JP2015044369A - Liquid jetting device and control method of liquid jetting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jetting device and a control method of a liquid jetting device capable of adjusting the amount of liquid jetted from a nozzle while maintaining the striking position precision.SOLUTION: A jetting drive pulse comprises a preliminary expansion element p11 (first pulse element), an expansion hold element p12, a shrinkage element p13 (second pulse element), shrinkage hold elements p14, p14' (third pulse element) and a recovery expansion element p15 (fourth pulse element). The length of the shrinkage hold element of the jetting drive pulses P3, P4 used in a line drawing printing mode (second mode) is set longer than the length of the shrinkage hold element of jetting drive pulses P1, P2 used in a solid printing mode (first mode).

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 are image recording apparatuses such as an ink jet printer and an ink jet plotter. Recently, various types of liquid ejecting apparatuses are utilized by utilizing the feature that a very small amount of liquid can be accurately landed 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.

  An ink jet recording head (a type of liquid ejecting head, hereinafter abbreviated as a recording head) mounted on the above-described printer includes a nozzle array (nozzle group) in which a plurality of nozzles for ejecting ink are arranged, and these For example, a piezoelectric element, a heating element, an electrostatic actuator, or the like is provided as pressure generating means for causing pressure fluctuation in the ink in the pressure chamber communicating with the nozzle and ejecting the ink from the nozzle. In this printer, the drive signal generated by the drive signal generation unit of the control device is applied to the pressure generation unit, so that the pressure generation unit is driven to eject ink. This drive signal includes one or more drive pulses for driving the pressure generating means to eject ink from the nozzles. The voltage (potential difference between the lowest potential and the highest potential) and the waveform of the drive pulse are set so that the amount of ejected ink and the flying speed become target values in design and specifications.

  Here, the printer performs, for example, so-called solid printing (see, for example, Patent Document 1) in which a predetermined range of a liquid landing target (recording paper) such as ink is filled with a specific color ink without gaps. In this case, it is possible to speed up the printing process by ejecting as much ink as possible onto the landing target at a high frequency. On the other hand, when performing line drawing printing (for example, see Patent Document 2) in which dots are arranged to represent lines, characters, etc., such as line diagrams, ruled lines, or text, ink is applied to a predetermined position on a recording medium. It is required to land with higher accuracy to ensure the quality of the recorded image. In this line drawing printing, since it is required to clarify the outline of a recorded image such as a line drawing, it is desirable that the amount of ink ejected at one time is smaller than that in the case of solid printing.

Japanese Patent Application Laid-Open No. 2004-243779 JP 2012-126128 A

  In order to change the amount of ink ejected from the nozzle, it is conceivable to change the voltage of the drive pulse. That is, for example, by reducing the voltage of the drive pulse, the amount of ink ejected from the nozzles also decreases. However, in this case, as the amount of ink changes, the ink flying speed also changes from the designed target value. Since the ink ejected from the nozzle of the recording head flies obliquely with respect to the landing target, if the flying speed of the ink changes, the landing position of the ink with respect to the landing target deviates from the original target position. In particular, in a configuration in which printing is performed by ejecting ink while moving the recording head relative to the landing target such as recording paper, the forward movement when moving from one side to the other in the width direction of the landing target and one from the other The relative landing position of the ink is shifted during both the backward movement and movement. As a result, when a line drawing or ruled line is printed, there is a possibility that the printed line or the like is rattled and the image quality is deteriorated. Although measures such as adjusting the ink ejection timing in accordance with the change in the flying speed can be considered, the processing becomes complicated and is not realistic.

  The present invention has been made in view of such circumstances, and an object thereof is a liquid ejecting apparatus capable of adjusting the amount of liquid ejected from a nozzle while maintaining landing position accuracy, and a liquid It is providing the control method of an injection apparatus.

The liquid ejecting apparatus of the present invention has been proposed to achieve the above-described object, and includes a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a pressure that causes pressure fluctuations in the liquid in the pressure chamber. A liquid ejecting head having a generating means and capable of ejecting a liquid from the nozzle by the operation of the pressure generating means;
Drive pulse generating means for generating a drive pulse for driving the pressure generating means;
A liquid ejecting apparatus comprising:
The drive signal can generate a first drive pulse and a second drive pulse whose voltage is the same as that of the first drive pulse;
The first drive pulse and the second drive pulse include a first pulse element that expands the pressure chamber from a reference volume, and a second pulse element that contracts the pressure chamber expanded by the first pulse element. At least a third pulse element that maintains a contracted state of the pressure chamber contracted by the second pulse element, and a fourth pulse element that expands the contracted pressure chamber to the reference volume,
The length of the third pulse element of the second drive pulse is set longer than the length of the third pulse element of the first drive pulse.

  In the above configuration, the drive pulse generating means generates the first drive pulse in the first mode in which the amount of liquid to land on the landing target is relatively large, and the amount of liquid to land on the landing position. It is desirable to employ a configuration in which the second drive pulse is generated in the second mode with relatively little.

  According to the present invention, the length of the third pulse element of the second drive pulse is set to be longer than the length of the third pulse element of the first drive pulse, so that compared to the case of the first drive pulse. The amount (weight) of the liquid is reduced while the flying speed of the liquid when the liquid is ejected by the second driving pulse is kept constant (without greatly changing from the designed target value). Can do. In other words, for example, priority is given to landing a larger amount of liquid on the landing target or to increase the liquid ejection processing speed by ejecting liquid at a higher frequency (as a result, landing on the landing position). In the first mode, the liquid is ejected using the first driving pulse in which the length of the third pulse element is set to a relatively short value, and thus the landing is performed. It becomes possible to perform the injection process with respect to the object more efficiently. On the other hand, compared with the case of the first mode, the landing accuracy of the liquid with respect to the landing target and the clarity of the outline of the landing pattern (image such as a line drawing) are required to be higher (as a result, the landing position is In the second mode, where the amount of liquid to land is relatively small), the liquid is ejected using the second drive pulse in which the length of the third pulse element is set to a relatively long value. After the liquid is ejected at the predetermined timing Tn, the weight of the liquid can be relatively decreased while maintaining the flying speed of the liquid at the next timing Tn + 1 at the designed target value. . As a result, when landing dots such as lines, rules, or texts are lined up and a landing pattern such as a line or character is formed on the landing target, a clear image (line) with less blurring while suppressing liquid landing position deviation. It is possible to form a figure.

The control method of the liquid ejecting apparatus of the present invention includes a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a pressure generation unit that causes a pressure fluctuation in the liquid in the pressure chamber. A liquid ejecting head capable of ejecting liquid from a nozzle by the operation of the means, and a drive pulse generating means for generating a drive pulse for driving the pressure generating means,
The drive pulse generating means can generate a first drive pulse and a second drive pulse whose voltage is the same as that of the first drive pulse,
The first drive pulse and the second drive pulse include a first pulse element that expands the pressure chamber from a reference volume, and a second pulse element that contracts the pressure chamber expanded by the first pulse element. A liquid jet having at least a third pulse element that maintains a contracted state of the pressure chamber contracted by the second pulse element and a fourth pulse element that expands the contracted pressure chamber to the reference volume. An apparatus control method comprising:
The length of the third pulse element of the second drive pulse is set longer than the length of the third pulse element of the first drive pulse.

2 is a block diagram illustrating an electrical configuration of a printer. FIG. 2 is a perspective view illustrating an internal configuration of the printer. FIG. It is a wave form diagram explaining the structure of a drive signal. FIG. 3 is a cross-sectional view illustrating a configuration of a recording head. It is a wave form diagram explaining the structure of an ejection drive pulse. It is a graph which shows the change of the amount of ink ejected from the nozzle with respect to the change of the time of the contraction hold element after the contraction element of a drive pulse, and a flight speed. It is a wave form diagram explaining the modification of an ejection 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 block diagram illustrating the electrical configuration of the printer 1, and FIG. 2 is a perspective view illustrating the internal configuration of the printer 1. The external device 2 is an electronic device that handles image data, such as a computer, a digital camera, or a portable information terminal. The external device 2 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 paper feed mechanism 3, a carriage moving mechanism 4 (moving means), a linear encoder 5, a recording head 6, and a printer controller 7. The recording head 6 is fixed to the bottom surface side of the carriage 16 on which the ink cartridge 17 is mounted. The carriage 16 is configured to reciprocate along the guide rod 18 by the carriage moving mechanism 4. That is, the printer 1 sequentially transports a recording medium such as recording paper (corresponding to the landing target in the present invention) by the paper feed mechanism 3 and moves the recording head 6 relative to the recording medium while moving the recording head 6 relative to the recording medium. Ink is ejected from the nozzle 34 (see FIG. 4), and the ink is landed on the recording medium, thereby recording an image or the like.

  The printer controller 7 is a type of control means, and is a control unit that controls each part of the printer. The printer controller 7 includes an interface (I / F) unit 8, a CPU 9, a storage unit 10, and a drive signal generation unit 11. The interface unit 8 transmits / receives printer status data when sending print data or a print command from the external device 2 to the printer 1 or outputting status information of the printer 1 to the external device 2 side. The CPU 9 is an arithmetic processing device for controlling the entire printer. The memory | storage part 10 is an element which memorize | stores the data used for the program and various control of CPU9, and contains ROM, RAM, and NVRAM (nonvolatile memory element). The CPU 9 controls each unit according to a program stored in the storage unit 10.

  The drive signal generator 11 (corresponding to the drive pulse generator in the present invention) generates an analog voltage signal based on the waveform data relating to the waveform of the drive signal. The drive signal generator 11 amplifies the voltage signal to generate the drive signal COM. For example, as illustrated in FIG. 3, the drive signal generation unit 11 in the present embodiment generates a drive signal including one or more ejection drive pulses. The drive signal generator 11 generates two types of drive signals COM1 and COM2. Details of this point will be described later.

  Next, the print engine 13 will be described. As shown in FIG. 1, the print engine 13 includes a recording head 6, a carriage moving mechanism 4, a paper feed mechanism 3, a linear encoder 5, and the like. The carriage moving mechanism 4 includes a carriage 16 to which a recording head 6 which is a kind of liquid ejecting head is attached, and a drive motor (for example, a DC motor) that drives the carriage 16 via a timing belt or the like (see FIG. The recording head 6 mounted on the carriage 16 is moved in the main scanning direction. The paper feed mechanism 3 includes a paper feed motor and a paper feed roller, and sequentially feeds a recording medium such as recording paper onto the platen to perform sub-scanning. Further, the linear encoder 5 outputs an encoder pulse corresponding to the scanning position of the recording head 6 mounted on the carriage 16 to the printer controller 7 as position information in the main scanning direction. The printer controller 7 can grasp the scanning position (current position) of the recording head 6 based on the encoder pulse received from the linear encoder 5 side.

  FIG. 4 is a cross-sectional view of a main part for explaining the configuration of the recording head 6. The recording head 6 includes a case 19, a vibrator unit 15 housed in the case 19, a flow path unit 20 joined to the bottom surface (tip surface) of the case 19, and the like. The case 19 is made of, for example, an epoxy resin, and a housing empty portion 21 in which the vibrator unit 15 is housed is formed. The vibrator unit 15 includes a piezoelectric element 22 that functions as a pressure generating unit, a fixing plate 23 to which the piezoelectric element 22 is bonded, and a flexible cable 24 that supplies a driving signal (driving pulse) to the piezoelectric element 22. Yes. The piezoelectric element 22 is a laminated type produced by cutting a piezoelectric plate in which piezoelectric layers and electrode layers are alternately laminated into a comb-like shape, and can be expanded and contracted in a direction perpendicular to the laminating direction (electric field direction) ( It is a piezoelectric element of a longitudinal vibration mode that is a field transverse effect type).

  The flow path unit 20 is configured by joining a nozzle plate 27 to one surface of the flow path forming substrate 26 and a diaphragm 28 to the other surface of the flow path forming substrate 26. The flow path unit 20 is provided with a reservoir 30 (common liquid chamber), an ink supply port 31, a pressure chamber 32, a nozzle communication port 33, and a nozzle 34. A series of ink flow paths from the ink supply port 31 to the nozzle 34 through the pressure chamber 32 and the nozzle communication port 33 are formed corresponding to each nozzle 34.

  The nozzle plate 27 is a thin plate made of metal such as stainless steel in which a plurality of nozzles 34 are formed in rows at a pitch (for example, 360 dpi) corresponding to the dot formation density. The nozzle plate 27 is provided with a plurality of nozzle rows (nozzle groups) by arranging nozzles 34, and one nozzle row is composed of, for example, 360 nozzles 34.

  The diaphragm 28 has a double structure in which an elastic film 38 is laminated on the surface of a support plate 37. In the present embodiment, the vibration plate 28 is manufactured using a composite plate material in which a stainless plate, which is a kind of metal plate, is used as the support plate 37 and a resin film is laminated on the surface of the support plate 37 as an elastic film 38. The diaphragm 28 is provided with a diaphragm portion 39 that changes the volume of the pressure chamber 32. The diaphragm 28 is provided with a compliance portion 40 that seals a part of the reservoir 30.

  The diaphragm 39 is produced by partially removing the support plate 37 by etching or the like. That is, the diaphragm portion 39 includes an island portion 41 to which the distal end surface of the piezoelectric element 22 is joined, and an elastic portion 42 surrounding the island portion 41. The compliance part 40 is produced by removing the support plate 37 in the region facing the opening surface of the reservoir 30 by etching or the like in the same way as the diaphragm part 39, and the pressure fluctuation of the liquid stored in the reservoir 30 is reduced. Functions as a damper to absorb.

  Since the tip end surface of the piezoelectric element 22 is joined to the island portion 41, the volume of the pressure chamber 32 can be changed by expanding and contracting the free end portion of the piezoelectric element 22. A pressure fluctuation occurs in the ink in the pressure chamber 32 in accordance with the volume fluctuation. The recording head 6 ejects ink from the nozzles 34 using this pressure fluctuation.

FIG. 3 is a waveform diagram illustrating the configuration of the drive signals (first drive signal COM1 and second drive signal COM2) generated by the drive signal generation unit 11.
In the present embodiment, the drive signal generator 11 generates different drive signals COM1 and COM2 according to the print mode. Specifically, in the solid print mode (corresponding to the first mode in the present invention) in which a predetermined area of the recording medium is filled with no gaps, the first drive signal COM1 is generated, and a diagram, ruled line, character, etc. In the line drawing printing mode (corresponding to the second mode in the present invention) in which ink dots are arranged to represent lines, characters, and the like as in the above text, the second drive signal COM2 is generated. The unit period that is the repetition period of the drive signals COM1 and COM2 is a distance corresponding to the width of the pixel when the nozzle 34 ejects ink while the recording head 6 moves relative to the recording medium. It corresponds to the time to move. The solid print mode is a mode in which ink is ejected at a relatively high frequency, whereas the line drawing print mode is a mode in which ink is ejected at a frequency lower than that in the solid print mode. Therefore, the unit of the second drive signal COM2 The period T ′ is longer than the unit period T of the first drive signal COM1. In the present embodiment, it is possible to form dots of two types with respect to one pixel in each printing mode. Therefore, the printer 1 can express a total of three tones including non-recording in which dots are not formed for pixels.

  The unit cycle T of the first drive signal COM1 in this embodiment is divided into two periods, specifically, a period T11 and a period T12. In the period T11, the first injection driving pulse P1 is generated, and in the period T12 following the period T11, the second injection driving pulse P2 is generated. The first ejection drive pulse P1 and the second ejection drive pulse P2 have the same waveform. When these ejection drive pulses P1 and P2 are selected and sequentially applied to the piezoelectric element 22 within the unit period T, ink is ejected from the nozzle 34 twice in succession, and a pixel formation area (virtual region) on the recording medium. The total amount of ink lands on a typical pixel formation scheduled area) to form the maximum dot (large dot) in the solid print mode. In addition, when only one of the ejection drive pulses P1 and P2 is selected and applied to the piezoelectric element 22 in the unit period T, ink is ejected only once from the nozzle 34, and the pixel on the recording medium. A dot (small dot) smaller than the large dot is formed by landing on the formation region. Further, in the case of non-recording in which no dot is formed in the pixel formation region in the unit period T, neither of the ejection drive pulses P1 and P2 is selected. As a result, ink is not ejected from the nozzle 34. Each drive pulse included in the first injection drive signal COM1 corresponds to the first drive pulse in the present invention.

  The unit cycle T ′ of the second drive signal COM2 in the present embodiment is divided into two periods, specifically, a period T21 and a period T22, similarly to the first drive signal COM1. Then, the third injection driving pulse P3 is generated in the period T21, and the fourth injection driving pulse P4 is generated in the period T22 following the period T21. The third ejection driving pulse P3 and the fourth ejection driving pulse P4 have the same waveform. When these ejection driving pulses P3 and P4 are selected and sequentially applied to the piezoelectric element 22 within the unit period T ′, ink is ejected twice from the nozzle 34 in a pixel formation region on the recording medium. The total amount of ink is landed to form the largest dot (large dot) in the line drawing printing mode. In addition, when only one of the ejection drive pulses P3 and P4 is selected and applied to the piezoelectric element 22 in the unit cycle T ′, ink is ejected from the nozzle 34 only once, and the recording medium is printed on the recording medium. A dot (small dot) smaller than the large dot is formed by landing on the pixel formation region. Further, in the case of non-recording in which no dot is formed in the pixel formation region in the unit period T ′, neither of the ejection drive pulses P3 and P4 is selected. As a result, ink is not ejected from the nozzle 34. Each drive pulse included in the second injection drive signal COM2 corresponds to a second drive pulse in the present invention.

  The basic configuration (pulse components, drive voltage, etc.) of the drive pulses P3, P4 of the second ejection drive signal COM2 is substantially the same as the configuration of the drive pulses P1, P2 of the first drive signal COM1. However, the time of the contraction hold element p14 ′ following the contraction element p13 is designed to be shorter than the contraction hold element p14 of the drive pulse of the first drive signal COM1. Details of this point will be described below.

FIG. 5 is a waveform diagram illustrating the configuration of the ejection drive pulse that forms the medium dot, and FIG. 5A is a waveform diagram of the first ejection drive pulse P1 and the second ejection drive pulse P2 in the first drive signal COM1, b) is a waveform diagram showing the configuration of the third injection drive pulse P3 and the fourth injection drive pulse P4 in the second drive signal COM2.
As shown in FIG. 5 (a), the first injection drive pulse P1 and the second injection drive pulse P2 include a preliminary expansion element p11 (first pulse element), an expansion hold element p12, and a contraction element (pressure element). ) P13 (second pulse element), contraction hold element p14 (third pulse element), and return expansion element p15 (fourth pulse element). The pre-expansion element p11 is a pulse element in which the potential changes (increases) to the plus side with a constant gradient from the reference potential Vb that is the base point of the potential change to the first expansion potential VH1, and the expansion hold element p12 is the pre-expansion element p11. This is a constant pulse element at the first expansion potential VH1, which is the terminal potential of. The contraction element p13 is a pulse element in which the potential changes (decreases) with a constant gradient from the first expansion potential VH1 to the first contraction potential VL1 (VL1 <Vb). The contraction hold element p14 The pulse element is a constant pulse element (a kind of holding element) at one contraction potential VL1, and the return expansion element p15 is a pulse element that returns the potential from the first contraction potential VL1 to the reference potential Vb.

  When the first ejection drive pulse P1 or the second ejection drive pulse P2 configured as described above is applied to the piezoelectric element 22, first, the piezoelectric element 22 is contracted in the longitudinal direction of the element by the preliminary expansion element p11. Accordingly, the pressure chamber 32 expands from the reference volume corresponding to the reference potential Vb to the expansion volume corresponding to the first expansion potential VH1 (expansion step). Due to this expansion, the meniscus in the nozzle 34 is largely drawn to the pressure chamber 32 side. And the expansion state of this pressure chamber 32 is maintained over the supply period of the expansion hold element p12 (hold process). After the expansion state by the expansion hold element p12 is maintained, the contraction element p13 is applied to the piezoelectric element 22, and the piezoelectric element 22 expands accordingly. Accordingly, the pressure chamber 32 is contracted from the expansion volume to the contraction volume corresponding to the first contraction potential VL1 (pressurization process). As a result, the ink in the pressure chamber 32 is pressurized, the central portion of the nozzle 34 meniscus is pushed out to the ejection side, and the pushed portion extends like a liquid column. Subsequently, the contraction state of the pressure chamber 32 is maintained for a certain time by the contraction hold element p14. During this time, the meniscus and the liquid column are separated, and the separated portion is ejected as an ink droplet from the nozzle 34 and flies toward the recording medium. Thereafter, the return expansion element p <b> 15 is applied to the piezoelectric element 22. By applying the return expansion element p15, the pressure chamber 32 returns to the steady volume. The return expansion element p15 also functions as a vibration suppression element that suppresses vibration (residual vibration) after the ink is ejected.

  As shown in FIG. 5 (b), the third injection drive pulse P3 and the fourth injection drive pulse P4 of the second drive signal COM2 include a preliminary expansion element p11 (first pulse element), an expansion hold element p12, It comprises a contraction element p13 (second pulse element), a contraction hold element p14 '(third pulse element), and a return expansion element p15 (fourth pulse element). That is, each pulse element of the fifth injection drive pulse P5 excluding the contraction hold element p14 ′ is common to that of the first injection drive pulse P1 and the second injection drive pulse P2 in the first drive signal COM1. Therefore, the driving voltage (potential difference between the lowest potential VL1 and the highest potential VH1) VD1, the first ejection driving pulse P1, and the second ejection driving pulse P2 of the third ejection driving pulse P3 and the fourth ejection driving pulse P4. The drive voltage VD1 is also the same value. On the other hand, the contraction hold element p14 ′ of the ejection drive pulses P3 and P4 is a pulse element in which the time for maintaining the first contraction potential VL1 is set longer than the contraction hold element p14 of the ejection drive pulses P1 and P2. That is, the time width Pw2 of the contraction hold element p14 ′ of the ejection drive pulses P3 and P4 is longer than the time width Pw1 of the contraction hold element p14 of the ejection drive pulses P1 and P2. Thus, after the third ejection driving pulse P3 or the fourth ejection driving pulse P4 is applied to the piezoelectric element 22 at a predetermined timing Tn and ink is ejected from the nozzle 34, the third ejection driving pulse P3 is performed at the next timing Tn + 1. Alternatively, when the fourth ejection driving pulse P4 is applied to the same piezoelectric element 22 and ink is ejected from the same nozzle 34, the flying speed Vm of the ink ejected at the timing Tn + 1 is not changed (target). The amount (weight) Iw of ink ejected (while maintaining the flying speed) is configured to be smaller than the amount of ink ejected by the ejection drive pulses P1 and P2 in the first drive signal COM1. ing. This point will be described later.

  FIG. 6 shows the amount Iw [ng] of ink ejected from the nozzle 34 and the flying speed with respect to the change in the time of the contraction hold element after the contraction element of the drive pulse (horizontal axis: hereinafter referred to as hold time as appropriate). It is a graph which shows the change (vertical axis) of Vm [m / s]. Here, the graph of FIG. 6 is based on the line drawing printing mode, and a predetermined timing at a driving frequency assumed in the line drawing printing mode (an average frequency when ink is continuously ejected in the mode). After the ink is ejected with any one of the drive pulses P3, P4 of the second drive signal COM2 at Tn, the drive pulse P3, P4 of any of the second drive signals COM2 at the timing Tn + 1 when the ink is ejected next. The change in the flying speed Vm and the weight Iw of the ink according to the hold time when the ink is ejected is shown. More specifically, for example, after ink is ejected by the third ejection drive pulse P3 at time T21 in the unit cycle T ′, ink is ejected by the fourth ejection drive pulse P4 at the subsequent time T22. This is a change in the flying speed Vm and the weight Iw of the ink ejected by the fourth ejection driving pulse P4. Alternatively, for example, after the ink is ejected by the fourth ejection driving pulse P4 at the time T22 in the unit cycle T ′ (n), the ink is ejected by the third ejection driving pulse P3 at the time T21 of the subsequent unit cycle T ′ (n + 1). Is a change in the flying speed Vm and the weight Iw of the ink ejected by the third ejection drive pulse P3 when the is ejected. That is, this graph shows the influence on the ink ejection at the timing Tn when only the drive pulse hold time at the timing Tn is changed. Therefore, elements other than the hold time (such as drive voltage) remain constant.

  As shown in FIG. 6, the weight Iw of the ink ejected at timing Tn + 1 changes by changing the hold time of the drive pulse at timing Tn. This is because changing the hold time changes the timing of vibration suppression by the return expansion element p15 with respect to vibration (residual vibration) generated when ink is ejected by the contraction element p13. That is, by changing the hold time, the degree of vibration suppression at timing Tn changes, and the weight Iw of ink ejected at timing Tn + 1 changes due to the influence of the vibration. In the driving cycle assumed in the line drawing printing mode, the ink weight Iw tends to decrease by setting the driving pulse hold time longer. On the other hand, as shown in the figure, even if the drive pulse hold time at the timing Tn is changed, the flying speed Vm of the ink ejected at the timing Tn + 1 does not change and is substantially constant. This is related to the drive pulse at Tn + 1, and the drive voltage of the drive pulse (potential difference from the lowest potential to the highest potential) and the slope of the pre-expansion element or contraction element (the rate of change of potential with respect to time) are constant. This is because it does not change. Therefore, only the ink weight Iw of Tn + 1 can be changed while the flying speed Vm is kept constant, depending on the degree of damping of the residual vibration generated when the ink is ejected at Tn.

  In the present embodiment, the time Pw2 of the contraction hold element p14 ′ of the ejection drive pulses P3 and P4 in the second drive signal COM2 is greater than the time Pw1 of the contraction hold element p14 of the ejection drive pulses P1 and P2 in the first drive signal COM1. Is set to be longer, the ink weight is reduced in the line drawing printing mode while keeping the ink flying speed constant (design target value) compared to the solid printing mode. . That is, in the solid printing mode, it is desirable that the amount of ink landed on the recording medium is as large as possible. Therefore, the amount of ink ejected at one time and ejection at a higher frequency than damping of residual vibration. Takes precedence. For this reason, the time Pw1 of the contraction hold element p14 of the ejection drive pulses P1, P2 in the first drive signal COM1 is set to a relatively short value. Thereby, it becomes possible to eject ink with a shorter period. Further, since the degree of vibration suppression by the return expansion element of the ejection drive pulses P1 and P2 is reduced, the residual vibration due to ejection at the timing Tn can be used to increase the weight of ink at the time of ejection at the timing Tn + 1. It becomes possible to perform solid printing efficiently.

  On the other hand, in the line drawing printing mode, the ink landing accuracy on the recording medium and the clarity of the outline of the image (line) are required to be higher than those in the solid printing mode. Accordingly, the time Pw2 of the contraction hold element p14 ′ of the ejection drive pulses P3 and P4 in the second drive signal COM2 in the line drawing print mode is set to be longer than in the solid print mode, thereby ejecting ink at the timing Tn. Thereafter, the ink weight Iw can be reduced as compared with the solid printing mode while the flying speed Vm of the ink at the time of ink ejection at the timing Tn + 1 is maintained at the designed target value. As a result, when lines and characters are recorded on a recording medium by arranging dots such as a diagram, ruled line, or text, a clear image (such as a diagram) with less blurring is recorded while suppressing landing position deviation. It becomes possible. Further, even when the time Pw2 of the contraction hold element p14 ′ of the ejection drive pulses P3 and P4 in the second drive signal COM2 is set to be relatively long, in the line drawing print mode, the frequency at which the ink is ejected is the solid print mode. Therefore, it is difficult to cause inconveniences such as a long time for the entire printing process.

  As described above, according to the printer 1 of the present invention, by changing the time of the contraction hold element of the drive pulse in accordance with the printing mode, it is possible to perform ink ejection control more suitable for these printing modes. That is, it is possible to cope with both a printing mode in which priority is given to the amount of liquid and the processing speed, and a printing mode in which priority is given to landing accuracy and high image quality.

  In addition, this invention is not limited to each above-mentioned embodiment, A various deformation | transformation is possible based on description of a claim.

  For example, regarding the configuration of the drive signals COM1 and 2, in the above-described embodiment, the configuration in which two injection drive pulses are included in a unit cycle is illustrated, but the present invention is not limited thereto, and three or more injection drive pulses are included. It is also possible to adopt a configuration. In short, the hold time of each drive pulse in the second drive signal COM2 is set longer than the hold time of each drive pulse in the first drive signal COM1, regardless of the number of drive pulses of the drive signals COM1 and COM2. Thus, the same effects as described above can be obtained.

Further, the type (waveform) of the drive pulse included in the drive signal is not limited to the above-described example.
For example, FIG. 7 is a waveform diagram showing a configuration example of the fifth ejection driving pulse P5 and the sixth ejection driving pulse P6 in which the amount of ink ejected is smaller than in the case of the ejection driving pulses P1 to P4. These ejection drive pulses P5 and P6 differ from the ejection drive pulses P1 to P4 in that they have an intermediate hold element that maintains an intermediate potential VM (VL2 <VM <VH2) in the middle of the contraction element. .

  That is, as shown in FIG. 7A, the fifth injection drive pulse P5 includes a preliminary expansion element p21 (first pulse element), an expansion hold element p22, a first contraction element p23, and an intermediate hold element p24. And a second contraction element p25, a contraction hold element p26 (third pulse element), and a return expansion element p27 (fourth pulse element). The first contraction element p23, the intermediate hold element p24, and the second contraction element p25 correspond to the second pulse element in the present invention.

  Further, as shown in FIG. 7B, the sixth injection drive pulse P6 includes the preliminary expansion element p21, the expansion hold element p22, the first contraction element p23, the intermediate hold element p24, and the second contraction element p25. And a contraction hold element p26 'and a return expansion element p27. That is, each pulse element of the sixth injection drive pulse P6 excluding the contraction hold element p26 ′ is common to that of the fifth injection drive pulse P5. Therefore, the driving voltage VD2 of the sixth ejection driving pulse P6 and the driving voltage VD2 of the fifth ejection driving pulse P5 are the same value. On the other hand, the contraction hold element p26 ′ of the sixth injection drive pulse P6 is a pulse element having a longer time for maintaining the second contraction potential VL2 than the contraction hold element p26 of the fifth injection drive pulse P5. That is, the time width Pw4 of the contraction hold element p26 ′ of the sixth injection drive pulse P6 is longer than the time width Pw3 of the contraction hold element p26 of the fifth injection drive pulse P5. Thus, after the sixth ejection drive pulse P6 is applied to the piezoelectric element 22 at timing Tn and ink is ejected from the nozzle 34, another ejection drive pulse is applied to the same piezoelectric element 22 at timing Tn + 1, and the nozzle 34. Ink was ejected with the fifth ejection drive pulse P5, with the amount of ink Iw ejected without greatly changing the flying speed Vm of the ejected ink from the designed target value. The amount of ink at the time can be reduced.

  In each of the above embodiments, the configuration in which the ink is ejected while moving the recording head 6 with respect to the recording medium is exemplified, but the present invention is not limited to this. For example, a configuration in which ink is ejected while moving the recording medium with respect to the recording head 6 while the position of the recording head 6 is fixed may be employed. In short, the present invention can be applied to any configuration in which ink is ejected while the recording head 6 and the recording medium move relative to each other to land the ink on the recording medium.

Furthermore, in the above-described embodiment, the so-called longitudinal vibration type piezoelectric element 22 is exemplified as the pressure generating unit. However, the pressure generation unit is not limited thereto, and for example, a so-called flexural vibration type piezoelectric element can be employed. In this case, with respect to each drive pulse exemplified in the above embodiment, the waveform changes in the direction of potential change, that is, upside down.
Furthermore, the pressure generating means is not limited to the piezoelectric element, and when various pressure generating means such as a heat generating element that generates bubbles in the pressure chamber or an electrostatic actuator that changes the volume of the pressure chamber using electrostatic force is used. The present invention can also be applied.

  In the above description, the ink jet printer 1 which is a kind of liquid ejecting apparatus has been described as an example. However, the present invention can also be applied to other liquid ejecting apparatuses that eject liquid using drive pulses. it can. For example, a display manufacturing apparatus that manufactures color filters such as liquid crystal displays, an electrode manufacturing apparatus that forms electrodes such as organic EL (Electro Luminescence) displays and FEDs (surface emitting displays), and chips that manufacture biochips (biochemical elements) The present invention can also be applied to a manufacturing apparatus and a micropipette that supplies an accurate amount of a very small amount of sample solution.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 6 ... Recording head, 7 ... Printer controller, 11 ... Drive signal generation part, 13 ... Print engine, 14 ... Head control part, 15 ... Actuator unit, 22 ... Piezoelectric element, 34 ... Nozzle

Claims (3)

A liquid ejector that has a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a pressure generation unit that causes a pressure fluctuation in the liquid in the pressure chamber, and can eject the liquid from the nozzle by the operation of the pressure generation unit Head,
Drive pulse generating means for generating a drive pulse for driving the pressure generating means;
A liquid ejecting apparatus comprising:
The drive pulse generating means can generate a first drive pulse and a second drive pulse whose voltage is the same as that of the first drive pulse,
The first drive pulse and the second drive pulse include a first pulse element that expands the pressure chamber from a reference volume, and a second pulse element that contracts the pressure chamber expanded by the first pulse element. At least a third pulse element that maintains a contracted state of the pressure chamber contracted by the second pulse element, and a fourth pulse element that expands the contracted pressure chamber to the reference volume,
The length of the third pulse element of the second drive pulse is set longer than the length of the third pulse element of the first drive pulse.   The drive pulse generating means generates the first drive pulse in the first mode in which the amount of liquid to be landed on the landing target is relatively large, and the amount of liquid to land on the landing position is relatively The liquid ejecting apparatus according to claim 1, wherein the second driving pulse is generated in a small second mode. A liquid ejector that has a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a pressure generation unit that causes a pressure fluctuation in the liquid in the pressure chamber, and can eject the liquid from the nozzle by the operation of the pressure generation unit A head and drive pulse generating means for generating a drive pulse for driving the pressure generating means,
The drive pulse generating means can generate a first drive pulse and a second drive pulse whose voltage is the same as that of the first drive pulse,
The first drive pulse and the second drive pulse include a first pulse element that expands the pressure chamber from a reference volume, and a second pulse element that contracts the pressure chamber expanded by the first pulse element. A liquid jet having at least a third pulse element that maintains a contracted state of the pressure chamber contracted by the second pulse element and a fourth pulse element that expands the contracted pressure chamber to the reference volume. An apparatus control method comprising:
The method of controlling a liquid ejecting apparatus, wherein a length of the third pulse element of the second drive pulse is set longer than a length of the third pulse element of the first drive pulse.

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