JP2017202588A - Drive waveform generation device, device for discharging liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive waveform generation device which reduces generation of mists.SOLUTION: A drive waveform is configured from drive pulses P1, P2, P3, P4, which are driving signals, in a time sequence, the drive pulse P4 becomes a final drive pulse, the drive pulse P3 becomes a drive pulse just before the final drive pulse, and each drive pulse P1 to P4 is a single pulse including an expansion waveform element (pulling-in waveform element) a, a holding waveform element b, and a contraction waveform element (pushing waveform element) c. When a potential difference between an intermediate potential Vm and a rising potential by the expansion waveform element a is represented by a crest value, the drive pulse P3 just before the final pulse is represented by a crest value Va, and the final drive pulse P4 is represented by a crest value Vb smaller than the crest value Va (Vb<Va).SELECTED DRAWING: Figure 7

Description

  The present invention relates to a drive waveform generation device, a head drive device, and a device for ejecting liquid.

  When the liquid is ejected from the liquid ejection head, if the distance between the head and the landing surface to which the liquid adheres is long, the mist generated along with the liquid ejection tends to float.

  Conventionally, when the distance from the head to the landing surface is long, there is an attempt to suppress the generation of mist by slowing the discharge speed of the droplet (Patent Document 1).

JP 2006-248001 A

  As described above, when the mist generated due to the liquid discharge easily floats, the floated mist adheres to the inside of the apparatus and contaminates the inside of the apparatus, adheres to the nozzle surface of the head, and causes nozzle clogging or jet bending. There is a problem.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the occurrence of mist.

In order to solve the above-described problem, a drive waveform generation device according to claim 1 of the present invention includes:
An apparatus for generating a drive waveform including a plurality of drive pulses for discharging liquid from a liquid discharge head in time series,
The drive waveform is a waveform in which the speed of the liquid ejected by the final drive pulse among the plurality of drive pulses is slower than the speed of the liquid ejected by the drive pulse immediately before the final drive pulse. The configuration.

  According to the present invention, generation of mist can be reduced.

It is a plane explanatory view of a mechanism part in an example of a device which discharges liquid concerning the present invention. It is a principal part side surface explanatory drawing similarly. FIG. 6 is an explanatory cross-sectional view in a direction (liquid chamber longitudinal direction) orthogonal to a nozzle arrangement direction of an example of a liquid discharge head. It is a cross-sectional explanatory drawing of a nozzle arrangement direction (liquid chamber short direction) similarly. It is block explanatory drawing of the control part of the apparatus. It is block explanatory drawing of an example of the part which concerns on head drive control. It is explanatory drawing of the drive waveform in 1st Embodiment of this invention. It is explanatory drawing with which it uses for operation | movement description of the same embodiment. It is explanatory drawing of the drive waveform in 2nd Embodiment of this invention. It is explanatory drawing of the drive waveform in 3rd Embodiment of this invention. It is explanatory drawing of the drive waveform in 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an apparatus for ejecting liquid according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory plan view of a mechanism portion of the apparatus, and FIG.

  This apparatus is a serial type apparatus, and a carriage 3 is held by a guide mechanism such as a main guide member 1 so as to be movable in the main scanning direction. The carriage 3 is reciprocated in the main scanning direction (carriage moving direction) by a main scanning motor 5 constituting a main scanning moving mechanism via a timing belt 8 spanned between the driving pulley 6 and the driven pulley 7.

  The carriage 3 is equipped with two liquid discharge units 40A and 40B (referred to as “liquid discharge unit 40” when not distinguished from each other). The liquid discharge unit 40 is configured by integrating a liquid discharge head 41 as liquid discharge means and a head tank 42 that supplies liquid to the liquid discharge head 41.

  The liquid discharge head 41 has two nozzle rows in which a plurality of nozzles are arranged. One nozzle row of the head 41A of the liquid discharge unit 40A discharges black (K) droplets, and the other nozzle row discharges cyan (C) droplets. Also, one nozzle row of the head 41B of the liquid discharge unit 40B discharges magenta (M) droplets, and the other nozzle row discharges yellow (Y) droplets.

  In addition, as a liquid discharge means, what is equipped with the several nozzle row | line | column which discharges the droplet of each color which arranged the several nozzle in the nozzle surface of one liquid discharge head etc. can also be used.

  The head tank 42 includes a plurality of tank parts corresponding to the two nozzle rows of the heads 41, each paired with two tank parts that store liquids of the respective colors.

  On the apparatus main body side, a cartridge holder 51 to which a main tank (liquid cartridge) 50 (50y, 50m, 50c, 50k) containing liquid of each color is replaceably mounted is disposed.

  The cartridge holder 51 is provided with a liquid feed pump unit 52, and each color is supplied from the main tank 50 to the tank portion of each head tank 42 through a supply tube (also referred to as a liquid supply path) 56 of each color by the liquid feed pump unit 52. Liquid is supplied.

  On the other hand, in order to convey the sheet material 10, a conveyance belt 12, which is a conveyance unit for adsorbing the sheet material 10 and conveying it at a position facing the head 41 of the liquid discharge unit 40, is provided. The adsorption of the sheet material 10 by the transport belt 12 can be performed by electrostatic adsorption or air adsorption.

  The conveyor belt 12 is an endless belt and is stretched between the conveyor roller 13 and the tension roller 14. The transport belt 12 rotates in the sub-scanning direction when the transport roller 13 is rotationally driven by the sub-scanning motor 16 via the timing belt 17 and the timing pulley 18.

  Further, on one side of the carriage 3 in the main scanning direction, a maintenance / recovery mechanism 20 that performs maintenance / recovery of the head 41 is disposed on the side of the transport belt 12. On the other side of the carriage 3 in the main scanning direction, idle discharge receivers 81 for receiving liquid preliminarily discharged (empty discharge) from the head 41 are arranged on the sides of the conveyance belt 12.

  The maintenance / recovery mechanism 20 includes, for example, a suction cap 21 for capping the nozzle surface 41a of the head 41, a moisturizing cap 22, a wiper member 23 for wiping the nozzle surface 41a, and an empty discharge receiver 24 for receiving an empty liquid. Yes. Note that the idle discharge can be performed on the suction cap 21.

  In addition, an encoder scale 123 having a predetermined pattern is stretched between both side plates along the main scanning direction of the carriage 3, and an encoder sensor 124 formed of a transmission type photosensor that reads the pattern of the encoder scale 123 is provided on the carriage 3. Provided. These encoder scale 123 and encoder sensor 124 constitute a linear encoder (main scanning encoder) that detects the movement of the carriage 3.

  Further, a code wheel 125 is attached to the shaft of the transport roller 13 and an encoder sensor 126 including a transmission type photo sensor for detecting a pattern formed on the code wheel 125 is provided. These code wheel 125 and encoder sensor 126 constitute a rotary encoder (sub-scanning encoder) that detects the amount and position of movement of the conveyor belt 12.

  In the apparatus configured as described above, the sheet material 10 is fed onto the conveyance belt 12 and sucked, and is conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 12.

  Therefore, by driving the head 41 in accordance with the image signal while moving the carriage 3 in the main scanning direction, liquid is discharged onto the stopped sheet material 10 to record one line. Then, after the sheet material 10 is conveyed by a predetermined amount, the next line is recorded.

  Upon receiving a recording end signal or a signal that the rear end of the sheet material 10 has reached the recording area, the printing operation is terminated, and the sheet material 10 is discharged to a discharge tray (not shown).

  Next, an example of the liquid discharge head will be described with reference to FIGS. 3 is a cross-sectional explanatory diagram in a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIG. 4 is a cross-sectional explanatory diagram in the same nozzle arrangement direction (liquid chamber short direction).

  In the liquid discharge head, the nozzle plate 101, the flow path plate 102, and the vibration plate member 103 are joined. And the piezoelectric actuator 111 which displaces the diaphragm member 103, and the frame member 120 as a common flow path member are provided.

  As a result, the liquid supply also serves as an individual liquid chamber (also referred to as a pressure chamber, a pressurizing chamber, etc.) 106 that communicates with a plurality of nozzles 104 that discharge droplets, and a fluid resistance unit that supplies liquid to the individual liquid chamber 106. A passage 107 and a liquid introduction portion 108 that communicates with the liquid supply passage 107 are formed. Adjacent individual liquid chambers 106 are separated by a partition wall 106A in the nozzle arrangement direction.

  Then, the liquid is supplied from the common liquid chamber 110 serving as the common flow path of the frame member 120 to the plurality of individual liquid chambers 106 through the filter section 109 formed in the diaphragm member 103 through the liquid introduction section 108 and the liquid supply path 107. .

  The piezoelectric actuator 111 is disposed on the opposite side of the individual liquid chamber 106 with a deformable vibration region 130 forming a wall surface of the individual liquid chamber 106 of the vibration plate member 103 interposed therebetween.

  The piezoelectric actuator 111 has a plurality of stacked piezoelectric members 112 joined on a base member 113. The piezoelectric member 112 is grooved by half-cut dicing to form a columnar piezoelectric element (piezoelectric column) 112A for giving a driving waveform and a column 112B in a comb-like shape at a predetermined interval.

  The piezoelectric element 112 </ b> A is bonded to the island-shaped convex portion 103 a formed in the vibration region 130 of the diaphragm member 103. Further, the support column 112 </ b> B is joined to the convex portion 103 b of the diaphragm member 103.

  This piezoelectric member 112 is formed by alternately laminating piezoelectric layers and internal electrodes, and each internal electrode is pulled out to the end face to be provided with an external electrode. This piezoelectric member 112 can be used to apply a drive waveform to the external electrode of the piezoelectric element 112A. An FPC 115 as a flexible wiring board having flexibility is connected.

  A common liquid chamber 110 to which liquid is supplied from the head tank 42 is formed in the frame member 120.

  In this liquid ejection head, for example, the voltage applied to the piezoelectric element 112A is lowered from the intermediate potential, the piezoelectric element 112A contracts, the vibration region 130 of the diaphragm member 103 descends, and the volume of the individual liquid chamber 106 expands. As a result, the liquid flows into the individual liquid chamber 106.

  Thereafter, the voltage applied to the piezoelectric element 112A is increased to extend the piezoelectric element 112A in the stacking direction, and the vibration region 130 of the vibration plate member 103 is deformed toward the nozzle 104 to contract the volume of the individual liquid chamber 106. Thereby, the liquid in the individual liquid chamber 106 is pressurized, and the liquid is ejected (jetted) from the nozzle 104.

  Then, by returning the voltage applied to the piezoelectric element 112A to the intermediate potential, the vibration region 130 of the diaphragm member 103 is restored to the initial position. As a result, the individual liquid chamber 106 expands and negative pressure is generated, so that the liquid is filled into the individual liquid chamber 106 from the common liquid chamber 110 through the liquid supply path 107. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation for the next discharge is started.

  Next, an outline of the control unit of this apparatus will be described with reference to FIG. FIG. 5 is a block diagram of the control unit.

  The control unit 500 includes a main control unit 500A including a CPU 501 that controls the entire apparatus, a ROM 502 that stores fixed data such as various programs including programs executed by the CPU 501, and a RAM 503 that temporarily stores image data and the like. ing.

  The control unit 500 includes a rewritable nonvolatile memory 504 for holding data while the apparatus is powered off. The control unit 500 includes an ASIC 505 that processes various signal processing for image data, image processing for performing rearrangement, and other input / output signals for controlling the entire apparatus.

  The control unit 500 includes a data transfer unit for driving and controlling the liquid discharge head 41, a print control unit 508 including a drive signal generation unit, and a drive IC for driving the liquid discharge head 41 (herein referred to as “head driver”). .) 509.

  The control unit 500 is connected to the main scanning motor 5 that moves and scans the carriage 3, the sub-scanning motor 16 that moves the conveyor belt 12 around, the movement of the caps 21 and 22 of the maintenance / recovery mechanism 20 and the wiper member 23, and the cap 21. A motor drive unit 510 for driving a maintenance / recovery motor 556 for driving the suction means and the like is provided.

  The control unit 500 includes a supply system driving unit 512 that drives the liquid feeding pump 54 of the liquid feeding pump unit 52.

  The control unit 500 has an I / O unit 513. The I / O unit 513 can process various sensor information, and acquires information from various sensor groups 515 mounted on the apparatus. Information necessary for controlling the apparatus is extracted and used to control the print control unit 508 and the motor drive unit 510. The sensor group 515 includes an optical sensor for detecting the position of the sheet material 10, an interlock switch for detecting opening and closing of the cover, and the like.

  An operation panel 514 for inputting and displaying information necessary for this apparatus is connected to the control unit 500.

  Here, the control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side. From the host 600 side such as an information processing apparatus such as a personal computer or an image reading apparatus, a cable or network Via the I / F 506.

  The CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, performs necessary image processing, data rearrangement processing, and the like in the ASIC 505, and prints the image data. The data is transferred from the unit 508 to the head driver 509. In order to output an image, dot pattern data can be generated by the printer driver 601 on the host 600 side or by the control unit 500.

  The print control unit 508 transfers the image data as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 509.

  The print control unit 508 includes a drive waveform generation unit including a D / A converter that performs D / A conversion of drive waveform pattern data, a voltage amplifier, a current amplifier, and the like. The print control unit 508 generates a drive waveform including a plurality of drive signals (drive pulses) in time series and outputs the drive waveform to the head driver 509.

  The head driver 509 selects a driving pulse constituting a driving waveform supplied from the print control unit 508 based on image data corresponding to one line of the liquid discharging head 41 input serially, and the pressure of the liquid discharging head 41 This is given to the piezoelectric element 112A as the generating means. Thereby, the liquid discharge head 41 is driven.

  At this time, all or a part of the plurality of drive signals constituting the drive waveform (a part of the waveform element forming the drive signal) is selected. Thereby, for example, dots having different sizes such as large droplets, medium droplets, and small droplets can be separated.

  Next, an example of a portion related to head drive control will be described with reference to a block diagram of FIG.

  The print control unit 508 includes a drive waveform generation unit 701 as a drive waveform generation device according to the present invention. Data transfer that outputs 2-bit image data (gradation signals 0 and 1) corresponding to the print image and a selection signal (droplet control signal) for selecting a clock signal, a latch signal, and a drive pulse constituting a drive waveform Part 702.

  Here, the drive waveform generator 701 generates and outputs a drive waveform PV in which a plurality of drive pulses (drive signals) for ejecting liquid are arranged in time series within one printing cycle (one drive cycle).

  Note that the selection signal is a signal for instructing opening and closing of the analog switch AS, which is a switch unit of the head driver 509, for each droplet. The drive pulse (or waveform element) to be selected in accordance with the printing cycle of the drive waveform PV makes a state transition to the H level (ON), and when not selected, the state transitions to the L level (OFF).

  The head driver 509 includes a shift register 711, a latch circuit 712, a decoder 713, a level shifter 714, and an analog switch array 715.

  The shift register 711 inputs the transfer clock (shift clock) and serial image data (gradation data: 2 bits / 1 channel (1 nozzle)) from the data transfer unit 702. The latch circuit 712 includes each register of the shift register 711. The value is latched by the latch signal.

  The decoder 713 decodes the gradation data and the selection signal and outputs the result. The level shifter 714 converts the logic level voltage signal of the decoder 713 to a level at which the analog switch AS of the analog switch array 715 can operate.

  The analog switch AS of the analog switch array 715 is turned on / off (opened / closed) by the output of the decoder 713 given through the level shifter 714.

  The analog switch AS of the analog switch array 715 is connected to the individual electrode of the piezoelectric element 112A, and the drive waveform PV from the drive waveform generation unit 701 is input. Therefore, the analog switch AS is turned on according to the result of decoding the serially transferred image data (gradation data) and the selection signal by the decoder 713. As a result, a drive pulse (or a waveform element) that is a required drive signal constituting the drive waveform PV is passed (selected) and applied to the individual electrode of the piezoelectric element 112A.

  Next, a first embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory diagram of drive waveforms in the same embodiment.

  The drive waveform PV is composed of drive pulses P1, P2, P3, and P4 which are drive signals in time series, and the drive pulse P4 is the final drive pulse and the drive pulse P3 is the previous drive pulse. In addition, the number of drive pulses should just be two or more, and is not restricted to four (it is the same hereafter).

  Each drive pulse P1 to P4 is a single pulse including an expansion waveform element (pulling waveform element) a, a holding waveform element b, and a contraction waveform element (pushing waveform element) c. In order to simplify the drawing, the symbols a to c are added only for the drive pulse P1, but the other drive pulses P2 to P4 are the same. Moreover, the number of drive pulses should just be two or more, and is not restricted to four.

  The expansion waveform element a falls from the intermediate potential Vm and expands the individual liquid chamber 106. The holding waveform element b holds the falling potential due to the expansion waveform element a for a certain period of time. The contraction waveform element c rises to an intermediate potential Vm from the potential held by the holding waveform element b (falling potential by the expansion waveform element a), contracts the individual liquid chamber 106, and discharges the liquid.

  Here, when the potential difference between the rising start potential due to the contraction waveform element c and the intermediate potential Vm, that is, the potential difference between the intermediate potential Vm and the falling potential due to the expansion waveform element a is a peak value, the immediately preceding drive pulse P3 has a peak value. Va is the peak value Vb (Vb <Va) smaller than the peak value Va for the final drive pulse P4. The driving pulses P1 and P2 are also set to the peak value Va.

  In this case, the crest value Vb of the final drive pulse P4 is a speed at which microdroplets are not generated together with the main droplet accompanying ejection, and is faster than the speed of the microdroplets generated along with ejection by the immediately preceding drive pulse P3. The value is set to eject droplets at speed.

  Of the two consecutive drive pulses, when the time from the end point of the contraction waveform element c of the previous drive pulse to the start point of the expansion waveform element a of the subsequent drive pulse is the first pulse interval, the drive pulse The same interval Td1 is set between P1 and P2, P2 and P3, and P3 and P4.

  Of the two consecutive drive pulses, when the time from the start point of the contraction waveform element c of the previous drive pulse to the start point of the contraction waveform element c of the subsequent drive pulse is the second pulse interval, the drive pulse Between P1 and P2, P2 and P3, and P3 and P4, the natural vibration period Tc × n (n = 1 or more integer) of the head is set. In the present embodiment, n = 1 and the second pulse interval is the natural vibration period Tc.

  The operation of this embodiment will be described with reference to FIG. FIG. 8 is an explanatory diagram for explaining the operation.

  First, as shown in FIGS. 8A to 8D, the droplets D1 to D4 are sequentially ejected by the driving pulses P1 to P4.

  Here, the velocities of the droplets D1 to D3 ejected by the drive pulses P1 to P3 have the same crest value, and the second pulse interval is the natural vibration period Tc, so that a relationship of D1 <D2 <D3 is established.

  Accordingly, as shown in FIG. 8E, the droplet D3 catches up with the preceding droplets D1 and D2 during the flight and merges into one droplet D11.

  Here, a droplet D3 (main droplet) is accompanied by a minute droplet M1 accompanying a droplet generated by the immediately preceding drive pulse P3. At this time, since the speed of the droplet D4 by the drive pulse P4 is faster than the speed of the microdroplet M1, the microdroplet M1 is merged with the subsequent drop D4 as shown in FIGS. Don't scatter.

  Since the peak value Vb of the final drive pulse P4 is smaller than the peak value Va of the immediately preceding drive pulse P3, the droplet D4 does not catch up with the preceding droplet D11 as shown in FIG. 10a is landed at substantially the same position following the droplet D11 to form one dot.

  By using such a drive waveform, generation of mist can be reduced.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory diagram of drive waveforms in the same embodiment.

  The drive waveform PV is composed of drive pulses P1, P2, P3, and P4 which are drive signals in time series, and the drive pulse P4 is the final drive pulse and the drive pulse P3 is the previous drive pulse.

  In the present embodiment, each of the drive pulses P1 to P4 is the same as the peak value Va.

  Further, the first pulse interval between the drive pulses P1 and P2 and between the drive pulses P2 and P3 is the same as the interval Td1. On the other hand, the first pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is set to an interval Td2 (Td2> Td1).

  The second pulse interval between the drive pulses P1 and P2 and P2 and P3 is the natural vibration period Tc. On the other hand, the second pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is the interval Te (Te> Tc).

  As described above, the first pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is set as the interval Td2, and the second pulse interval is shifted from the natural vibration period Tc. It can be made slower than the speed of the droplet 3 by the immediately preceding drive pulse P3.

  Therefore, the speed of the droplets ejected by the final drive pulse P4 is a speed at which microdroplets are not generated along with the main droplets along with ejection, and is faster than the speed of the microdroplets generated along with ejection by the immediately preceding drive pulse P3. Fast speed.

  Thereby, generation | occurrence | production of mist can be suppressed similarly to the said 1st Embodiment.

  Since the voltage value of the drive waveform PV can be fixed, it is possible to easily deal with binary drive pulses such as single pulses or rectangular waves.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is an explanatory diagram of drive waveforms in the same embodiment.

  The drive waveform PV is composed of drive pulses P1, P2, P3, and P4 which are drive signals in time series, and the drive pulse P4 is the final drive pulse and the drive pulse P3 is the previous drive pulse.

  In the present embodiment, the peak values of the drive pulses P1 to P4 are the same as the peak value Va.

  Further, the first pulse interval between the drive pulses P1 and P2 and P2 and P3 is the same as the interval Td1. On the other hand, the first pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is set to an interval Td3 (Td3 <Td1). That is, the first pulse interval between the last drive pulse and the immediately preceding drive pulse is longer than the first pulse interval of the drive pulse up to the immediately preceding drive pulse.

  The second pulse interval between the drive pulses P1 and P2 and P2 and P3 is the natural vibration period Tc. On the other hand, the second pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is an interval Tf (Tf <Tc), which is different from the natural vibration period Tc.

  In this way, the first pulse interval between the last drive pulse P4 and the immediately preceding drive pulse P3 is the interval Td3, and the first pulse interval is different from the natural vibration period Tc. It can be made slower than the speed of the droplet by the immediately preceding drive pulse P3.

  Therefore, the speed of the droplets ejected by the final drive pulse P4 is a speed at which microdroplets are not generated along with the main droplets along with ejection, and is faster than the speed of the microdroplets generated along with ejection by the immediately preceding drive pulse P3. Fast speed.

  Thereby, generation | occurrence | production of mist can be suppressed similarly to the said 1st Embodiment.

  Since the voltage value of the drive waveform PV can be fixed, it is possible to easily deal with binary drive pulses such as single pulses or rectangular waves.

  Furthermore, since the waveform length of the entire drive waveform can be made shorter than in the first and second embodiments, the number of drive weeks can be increased.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory diagram of drive waveforms in the same embodiment.

  The drive waveform PV is composed of drive pulses P1, P2, P3, and P4 which are drive signals in time series, and the drive pulse P4 is the final drive pulse and the drive pulse P3 is the previous drive pulse.

  In the present embodiment, the driving pulse P1 has a peak value Va1, the driving pulse P2 has a peak value Va2 (Va2> Va1), the driving pulse P3 has a peak value Va3 (Va3> Va2), and the driving pulse P4 has a peak value Vb (Vb <Va1). ).

  Further, the first pulse interval between the drive pulses P1 and P2, P2 and P3, and P3 and P4 is an interval Td3 (Td3 <Td1).

  The second pulse intervals between the drive pulses P1 and P2, P2 and P3, and P3 and P4 are all intervals Tf (Tf <Tc), and are different from the natural vibration period Tc.

  As described above, since the drive pulses P1 to P3 have their peak values sequentially increased, even if the second pulse interval deviates from the natural vibration period Tc, the droplet velocity is sequentially increased as in the first embodiment. Get faster. Therefore, as in the first embodiment, the droplets ejected by the driving pulses P1 to P3 are merged during the flight.

  Further, since the crest value of the drive pulse P4 is smaller than the crest value of the drive pulse P3, the droplet velocity by the drive pulse P4 can be made slower than the droplet velocity by the immediately preceding drive pulse P3.

  Therefore, the speed of the droplets ejected by the final drive pulse P4 is a speed at which microdroplets are not generated along with the main droplets along with ejection, and is faster than the speed of the microdroplets generated along with ejection by the immediately preceding drive pulse P3. Fast speed.

  Thereby, generation | occurrence | production of mist can be suppressed similarly to the said 1st Embodiment.

  And since the waveform length of the whole drive waveform can be made shorter than the said 1st thru | or 3rd embodiment, a drive frequency can be made high.

  In the present application, the liquid to be ejected is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, and the viscosity becomes 30 mPa · s or less at room temperature, normal pressure, or by heating and cooling. It is preferable. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, solutions, suspensions, emulsions, and the like. These include, for example, inkjet inks, surface treatment liquids, components of electronic devices and light emitting devices, and formation of electronic circuit resist patterns It can be used in applications such as liquids for use, three-dimensional modeling material liquids, and the like.

  As energy generation sources for discharging liquid, piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements), thermal actuators using electrothermal transducers such as heating resistors, electrostatic actuators consisting of a diaphragm and counter electrode are used. To be included.

  In addition, the “device for ejecting liquid” includes not only a device capable of ejecting a liquid to an object to which the liquid can adhere, but also a device that ejects the liquid in the air or in the liquid. .

  This “apparatus for discharging liquid” may include means for feeding, transporting, and discharging a liquid to which liquid can adhere, as well as a pre-processing apparatus and a post-processing apparatus.

  For example, as a “liquid ejecting device”, an image forming device that forms an image on paper by ejecting ink, a powder is formed in layers to form a three-dimensional model (three-dimensional model) There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto the powder layer.

  Further, the “apparatus for ejecting liquid” is not limited to an apparatus in which significant images such as characters and figures are visualized by the ejected liquid. For example, what forms a pattern etc. which does not have a meaning in itself, and what forms a three-dimensional image are also included.

  The above-mentioned “applicable liquid” means that the liquid can be attached at least temporarily and adheres and adheres, or adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic parts such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and test cells. Yes, unless specifically limited, includes everything that the liquid adheres to.

  The material of the above-mentioned “material to which liquid can adhere” is not limited as long as liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics can be adhered even temporarily.

  In addition, the “device for ejecting liquid” includes a device in which the liquid ejection head and the device to which the liquid can adhere move relatively, but is not limited thereto. Specific examples include a serial type apparatus that moves the liquid discharge head, a line type apparatus that does not move the liquid discharge head, and the like.

  In addition, as the “device for ejecting liquid”, other than the above, a treatment liquid coating apparatus that ejects a treatment liquid onto a sheet in order to apply the treatment liquid to the surface of the sheet for the purpose of modifying the surface of the sheet, There is an injection granulation apparatus that granulates raw material fine particles by spraying a composition liquid in which raw materials are dispersed in a solution through a nozzle.

  Note that the terms “image formation”, “recording”, “printing”, “printing”, “printing”, “modeling” and the like in the terms of the present application are all synonymous.

40 Liquid discharge unit 41 Liquid discharge head (head)
106 Individual liquid chamber 500 Control unit 502 Print control unit 701 Drive waveform generation unit 702 Data transfer unit

Claims (7)

An apparatus for generating a drive waveform including a plurality of drive pulses for discharging liquid from a liquid discharge head in time series,
The drive waveform is a waveform in which the speed of the liquid ejected by the final drive pulse among the plurality of drive pulses is slower than the speed of the liquid ejected by the drive pulse immediately before the final drive pulse. A drive waveform generator characterized by the above. The drive pulse falls from an intermediate potential, and an expansion waveform element that expands an individual liquid chamber of the liquid discharge head;
Including a contraction waveform element that rises from a falling potential of the expansion waveform element to the intermediate potential and contracts the individual liquid chamber to discharge the liquid;
When the potential difference between the intermediate potential and the rising start potential of the contraction waveform element is a peak value,
The drive waveform generation apparatus according to claim 1, wherein a peak value of the final drive pulse is smaller than a peak value of the immediately preceding drive pulse. The drive pulse falls from an intermediate potential, and an expansion waveform element that expands an individual liquid chamber of the liquid discharge head;
Including a contraction waveform element that rises from a falling potential of the expansion waveform element to the intermediate potential and contracts the individual liquid chamber to discharge the liquid;
Of the two drive pulses that are continuous in time series, the interval from the end point of the contraction waveform element of the previous drive pulse to the start point of the expansion waveform element of the subsequent drive pulse is the first pulse interval, When the interval from the start point of the contraction waveform element of the drive pulse to the start point of the contraction waveform element of the subsequent drive pulse is the second pulse interval,
The second pulse interval between the last drive pulse and the immediately preceding drive pulse is different from the natural vibration period Tc × n (n is an integer of 1 or more),
The second pulse interval between the drive pulses before the immediately preceding drive pulse is a natural vibration period Tc × n (n = 1 or more integer),
The first pulse interval between the final drive pulse and the immediately preceding drive pulse is longer than the first pulse interval of the drive pulse up to the immediately preceding drive pulse. Drive waveform generator. The drive pulse falls from an intermediate potential, and an expansion waveform element that expands an individual liquid chamber of the liquid discharge head;
Including a contraction waveform element that rises from a falling potential of the expansion waveform element to the intermediate potential and contracts the individual liquid chamber to discharge the liquid;
Of the two drive pulses that are continuous in time series, the interval from the end point of the contraction waveform element of the previous drive pulse to the start point of the expansion waveform element of the subsequent drive pulse is the first pulse interval, When the interval from the start point of the contraction waveform element of the drive pulse to the start point of the contraction waveform element of the subsequent drive pulse is the second pulse interval,
The second pulse interval between the last drive pulse and the immediately preceding drive pulse is different from the natural vibration period Tc × n (n is an integer of 1 or more),
The second pulse interval between the drive pulses before the immediately preceding drive pulse is a natural vibration period Tc × n (n = 1 or more integer),
The first pulse interval between the final drive pulse and the immediately preceding drive pulse is shorter than the first pulse interval of the drive pulse up to the immediately preceding drive pulse. Drive waveform generator. The drive pulse falls from an intermediate potential, and an expansion waveform element that expands an individual liquid chamber of the liquid discharge head;
Including a contraction waveform element that rises from a falling potential of the expansion waveform element to the intermediate potential and contracts the individual liquid chamber to discharge the liquid;
When the potential difference between the intermediate potential and the rising start potential of the contraction waveform element is a peak value,
Among the plurality of drive pulses, the peak value of the immediately preceding drive pulse is the largest,
The peak value of the final drive pulse is smaller than the peak value of the previous drive pulse,
Of the two drive pulses that are continuous in time series, the interval from the end point of the contraction waveform element of the previous drive pulse to the start point of the expansion waveform element of the subsequent drive pulse is the first pulse interval, When the interval from the start point of the contraction waveform element of the drive pulse to the start point of the contraction waveform element of the subsequent drive pulse is the second pulse interval,
Between the plurality of drive pulses, the second pulse interval is different from the natural vibration period Tc × n (n = 1 or more integer),
The drive waveform generation apparatus according to claim 1, wherein the first pulse interval is the same among the plurality of drive pulses. The speed of the liquid ejected by the immediately preceding drive pulse is the speed at which microdroplets are generated together with the main drops
The speed of the liquid ejected by the final drive pulse is a speed at which the microdroplet is not generated, and is faster than the speed of the microdroplet generated by the ejection by the immediately preceding drive pulse. The drive waveform generation device according to 1 to 5.   An apparatus for ejecting liquid, comprising the drive waveform generating apparatus according to claim 1.

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