waveform according to the ejection characteristics of each nozzle 111 is applied to the piezoelectric element 140 of each nozzle 111, and the variation in ejection characteristics between the nozzles 111 is reduced.

[0092] In this embodiment, the trimming portions of the drive pulses P1, P2 are the falling hold waveform elements a12, 22 portions before the start of the falling waveform elements a13, 23 which are the expansion waveform elements that mainly expand the pressure chamber 121. Therefore, trimming can be performed even if the periods of the hold waveform elements b1, b2 of the drive pulses P1, P2 become shorter.

[0093] As a result, even in a head with a short natural period, that is, a short bottom hold time of the drive pulse (period of hold waveform elements b1, b2), it is possible to reduce variation in ejection characteristics between nozzles by performing trimming.

[0094] Here, the comparative example 1 will be described with reference to Fig. 12. Fig. 12 is an explanatory diagram for explaining an example of a common drive waveform, a selection signal, and a trimming waveform in the comparative example 1.

[0095] 12(a), the drive pulse P1 is composed of a falling waveform element a11, a falling hold waveform element a12, a falling waveform element a13, a hold waveform element b1, and a rising waveform element c1. The drive pulse P2 is composed of a falling waveform element a21, a falling hold waveform element a22, a falling waveform element a23, a hold waveform element b2, and a rising waveform element c2.

[0096] The driving pulses P1 and P2 of this comparison example 1 also have waveforms that cause two-stage expansion, but in the driving pulses P1 and P2, the falling waveform elements a11 and a21 that fall from the first potential (reference potential) V1 are the expansion waveform elements that cause the main expansion of the pressure chamber 121.

[0097] The first selection signal A1 for small droplets changes from the OFF state to the ON state at time t3, changes from the ON state to the OFF state at time t4, and then changes to the ON state at time t5. The second selection signal A2 for large droplets changes to the ON state at time t0, changes to the OFF state at time t1, maintains the ON state from time t2 to time t4, changes from the ON state to the OFF state at time t4, and then changes to the ON state at time t5.

[0098] Therefore, in the trimming waveform Vt1 for small droplets, the retain waveform element b2 of the drive pulse P2 is trimmed as shown in Fig. 12(c1).In addition, in the trimming waveform Vt2 for large droplets, the retain waveform element b1 of the drive pulse P1 and the retain waveform element b2 of the drive pulse P2 are trimmed as shown in Fig. 12(c2).

[0099] However, as the printing speed of line printers and the like increases, the head is driven at high speed, so the natural period of the pressure chamber of the head tends to become shorter. Also, when attempting to eject droplets at a smaller size in order to improve image quality, the natural period of the pressure chamber of the head tends to become shorter.

[0100] If trimming as in Comparative Example 1 is performed on a head with such a short natural period, after subtracting the time required for switching and the time required for voltage change, it becomes impossible to secure sufficient time for the periods of the hold waveform elements b1 and b2.

[0101] For example, in the case of a head with a natural period of about 3 μsec, the time from the start of the falling waveform elements a11, a21 to the end of the rising waveform elements c1, c2 is only about 1.5 to 2.5 μsec, which leaves almost no time available for the sustain waveform elements b1, b2, making it impossible to correct variations in the ejection characteristics.

[0102] In contrast, in this embodiment, trimming is not performed on the retained waveform elements b1 and b2 of the drive pulses P1 and P2 that retain the pressure chamber 121 in the most expanded state, so that trimming can be performed to reduce variation in the ejection characteristics even for heads with short natural periods.

[0103] Furthermore, in Comparative Example 1, the driving pulse P2 is applied with the same trimmed waveform whether it is a small droplet or a large droplet.

[0104] Therefore, for example, if an optimal trimming waveform is set for small droplets, the trimming may be insufficient for correcting large droplets, making it impossible to reduce the variation in ejection characteristics. In this case, if the selection signals for small droplets and large droplets are separated, a selection signal for the number of nozzles x the type of droplet would have to be provided, which would increase the number of signal lines.

[0105] In contrast, in this embodiment, as described above, when the drive pulse P2 is applied, in the small droplet trimming waveform Vt1, the waveform portion corresponding to the falling waveform element a21 changes in potential from the first potential V1 to the third potential V3, with the amount of change being ΔV13. In contrast, in the large droplet trimming waveform Vt2, the waveform portion corresponding to the falling waveform element a21 changes in potential from the second potential V2, which is different from the first potential V1, to the third potential V3, with the amount of change being ΔV23 (ΔV23>ΔV13).

[0106] That is, even if the trimming time t4 of the drive pulse P2 is the same for small droplets and large droplets, the trimming voltage (the voltage of the first step falling waveform element a21) can be made different for small droplets and large droplets.

[0107] This makes it possible to make the amount of correction to the droplet speed of the ejected droplets by the drive pulse P2 different for small droplets and large droplets, thereby reducing variations in the ejection characteristics.

[0108] The effect of this will be described with reference to Fig. 13. Fig. 13 shows an example of the droplet velocity due to a common drive waveform and a trimming waveform corrected by a selection signal.

[0109] 13(a) to (c), time T1 indicates time point t4 in FIG. 11, and period TL2 indicates the trimming period of the falling held waveform element a22.

[0110] When no trimming (no correction) is performed and the drive pulse P2 of the common drive waveform Vcom is applied as is, the droplet speed differs between small droplets and large droplets, as shown in Fig. 13(a). In this example, the droplet speed can be corrected by allocating a selection signal that shortens (shortens) the time T1 as the droplet speed increases, and lengthens (slows) the time T1 as the droplet speed decreases.

[0111] Here, when the first potential V1 and the second potential V2 are set to the same value (V1=V2), as shown in FIG. 13(b), the droplet velocity of the small droplets is corrected to approximately 7 m / s, but the large droplets corrected with the same correction voltage still retain an inclination, and the correction is insufficient.

[0112] In contrast, by making the first potential V1 and the second potential V2 different (V1≠V2), the droplet velocities of both small and large droplets can be corrected to approximately 7 m / s, as shown in FIG. 13(c).

[0113] In this case, the trimming voltages for small and large droplets are made different depending on the waveform shape of the common driving waveform Vcom, and the trimming time T1 (time t4) remains common to both small and large droplets, so it is possible to correct the ejection characteristics of small and large droplets without increasing the number of signal lines for the selection signal.

[0114] Next, a second embodiment of the present invention will be described with reference to Fig. 14. Fig. 14 is an explanatory diagram for explaining a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in the second embodiment.

[0115] As shown in FIG. 14(a), the common drive waveform Vcom of this embodiment sets the second potential V2 of the inter-pulse hold waveform portion d2 to be between the first potential V1 and the third potential V3, which is the start potential of the expansion waveform element (falling waveform element a23) of the drive pulse P2 (V1>V2>V3).

[0116] The second potential V2 of the inter-pulse hold waveform portion d2 is the end potential of the rising waveform element c1 of the drive pulse P1 and is also the start potential of the falling waveform element a21 of the drive pulse P2. The rest is the same as in the first embodiment, so a description thereof will be omitted.

[0117] The timing at which the first selection signal A1 and the second selection signal A2 are switched to the ON state and the OFF state is the same as in the first embodiment, as shown in FIGS. 14(b1) and 14(b2).

[0118] As a result, as shown in Figure 14 (c1), the trimming waveform Vt1 for small droplets is maintained at the first potential V1 from time t0 to time t4, and at time t4 falls from the first potential V1 to a third potential V3, which is the start potential of the falling waveform element a23, which is an expansion waveform element of the drive pulse P2.

[0119] Thereafter, the trimming waveform Vt1 for small droplets becomes similar to the common drive waveform Vcom, and becomes a waveform including the portion of the falling hold waveform element a22 of the drive pulse P2 after time t4, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0120] In other words, the first selection signal A1 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the first potential V1 to the start potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0121] Furthermore, as shown in FIG. 14(c2), the trimming waveform Vt2 for large droplets is held at the first potential V1 from time t0 to time t2, and at time t2 falls from the first potential V1 to a fifth potential V5, which is the holding potential of the falling holding waveform element a12 of the driving pulse P1.

[0122] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom from time t2 to time t3, and becomes a waveform that includes the portion of the falling hold waveform element a12 of the drive pulse P1 after time t2, the falling waveform element a13, the hold waveform element b1, and the rising waveform element c1.

[0123] Furthermore, the large droplet trimming waveform Vt2 is held at the second potential V2 until time t4, at which time it falls from the second potential V2 to a third potential V3 which is the start potential of the falling waveform element a23 which is an expansion waveform element of the driving pulse P2.

[0124] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom, and becomes a waveform including the portion of the falling hold waveform element a22 of the drive pulse P2 after time t4, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0125] In other words, the second selection signal A2 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the second potential V2 to the starting potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0126] In the second embodiment as well, the same effects as those in the first embodiment can be obtained.

[0127] Next, a third embodiment of the present invention will be described with reference to Fig. 15. Fig. 15 is an explanatory diagram for explaining a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in this embodiment.

[0128] As shown in FIG. 15(a), the common drive waveform Vcom of this embodiment has a second potential V2 of the inter-pulse hold waveform portion d2 set to a potential (V1>V3>V2) lower than the first potential V1 and the third potential V3 which is the start potential of the expansion waveform element (falling waveform element a23) of the drive pulse P2.

[0129] That is, in this embodiment, the drive pulse P2 includes a rising waveform element e2, a rising hold waveform element f2, a falling waveform element a2 which is an expansion waveform element, a hold waveform element b2, and a rising waveform element c2.

[0130] The rising waveform element e2 of the drive pulse P2 rises from the second potential V2 held in the inter-pulse hold waveform portion d2 to the third potential V3, causing the pressure chamber 121 to contract. The rising hold waveform element f2 of the drive pulse P2 is a waveform element that holds the third potential V3 that rose in the rising waveform element e2. This rising hold waveform element f2 becomes the waveform portion that performs trimming, and the period of the rising hold waveform element f2 is set as the trimming period TL2. The falling waveform element a2 of the drive pulse P2 is an expansion waveform element that falls from the third potential V3 held in the rising hold waveform element f2 to the fourth potential V4, causing the pressure chamber 121 to expand.

[0131] The hold waveform element b2 of the drive pulse P2 holds the fourth potential V4, which is the end potential of the falling waveform element a2. The rising waveform element c2 of the drive pulse P2 is a contraction waveform element that rises from the fourth potential V4 held in the hold waveform element b2 to the first potential V1, and contracts the pressure chamber 121 to eject liquid.

[0132] The timing at which the first selection signal A1 and the second selection signal A2 are switched to the ON state and the OFF state is the same as in the first embodiment, as shown in FIGS. 15(b1) and 15(b2).

[0133] As a result, as shown in Figure 15 (c1), the trimming waveform Vt1 for small droplets is maintained at the first potential V1 from time t0 to time t4, and at time t4 falls from the first potential V1 to a third potential V3, which is the start potential of the falling waveform element a2, which is an expansion waveform element of the drive pulse P2.

[0134] Thereafter, the trimming waveform Vt1 for small droplets becomes similar to the common driving waveform Vcom, and becomes a waveform including the portion of the rising hold waveform element f2 of the driving pulse P2 after time t4, the falling waveform element a2, the hold waveform element b2, and the rising waveform element c2.

[0135] In other words, the first selection signal A1 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the first potential V1 to the start potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0136] Furthermore, as shown in FIG. 15(c2), the trimming waveform Vt2 for large droplets is held at the first potential V1 from time t0 to time t2, and at time t2 falls from the first potential V1 to a fifth potential V5, which is the holding potential of the falling holding waveform element a12 of the driving pulse P1.

[0137] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom from time t2 to time t3, and becomes a waveform that includes the portion of the falling hold waveform element a12 of the drive pulse P1 after time t2, the falling waveform element a13, the hold waveform element b1, and the rising waveform element c1.

[0138] Furthermore, the large drop trimming waveform Vt2 is held at the second potential V2 until time t4, and at time t4 rises from the second potential V2 to a third potential V3 which is the start potential of the falling waveform element a2 which is the expansion waveform element of the drive pulse P2.

[0139] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common driving waveform Vcom, and becomes a waveform including the portion of the rising hold waveform element f2 of the driving pulse P2 after time t4, the falling waveform element a2, the hold waveform element b2, and the rising waveform element c2.

[0140] In other words, the second selection signal A2 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the second potential V2 to the starting potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0141] In the third embodiment as well, the same effects as those in the first embodiment can be obtained.

[0142] The above first to third embodiments can be used selectively depending on the tendency of variation in the ejection characteristics for each droplet type.

[0143] Next, an example of correction for two nozzles with different droplet velocities will be described with reference to Fig. 16. Fig. 16 is an explanatory diagram for the same description.

[0144] 16(a) shows droplets ejected by the common drive waveform Vcom before correction (before trimming adjustment). Before correction, the droplet speed of nozzle N1 is faster than that of nozzle N2 for both small and large droplets, but the difference in droplet speed between nozzle N1 and nozzle N2 is larger for large droplets.

[0145] 16(b) shows an example in which the droplet velocities of nozzles N1 and N2 are corrected using the common drive waveform Vcom of Comparative Example 1. In this case, the droplet velocities of nozzles N1 and N2 match for small droplets, but because the correction is made using the same trimming waveform, the correction is insufficient for large droplets, and a difference in the droplet velocities of nozzles N1 and N2 remains.

[0146] Fig. 16(c) shows an example in which the droplet speeds of nozzles N1 and N2 are corrected using the common drive waveform Vcom of the first embodiment. For small droplets, the falling waveform element of Fig. 11(c1) is a trimming waveform Vt1 with a potential difference of ΔV13, and for large droplets, the falling waveform element of Fig. 11(c2) is a trimming waveform Vt2 with a potential difference of ΔV23, making it possible to input a trimming waveform with a different potential difference for each droplet type. This makes it possible to match the droplet speeds of nozzles N1 and N2 for both small and large droplets.

[0147] Next, a fourth embodiment of the present invention will be described with reference to Fig. 17. Fig. 17 is an explanatory diagram for explaining a common drive waveform, a selection signal, and a trimming waveform (applied waveform) in this embodiment.

[0148] 17(a), the common drive waveform Vcom of this embodiment includes a hold waveform portion d1 where the first potential V1 is held, an inter-pulse hold waveform portion d2 where the first potential V1 is held, and drive pulses P1 and P2. When ejecting small droplets, a part of the drive pulse P1 and the drive pulse P2 are selected, and when ejecting large droplets, the drive pulses P1 and P2 are selected.

[0149] The driving pulse P1 includes a falling waveform element a11, a falling hold waveform element a12, a falling waveform element a13, a hold waveform element b1, and a rising waveform element c1.

[0150] The falling waveform element a11 of the drive pulse P1 falls from the first potential V1 held in the hold waveform portion d1 to the second potential V2, expanding the pressure chamber 121. The falling hold waveform element a12 of the drive pulse P1 is a waveform element that holds the second potential V2, which is also the end potential. The falling hold waveform element a12 is a waveform portion that performs trimming, and the period of the falling hold waveform element a12 is set as a trimming period Tl1. The falling waveform element a23 of the drive pulse P1 is an expansion waveform element that falls from the second potential V2 held in the falling hold waveform element a12 to the fifth potential V5, expanding the pressure chamber 121.

[0151] The hold waveform element b1 holds the fifth potential V5 which is the end potential of the falling waveform element a13. The rising waveform element c1 is a contraction waveform element which rises from the fifth potential V5 held in the hold waveform element b1 to the first potential V1 of the inter-pulse hold waveform portion d2, contracting the pressure chamber 121 to eject liquid.

[0152] The driving pulse P2 includes a falling waveform element a21, a falling hold waveform element a22, a falling waveform element a23, a hold waveform element b2, and a rising waveform element c2.

[0153] The falling waveform element a21 of the drive pulse P2 falls from the first potential V1 held in the inter-pulse hold waveform portion d2 to the third potential V3, which is the start potential of the falling waveform element a23, to expand the pressure chamber 121. The falling hold waveform element a22 is the end potential of the falling waveform element a21, and is a waveform element that holds the third potential V3, which is the start potential of the falling waveform element a23. The falling hold waveform element a22 is the waveform portion that performs trimming, and the period of the falling hold waveform element a22 is set as the trimming period TL2. The falling waveform element a23 is an expansion waveform element that falls from the third potential V3 held in the falling hold waveform element a22 to the fourth potential V4 to expand the pressure chamber 121.

[0154] The hold waveform element b2 holds the fourth potential V4, which is the end potential, in the falling waveform element a23. The rising waveform element c2 is a contraction waveform element that rises from the fourth potential V4 held in the hold waveform element b2 to the first potential V1, contracting the pressure chamber 121 and ejecting liquid.

[0155] In this embodiment, the relationship between the first potential V1 to the fifth potential V5 is set as V1>V2>V3>V5>V4.

[0156] 17(b1), the first selection signal A1 is turned on before time t0 and turns off at time t1 during the falling hold waveform element a12 of the drive pulse P1. By turning the first selection signal A1 off, the second potential V2 is held until it turns on again. After that, the first selection signal A1 turns on at time t5 within the period of the falling hold waveform element a22 of the drive pulse P2.

[0157] As a result, as shown in FIG. 17(c1), the trimming waveform Vt1 for small droplets becomes the same as the falling waveform element a11 and part of the falling hold waveform element 22 of the driving pulse P1 from time t0 to time t2, and the second potential V2 is held from time t2 to time t5.

[0158] Thereafter, the trimming waveform Vt1 for small droplets falls from the second potential V2 to the third potential V3 at time t5, and thereafter becomes similar in waveform to the common drive waveform Vcom, and becomes a waveform that includes the portion of the falling hold waveform element a22 of the drive pulse P2 after time t5, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0159] In other words, the first selection signal A1 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the second potential V2 to the start potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0160] The second selection signal A2 goes to the ON state before time t0, and goes to the OFF state at time t1 in the middle of the hold waveform portion d1 before the start of the falling waveform element a11 of the drive pulse P1. After that, the second selection signal A2 goes to the ON state at time t3 within the period of the falling hold waveform element a12 of the drive pulse P1.

[0161] Furthermore, the second selection signal A2 turns OFF at time t4 midway through the inter-pulse hold waveform portion d2 before the start of the falling waveform element a21 of the drive pulse P2, and turns ON at time t5 within the period of the falling hold waveform element a22 of the drive pulse P2.

[0162] As a result, as shown in Figure 11 (c2), the trimming waveform Vt2 for large droplets is held at the first potential V1 from time t0 to time t3, and at time t3 falls from the first potential V1 to the second potential V2, which is the hold potential of the falling hold waveform element a12 of the drive pulse P1.

[0163] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom from time t3 to time t4, and becomes a waveform that includes the portion of the falling hold waveform element a12 of the drive pulse P1 after time t3, the falling waveform element a13, the hold waveform element b1, and the rising waveform element c1.

[0164] Furthermore, the large droplet trimming waveform Vt2 is held at the first potential V1 until time t5, and at time t5 falls from the first potential V1 to a third potential V3 which is the start potential of the falling waveform element a23 which is an expansion waveform element of the drive pulse P2.

[0165] Thereafter, the large droplet trimming waveform Vt2 becomes the same waveform as the common drive waveform Vcom, and becomes a waveform including the portion of the falling hold waveform element a22 of the drive pulse P2 after time t5, the falling waveform element a23, the hold waveform element b2, and the rising waveform element c2.

[0166] In other words, the second selection signal A2 is a selection signal that controls the ON / OFF of the analog switch AS, which serves as a selection means, so that a waveform of the common driving waveform Vcom that changes from the first potential V1 to the start potential (third potential V3) of the expansion waveform element is applied to the piezoelectric element 140.

[0167] In this embodiment, the trimming time of the drive pulse 2 for small droplets and large droplets is the same at time t5, but the trimming voltage for small droplets can be ΔV23 from the second potential V2 to the third potential V3, and for large droplets can be ΔV13 from the first potential V1 to the third potential V3.

[0168] This makes it possible to make the trimming voltage (the voltage of the falling waveform element a1) of the driving pulse P2 commonly used for small droplets and large droplets different, thereby reducing variations in the ejection characteristics.

[0169] Furthermore, in the first to third embodiments, the potential difference of the droplet trimming waveform utilizes the reference potential of the common drive waveform Vcom, whereas in this embodiment, the potential difference is created by utilizing the potential of the voltage holding portion of another drive pulse (the potential of the falling hold waveform element a12).

[0170] In this way, by using the potential holding portion immediately before the expansion waveform element of the other drive pulse of the common drive waveform Vcom for trimming, it is possible to correct the ejection variation even for a head with a short inherent period. In addition, there is no need to extend the waveform length for trimming, and it can also be applied to heads that are driven at high frequencies.

[0171] In the present application, the liquid to be ejected may have a viscosity and surface tension that allows it to be ejected from the head, and is not particularly limited, but it is preferable that the viscosity of the liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, an edible material such as a natural colorant, etc., and these can be used for applications such as inkjet ink, surface treatment liquid, a liquid for forming a component of an electronic element or a light-emitting element, an electronic circuit resist pattern, a material liquid for three-dimensional modeling, etc.

[0172] Energy sources for ejecting liquid include piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a vibration plate and an opposing electrode.

[0173] Furthermore, the term "device for ejecting liquid" includes not only devices capable of ejecting liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0174] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0175] For example, examples of "devices that eject liquid" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0176] Furthermore, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0177] The above-mentioned "object to which liquid can adhere" means an object to which liquid can adhere at least temporarily, and to which the liquid adheres and sticks, or to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects to which liquid can adhere.

[0178] The material of the above-mentioned "object to which liquid can adhere" may be any material to which liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0179] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object to which liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which a liquid ejection head moves, a line type device in which a liquid ejection head does not move, etc.

[0180] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0181] In the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous. [Explanation of symbols]

[0182] 1 Liquid ejection head (head) 21 Pressure Chamber 42 Piezoelectric element 100 Head Module 500 printing equipment 510 Loading section 520 Pre-processing section 530 Printing Department 533 Discharge Unit 540 Drying section 550 Unloading section 400 Head drive control device 401 Head control unit 402 Drive Waveform Generator 403 Waveform data storage section 410 Head Driver

Claims

1. A head having a plurality of nozzles for ejecting liquid; a selection means for selecting whether or not to pass a drive waveform for driving a piezoelectric element of the head; a means for outputting a selection signal for controlling the selection means to select whether to pass or not pass the driving waveform; the drive waveform includes an expansion waveform element that expands a pressure chamber of the head, The output means includes at least a first selection signal for controlling the selection means so that a waveform that changes from a first potential to a start potential of the expansion waveform element is applied to the piezoelectric element; a second selection signal for controlling the selection means so that a waveform that changes from a second potential different from the first potential to a start potential of the expansion waveform element is applied to the piezoelectric element, among the driving waveforms. A liquid ejection device comprising:

2. The output means outputs the first selection signal or the second selection signal in accordance with the volume of liquid to be ejected from the nozzle.

2. The liquid dispensing device according to claim 1.

3. The first potential is the same as the start potential of the driving waveform.

3. The liquid ejection device according to claim 1 or 2.

4. When a portion in which a predetermined potential is held that is included in the drive waveform is defined as a potential holding portion, the first potential is the same potential as any one of the potential holding portions, The second potential is the same potential as one of the potential holding portions that holds a potential that is different from the potential holding portion that holds the same potential as the first potential.

4. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

5. The drive waveform includes a waveform that holds a start potential of the expansion waveform element before the expansion waveform element; The selection means is switched from non-passing to passing during a portion of the waveform that maintains the start potential.

5. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

6. The timing at which the selection means switches from non-selection to selection differs between at least two nozzles.

6. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

7. a selection means for selecting whether to pass or not pass a drive waveform that drives a piezoelectric element of a head having a plurality of nozzles that eject liquid; a means for outputting a selection signal for controlling the selection means to select whether to pass or not pass the driving waveform; the drive waveform includes an expansion waveform element that expands a pressure chamber of the head, The output means includes at least a first selection signal for controlling the selection means so that a waveform that changes from a first potential to a start potential of the expansion waveform element is applied to the piezoelectric element; a second selection signal for controlling the selection means so that a waveform that changes from a second potential different from the first potential to a start potential of the expansion waveform element is applied to the piezoelectric element, among the driving waveforms. A head drive control device comprising:

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