JP2013082154A - Liquid ejecting device, and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejecting device capable of increasing micro-vibration frequency than before without uselessly elongating a drive signal, and suppressing viscosity increase of liquid more effectively, and to provide a method for controlling the same.SOLUTION: An ejection drive pulse DP includes a damping element p14 damping pressure vibration accompanying ejection of ink, the damping element includes a first damping element ca1 of the prior stage and a second damping element ca2 of the subsequent stage, and the second damping element can be used as a subsidiary micro-vibration drive pulse CP.

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet recording apparatus, and a control method for the liquid ejecting apparatus, and in particular, drives the pressure generating means by applying a driving waveform included in a driving signal to the pressure generating means, The present invention relates to a liquid ejecting apparatus that ejects a liquid from a nozzle by causing a pressure fluctuation in a liquid in a pressure chamber communicating with the nozzle, and a control method for the liquid ejecting apparatus.

  The liquid ejecting apparatus includes an ejecting head and ejects (discharges) various liquids from the ejecting head. As this liquid ejecting apparatus, for example, there is an image recording apparatus such as an ink jet printer or an ink jet plotter, but recently, various types of manufacturing have been made by taking advantage of the ability to accurately land a very small amount of liquid on a predetermined position. It is also applied to devices. For example, a display manufacturing apparatus for manufacturing a color filter such as a liquid crystal display, an electrode forming apparatus for forming an electrode such as an organic EL (Electro Luminescence) display or FED (surface emitting display), a chip for manufacturing a biochip (biochemical element) Applied to manufacturing equipment. The recording head for the image recording apparatus ejects liquid ink, and the color material ejecting head for the display manufacturing apparatus ejects solutions of R (Red), G (Green), and B (Blue) color materials. The electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and the bioorganic matter ejecting head for the chip manufacturing apparatus ejects a bioorganic solution.

  In this type of liquid ejecting head, since the liquid (meniscus) is exposed to the outside air at the nozzle, the liquid component may be thickened due to evaporation of the solvent component contained in the liquid. When the viscosity of the liquid increases, there is a possibility that the liquid may not be ejected normally from the nozzle. In order to suppress such thickening of the liquid, for the nozzle that does not eject the liquid during the liquid ejecting operation (for example, during the printing operation in the printer), the corresponding pressure generating means (for example, a piezoelectric vibrator or a heating element) ), The liquid and the meniscus in the pressure chamber are vibrated to such an extent that the liquid is not ejected from the nozzle. That is, by this fine vibration operation, the liquid in the vicinity of the nozzle is agitated and the thickening is suppressed (for example, see Patent Document 1). In Patent Document 1, the fine vibration pressurizing pulse for pressurizing the pressure chamber to such an extent that the droplets are not ejected and the microvibration depressurizing pulse for depressurizing the pressure chamber to the extent that the droplets are not ejected are divided into drive signals. The meniscus is configured to be finely oscillated by being applied to the pressure generating element by combining these fine vibration pressurizing pulse and fine vibration depressurizing pulse.

JP 2007-83737 A

  By the way, for example, a printer (so-called label printer) used for the purpose of repeatedly printing a specific image such as a barcode, or the length of a nozzle group of a recording head can correspond to the maximum recording width of a recording medium such as recording paper. In a so-called line-type printer, etc., a state where a specific nozzle does not eject liquid or the like may be longer than other nozzles. In this case, the thickening of the nozzle may not be suppressed only by the fine vibration described above. For this reason, in order to more reliably prevent thickening of the liquid in the liquid ejecting head, a flushing process in which ink is periodically discarded and a cleaning process in which ink is sucked from the nozzles are effective. However, these processes not only waste liquid, but also have a problem of reduced throughput due to additional processing time. Therefore, it is desirable to reduce the number of times of the above-mentioned flushing process or the like by increasing the number of times of the above-mentioned fine vibration as much as possible. However, in this case, if more fine vibration drive pulses are included in the drive signal, there is a problem that the drive signal becomes longer and the recording frequency is lowered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to increase the number of microvibrations more than before without unnecessarily lengthening the drive signal, and to increase the liquid more effectively. It is an object to provide a liquid ejecting apparatus capable of suppressing viscosity and a control method thereof.

A liquid ejecting apparatus of the present invention has been proposed to achieve the above object, and a liquid ejecting head that ejects liquid from a nozzle by driving a pressure generating unit by applying a driving waveform;
Drive signal generating means for generating a drive signal including an ejection drive waveform used for ejecting the liquid and a micro-vibration drive waveform for micro-vibrating the liquid;
A liquid ejecting apparatus comprising:
The ejection drive waveform includes a damping element that dampens pressure vibration associated with liquid ejection,
The vibration damping element has a first vibration damping element and a second vibration damping element after the first vibration damping element,
The second damping element can be used as a fine vibration driving waveform.

  According to the present invention, the vibration damping element of the injection drive waveform has the first vibration damping element and the second vibration damping element after the first vibration damping element, and the second vibration damping element at the rear stage is a fine vibration. It can be used as a drive waveform and has two functions of a residual vibration damping function and a fine vibration function. For this reason, it is possible to increase the number of microvibrations compared to the prior art without unnecessarily lengthening the drive signal, and it is possible to suppress the thickening of the liquid more effectively. For this reason, the frequency of a flushing process, a cleaning process, etc. can be reduced. As a result, it is possible to reduce the amount of liquid consumption associated with these processes, and it is possible to suppress a decrease in throughput due to the additional processing time.

  In the above configuration, the second damping element includes a first changing unit that changes the first potential to a second potential different from the first potential, a damping holding unit that holds the second potential, and the second It is desirable to employ a configuration having a second changing portion that changes from a potential to the first potential.

In the above configuration, the damping element has a hold element having a constant potential between the first damping element and the second damping element,
It is desirable that the drive waveform can be switched in the middle of the hold element.

Further, the control method of the liquid ejecting apparatus of the present invention includes a liquid ejecting head that ejects liquid from a nozzle by driving a pressure generating unit by applying a driving waveform, and an ejection driving waveform used for ejecting liquid and a liquid that vibrates slightly. A drive signal generating means for generating a drive signal including a micro-vibration drive waveform, and a control method of a liquid ejecting apparatus,
In the ejection drive waveform, provided with a damping element that dampens pressure vibration associated with liquid ejection,
The vibration damping element includes a first vibration damping element and a second vibration damping element following the first vibration damping element,
By applying the second damping element alone to the pressure generating means, it acts as a fine vibration driving waveform.

2 is a plan view illustrating an internal configuration of the printer. FIG. 2 is a side view illustrating an internal configuration of the printer 1. FIG. 3 is a cross-sectional view of a main part for explaining the configuration of a recording head. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is a figure explaining the structure of a drive signal, and the selection pattern of a drive pulse. It is a wave form diagram explaining the structure of an ejection drive pulse and a micro vibration drive pulse. It is a figure explaining the structure of the drive signal in 2nd Embodiment, and the selection pattern of a drive pulse.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of the liquid ejecting apparatus of the invention.

  FIG. 1 is a plan view illustrating the internal configuration of the printer 1, and FIG. 2 is a side view illustrating the internal configuration of the printer 1. The printer 1 includes a plurality of recording heads 2 (2 a to 2 d) arranged along the conveyance direction of the recording paper 14 (recording medium or a kind of landing target), and a paper feed that supplies the recording paper 14 to the conveyance belt 3. A roller 10, a paper feed motor 9 that drives the paper feed roller 10, a transport mechanism 16 that transports the recording paper 14 by the transport belt 3, and a linear encoder that includes the linear scale 13 and the detection head 7 are provided. The printer 1 according to the present embodiment performs the recording process (or the printing process or the liquid ejecting process) with respect to the recording paper 14 while transporting only the recording paper 14 with the position of the recording head 2 fixed. This is a so-called line printer that records images and the like.

  The paper feed roller 10 is disposed on the upstream side of the transport mechanism 16 and is a pair of upper and lower rollers 10a that can be synchronously rotated in opposite directions while sandwiching the recording paper 14 fed from a paper feed unit (not shown). 10b. The paper feed roller 10 is driven by power from the paper feed motor 9. The paper feed roller 10 cooperates with a skew correction roller (not shown) to correct the inclination of the recording paper 14 with respect to the transport direction and the positional deviation in the direction orthogonal to the transport direction, and then feeds the recording paper 14 to the transport mechanism 16. Supply to the side.

  The transport mechanism 16 includes a transport motor 12 that is a drive source of the transport belt 3, a drive roller 4 to which power is transmitted from the transport motor 12, a driven roller 5 disposed upstream of the drive roller 4, and a drive It is composed of a conveyor belt (endless belt) 3 stretched between the roller 4 and the driven roller 5, a tension roller 6, a pressure roller 11, and a charging unit 17 (see FIG. 2). The tension roller 6 is disposed between the driving roller 4 and the driven roller 5, is inscribed in the transport belt 3, and applies tension to the transport belt 3 by the biasing force of a biasing member such as a spring. The pressure roller 11 is a roller that presses the recording paper 14 toward the conveyance belt 3, and is disposed immediately above the driven roller 5 with the conveyance belt 3 interposed therebetween.

  The belt charging unit 17 includes a charging roller 8 and a charging power source 15. The charging roller 8 is disposed on the lower side on the upstream side of the driven roller 5 with the conveyance belt 3 interposed therebetween, and is in contact with the conveyance belt 3. The charging power source 15 is electrically connected to the charging roller 8 and applies an AC voltage to the charging roller 8. The driven roller 5 is grounded as shown in FIG. 2, and serves as a counter electrode for the charging roller 8 that faces the conveyance belt 3. In the belt charging unit 17, the charging power supply 15 supplies electric charges to the conveying belt 3 via the charging roller 8 to charge the conveying belt 3. Then, dielectric polarization occurs in the recording paper 14 placed on the charged transport belt 3, and an electrostatic force acts between the recording paper 14 and the transport belt 3. Further, the pressure roller 11 presses the recording paper 14 placed on the charged conveying belt 3 against the conveying belt 3 to improve the adhesion of the recording paper 14 to the conveying belt 3.

  As shown in FIG. 1, a linear scale 13 is disposed on the outer peripheral surface of the conveyor belt 3 over the entire belt. The linear scale 13 is configured by arranging a plurality of slit-shaped detection patterns at regular intervals (for example, 180 dpi) in the conveyance direction of the conveyance belt 3. The detection pattern of the linear scale 13 is optically detected by the detection head 7, and the detection signal is output as an encoder signal to the printer controller 36 (see FIG. 4). Therefore, the printer controller 36 can grasp the conveyance amount of the recording paper 14 by the conveyance mechanism 16 (conveyance belt 3) based on the encoder signal. The encoder signal defines the generation timing of a drive signal for driving the piezoelectric vibrator 23 that is a pressure generating means of the recording head 2.

  FIG. 3 is a cross-sectional view of a main part of the recording head 2 in the present embodiment. Since the recording heads 2a to 2d have the same configuration, a single recording head will be described below as a representative. The recording head 2 in the present embodiment is a so-called line-type recording head in which nozzle groups are arranged at a predetermined pitch so as to correspond to the maximum recording width of the recording paper 14. One recording head 2 may be configured by connecting a plurality of unit heads.

  As shown in FIG. 1, the recording head 2 in this embodiment includes a yellow recording head 2a that ejects (ejects) yellow (Y) ink, and a magenta recording head 2b that ejects magenta (M) ink. , A cyan recording head 2c that ejects cyan (C) ink, and a black recording head 2d that ejects black (K) ink. On the nozzle surfaces (nozzle plates 32) of the recording heads 2a, 2b, 2c, and 2d for each color, a plurality of nozzles 31 are arranged over a length that is greater than or equal to the maximum width of the recording paper that the printer 1 can handle. . The recording heads 2a, 2b, 2c, and 2d have a nozzle surface facing the recording paper 14 and a predetermined interval (so-called paper gap or platen gap) is formed between the nozzle surface and the recording paper 14 It is arranged by.

  The recording head 2 in the present embodiment is composed of a pressure generating unit 18 and a flow path unit 19, which are integrated by overlapping them. The pressure generation unit 18 includes a pressure chamber plate 21 for partitioning the pressure chamber 20, a communication port plate 22 having a supply side communication port 25 and a first communication port 27a, and a diaphragm on which the piezoelectric vibrator 23 is mounted. 24 are laminated and integrated by firing or the like. The flow path unit 19 includes a supply port plate 28 having a supply port 26 and a second communication port 27b, a reservoir plate 30 having a reservoir 29 and a third communication port 27c, and a nozzle having a nozzle 31 formed therein. It is configured by adhering plate members made of plates 31 in a laminated state.

  The nozzle plate 31 in this embodiment forms a nozzle row (a kind of nozzle group) in which a plurality of nozzles 31 that eject ink are arranged in a direction orthogonal to the conveyance direction of the recording paper 14. The nozzle row in the present embodiment is composed of nozzles 31 established at a pitch of 360 dpi, for example, and the total length of the nozzle row (the distance from the nozzle 31 located at one end of the nozzle row to the nozzle 31 located at the other end) is recorded. The length corresponds to the maximum recording width of the paper 14. The number of nozzles 31 forming one nozzle row 33 and the formation pitch are not limited to those illustrated.

  A piezoelectric vibrator 23 is disposed on the outer surface of the vibration plate 24 opposite to the pressure chamber 20 corresponding to each pressure chamber 20. The illustrated piezoelectric vibrator 23 is a so-called flexural vibration mode piezoelectric vibrator, and is configured such that a piezoelectric body 23c is sandwiched between a drive electrode 23a and a common electrode 23b. When a drive signal (drive pulse) is applied to the drive electrode of the piezoelectric vibrator 23, an electric field corresponding to the potential difference is generated between the drive electrode 23a and the common electrode 23b. This electric field is applied to the piezoelectric body 23c, and is deformed according to the strength of the electric field applied with the piezoelectric body 23c. That is, as the potential of the drive electrode 23a is increased, the central portion in the width direction (nozzle row direction) of the piezoelectric layer 20c is bent toward the inside of the pressure chamber 20 (the side closer to the nozzle plate 31), and the volume of the pressure chamber 20 is increased. The diaphragm 24 is deformed so as to decrease. On the other hand, as the electric potential of the drive electrode 23a is lowered (closer to 0), the central portion in the short direction of the piezoelectric layer 20c bends to the outside of the pressure chamber 20 (side away from the nozzle plate 31), and the volume of the pressure chamber 20 increases. The diaphragm 24 is deformed so as to increase.

Next, the electrical configuration of the printer 1 will be described.
FIG. 4 is a block diagram illustrating the electrical configuration of the printer 1. The external device 35 is an electronic device (or information processing device) that handles images, such as a computer or a digital camera. The external device 35 is communicably connected to the printer 1 and transmits print data corresponding to the image or the like to the printer 1 so that the printer 1 prints an image or text on a recording medium such as recording paper.

  The printer 1 in this embodiment includes a transport mechanism 16, a detection head 7, a charging power supply 15 recording head 2, a printer controller 36, and the like.

  The printer controller 36 is a type of control means, and is a control unit that controls each part of the printer. The printer controller 36 includes an interface (I / F) unit 37, a CPU 38, a storage unit 39, and a drive signal generation unit 40. The interface unit 37 transmits and receives printer status data such as sending print data and a print command from the external device 35 to the printer 1 and receiving the status information of the printer 1 from the external device 35. The CPU 38 is an arithmetic processing unit for controlling the entire printer. The storage unit 39 is an element that stores a program for the CPU 38 and data used for various controls, and includes a ROM, a RAM, and an NVRAM (nonvolatile storage element). The CPU 38 controls each unit according to a program stored in the storage unit 39.

  The drive signal generation unit 40 functions as drive signal generation means in the present invention, and generates an analog voltage signal based on waveform data relating to the waveform of the drive signal. The drive signal generator 40 amplifies the voltage signal to generate the drive signal COM. The printer 1 according to the present embodiment can perform multi-gradation recording in which dots having different sizes are formed on the recording paper 14 by ejecting ink droplets having different liquid amounts. The recording process can be performed with four gradations of medium dots, small dots, and non-ejection (fine vibration). Then, the drive signal generation unit 40, for example, the first injection drive pulse DP1, the second injection drive pulse DP2, the third injection drive pulse DP3, the first slight vibration drive pulse VP1, and the second fine vibration shown in FIG. A drive signal COM including a drive pulse VP2 (both being a kind of drive waveform) is generated.

  The drive signal COM is repeatedly generated according to the latch signal LAT generated based on the encoder signal. The latch signal LAT is a signal that defines the start timing of the recording cycle. Therefore, it can be said that the unit period of the drive signal COM is a section divided by the latch signal LAT. The change signal CH is a signal used for selectively applying each drive pulse to the piezoelectric vibrator 23 and is generated based on the latch signal LAT. The change signal CH in the present embodiment is composed of a total of seven CH1 to CH7. Each change signal CH is generated at a predetermined timing based on the generation timing of the latch signal LAT.

  In the present embodiment, the unit cycle T, which is the generation cycle of the drive signal COM and the recording cycle, is divided into eight periods T1 to T8 in total by the latch signal LAT and the change signals CH1 to CH7. In the period T1, the first stage of the first injection drive pulse DP1 is generated. In the period T2, the first auxiliary micro-vibration drive pulse CP1 (the second damping element ca2) that is the subsequent stage of the first injection drive pulse DP1. In addition, a kind of micro-vibration driving waveform in the present invention) is generated, and the first micro-vibration driving pulse VP1 is generated in the period T3. In addition, in the period T4, the front part of the second injection driving pulse DP2 is generated, and in the period T5, the second auxiliary micro-vibration driving pulse CP2 (the second damping element ca2) that is the subsequent stage part of the second injection driving pulse DP2. In addition, a fine vibration drive waveform (a kind of auxiliary fine vibration drive waveform) in the present invention is generated, and the second fine vibration drive pulse VP2 is generated in the period T6. Further, a preceding stage of the third injection driving pulse DP3 is generated in the period T7, and in the period T8, a third auxiliary micro-vibration driving pulse CP3 (in the second damping element ca2) that is the rear end portion of the third injection driving pulse DP3. In addition, a fine vibration drive waveform (a kind of auxiliary fine vibration drive waveform) in the present invention is generated.

  As described above, in the printer 1 according to the present invention, the ejection drive pulse DP is divided into the front stage part and the rear stage part by the change signal CH, and the piezoelectric vibrator 23 by itself using the rear stage part as the auxiliary fine vibration drive pulse CP. It is characterized in that it can be applied to the. Details of this point will be described later.

The ejection drive pulses DP1 to DP3 are drive pulses in which a drive voltage (potential difference from the lowest potential of the drive pulse to the highest potential), a waveform, and the like are determined in order to eject ink from the nozzle 31.
FIG. 6A is a waveform diagram illustrating the configuration of the ejection drive pulses DP1 to DP3. Since the ejection drive pulses DP1 to DP3 in the present embodiment have the same waveform, one will be described below as a representative. The injection drive pulse DP in the present embodiment includes an expansion element p11, an expansion hold element p12, a contraction element (injection element) p13, and a vibration suppression element p14. The expansion element p11 corresponds to the reference volume of the pressure chamber 20 (the volume that serves as a reference for expansion or contraction), and the first expansion potential VL1 that is lower than the reference potential Vb from the reference potential Vb that is the base point of the potential change of the drive pulse. This is a waveform element in which the potential drops to the negative (or ground GND) side (changes to the first polarity side) at a constant gradient that does not cause ink to be ejected. The expansion hold element p12 is a waveform element that maintains the first expansion potential VL1 that is the terminal potential of the expansion element p11 for a predetermined time. The contraction element p13 steeply rises from the first expansion potential VL1 to the first contraction potential VH1 higher than the reference potential Vb (changes to the second polarity side) so that the ink from the nozzle 31 is increased. Is a waveform element that causes a pressure fluctuation to such an extent that can be injected. The vibration damping element p14 is a waveform element that reduces pressure vibration (residual vibration) in the pressure chamber 20 that is caused by ink being ejected from the nozzle 31 by application of the contraction element p13.

  The damping element p14 includes a first damping element ca1 at the preceding stage following the contraction element p13, an intermediate holding element ha (corresponding to a holding element in the present invention) following the first damping element ca1, and the intermediate holding element ha. And a second damping element ca2. The first damping element ca1 includes a shrinkage hold element ph that maintains the first contraction potential VH1 for a predetermined time, and a damping contraction element that decreases the potential with a gradient that does not cause ink to be ejected from the first contraction potential VH1 to the reference potential Vb. pc. Then, the duration time of the contraction hold element ph is set so that the vibration damping contraction element pc is applied to the piezoelectric vibrator 23 at a timing that can cancel out the pressure vibration (residual vibration) of the ink in the pressure chamber 20. ing. The intermediate hold element ha is a waveform element that maintains the reference potential Vb, which is the rear end potential of the damping contraction element pc, for a certain period of time. In the middle of the intermediate hold element ha, it is possible to switch between the front stage (first half of p11, p12, p13, ca1, and ha) and the rear stage (second half of ha and ca2) of the injection drive pulse DP by the change signal CH. It has become.

  The second damping element ca2 has an intermediate potential VM (second potential) between the reference potential Vb and the first expansion potential VL1 from the reference potential Vb (corresponding to the first potential) that is the rear end potential of the intermediate hold element ha. The first change portion a1 in which the potential changes to the minus side with a gentle gradient that does not cause ink to be ejected until the equivalent potential), the damping hold portion a2 that is constant at the intermediate potential VM, and from the intermediate potential VM to the reference potential Vb. And a second change part a3 in which the potential changes to the plus side. Then, the first change portion from the rear end of the contraction element p13 is applied so that the first change portion a1 of the second damping element ca2 is applied to the piezoelectric vibrator 23 at a timing at which the residual vibration in the pressure chamber 20 can be canceled. The time to the beginning of a1 is set. The potential difference from the reference potential Vb to the intermediate potential VM is smaller than the potential difference from the first contraction potential VH1 to the reference potential Vb. Therefore, the magnitude of the pressure fluctuation due to the first change part a1 of the second damping element ca2 is smaller than the magnitude of the pressure fluctuation due to the damping contraction element pc of the first damping element ca1, but the first damping element Residual vibration is damped in two steps, the element ca1 (damping / shrinking element pc) and the second damping element ca2 (first changing part a1). Is suppressed more effectively.

  When the ejection drive pulse DP (both the front and rear stages) is supplied to the piezoelectric vibrator 23, first, the expansion element p11 applies pressure to the central part in the width direction of the operating parts of the piezoelectric vibrator 23 and the diaphragm 24. It bends to the outside of the chamber 20 (side away from the nozzle plate 32). As a result, the pressure chamber 20 expands from the reference volume corresponding to the reference potential Vb to the expansion volume corresponding to the first expansion potential VL1. By this expansion, the meniscus in the nozzle 31 is drawn into the pressure chamber 20 side, and ink is supplied into the pressure chamber 20 from the reservoir 29 side through the supply port 26. The expanded state of the pressure chamber 20 is maintained over the supply period of the expansion hold element p12. Thereafter, the contraction element p <b> 13 is applied, so that the piezoelectric vibrator 23 and the central part of the operating part are greatly bent inside the pressure chamber 20. Thereby, the pressure chamber 20 is rapidly contracted from the expansion volume to the contraction volume corresponding to the first contraction potential VH1. The ink in the pressure chamber 20 is pressurized by the rapid contraction of the pressure chamber 20, and a predetermined amount (for example, several ng to several tens of ng) of ink is ejected from the nozzle 31. The contraction state of the pressure chamber 20 is maintained over the supply period of the contraction hold element ph of the first damping element ca1, and during this time, the pressure vibration of the ink in the pressure chamber 20 caused by the ink ejection increases and decreases periodically. repeat. Then, the damping contraction element pc of the first damping element ca1 is applied to the piezoelectric vibrator 23 in accordance with the timing at which the ink pressure in the pressure chamber 20 rises. The central portion bends toward the outside of the pressure chamber 20. Thereby, the pressure chamber 20 returns to the reference volume, and the residual vibration of the ink in the pressure chamber 20 is reduced. Thereafter, the reference volume of the pressure chamber 20 is maintained over the period of the intermediate hold element ha. Then, the first change portion a1 of the second damping element ca2 is applied to the piezoelectric vibrator 23 at a timing when the ink pressure of the residual vibration that cannot be suppressed only by the first damping element ca rises. Along with this, the piezoelectric vibrator 23 and the central portion of the operating portion are bent toward the outside of the pressure chamber 20. Accordingly, the pressure chamber 20 is slightly expanded from the reference volume to the intermediate expansion volume, and the residual vibration of the ink in the pressure chamber 20 is further suppressed. The expanded state of the pressure chamber 20 is maintained over the application period of the vibration suppression hold unit a2, and then returned to the reference state by the second changing unit a3.

  FIG. 6B is a waveform diagram illustrating the configuration of the micro-vibration driving pulse VP (VP1, VP2). The fine vibration drive pulse VP is a drive pulse set to a drive voltage or waveform that can slightly vibrate the meniscus to such an extent that ink is not ejected from the nozzle 31 in order to suppress ink thickening at the nozzle 31 during the recording process. . The micro-vibration driving pulse VP in the present embodiment includes a micro-vibration expansion element p21, a micro-vibration expansion hold element p22, and a micro-vibration contraction element p23. The micro-vibration expansion element p21 is a waveform element in which the potential rises with a gentle gradient from the reference potential Vb to the second expansion potential VL2 so that ink is not ejected from the nozzle 31. The second expansion potential VL2 is set to a value between the intermediate potential VM and the first expansion potential VL1 (VL1 <VL2 <VM). The fine vibration expansion hold element p22 is a waveform element that maintains the second expansion potential VL2 that is the terminal potential of the fine vibration expansion element p21 for a certain period of time. Further, the fine vibration contraction element p23 is a waveform element that lowers the potential with a sufficiently gentle gradient from the second expansion potential VL2 to the reference potential Vb in an attitude in which ink is not ejected from the nozzle 31.

  When the micro-vibration driving pulse VP configured in this way is applied to the piezoelectric vibrator 23, first, the micro-vibration expansion element p21 causes the central portion in the width direction of the operating portion of the piezoelectric vibrator 23 and the diaphragm 24 to be in the reference state. To the outside of the pressure chamber 20. As a result, the pressure chamber 20 contracts from the reference volume corresponding to the reference potential Vb to the fine vibration expansion volume corresponding to the second expansion potential VL2. By this expansion, the pressure in the pressure chamber 20 is reduced to such an extent that it is not ejected from the nozzle 31. The expansion state of the pressure chamber 20 is maintained over the application period of the fine vibration expansion hold element p22. Thereafter, by applying the micro-vibration contraction element p23, the piezoelectric vibrator 23 and the central portion of the operating portion are bent to the inside of the pressure chamber 20 to return to the reference state. As a result, the pressure chamber 20 returns from the minute vibration expansion volume to the reference volume, and the residual vibration of the ink in the pressure chamber 20 is reduced. With a series of volume fluctuations of the pressure chamber 20, a relatively gentle pressure vibration is generated in the pressure chamber 20, and the meniscus exposed to the nozzle 31 slightly vibrates due to the pressure fluctuation. Due to the slight vibration of the meniscus, the thickened ink in the vicinity of the nozzle 31 is dispersed, and as a result, the thickening of the ink can be prevented.

  In the printer 1 according to the present invention, when the second damping element ca2 that is the subsequent stage of the ejection driving pulse DP is applied alone to the piezoelectric vibrator 23, it also functions as the auxiliary fine vibration driving pulse CP. That is, the first change portion a1 of the second damping element ca2 causes the central portion in the width direction of the operating portion of the piezoelectric vibrator 23 and the diaphragm 24 to be bent from the reference state to the outside of the pressure chamber 20. As a result, the pressure chamber 20 contracts from the reference volume corresponding to the reference potential Vb to the intermediate expansion volume corresponding to the intermediate potential VM. By this expansion, the pressure in the pressure chamber 20 is reduced to such an extent that it is not ejected from the nozzle 31. And the expansion state of this pressure chamber 20 is maintained over the application period of the vibration suppression hold part a2. Thereafter, when the second change portion a3 is applied, the piezoelectric vibrator 23 and the central portion of the operating portion are bent to the inside of the pressure chamber 20 to return to the reference state. Thereby, the pressure chamber 20 returns from the intermediate expansion volume to the reference volume, and the residual vibration of the ink in the pressure chamber 20 is reduced. With a series of volume fluctuations of the pressure chamber 20, a relatively gentle pressure vibration is generated in the pressure chamber 20, and the meniscus exposed to the nozzle 31 slightly vibrates due to the pressure fluctuation.

  In the above configuration, in the case of non-recording in which ink is not ejected from the nozzles 31 at a predetermined recording period (unit period) T, as shown in FIG. 5, the first auxiliary micro-vibration driving pulse CP1 in the period T2 and the first in the period T3. One fine vibration drive pulse VP1, a second auxiliary fine vibration drive pulse CP2 in period T5, a second fine vibration drive pulse VP2 in period T6, and a third auxiliary fine vibration drive pulse CP3 in period T8 are selected. Sequentially applied to the piezoelectric vibrator 23. In other words, in the present embodiment, a total of five micro-vibration driving pulses are applied to the piezoelectric vibrator 23 during non-recording to perform micro-vibration. Thereby, the ink in the nozzle 31 and the pressure chamber 20 is agitated, and the viscosity of the ink is prevented.

  In the case where small dots are formed at a predetermined recording cycle T, in the present embodiment, a front stage portion of the second ejection drive pulse DP2 in the period T4 and a rear stage section (second damping element) of the second ejection drive pulse DP2 in the period T5. ca2 and second auxiliary fine vibration driving pulse CP2) are selected and sequentially applied to the piezoelectric vibrator 23. As a result, an amount of ink corresponding to the small dot is ejected once from the nozzle 31 and landed on the pixel area on the recording medium to form a small dot. Pressure vibration (residual vibration) in the pressure chamber 20 caused by ejecting ink is suppressed by the two-stage vibration damping element p14. Further, when forming a medium dot at a predetermined recording cycle T, in the present embodiment, a preceding stage of the first ejection driving pulse DP1 in the period T1 and a subsequent stage (second control) of the first ejection driving pulse DP1 in the period T2. Vibration element ca2, first auxiliary micro-vibration driving pulse CP1), a preceding stage of third injection driving pulse DP3 in period T7, and a subsequent stage of second injection driving pulse DP3 in period T8 (second damping element ca2, 3 auxiliary fine vibration drive pulses CP3) are selected and sequentially applied to the piezoelectric vibrator 32. As a result, an amount of ink corresponding to the small dots is ejected from the nozzle 31 twice in succession, and these inks land on the pixel area on the recording medium to form medium dots. Pressure vibration in the pressure chamber 20 caused by ejecting ink by each ejection drive pulse DP is suppressed by the respective two-stage vibration damping elements p14.

  When large dots are formed at a predetermined recording cycle T, in this embodiment, the first stage of the first ejection drive pulse DP1 during the period T1 and the rear stage (second control) of the first ejection drive pulse DP1 during the period T2. Vibration element ca2, first auxiliary micro-vibration driving pulse CP1), a preceding stage of second injection driving pulse DP2 in period T4, and a subsequent stage of second injection driving pulse DP2 in period T5 (second damping element ca2, 2 auxiliary fine vibration drive pulses CP2), a preceding stage of the third injection drive pulse DP3 in the period T7, and a subsequent stage part of the third injection drive pulse DP3 in the period T8 (second damping element ca2, third auxiliary fine vibration drive). Pulse CP3) is selected and sequentially applied to the piezoelectric vibrator 32. As a result, the ink corresponding to the small dots is ejected from the nozzle 31 three times in succession, and these inks land on the pixel area on the recording medium to form large dots. Pressure vibration in the pressure chamber 20 caused by ejecting ink by each ejection drive pulse DP is suppressed by the respective two-stage vibration damping elements p14. Note that large, medium, and small indicating dot sizes are relative, and the actual dot size and liquid amount are determined according to the specifications of the printer 1.

  Thus, in the printer 1 according to the present invention, the vibration damping element p14 of the ejection drive pulse DP is divided into the first vibration damping element ca1 in the front stage and the second vibration damping element ca2 in the rear stage, and the second vibration damping element in the rear stage. The vibration element ca2 can be used as a fine vibration drive pulse (auxiliary fine vibration drive pulse), and has two functions of a residual vibration damping function and a fine vibration function. For this reason, the number of micro-vibrations can be increased more than before without unnecessarily lengthening the drive signal COM, and the ink viscosity can be more effectively suppressed. For this reason, the frequency of a flushing process, a cleaning process, etc. can be reduced. As a result, it is possible to reduce the amount of ink consumed by these processes, and it is possible to suppress a decrease in throughput due to the provision of a separate processing time.

  The second damping element ca2 subsequent to the damping element p14 has a driving voltage (potential difference between the reference potential Vb and the intermediate voltage VM) of the second damping element ca2 lower than the driving voltage of the other elements. There is little possibility that ink is erroneously ejected from the nozzles 31. In addition, since the second damping element ca2 can align the starting potential (starting potential of the first changing portion a1) and the terminating potential (ending potential of the second changing portion a3) with the reference potential Vb, the piezoelectric element alone Suitable for application to the vibrator 32. For this reason, the second damping element ca2 is optimal as the auxiliary fine vibration driving pulse CP.

  By the way, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the description of the scope of claims.

  FIG. 7 is a diagram illustrating the configuration of the drive signal COM in the second embodiment and the selection pattern of each drive pulse during non-recording. In this embodiment, the configuration of the drive signal COM is the same as that of the drive signal COM of the first embodiment, but two types of drive pulse selection patterns at the time of non-recording are prepared. This is different from the embodiment. Specifically, when recording is being performed on the recording medium (recording paper 14), the first time when the nozzle 31 corresponding to the recording area of the recording medium (area where ink is ejected) is not recording is the first one. While the drive pulse is selected based on the selection pattern (non-1), the drive pulse is selected based on the second selection pattern (non-2) when the nozzle 31 corresponding to outside the recording area of the recording medium is not recording. Is configured to be performed. Since there is a high possibility that ink is ejected from the nozzles 31 corresponding to the recording area, the progress of the thickening is relatively low. For this reason, in the first selection pattern, only the first fine vibration drive pulse VP1 in the period T3 and the second fine vibration drive pulse VP2 in the period T6 are selected and applied to the piezoelectric vibrator 23. On the other hand, since the ink is not ejected from the nozzle 31 corresponding to the outside of the recording area, the progress of the thickening is higher than that of the nozzle 31 in the recording area. For this reason, in the second selection pattern, the first auxiliary vibration driving pulse CP1 in the period T1, the first vibration driving pulse VP1 in the period T2, the second auxiliary vibration driving pulse CP2 in the period T5, and the period T6. The second micro-vibration drive pulse VP2 and the third auxiliary micro-vibration drive pulse CP3 in the period T8 are selected and applied to the piezoelectric vibrator 23. Thereby, more fine vibrations are performed and thickening is prevented. In this way, by changing the selection pattern at the time of non-recording according to the nozzles 31 inside and outside the recording area of the recording medium, fine vibration can be efficiently performed without waste. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  Further, regarding the intermediate hold element ha, the first embodiment has exemplified the configuration in which the potential of the intermediate hold element ha is the reference potential Vb. However, the present invention is not limited to this, and the potential of the intermediate hold element ha is the reference potential. A configuration different from Vb may be employed. In this case, it is desirable to insert an adjustment element for adjusting the potential from the terminal potential of the intermediate hold element ha to the reference potential Vb between the intermediate hold element ha and the first change part a1.

Further, in each of the above-described embodiments, the so-called flexural vibration type piezoelectric vibrator 23 is exemplified as the pressure generating means. However, the present invention is not limited to this, and the present invention is also applied to, for example, a so-called longitudinal vibration type piezoelectric vibrator. It is also possible. In this case, the waveform of each driving signal (driving pulse) illustrated is a waveform in which the potential change direction, that is, the top and bottom are inverted.
Further, in each of the above embodiments, a so-called line type printer is exemplified, but the present invention is not limited to this, and the present invention can also be applied to a so-called serial printer that performs recording while reciprocating a recording head with respect to a recording medium. it can.
In addition, the waveforms of the ejection drive pulse DP and the fine vibration drive pulse VP in the drive signal COM are not limited to those illustrated, and various waveforms can be employed. However, regarding the ejection drive pulse DP, the damping element is divided into at least two stages, that is, a front stage part and a rear stage part, and it is necessary that the rear stage part can be applied to the piezoelectric vibrator 32 independently.

  Further, in the above embodiment, the first expansion potential VL1 is lower than the reference potential Vb, the first contraction potential VH1 is higher than the reference potential Vb, and the intermediate potential VM is lower than the reference potential Vb. VL1 may be higher than the reference potential Vb, the first contraction potential VH1 may be lower than the reference potential Vb, and the intermediate potential VM may be higher than the reference potential Vb.

  The present invention is not limited to a printer, as long as it is a liquid ejecting apparatus capable of controlling the ejection of liquid by driving a pressure generating means by applying a drive waveform. The present invention can also be applied to a recording apparatus or a liquid ejecting apparatus other than the recording apparatus, such as a display manufacturing apparatus, an electrode manufacturing apparatus, or a chip manufacturing apparatus. In the display manufacturing apparatus, a solution of each color material of R (Red), G (Green), and B (Blue) is ejected from the color material ejecting head. Moreover, in an electrode manufacturing apparatus, a liquid electrode material is ejected from an electrode material ejection head. In the chip manufacturing apparatus, a bioorganic solution is ejected from a bioorganic ejecting head.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording head, 14 ... Recording paper, 20 ... Pressure chamber, 23 ... Piezoelectric vibrator, 31 ... Nozzle, 36 ... Printer controller, 38 ... CPU, 40 ... Drive signal generation part

Claims (4)

A liquid ejecting head that ejects liquid from a nozzle by driving a pressure generating means by applying a driving waveform;
Drive signal generating means for generating a drive signal including an ejection drive waveform used for ejecting the liquid and a micro-vibration drive waveform for micro-vibrating the liquid;
A liquid ejecting apparatus comprising:
The ejection drive waveform includes a damping element that dampens pressure vibration associated with liquid ejection,
The vibration damping element has a first vibration damping element and a second vibration damping element after the first vibration damping element,
The liquid ejecting apparatus, wherein the second damping element can be used as a fine vibration driving waveform.   The second damping element includes a first changing unit that changes the first potential to a second potential different from the first potential, a damping holding unit that holds the second potential, and the second potential to the first potential. The liquid ejecting apparatus according to claim 1, further comprising: a second changing unit that changes the potential to one potential. The damping element has a hold element having a constant potential between the first damping element and the second damping element,
The liquid ejecting apparatus according to claim 1, wherein the drive waveform can be switched in the middle of the hold element. A liquid ejection head that ejects liquid from a nozzle by driving pressure generation means by applying a drive waveform, and a drive signal that generates a drive signal including an ejection drive waveform used for ejecting liquid and a micro-vibration drive waveform that slightly vibrates the liquid A liquid ejecting apparatus including the generating unit,
In the ejection drive waveform, provided with a damping element that dampens pressure vibration associated with liquid ejection,
The vibration damping element includes a first vibration damping element and a second vibration damping element following the first vibration damping element,
A control method for a liquid ejecting apparatus, wherein the second vibration damping element is applied alone to the pressure generating means to act as a fine vibration driving waveform.

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