Liquid dispensing device, head drive control device

Abstract

To reduce variations in discharge characteristics.SOLUTION: A common drive waveform Vcom includes a non-discharge pulse Pb and a discharge pulse Pa in time series, wherein the non-discharge pulse Pb is composed of an expansion waveform element d for expanding a pressure chamber 121, a holding waveform element e for holding a state of the pressure chamber 121 expanded by the expansion waveform element d, and a contraction waveform element f for contracting the pressure chamber 121 from the held state by the holding waveform element e, and a method for discharging a liquid performs control to switch a selection switch Sa to an ON state or an OFF state so as to pass not only the discharge pulse Pa but also a part of the waveform of the non-discharge pulse Pb when the liquid is discharged from a nozzle 111, and adjusts a trimming waveform Vt applied to a piezoelectric element 140 by changing a time point t2 when the selection switch Sa is switched to the ON state from the OFF state.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a device for discharging a liquid and a head drive control device.

Background Art

[0002] Due to manufacturing variations and the like, variations occur in the liquid discharge speed and discharge amount between heads or between nozzles in a liquid discharge head.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when the natural vibration period of the head becomes short, the period of the holding waveform element that holds the pressure chamber in the expanded state also becomes short. Therefore, in the configuration disclosed in Patent Document 1, there is a problem that the holding waveform element that holds the pressure chamber in the expanded state cannot be trimmed (cut off), and variations in discharge characteristics cannot be reduced.

[0006] The present invention has been made in view of the above problems, and an object thereof is to reduce variations in discharge characteristics.

Means for Solving the Problems

[0007] In order to solve the above problems, the liquid discharging device according to claim 1 of the present invention a head for discharging a liquid, The head comprises a switching means for selecting whether to pass or not pass the drive waveform that drives the piezoelectric element of the head, The drive waveform includes, in time series, non-discharge pulses that drive the piezoelectric element to an extent that does not discharge the liquid, and discharge pulses that discharge the liquid. The system includes means for controlling the switching means to switch to an ON state or an OFF state in the waveform portion of the non-discharge pulse, thereby adjusting the waveform applied to the piezoelectric element. 、 The non-discharge pulse includes a contraction waveform element that contracts the pressure chamber of the head, a holding waveform element that maintains the contracted state by the contraction waveform element, and an expansion waveform element that expands the pressure chamber from the state maintained by the holding waveform element. The adjusting means turns the switching means OFF in the portion of the held waveform element and turns the switching means ON at a point after the end of the expanded waveform element. This was the structure.

[0008] According to the present invention, variations in discharge characteristics can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating a printing apparatus as a liquid dispensing device according to the first embodiment of the present invention. [Figure 2] This is a plan view diagram of the ejection unit of the printing machine. [Figure 3] This is an external perspective view diagram illustrating an example of a discharge unit head, seen from the nozzle side. [Figure 4] This is a perspective view diagram illustrating the external appearance, seen from the opposite side of the nozzle. [Figure 5] This is also a disassembled perspective diagram. [Figure 6] This is also an exploded perspective view illustrating the flow channel components. [Figure 7] Figure 6 is an enlarged perspective view illustrating the main part. [Figure 8] This is also a cross-sectional perspective view of the flow channel section. [Figure 9] This is a block diagram illustrating the parts related to the head drive control device. [Figure 10] This is an explanatory diagram illustrating an example of the section that selects the common drive waveform for the head driver. [Figure 11]An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the first embodiment of the present invention. [Figure 12] It is also an explanatory diagram of the waveform lengths of the drive waveform and the trimming waveform. [Figure 13] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform used for explaining trimming in Comparative Example 1. [Figure 14] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the second embodiment of the present invention. [Figure 15] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the third embodiment of the present invention. [Figure 16] It is also an explanatory diagram of the waveform lengths of the drive waveform and the trimming waveform. [Figure 17] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the fourth embodiment of the present invention. [Figure 18] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the fifth embodiment of the present invention. [Figure 19] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the sixth embodiment of the present invention. [Figure 20] An explanatory diagram of an example of a drive waveform, a state of a selection switch, and a trimming waveform (applied waveform) used for explaining trimming in the seventh embodiment of the present invention.

Embodiments for Carrying Out the Invention

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

[0011] The printing apparatus 1 is a liquid dispensing device and includes a loading section 10 for loading sheet material P, a pre-processing section 20, a printing section 30, a drying section 40, a reversing mechanism section 60, and an unloading section 50.

[0012] The printing apparatus 1 applies a pretreatment liquid to the sheet material P supplied from the loading section 10 as needed in the pretreatment section 20, applies the 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 discharge section 50.

[0013] The loading section 10 includes loading trays 11 (lower loading tray 11A, upper loading tray 11B) that accommodate 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 loading trays 11, supplying the sheet materials P to the pre-processing section 20.

[0014] The pre-processing unit 20 includes, for example, a coating unit 21 which is a means for applying a processing liquid that has the effect of coagulating ink and preventing show-through to the back of the sheet material P to the printed surface.

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

[0016] Furthermore, the printing unit 30 includes a transfer cylinder 34 that receives the sheet material P fed from the pre-processing unit 20 and transfers the sheet material P to the drum 31, and a transfer cylinder 35 that receives the sheet material P conveyed by the drum 31 and transfers it to the drying unit 40.

[0017] The sheet material P, which has been transported from the pre-processing unit 20 to the printing unit 30, is gripped at the tip by a gripping means (sheet gripper) provided on the transfer cylinder 34 and transported as the transfer cylinder 34 rotates. The sheet material P transported by the transfer cylinder 34 is then transferred 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 tip of the sheet material P is gripped by the gripping means (sheet gripper). Multiple suction holes are formed dispersed on the surface of the drum 31, and the suction means generates a suction airflow directed inward from the required suction holes of the drum 31.

[0019] The sheet material P, which has been transferred from the transfer drum 34 to the drum 31, is then gripped at the tip by the sheet gripper and attached to the drum 31 by the suction airflow from the suction means, and is conveyed as the drum 31 rotates.

[0020] The liquid dispensing unit 32 is equipped with dispensing units 33 (33A to 33D), which are liquid dispensing means. For example, dispensing unit 33A dispenses cyan (C) liquid, dispensing unit 33B dispenses magenta (M) liquid, dispensing unit 33C dispenses yellow (Y) liquid, and dispensing unit 33D dispenses black (K) liquid. In addition, dispensing units that dispense special liquids such as white and gold (silver) can also be used.

[0021] The discharge unit 33 is a full-line type head in which multiple liquid discharge heads (heads) 100, each having multiple nozzles 111 arranged in a two-dimensional matrix, are arranged in a staggered pattern on a base member 331, as shown in Figure 2, for example.

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

[0023] The sheet material P to which liquid has been applied in the liquid discharge section 32 is passed from the drum 31 to the transfer cylinder 35, and then to the transfer mechanism 41 which transfers the sheet material P to the drying section 40.

[0024] The drying unit 40 heats the sheet material P, which is transported by the transport mechanism unit 41, with the heating means 42 to dry the liquid adhering to the sheet material P. As a result, water and other liquid components in the liquid evaporate, the coloring agent contained in the liquid is fixed onto the sheet material P, and curling of the sheet material P is suppressed.

[0025] The reversal mechanism 60 is a mechanism that reverses the sheet material P in a switchback manner 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 cylinder 34 through the double-sided transport path 61.

[0026] The discharge unit 50 is equipped with a discharge tray 51 on which multiple sheet materials P are loaded. The sheet materials P, which are transported from the drying unit 40 via the reversing mechanism unit 60, are sequentially stacked and held on the discharge tray 51.

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

[0028] The head 100 is a circulating liquid discharge head and includes a nozzle plate 110, a flow path plate (individual flow path member) 120, a diaphragm member 130, a common flow path branch member 150, a damper member 160, a common flow path main 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 actuator board 102 is formed by the individual flow path member 120 and the diaphragm member 130.

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

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

[0031] The diaphragm member 130 forms a diaphragm 131, which is a deformable wall surface of the pressure chamber 121, and a piezoelectric element 140 is integrally provided on the diaphragm 131. The diaphragm member 130 also has a supply-side opening 132 leading to an individual supply channel 122 and a recovery-side opening 133 leading to an individual recovery channel 123. The piezoelectric element 140 is a pressure generating means that deforms the diaphragm 131 to pressurize the liquid in the pressure chamber 121.

[0032] The common channel branch member 150 is formed by alternately arranging multiple common supply channel branches 152 that lead to two or more individual supply channels 122 and multiple common recovery channel branches 153 that lead to two or more individual recovery channels 123.

[0033] The common channel branch member 150 has through holes that serve as supply ports 154 passing through the supply-side opening 132 of the individual supply channel 122 and the common supply channel branch 152, and through holes that serve as recovery ports 155 passing through the recovery-side opening 133 of the individual recovery channel 123 and the common recovery channel branch 153.

[0034] Furthermore, the common channel branch member 150 forms a part 156a of one or more common supply channel main channels 156 that leads to multiple common supply channel branch channels 152, and a part 157a of one or more common recovery channel main channels 157 that leads to multiple common recovery channel branch channels 153.

[0035] The damper member 160 has a supply-side damper that faces (opposes) the supply port 154 of the common supply channel branch 152, and a recovery-side damper that faces (opposes) the recovery port 155 of the common recovery channel branch 153.

[0036] Here, the common supply channel branch 152 and the common recovery channel branch 153 are constructed by sealing grooves arranged alternately on the common channel branch member 150, which is the same component, with damper members 160 that form deformable walls.

[0037] The common channel main channel member 170 forms a common supply channel main channel 156 that leads to a plurality of common supply channel branches 152, and a common recovery channel main channel 157 that leads to a plurality of common recovery channel branches 153.

[0038] The frame member 180 has a portion 156b of the main supply channel 156 and a portion 157b of the main common recovery channel 157. The portion 156b of the main common supply channel 156 leads to a supply port 181 provided on the frame member 180, and the portion 157b of the main common recovery channel 157 leads to a recovery port 182 provided on the frame member 180.

[0039] In this head 100, by applying a drive pulse to the piezoelectric element 140, the piezoelectric element 140 deforms and bends, pressurizing the liquid in the pressure chamber 121, causing the liquid to be discharged in droplet form from the nozzle 111.

[0040] Furthermore, when the head 100 is not discharging liquid, or when liquid is not discharged from the nozzle 111, it is circulated through the circulation path to which the recovery port 182 and the supply port 181 are connected.

[0041] Next, the head drive control device that controls the drive of the head will be explained with reference to the block diagram in Figure 9.

[0042] The head drive control device 400 includes a head control unit 401, a drive waveform generation unit 402 and a waveform data storage unit 403 which constitute the drive waveform generation means, a head driver 410, and a discharge timing generation unit 404 for generating discharge timing.

[0043] When the head control unit 401 receives the discharge timing pulse stb, it outputs a discharge synchronization signal LINE, which triggers the generation of a common drive waveform, to the drive waveform generation unit 402. The head control unit 401 also outputs a discharge timing signal CHANGE, which corresponds to the delay amount from the discharge synchronization signal LINE, to the drive waveform generation unit 402.

[0044] The drive waveform generation unit 402 generates and outputs a common drive waveform Vcom at timings based on the discharge synchronization signal LINE and the discharge timing signal CHANGE.

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

[0046] The head control unit 401 also serves as an adjustment mechanism. It receives image data and, based on this image data, generates a selection signal MN for each nozzle 111 to select a predetermined required waveform portion of the common drive waveform Vcom, according to the size of the liquid discharged from each nozzle 111 of the head 100 and the variation in the characteristics of each nozzle 111. Therefore, the selection signal MN is output for each nozzle 111. Furthermore, the selection signal MN is a signal whose timing is synchronized with the discharge timing signal CHANGE.

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

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

[0049] The head driver 410 includes a shift register 411, a latch circuit 412, a grayscale decoder 413, a level shifter 414, and an analog switch array 415.

[0050] The shift register 411 receives image data SD and a synchronization clock signal SCK transferred from the head control unit 401. 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.

[0051] The grayscale 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 converts the logic level voltage signal of the grayscale 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 switched on / off by the output of the gradation decoder 413 provided via the level shifter 414, and is a means for passing / blocking (cutting off) the common drive waveform Vcom.

[0053] This analog switch AS is provided for each nozzle 111 of the head 100 and is connected to the individual electrodes of the piezoelectric element 140 corresponding to each nozzle 111. The analog switch AS also receives a common drive waveform Vcom from the drive waveform generation unit 402. Furthermore, 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 grayscale decoder 413 provided via the level shifter 414, thereby selecting the waveform portion applied to the piezoelectric element 140 corresponding to each nozzle 111 from the common drive waveform Vcom. As a result, the size of the droplets ejected from the nozzle 111 is controlled.

[0055] The discharge timing generation unit 404 generates and outputs a discharge timing pulse stb each time the sheet material P is moved by a predetermined amount, based on the detection result of the rotary encoder 405, which detects the amount of rotation of the drum 31. The rotary encoder 405 consists 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 the part that selects the common drive waveform of the head driver will be explained with reference to Figure 10. Figure 10 is an explanatory diagram of the switch part of the head driver.

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

[0058] By switching the selection switch Sa to the ON or OFF state by the selection signal MN, the required waveform portion of the common drive waveform Vcom is extracted (trimmed) and applied to the piezoelectric element 140 as the trimmed waveform (applied waveform) Vt.

[0059] In other words, the common drive waveform Vcom passes through when the selection switch Sa is in the ON position, and does not pass through when the selection switch Sa is in the OFF position. When the selection switch Sa is in the OFF position, the common drive waveform Vcom does not pass through, 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 trimmed waveform Vt) is maintained at the potential when the selection switch Sa is in the OFF position.

[0060] Next, trimming in the first embodiment of the present invention will be described with reference to Figures 11 and 12. Figure 11 is an explanatory diagram of an example of the drive waveform, the state of the selection switch, and the trimming waveform (applied waveform) in the same embodiment, and Figure 12 is an explanatory diagram of the waveform lengths of the drive waveform and trimming waveform.

[0061] The common drive waveform Vcom in this embodiment includes a non-discharge pulse Pb and a discharge pulse Pa in time series. The discharge pulse Pa is a discharge drive waveform that pressurizes the pressure chamber 121 to discharge liquid from the nozzle 111. The discharge pulse Pa is, for example, a pulse that discharges a small drop, but is not limited to a small drop pulse (the same applies to the following embodiments). The non-discharge pulse Pb is a micro-drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0062] The discharge pulse Pa consists of an expansion waveform element a that expands the pressure chamber 121, a holding waveform element b that maintains the state of the pressure chamber 121 expanded by the expansion waveform element a, and a contraction waveform element c that contracts the pressure chamber 121 from the state maintained by the holding waveform element b and discharges the liquid.

[0063] In this embodiment, the expanding waveform element a falls down to a potential V3 (V1 > V3) which is the potential difference ΔVa from the intermediate potential (or reference potential; the same applies hereinafter) V1. The holding waveform element b holds the potential V3 at the end of the expanded waveform element a. The contracting waveform element c rises from the potential V3 held by the holding waveform element b down to the intermediate potential V1.

[0064] The non-discharge pulse Pb consists of an expansion waveform element d that expands the pressure chamber 121, a holding waveform element e that maintains the state of the pressure chamber 121 expanded by the expansion waveform element d, and a contraction waveform element f that contracts the pressure chamber 121 from the state maintained by the holding waveform element e.

[0065] In this embodiment, the expanding waveform element d falls down to a potential V2 (V1>V2>V3) with a potential difference ΔVb from the intermediate potential V1. The holding waveform element e holds the potential V2 at the end of the expanded waveform element d. The contracting waveform element f rises from the potential V2 held by the holding waveform element e down to the intermediate potential V1.

[0066] Thus, in this embodiment, the non-discharge pulse Pb is a pull-type pulse that, in time series, falls from an intermediate potential V1, expands the pressure chamber 121, maintains the expanded state, and then rises to contract the pressure chamber 121.

[0067] In this embodiment, as shown in Figure 11(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that not only the discharge pulse Pa but also a portion of the waveform of the non-discharge pulse Pb is allowed to pass through.

[0068] Here, the selection switch Sa is turned ON at time t0, before the start of the expansion waveform element d of the non-discharge pulse Pb, and then turned OFF at time t1, during the hold waveform element e.

[0069] At this time, all of the expanding waveform element d of the non-discharge pulse Pb is selected and passes through, and a portion of the holding waveform element e that holds the potential V2 at the end of the expanding waveform element d is selected and passes through the selection switch Sa. When the selection switch Sa is turned OFF, the potential of the piezoelectric element 140 is held at the potential V2 that was present when the selection switch Sa was turned OFF.

[0070] Subsequently, at time point t2, after the end of the contraction waveform element f of the non-discharge pulse Pb, the selection switch Sa is switched from the OFF state to the ON state. When the selection switch Sa is turned ON, the potential of the piezoelectric element 140 rises from the potential V2 held by the holding waveform element e to the intermediate potential V1.

[0071] As a result, the trimmed waveform Vt, as shown in Figure 11(c), falls from the intermediate potential V1 to potential V2 according to the expanding waveform element d of the non-discharge pulse Pb from time t0, and potential V2 is maintained after time t1, and at time t2 it rises from potential V2 to the intermediate potential V1. After that, it takes on the same waveform shape as the common drive waveform Vcom.

[0072] As shown in Figure 12, the waveform length Wa of the common drive waveform Vcom input to the selection switch Sa and the waveform length Wb of the trimmed waveform Vt are the same.

[0073] Here, by changing the time t2 at which the selection switch Sa is switched from the ON state to the OFF state at time t1, and then back to the ON state, the timing at which the trimming waveform Vt rises from potential V2 to the intermediate potential V1 and contracts the pressure chamber 121 changes. The timing at which the pressure chamber 121 contracts changes, which alters the discharge characteristics.

[0074] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set, for example, within the trimming region Tw in Figure 11(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0075] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, variations in discharge characteristics can be corrected even for heads with a short natural period (also called natural vibration period or resonance period) of the pressure chamber 121.

[0076] Furthermore, as in this embodiment, when the non-discharge pulse Pb is a pull-type pulse, the variation in the amount of discharge curvature can be reduced by controlling the state of the meniscus (such as the shape of the meniscus) through trimming to correct the shape of the discharged droplet.

[0077] Here, Comparative Example 1 will be explained with reference to Figure 13. Figure 13 is an explanatory diagram illustrating an example of the drive waveform, the state of the selection switch, and the trimming waveform in Comparative Example 1.

[0078] In this comparative example 1, as shown in Figure 13(a), the discharge pulse Pa is composed of an expansion waveform element a, a holding waveform element b, and a contraction waveform element c.

[0079] The expansion waveform element a here is a waveform that performs two-stage expansion. The expansion waveform element a includes a first-stage expansion waveform element a1 that expands the pressure chamber 121, a first-stage holding waveform element a2 that maintains the expanded state created by the first-stage expansion waveform element a1, and a second-stage expansion waveform element a3 that further expands the pressure chamber 121 from the state maintained by the first-stage holding waveform element a2.

[0080] The first stage expansion waveform element a1 falls from the intermediate potential V1 to potential V4 (V1>V4>V3). The first stage holding waveform element a2 holds potential V4. The second stage expansion waveform element a3 falls from potential V4 to potential V3.

[0081] The retaining waveform element b retains the terminal potential V3 of the second-stage expanding waveform element a3. The contracting waveform element c rises from the retained potential V3 to the intermediate potential V1.

[0082] As shown in Figure 13(b), the selection switch Sa changes from the ON state to the OFF state during the first stage of the expanded waveform element a2, and from the OFF state to the ON state during the holding waveform element b.

[0083] As a result, the discharge pulse Pa of the common drive waveform Vcom shown in Figure 13(a) is trimmed, and a trimmed waveform (applied waveform) Vt is obtained in which the width Pw of the held waveform element b is changed, as shown in Figure 13(c).

[0084] Incidentally, as printing speeds for line printers and other devices increase, the natural period of the print head's pressure chamber tends to shorten in order to drive the print head at high speed. Also, when attempting to make ejected droplets smaller for the purpose of improving image quality, the natural period of the print head's pressure chamber tends to shorten as well.

[0085] 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 displacement, it becomes impossible to allocate sufficient time for the duration (width Pw) of the held waveform element b.

[0086] For example, in the case of a head with a natural period of about 3 μsec, the time from the start of the expanding waveform element a to the end of the contracting waveform element c is only about 1.5 to 2.5 μsec, so there is almost no time left to adjust the width Pw, making it impossible to correct for variations in ejection characteristics.

[0087] In contrast, in this embodiment, trimming is not performed on the holding waveform element b of the discharge pulse Pa that maintains the state in which the pressure chamber 121 is most expanded. Therefore, even for heads with short natural periods, trimming can be performed to reduce variations in discharge characteristics.

[0088] Next, trimming in a second embodiment of the present invention will be described with reference to Figure 14. Figure 14 is an explanatory diagram of an example of the drive waveform, the state of the selection switch, and the trimming waveform (applied waveform) in the same embodiment.

[0089] As shown in Figure 14(a), the common drive waveform Vcom of this embodiment includes a non-discharge pulse Pb and a discharge pulse Pa in time series. The discharge pulse Pa is a discharge drive waveform that pressurizes the pressure chamber 121 to discharge liquid from the nozzle 111. The non-discharge pulse Pb is a slight drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0090] Since the discharge pulse Pa and the non-discharge pulse Pb are the same waveforms as those described in the first embodiment, their explanation will be omitted.

[0091] In this embodiment, as shown in Figure 14(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that not only the discharge pulse Pa but also a portion of the non-discharge pulse Pb passes through.

[0092] Here, at time t1, before the start of the expansion waveform element d of the non-discharge pulse Pb, the selection switch Sa is turned from ON to OFF, and at time t2, during the portion of the held waveform element e, the selection switch Sa is turned from OFF to ON.

[0093] At this time, the expanding waveform element d of the non-discharge pulse Pb does not pass through the selection switch Sa, and even after time t1, the potential of the piezoelectric element 140 is maintained at the intermediate potential V1 when the selection switch Sa is in the OFF state. Then, at time t2 when the selection switch Sa is in the ON state, the falling edge from the intermediate potential V1 to the potential V2 of the held waveform element e begins, and thereafter the common drive waveform Vcom passes through as is.

[0094] As a result, the trimmed waveform Vt, as shown in Figure 14(c), has a waveform in which the expansion waveform element d of the non-discharge pulse Pb starts at time t2, and thereafter has the same waveform shape as the common drive waveform Vcom.

[0095] Here, by changing the time t2 at which the selection switch Sa transitions from the OFF state to the ON state after being switched from the ON state to the OFF state at time t1, the timing at which the pressure chamber 121 expands due to the non-discharge pulse Pb changes. The discharge characteristics change as the timing of the expansion of the pressure chamber 121 changes.

[0096] Therefore, the timing for transitioning the selection switch Sa from the ON state to the OFF state, that is, the timing for changing the common drive waveform Vcom from a passing state to a non-passing state, is set so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0097] In this way, by trimming the expansion waveform element (potential falling waveform element) of the non-discharge pulse Pb (micro-drive section), the state of the meniscus (such as the shape of the meniscus) can be controlled to correct the shape of the discharged droplet and reduce variations in the amount of curvature of the discharged droplet.

[0098] Furthermore, since trimming is not performed on the holding waveform element b of the discharge pulse Pa, which maintains the state in which the pressure chamber 121 is most expanded, even heads with short natural periods can be trimmed to reduce variations in discharge characteristics.

[0099] Next, trimming in the third embodiment of the present invention will be described with reference to Figures 15 and 16. Figure 15 is an explanatory diagram of an example of the drive waveform, the state of the selection switch, and the trimming waveform (applied waveform) in the same embodiment, and Figure 16 is an explanatory diagram of the waveform lengths of the drive waveform and trimming waveform.

[0100] The common drive waveform Vcom in this embodiment includes a non-discharge pulse Pb and a discharge pulse Pa in time series. The discharge pulse Pa is a discharge drive waveform that pressurizes the pressure chamber 121 to discharge liquid from the nozzle 111. The discharge pulse Pa is, for example, a pulse that discharges small droplets. The non-discharge pulse Pb is a micro-drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0101] The discharge pulse Pa consists of an expansion waveform element a that expands the pressure chamber 121, a holding waveform element b that maintains the state of the pressure chamber 121 expanded by the expansion waveform element a, and a contraction waveform element c that contracts the pressure chamber 121 from the state maintained by the holding waveform element b and discharges the liquid.

[0102] The expanding waveform element a falls down to a potential V3 (V1 > V3) with a potential difference ΔVa from the intermediate potential (or reference potential) V1. The holding waveform element b holds the potential V3 at the end of the expanded waveform element a. The contracting waveform element c rises from the potential V3 held by the holding waveform element b down to the intermediate potential V1.

[0103] The non-discharge pulse Pb consists of a contraction waveform element g that contracts the pressure chamber 121, a holding waveform element h that maintains the state of the pressure chamber 121 contracted by the contraction waveform element g, and an expansion waveform element i that expands the pressure chamber 121 from the state maintained by the holding waveform element h.

[0104] The contracting waveform element g rises to a potential V5 (V5 > V1) with a potential difference ΔVb from the intermediate potential (or reference potential) V1. The holding waveform element h holds the potential V5 at the end of the contracting waveform element g. The expanding waveform element i falls from the potential V5 held by the holding waveform element h to the intermediate potential V1.

[0105] Thus, in this embodiment, the non-discharge pulse Pb is a push-type pulse that rises from an intermediate potential V1 in time series, contracts the pressure chamber 121, maintains the contracted state, and then falls down to expand the pressure chamber 121.

[0106] In this embodiment, as shown in Figure 15(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that not only the discharge pulse Pa but also a portion of the non-discharge pulse Pb passes through.

[0107] Here, the selection switch Sa is turned ON at time t0, before the start of the contraction waveform element g of the non-discharge pulse Pb, and then turned OFF at time t1, during the hold waveform element h.

[0108] At this time, all of the contraction waveform elements g of the non-discharge pulse Pb are selected and pass through, and a portion of the holding waveform elements h that maintain the potential V5 at the end of the contraction waveform elements g are selected and pass through. When the selection switch Sa is turned OFF, the potential of the piezoelectric element 140 is maintained at the potential V5 that was present when the selection switch Sa was turned OFF.

[0109] Subsequently, at time point t2, after the end of the holding waveform element h of the non-discharge pulse Pb, the selection switch Sa is switched from the OFF state to the ON state. When the selection switch Sa is turned ON, the potential of the piezoelectric element 140 falls from the potential V4 held by the holding waveform element h to the intermediate potential V1.

[0110] As a result, the trimmed waveform Vt rises from the intermediate potential V1 to the potential V5 according to the contraction waveform element g of the non-discharge pulse Pb from time t0, as shown in Figure 15(c). The potential V5 is maintained at time t1 and thereafter, and at time t2, the waveform falls from the potential V5 to the intermediate potential V1. After that, it takes on the same waveform shape as the common drive waveform Vcom.

[0111] As shown in Figure 16, the waveform length Wa of the common drive waveform Vcom input to the selection switch Sa and the waveform length Wb of the trimmed waveform Vt are the same length.

[0112] Here, by changing the time t2 at which the selection switch Sa is changed from the ON state to the OFF state at time t1, and then back to the ON state, the timing at which the trimming waveform Vt falls from potential V4 to the intermediate potential V1 and expands the pressure chamber 121 is changed. The timing at which the pressure chamber 121 expands changes the discharge characteristics.

[0113] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set, for example, within the trimming region Tw in Figure 15(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0114] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, variations in discharge characteristics can be corrected even for heads with a short natural period (also called natural vibration period or resonance period) of the pressure chamber 121.

[0115] Furthermore, as in this embodiment, when the non-discharge pulse Pb is a push-type pulse, the variation in the amount of discharge curvature can be reduced by controlling the state of the meniscus (such as the shape of the meniscus) through trimming to correct the shape of the discharged droplet. In addition, when the non-discharge pulse Pb is a push-type pulse, the droplet volume and droplet velocity of the discharged droplet can be corrected.

[0116] Next, trimming in the fourth embodiment of the present invention will be described with reference to Figure 17. Figure 17 is an explanatory diagram of an example of the drive waveform, the state of the selection switch, and the trimming waveform (applied waveform) in the said embodiment.

[0117] As shown in Figure 17(a), the common drive waveform Vcom of this embodiment includes a non-discharge pulse Pb and a discharge pulse Pa in time series. The discharge pulse Pa is a discharge drive waveform that pressurizes the pressure chamber 121 to discharge liquid from the nozzle 111. The non-discharge pulse Pb is a slight drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0118] Since the discharge pulse Pa and the non-discharge pulse Pb are the same waveforms as those described in the third embodiment, their explanation will be omitted.

[0119] In this embodiment, as shown in Figure 17(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that not only the discharge pulse Pa but also a portion of the non-discharge pulse Pb passes through.

[0120] Here, at time point t1, before the start of the contraction waveform element g of the non-discharge pulse Pb, the selection switch Sa is changed from the ON state to the OFF state, and at time point t2, during the waveform portion of the held waveform element h, the selection switch Sa is changed from the OFF state to the ON state.

[0121] At this time, the contraction waveform element g of the non-discharge pulse Pb does not pass through the selection switch Sa, and even after time t1, the potential of the piezoelectric element 140 is maintained at the intermediate potential V1 when the selection switch Sa is in the OFF state. Then, at time t2 when the selection switch Sa is in the ON state, the rising edge of the held waveform element h from the intermediate potential V1 to the potential V5 begins, and thereafter the common drive waveform Vcom passes through as is.

[0122] As a result, the trimmed waveform Vt, as shown in Figure 17(c), has a waveform in which the contraction waveform element g of the non-discharge pulse Pb starts at time t2, and thereafter has the same waveform shape as the common drive waveform Vcom.

[0123] Here, by changing the time t2 at which the selection switch Sa transitions from the OFF state to the ON state after being switched from the ON state to the OFF state at time t1, the timing at which the pressure chamber 121 is contracted by the non-discharge pulse Pb is changed. The discharge characteristics change as the timing of the contraction of the pressure chamber 121 changes.

[0124] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0125] In this way, by trimming the contraction waveform element (potential falling waveform element) of the non-discharge pulse Pb (micro-drive section), the state of the meniscus (such as the shape of the meniscus) can be controlled to correct the shape of the discharged droplet, thereby reducing variations in the amount of curvature of the discharged droplet.

[0126] Furthermore, since trimming is not performed on the holding waveform element b of the discharge pulse Pa, which maintains the state in which the pressure chamber 121 is most expanded, even heads with short natural periods can be trimmed to reduce variations in discharge characteristics.

[0127] Next, a fifth embodiment of the present invention will be described with reference to Figure 18. Figure 18 is an explanatory diagram illustrating an example of the drive waveform, the state of the selection switch, and the trimming waveform in this embodiment.

[0128] In this embodiment, the common drive waveform Vcom, as shown in Figure 18(a), includes a non-discharge pulse Pb, a discharge pulse Pa1, and a discharge pulse Pa2 in time series. Discharge pulses Pa1 and Pa2 are discharge drive waveforms that pressurize the pressure chamber 121 to discharge liquid from the nozzle 111. The non-discharge pulse Pb is a slight drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0129] The discharge pulses Pa1 and Pa2 consist of an expansion waveform element a that expands the pressure chamber 121, a holding waveform element b that maintains the state of the pressure chamber 121 expanded by the expansion waveform element a, and a contraction waveform element c that contracts the pressure chamber 121 from the state maintained by the holding waveform element b and discharges the liquid.

[0130] The expansion waveform element a of the discharge pulse Pa1 falls from the intermediate potential V1 to the potential V6 (V1 > V6). The holding waveform element b holds the potential V6 at the end of the stage expansion waveform element a. The contraction waveform element c rises from the potential V6 held by the holding waveform element b to the intermediate potential V1.

[0131] The expansion waveform element a of the discharge pulse Pa2 falls from an intermediate potential V1 to a potential V3 (V1>V6>V3). The holding waveform element b holds the potential V3 at the end of the stage expansion waveform element a. The contraction waveform element c rises from the potential V3 held by the holding waveform element b to an intermediate potential V1. This discharge pulse Pa2 is the same as the discharge pulse Pa described in each of the embodiments above.

[0132] The non-discharge pulse Pb consists of an expansion waveform element d that expands the pressure chamber 121, a holding waveform element e that maintains the state of the pressure chamber 121 expanded by the expansion waveform element d, and a contraction waveform element f that contracts the pressure chamber 121 from the state maintained by the holding waveform element e.

[0133] The expanding waveform element d falls from the intermediate potential V1 to potential V2 (V1 > V2). The holding waveform element e holds the potential V2 at the end of the stepped expanding waveform element b. The contracting waveform element f rises from the potential V2 held by the holding waveform element e to the intermediate potential V1.

[0134] In this embodiment, as shown in Figure 18(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that the discharge pulse Pa1 and discharge pulse Pa2, or not only the discharge pulse Pa2 but also a portion of the non-discharge pulse Pb, can pass through.

[0135] First, when performing simple micro-driving, the selection switch Sa is turned ON at time t0, before the start of the expansion waveform element d of the non-discharge pulse Pb, and then turned OFF at time t2, after the end of the contraction waveform element f.

[0136] As a result, as shown in Figure 18(c), the trimmed waveform Vt for the micro-drive becomes the same as the non-discharge pulse Pb.

[0137] Furthermore, when dispensing small droplets, a portion of the dispensing pulse Pa2 and the non-dispensing pulse Pb are passed through.

[0138] In other words, the selection switch Sa is turned ON at time t0, before the start of the expanding waveform element d of the non-discharge pulse Pb, and transitioned from the ON state to the OFF state at time t1, before the end of the holding waveform element e. When the selection switch Sa is turned OFF, the intermediate potential V1 held by the holding waveform element e of the non-discharge pulse Pb is maintained until the selection switch Sa is turned ON. Therefore, at time t4, after the end of the contracting waveform element c of the discharge pulse Pa1 and before the start of the discharge pulse Pa2, the selection switch Sa is turned from the OFF state to the ON state.

[0139] As a result, as shown in Figure 18(c), the trimmed waveform Vt of the droplet falls to potential V2 according to the expanding waveform element d of the non-discharge pulse Pb, is held at potential V2 until time t4, rises to the intermediate potential V1 at time t4, and thereafter becomes the same as the common drive waveform Vcom. In other words, when a droplet is discharged, a non-discharge pulse (micro-drive waveform) is generated that falls to potential V2 according to the expanding waveform element d of the non-discharge pulse Pb, is held at potential V2 until time t4, and rises to the intermediate potential V1 at time t4.

[0140] At this time, by changing the time t4 when the selection switch Sa transitions from the OFF state to the ON state, the timing at which the non-discharge pulse Pb causes the pressure chamber 121 to contract changes. As the timing of the contraction of the pressure chamber 121 changes, the relationship between the meniscus vibration and the subsequently applied discharge pulse Pa2 changes, and the discharge characteristics change.

[0141] Therefore, the timing t4, which is the timing at which the selection switch Sa transitions from the OFF state to the ON state, that is, the timing at which the common drive waveform Vcom changes from a non-passing state to a passing state, is set, for example, within the trimming region Tws in Figure 18(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0142] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, variations in discharge characteristics can be corrected even for heads with a short natural period (also called natural vibration period or resonance period) of the pressure chamber 121.

[0143] Furthermore, when dispensing the intermediate droplet, a portion of the dispensing pulses Pa1 and Pa2, as well as the non-dispensing pulse Pb, are allowed to pass through.

[0144] In other words, the selection switch Sa is turned ON at time t0, before the start of the expanding waveform element d of the non-discharge pulse Pb, and transitioned from the ON state to the OFF state at time t1, before the end of the holding waveform element e. When the selection switch Sa is turned OFF, the potential V2 held by the holding waveform element e of the non-discharge pulse Pb is maintained until the selection switch Sa is turned ON. Therefore, at time t3, after the end of the contracting waveform element f of the non-discharge pulse Pb, but before the start of the discharge pulse Pa1, the selection switch Sa is turned from the OFF state to the ON state.

[0145] As a result, as shown in Figure 18(c), the trimming waveform Vt of the intermediate drop falls to potential V2 according to the expanding waveform element d of the non-discharge pulse Pb, is held at potential V2 until time t3, rises to the intermediate potential V1 at time t3, and thereafter becomes the same as the common drive waveform Vcom. In other words, when the intermediate drop is discharged, the holding waveform element e of the non-discharge pulse Pb is maintained until time t3.

[0146] Here, by changing the time t3 at which the selection switch Sa transitions from the ON state to the OFF state after being switched from the OFF state to the ON state at time t1, the timing at which the pressure chamber 121 is contracted by the non-discharge pulse Pb is changed. As the timing of the contraction of the pressure chamber 121 changes, the discharge characteristics of the discharge pulse Pa1 change.

[0147] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set, for example, within the trimming region Twm in Figure 18(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0148] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, discharge variations can be corrected even for heads with short natural periods (natural vibration period, resonance period) in the pressure chamber 121.

[0149] Next, a sixth embodiment of the present invention will be described with reference to Figure 19. Figure 19 is an explanatory diagram illustrating an example of the drive waveform, the state of the selection switch, and the trimming waveform in this embodiment.

[0150] In this embodiment, the common drive waveform Vcom, as shown in Figure 19(a), includes a non-discharge pulse Pb, a discharge pulse Pa1, and a discharge pulse Pa2 in time series. Discharge pulses Pa1 and Pa2 are discharge drive waveforms that pressurize the pressure chamber 121 to discharge liquid from the nozzle 111. The non-discharge pulse Pb is a slight drive waveform (non-discharge drive waveform) that pressurizes the pressure chamber 121 to the extent that liquid is not discharged from the nozzle 111, causing the meniscus to vibrate.

[0151] The discharge pulses Pa1 and Pa2 consist of an expansion waveform element a that expands the pressure chamber 121, a holding waveform element b that maintains the state of the pressure chamber 121 expanded by the expansion waveform element a, and a contraction waveform element c that contracts the pressure chamber 121 from the state maintained by the holding waveform element b and discharges the liquid.

[0152] The expansion waveform element a of the discharge pulse Pa1 falls from the intermediate potential V1 to the potential V6 (V1 > V6). The holding waveform element b holds the potential V6 at the end of the stage expansion waveform element a. The contraction waveform element c rises from the potential V6 held by the holding waveform element b to the intermediate potential V1.

[0153] The expansion waveform element a of the discharge pulse Pa2 falls from an intermediate potential V1 to a potential V3 (V1>V6>V3). The holding waveform element b holds the potential V3 at the end of the stage expansion waveform element a. The contraction waveform element c rises from the potential V3 held by the holding waveform element b to an intermediate potential V1. This discharge pulse Pa2 is the same as the discharge pulse Pa described in each of the embodiments above.

[0154] The non-discharge pulse Pb consists of a contraction waveform element g that contracts the pressure chamber 121, a holding waveform element h that maintains the state of the pressure chamber 121 contracted by the contraction waveform element g, and an expansion waveform element i that expands the pressure chamber 121 from the state maintained by the holding waveform element h.

[0155] The contraction waveform element g rises from the intermediate potential V1 to potential V5 (V5 > V1). The holding waveform element h holds the potential V5 at the end of the contraction waveform element g. The expansion waveform element i falls from the potential V5 held by the holding waveform element h to the intermediate potential V1.

[0156] In this embodiment, as shown in Figure 19(b), when discharging liquid from the nozzle 111, control is performed to switch the selection switch Sa to the ON state or the OFF state so that the discharge pulse Pa1 and discharge pulse Pa2, or not only the discharge pulse Pa2 but also a portion of the non-discharge pulse Pb, can pass through.

[0157] First, when performing simple micro-driving, the selection switch Sa is turned ON at time t0, before the start of the contraction waveform element g of the non-discharge pulse Pb, and then turned OFF at time t2, after the end of the expansion waveform element i.

[0158] As a result, as shown in Figure 19(c), the trimmed waveform Vt for the micro-drive becomes the same as the non-discharge pulse Pb.

[0159] Furthermore, when dispensing small droplets, a portion of the dispensing pulse Pa2 and the non-dispensing pulse Pb are passed through.

[0160] In other words, the selection switch Sa is turned ON at time t0, before the start of the contraction waveform element g of the non-discharge pulse Pb, and transitioned from the ON state to the OFF state at time t1, before the end of the holding waveform element h. When the selection switch Sa is turned OFF, the potential V5 held by the holding waveform element h of the non-discharge pulse Pb is maintained until the selection switch Sa is turned ON. Therefore, at time t4, after the end of the contraction waveform element c of the discharge pulse Pa1 and before the start of the discharge pulse Pa2, the selection switch Sa is turned from the OFF state to the ON state.

[0161] As a result, as shown in Figure 19(c), the trimming waveform Vt of the droplet rises to potential V5 according to the contraction waveform element g of the non-discharge pulse Pb, is held at potential V5 until time t4, falls to the intermediate potential V1 at time t4, and thereafter becomes the same as the common drive waveform Vcom. In other words, when a droplet is discharged, a non-discharge pulse (micro-drive waveform) is generated that rises to potential V5 according to the contraction waveform element g of the non-discharge pulse Pb, is held at potential V5 until time t4, and falls to the intermediate potential V1 at time t4.

[0162] At this time, by changing the time t4 when the selection switch Sa transitions from the OFF state to the ON state, the timing at which the pressure chamber 121 expands due to the non-discharge pulse Pb changes. The discharge characteristics change as the timing of the expansion of the pressure chamber 121 changes.

[0163] Therefore, the timing t4, which is the timing at which the selection switch Sa transitions from the OFF state to the ON state, that is, the timing at which the common drive waveform Vcom changes from a non-passing state to a passing state, is set, for example, within the trimming region Tws in Figure 19(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0164] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, variations in discharge characteristics can be corrected even for heads with a short natural period (also called natural vibration period or resonance period) of the pressure chamber 121.

[0165] Furthermore, when dispensing the intermediate droplet, a portion of the dispensing pulses Pa1 and Pa2, as well as the non-dispensing pulse Pb, are allowed to pass through.

[0166] In other words, the selection switch Sa is turned ON at time t0, before the start of the expanding waveform element d of the non-discharge pulse Pb, and transitioned from the ON state to the OFF state at time t1, before the end of the holding waveform element h. When the selection switch Sa is turned OFF, the potential V5 held by the holding waveform element h of the non-discharge pulse Pb is maintained until the selection switch Sa is turned ON. Therefore, at time t3, after the end of the expanding waveform element i of the non-discharge pulse Pb but before the start of the discharge pulse Pa1, the selection switch Sa is turned from the OFF state to the ON state.

[0167] As a result, as shown in Figure 19(c), the trimming waveform Vt of the intermediate drop rises to potential V4 according to the contraction waveform element g of the non-discharge pulse Pb, is held at potential V5 until time t3, falls to the intermediate potential V1 at time t3, and thereafter becomes the same as the common drive waveform Vcom. In other words, when the intermediate drop is discharged, the holding waveform element h of the non-discharge pulse Pb is maintained until time t3.

[0168] Here, by changing the time t3 at which the selection switch Sa transitions from the ON state to the OFF state after being switched from the OFF state to the ON state at time t1, the timing at which the non-discharge pulse Pb expands the pressure chamber 121 is changed. As the timing of the expansion of the pressure chamber 121 changes, the discharge characteristics of the discharge pulse Pa1 change.

[0169] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set, for example, within the trimming region Twm in Figure 19(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0170] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, discharge variations can be corrected even for heads with short natural periods (natural vibration period, resonance period) in the pressure chamber 121.

[0171] Next, a seventh embodiment of the present invention will be described with reference to Figure 20. Figure 20 is an explanatory diagram illustrating an example of the drive waveform, the state of the selection switch, and the trimming waveform in this embodiment.

[0172] In this embodiment, the common drive waveform Vcom includes, in time series, a discharge pulse Pa1 and a discharge pulse Pa2, as shown in Figure 20(a). Discharge pulses Pa1 and Pa2 are discharge drive waveforms that pressurize the pressure chamber 121 to discharge liquid from the nozzle 111. In this embodiment, discharge pulse Pa1 is the first discharge pulse (leading discharge pulse), and discharge pulse Pa2 is the second discharge pulse (following discharge pulse).

[0173] The discharge pulses Pa1 and Pa2 consist of an expansion waveform element a that expands the pressure chamber 121, a holding waveform element b that maintains the state of the pressure chamber 121 expanded by the expansion waveform element a, and a contraction waveform element c that contracts the pressure chamber 121 from the state maintained by the holding waveform element b and discharges the liquid.

[0174] In this embodiment, the expansion waveform element a of the discharge pulse Pa1 is a waveform that expands the pressure chamber 121 in two stages. The expansion waveform element a of the discharge pulse Pa1 includes a first-stage expansion waveform element a1 that expands the pressure chamber 121, a first-stage holding waveform element a2 that maintains the expanded state created by the first-stage expansion waveform element a1, and a second-stage expansion waveform element a3 that further expands the pressure chamber 121 from the state maintained by the first-stage holding waveform element a2.

[0175] The first-stage expansion waveform element a1 is the first-stage expansion waveform element, falling from an intermediate potential V1 to a potential V2 (V1 > V2). The first-stage holding waveform element a2 holds the potential V2, which is the termination potential of the first-stage expansion waveform element. The second-stage expansion waveform element a3 is the second-stage expansion waveform element, falling from a potential V2 to a potential V6 (V2 > V6).

[0176] Furthermore, the falling potential V2 of the first-stage expansion waveform element a1 (the termination potential of the first-stage expansion waveform element) is the same as the falling potential of the expansion waveform element a of the non-discharge pulse Pb described in each of the embodiments above, and when it rises from potential V2, the pressure chamber 121 is only pressurized to the extent that no liquid is discharged.

[0177] The retained waveform element b retains the potential V6 at the end of the second stage expanded waveform element a3. The contracted waveform element c rises from the retained potential V6 to potential V7 (V1>V7>V2).

[0178] The expansion waveform element a of the discharge pulse Pa2 falls from the rising potential V7 of the contraction waveform element c of the discharge pulse Pa1 to potential V3 (V7 > V3). The holding waveform element b holds the potential V3 at the end of the stage expansion waveform element a. The contraction waveform element c rises from the potential V3 held by the holding waveform element b to the intermediate potential V1.

[0179] In this embodiment, when dispensing small droplets, a portion of the dispensing pulse Pa1 and the dispensing pulse Pa2 are passed through, as shown in Figure 20(b).

[0180] In other words, the selection switch Sa is turned ON at time t0, before the start of the first stage expansion waveform element a1 of the discharge pulse Pa1, and then turned OFF in the middle of the first stage holding waveform element a2. To put it another way, when selecting the second discharge pulse, discharge pulse Pa2, the switching means is turned OFF at the first holding waveform element a2, which is the termination potential portion of the first stage expansion waveform element of the first discharge pulse, discharge pulse Pa1.

[0181] When the selection switch Sa is in the OFF state, the potential V2 held by the first-stage holding waveform element a2 of the discharge pulse Pa1 is maintained until the selection switch Sa is in the ON state. Therefore, at a time t4 after the end of the contraction waveform element c of the discharge pulse Pa1 and before the start of the discharge pulse Pa2, the selection switch Sa is changed from the OFF state to the ON state. In other words, the switching means is turned ON at a time after the end of the contraction waveform element c of the discharge pulse Pa1, which is the first discharge pulse.

[0182] As a result, as shown in Figure 20(c), the trimmed waveform Vt of the droplet falls to potential V2 according to the first-stage expansion waveform element a1 of the discharge pulse Pa1, is held at potential V2 until time t4, falls to potential V7 at time t4, and thereafter becomes the same as the common drive waveform Vcom. In other words, when a droplet is discharged, the first-stage expansion waveform element a1 of the discharge pulse Pa1 is used to generate a non-discharge pulse (micro-drive waveform) that falls to potential V7 at time t4.

[0183] At this time, by changing the time t4 when the selection switch Sa transitions from the OFF state to the ON state, the timing of the expansion of the pressure chamber 121 changes. The discharge characteristics change as the timing of the expansion of the pressure chamber 121 changes.

[0184] Therefore, the timing t4, which is the timing at which the selection switch Sa transitions from the OFF state to the ON state, that is, the timing at which the common drive waveform Vcom changes from a non-passing state to a passing state, is set, for example, within the trimming region Tws in Figure 20(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0185] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, variations in discharge characteristics can be corrected even for heads with a short natural period (also called natural vibration period or resonance period) of the pressure chamber 121.

[0186] Furthermore, when dispensing the intermediate droplet, it is passed through dispensing pulses Pa1 and Pa2 as shown in Figure 20(b).

[0187] In other words, the selector switch Sa is turned OFF at time t1, before the start of the first-stage expansion waveform element a1 of the discharge pulse Pa1. With the selector switch Sa in the OFF state, the potential of the piezoelectric element 140 is maintained at the intermediate potential V1. Subsequently, at time t3, before the end of the first-stage holding waveform element a2, the selector switch Sa is turned ON from the OFF state. With the selector switch Sa in the ON state, the potential drops from the intermediate potential V1 to the potential V2 held by the first-stage holding waveform element a2.

[0188] As a result, as shown in Figure 20(c), the trimmed waveform Vt of the middle drop falls from the intermediate potential V1 to potential V2 at time t3, and thereafter becomes the same as the common drive waveform Vcom.

[0189] Here, by changing the time t3 at which the selection switch Sa transitions from the ON state to the OFF state after being switched from the OFF state to the ON state at time t1, the timing of the expansion of the pressure chamber 121 with a waveform corresponding to the first stage expansion waveform a1 is changed. The change in the timing of the expansion of the pressure chamber 121 changes the discharge characteristics of the discharge pulse Pa1.

[0190] Therefore, the timing for transitioning the selection switch Sa from the OFF state to the ON state, that is, the timing for changing the common drive waveform Vcom from a non-passing state to a passing state, is set, for example, within the trimming region Twm in Figure 20(a), so that the discharge characteristics of each nozzle 111 become the desired characteristics.

[0191] This allows for the application of a trimmed waveform Vt corresponding to the required correction amount (adjustment amount) for each nozzle, while maintaining the waveform length of the drive waveform. Furthermore, by trimming the waveform in the non-discharge pulse Pb (micro-drive portion) of the common drive waveform Vcom, discharge variations can be corrected even for heads with short natural periods (natural vibration period, resonance period) in the pressure chamber 121.

[0192] In this application, the discharged liquid is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the head, but it is preferable that its viscosity becomes 30 mPa·s or less at room temperature and atmospheric pressure, or when heated or cooled. More specifically, it is a solution, suspension, emulsion, etc. containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a functional material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or electronic circuit resist patterns, and material liquids for 3D molding.

[0193] The energy source for discharging liquid includes piezoelectric actuators (multilayer 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 a counter electrode.

[0194] Furthermore, "devices that discharge liquid" include not only devices that can discharge liquid onto surfaces to which liquid can adhere, but also devices that discharge liquid into air or into liquid.

[0195] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0196] For example, "devices that dispense liquids" include image forming machines, which dispense ink to form images on paper, and three-dimensional molding machines, which dispense molding liquid into a powder layer formed in layers to create three-dimensional objects.

[0197] Furthermore, "devices that dispense liquid" are not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images, are also included.

[0198] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0199] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to them, even temporarily.

[0200] Furthermore, "liquid dispensing devices" include devices in which the liquid dispensing head and the surface to which the liquid can adhere move relative to each other, but are not limited to these. Specific examples include serial-type devices in which the liquid dispensing head moves, and line-type devices in which the liquid dispensing head does not move.

[0201] Other examples of "devices that dispense liquids" include processing liquid coating devices that dispense processing liquid onto the surface of paper for purposes such as modifying the surface of the paper, and injection granulation devices that granulate fine particles of raw materials by spraying a compositional solution, in which raw materials are dispersed in a solution, through a nozzle.

[0202] In this application, the terms image formation, recording, printing, copying, printing, and shaping are all considered synonymous. [Explanation of Symbols]

[0203] 1. Printing device (device that dispenses liquid) 30 Printing Department 32 Liquid discharge part 33 Discharge Unit 100 Liquid Dispensing Heads (Heads) 121 Pressure Chamber 140 Piezoelectric elements 400 Head drive control device 401 Head Control Unit 402 Drive waveform generation unit 403 Waveform data storage unit 410 Head Driver

Claims

1. A head that dispenses liquid, The head comprises a switching means for selecting whether to pass or not pass the drive waveform that drives the piezoelectric element of the head, The drive waveform includes, in time series, non-discharge pulses that drive the piezoelectric element to an extent that does not discharge the liquid, and discharge pulses that discharge the liquid. The system includes means for controlling the switching means to switch to an ON state or an OFF state in the waveform portion of the non-discharge pulse, thereby adjusting the waveform applied to the piezoelectric element. The non-discharge pulse includes a contraction waveform element that contracts the pressure chamber of the head, a holding waveform element that maintains the contracted state by the contraction waveform element, and an expansion waveform element that expands the pressure chamber from the state maintained by the holding waveform element. The adjustment means turns the switching means OFF in the portion of the held waveform element and turns the switching means ON at a point after the end of the expanded waveform element. A device for dispensing liquid characterized by the following.

2. A head for dispensing liquid, The head comprises a switching means for selecting whether to pass or not pass the drive waveform that drives the piezoelectric element of the head, The drive waveform includes, in time series, non-discharge pulses that drive the piezoelectric element to an extent that does not discharge the liquid, and discharge pulses that discharge the liquid. The system includes means for controlling the switching means to switch to an ON state or an OFF state in the waveform portion of the non-discharge pulse, thereby adjusting the waveform applied to the piezoelectric element. The non-discharge pulse includes a contraction waveform element that contracts the pressure chamber of the head, a holding waveform element that maintains the contracted state by the contraction waveform element, and an expansion waveform element that expands the pressure chamber from the state maintained by the holding waveform element. The adjusting means turns the switching means OFF before the start of the contraction waveform element and turns the switching means ON after the end of the contraction waveform element. A device for dispensing liquid according to feature 1.

3. A head that dispenses liquid, The head comprises a switching means for selecting whether to pass or not pass the drive waveform that drives the piezoelectric element of the head, The drive waveform includes, in time series, a first discharge pulse for discharging the liquid and a second discharge pulse for discharging the liquid. The first discharge pulse includes an expansion waveform element that expands the pressure chamber of the head in at least two stages. The system includes means for adjusting the waveform applied to the piezoelectric element by controlling the switching means to be OFF at the terminal potential of the first stage of the expansion waveform element of the first discharge pulse when the second discharge pulse is selected, and to be ON after the terminal of the contraction waveform element of the first discharge pulse, and by generating a waveform that drives the piezoelectric element to the extent that the liquid is not discharged before the second discharge pulse. A device for dispensing liquid characterized by the following.

4. It includes a switching means for selecting whether to pass or not pass the drive waveform that drives the piezoelectric element of the head that discharges liquid, The drive waveform includes, in time series, a first discharge pulse for discharging the liquid and a second discharge pulse for discharging the liquid. The first discharge pulse includes an expansion waveform element that expands the pressure chamber of the head in at least two stages. The system includes means for adjusting the waveform applied to the piezoelectric element by controlling the switching means to be OFF at the termination potential of the first stage of the expanding waveform element of the first discharge pulse when the second discharge pulse is selected, and to be ON after the termination of the contracting waveform element of the first discharge pulse. A head drive control device characterized by the following:

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