JP2011189517A - Liquid injection device and control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid injection device, capable of further effectively recovering the injecting capability of a liquid injection head, and a control method of the liquid injection device. <P>SOLUTION: In an injection capability recovery drive signal COM2b in the second flushing, an interval ph between a preceding injection drive pulse DP1 to be generated first and a following injection drive pulse DP2 to be generated following the preceding injection drive pulse is set so that the following injection drive pulse is applied to a piezoelectric oscillator 30 with a gap of time from a maximal point MX1 of residual oscillation generated by applying the preceding injection drive pulse DP1 to the piezoelectric oscillator 30. In an injection capability recovery drive signal COM2a in the first flushing, the interval ph between the preceding injection drive pulse and the following injection drive pulse is set so that an application time tb of the following drive pulse to the piezoelectric oscillator 30 is closer to the top of the residual oscillation by the preceding injection drive pulse than in the second flushing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer including a liquid ejecting head that applies pressure fluctuation to a pressure chamber communicating with a nozzle and ejects liquid in the pressure chamber from the nozzle, and a control method for the liquid ejecting apparatus.

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting (discharging) liquid and ejects various liquids from the liquid ejecting head. As a representative example of this liquid ejecting apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejecting head is provided, and droplet-like ink is recorded on recording paper or the like from the nozzles of the recording head. An image recording apparatus such as an ink jet printer (hereinafter simply referred to as a printer) that records an image or the like by ejecting or landing on a medium (a target to be ejected) can be given. In recent years, it is applied not only to this image recording apparatus but also to various manufacturing apparatuses. For example, in a display manufacturing apparatus such as a liquid crystal display, a plasma display, an organic EL (Electro Luminescence) display, or an FED (surface emitting display), various liquid materials such as coloring materials and electrodes are used as pixel formation regions and electrode formations. A liquid ejecting apparatus is used for ejecting an area or the like.

  The printer generates a drive signal including a drive pulse, and applies the generated drive pulse to a pressure generating element (for example, a piezoelectric vibrator or a heat generating element) to drive it to generate pressure. There is a configuration in which a pressure change is applied to ink in a chamber (a type of pressure chamber), and the recording operation is performed by ejecting ink from a nozzle communicating with the pressure generation chamber using the pressure change.

  By the way, in a general printer, the nozzle surface of the recording head is sealed (capped) by a cap member when the power is off or in a standby state where printing is not performed with the power on. As a result, evaporation of the ink solvent from the nozzles is suppressed. However, during the printing operation (recording operation), the nozzle surface is released from the capping state, so that the meniscus at the nozzle is exposed to the atmosphere. For this reason, during the period in which the cap member is released, the ink solvent gradually evaporates from the nozzle as time passes, so that the viscosity of the ink in the vicinity of the nozzle increases. Even during capping, even if the nozzle formation surface of the recording head is sealed with a capping member or the like, a space is formed between the capping member and the nozzle surface, and the ink meniscus is exposed to the air remaining in this space. Therefore, it has been difficult to completely suppress the natural evaporation of the ink solvent. When such thickening of the ink becomes remarkable, there is a possibility that problems such as a decrease in the weight and flying speed of the ejected ink and a failure (ejection failure) may occur such that the ink is not ejected. In recent years, attempts have been made to eject a liquid having a higher viscosity than the conventionally treated ink (hereinafter also referred to as a high viscosity liquid). In such a printer that ejects a high-viscosity liquid, the ink tends to increase in viscosity. As the ink thickens, the viscosity of the ink in the vicinity of the meniscus becomes such that the pressure is not easily oscillated by the pressure generating element in a short period of time. In addition, there is a possibility that the landing position may be shifted due to bending of the flying direction of the ink.

  In order to prevent such ink ejection failure, various maintenance processes are performed. For example, by increasing the pressure in the pressure chamber by driving the pressure generating element and discharging the liquid droplets from the nozzle (discarding) (hereinafter referred to as flushing), the ink is thickened and the air bubbles are mixed in the ink. It has been done to forcibly remove. In order to more reliably discharge ink thickened by this flushing and air bubbles that exist with ink in the ink flow path (liquid flow path) from the nozzle, a pressure fluctuation as large as possible is applied to the ink and air bubbles. There is a need to. Therefore, a printer capable of generating a driving pulse for flushing (maintenance) in which the pressure variation applied to the pressure chamber is increased by resonating the pressure change applied to the pressure chamber by the pressure generating element with the natural vibration of the liquid generated in the pressure chamber. It has been proposed (see, for example, Patent Document 1).

JP 2009-73074 A

  However, when the above-described flushing drive pulse is used, the pressure fluctuation of the ink in the pressure chamber increases, and the residual vibration caused thereby increases. For this reason, when the next driving pulse is applied to the pressure generating element when the meniscus in the nozzle is disturbed and the meniscus becomes unstable, the flying bend of the ink ejected from the nozzle occurs, and the flying ink May not land at a predetermined position. In this way, when the meniscus is unstable and the transition is made from the flushing operation to the recording operation, there is a possibility that ejection failure occurs during the recording operation and the image quality of the recorded image is deteriorated. In addition, even after ejecting ink with particularly increased viscosity in the vicinity of the meniscus during flushing, if the flushing drive pulse is repeatedly applied to the pressure generating element and used continuously, it becomes difficult to suppress ink consumption. There was a problem. Furthermore, when the viscosity of the ink becomes more prominent and the viscosity of the ink becomes more difficult to swing, even if the flushing is performed using the flushing drive pulse, the ink having increased viscosity from the nozzle There is a problem that the ejection performance of the liquid ejecting head is difficult to be recovered in some cases.

  The present invention has been made in view of such circumstances, and an object thereof is a liquid ejecting apparatus capable of more effectively recovering the ejecting ability of the liquid ejecting head, and a control method for the liquid ejecting apparatus. Is to provide.

In order to achieve the above object, a liquid ejecting apparatus according to an aspect of the present invention provides a liquid ejecting head that applies pressure fluctuation to a pressure chamber by the operation of a pressure generating unit, and ejects liquid filled in the pressure chamber from a nozzle;
A drive signal generating unit capable of generating a drive signal including a drive pulse whose main purpose is to drive the pressure generating unit to eject liquid from the nozzle toward the ejection medium. There,
An ejection capability recovery mode is performed in which the liquid is ejected from a plurality of drive modes for driving the pressure generating means toward an area other than the ejection target medium to perform an ejection capability recovery process for the purpose of restoring the ejection capability. When set, the drive signal generating means generates an ejection capability recovery drive signal including a plurality of the drive pulses,
In the injection capacity recovery process, the second injection capacity recovery process is executed after at least the first injection capacity recovery process is executed,
The drive signal for recovering the injection capability in the second injection capability recovery process is the timing at which the preceding drive is deviated from the apex of the residual vibration generated by applying the preceding drive pulse generated previously to the pressure generating means. An interval between the preceding drive pulse and the subsequent drive pulse is set so that a subsequent drive pulse generated next to the pulse is applied to the pressure generating unit.
The drive signal for recovery of the injection capacity in the first injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. The interval between the preceding drive pulse and the subsequent drive pulse is set so as to be close to the apex of.
Note that the recovery of the jetting ability is close to the state before liquid viscosity is thickened (ideally the state at the time of manufacturing) by jetting the liquid thickened by evaporation of the liquid solvent from the nozzle. This means that the liquid ejection capability, that is, the amount of liquid to be ejected and the flying speed are brought close to an ideal state in terms of design and specifications.

According to this configuration, the drive signal for recovery of the injection capacity in the first injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is higher than that in the case of the second injection capacity recovery process. Since the interval between the preceding drive pulse and the subsequent drive pulse is set so as to be close to the top of the residual vibration due to, the first injection capability recovery process is caused by applying the preceding drive pulse to the pressure generating means. In the state where the meniscus in the nozzle moves from the pressure chamber side to the ejection side in response to the pressure vibration, the subsequent drive pulse is applied to the pressure generating means. As a result, the liquid jet pressure can be increased by resonating (synthesizing) the reaction of the meniscus drawn back to the pressure chamber side to return to the original position and the pressure fluctuation caused by the subsequent drive pulse. It is possible to easily eject the liquid that has become difficult to swing from the nozzle. As a result, it is possible to more effectively recover the jetting ability of the liquid jet head that has been lowered due to the thickening of the liquid. The drive signal for recovering the injection capacity in the second injection capacity recovery process is the timing at which the subsequent drive pulse is applied to the pressure generating means at a timing deviated from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating means. Since the interval between the preceding drive pulse and the subsequent drive pulse is set so as to be applied, it is possible to discharge the thickened liquid while stabilizing the meniscus by suppressing pressure fluctuations compared to the first jetting capacity recovery process. .
That is, in the initial stage of the ejection capacity recovery process, the liquid can be ejected with a higher pressure fluctuation and the thickened liquid can be discharged, and in the later stage of the ejection capacity recovery process, the liquid ejection time is higher than in the initial stage. The stability of the meniscus can be ensured by keeping the pressure fluctuation low. Thereby, it is possible to quickly shift to the process of jetting the liquid to the jetting target by converging the meniscus vibration as quickly as possible while enhancing the effect of restoring the jetting ability. In addition, since it is possible to perform the ejection capacity recovery process using a drive pulse whose main purpose is to eject liquid toward the ejection target medium without changing the waveform, a drive pulse dedicated to the ejection capacity recovery process is separately provided. There is no need to provide it. The state of resonance means a state where the flying speed of the liquid ejected from the nozzle is higher when the subsequent drive pulse is applied to the pressure generating means than in the state of not resonating.

  In the above configuration, the timing at which the subsequent drive pulse in the first injection capacity recovery process is applied to the pressure generating unit is −0 from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating unit. It is desirable to set the range from 2 Tc to +0.2 Tc.

  According to this configuration, the timing at which the subsequent drive pulse in the first injection capacity recovery process is applied to the pressure generating unit is −0... 0 from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating unit. Since it is set in the range of 2 Tc to +0.2 Tc, the meniscus in the nozzle is drawn deeper into the pressure chamber side in response to the pressure vibration generated by applying the preceding drive pulse to the pressure generating means, and then from the injection side. Subsequent drive pulses are applied to the pressure generating means at the timing of movement. As a result, the liquid jet pressure can be increased by resonating (synthesizing) the reaction of the meniscus drawn back to the pressure chamber side to return to the original position and the pressure fluctuation caused by the subsequent drive pulse. It is possible to easily eject the liquid that has become difficult to swing from the nozzle.

In the above configuration, a time measuring means for measuring a time during which the liquid ejecting head does not continuously eject the liquid,
It is desirable to have switching control means for controlling the timing for switching from the first injection capacity recovery process to the second injection capacity recovery process according to the time measured by the time measuring means.

  According to this configuration, the time counting unit that measures the time during which the liquid ejecting head does not continuously eject the liquid, and the second ejection from the first ejection capability recovery process according to the time counted by the time measuring unit. Switching control means for controlling the timing of switching to the capacity recovery process, so that the ejection capacity recovery process can be performed without excess or deficiency according to the viscosity of the liquid.

  In the above configuration, the switching control means delays the timing of switching from the first injection capacity recovery process to the second injection capacity recovery process as the time counted by the time measuring means is longer, while the time measuring means It is desirable that the timing of switching from the first injection capacity recovery process to the second injection capacity recovery process is advanced as the time counted by the above is shorter.

  According to this configuration, the switching control means delays the timing of switching from the first injection capacity recovery process to the second injection capacity recovery process as the time counted by the time measuring means is longer, while being timed by the time measuring means. As the remaining time is shorter, the timing of switching from the first ejection capacity recovery process to the second ejection capacity recovery process is advanced, so that it is possible to achieve both recovery of the ejection capacity and suppression of the liquid consumption. That is, the longer the time during which the liquid is not ejected, the higher the possibility that the viscosity of the liquid is higher. Therefore, the thickened liquid can be more reliably discharged by executing the first ejection capacity recovery process longer. . On the other hand, the shorter the time during which the liquid is not jetted, the higher the possibility that the viscosity of the liquid is relatively low. Therefore, the first jetting capacity recovery process is made shorter and the process proceeds to the second jetting capacity recovery process at an early stage. Thus, liquid consumption can be suppressed. Therefore, it is possible to perform a jetting capacity recovery process without excess or deficiency according to the viscosity of the liquid.

In the above configuration, in the injection capacity recovery process executed by the drive signal generating means, the third injection is performed after the first injection capacity recovery process is executed and before the second injection capacity recovery process is executed. The ability recovery process is executed,
The drive signal for recovering the injection capacity in the third injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse as compared with the case of the first injection capacity recovery process. The interval between the preceding drive pulse and the subsequent drive pulse is set so as to be far from the top of the nozzle and further closer to the vertex of the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. It is desirable.

  According to this configuration, in the injection ability recovery process executed by the drive signal generating means, the third injection ability recovery process is executed after the first injection ability recovery process is executed and before the second injection ability recovery process is executed. The injection capacity recovery process is executed, and the drive signal for recovery of the injection capacity in the third injection capacity recovery process is preceded by the timing at which the subsequent drive pulse is applied to the pressure generating means than in the case of the first injection capacity recovery process. The interval between the preceding drive pulse and the subsequent drive pulse is set so that it is far from the peak of the residual vibration due to the drive pulse and is closer to the peak of the residual vibration due to the previous drive pulse than in the case of the second ejection capacity recovery process. Thus, the ejection capability recovery process can be executed using the ejection capability recovery drive signal that is more in accordance with the viscosity of the liquid.

  The present invention is suitable when the liquid has a viscosity of 10 millipascal seconds or more and 30 millipascal seconds or less.

  That is, even if it is difficult for a high-viscosity liquid of 10 millipascal seconds or more to oscillate when a pressure fluctuation is applied, the nozzle is applied by applying the first drive signal to the pressure generating means in the ejection capacity recovery process. It is possible to recover the jetting ability by jetting the liquid that has become thicker and difficult to swing. Moreover, since it is a liquid of 30 millipascal seconds or less, the phenomenon that the rear end portion of the ejected liquid extends like a tail can be suppressed.

Further, the control method of the liquid ejecting apparatus of the present invention includes a liquid ejecting head that applies pressure fluctuation to the pressure chamber by the operation of the pressure generating means, and ejects the liquid filled in the pressure chamber from the nozzle, and the pressure generating means. And a drive signal generation unit capable of generating a drive signal including a drive pulse whose main purpose is to drive and eject liquid from the nozzle toward the ejection medium. ,
An ejection capability recovery mode is performed in which the liquid is ejected from a plurality of drive modes for driving the pressure generating means toward an area other than the ejection target medium to perform an ejection capability recovery process for the purpose of restoring the ejection capability. When set, the drive signal generating means generates a drive signal for recovering the injection capability including a plurality of the drive pulses. In the injection capability recovery process, the second is performed after at least the first injection capability recovery process is executed. The injection capacity recovery process of
The drive signal for recovering the injection capability in the second injection capability recovery process is the timing at which the preceding drive is deviated from the apex of the residual vibration generated by applying the preceding drive pulse generated previously to the pressure generating means. An interval between the preceding drive pulse and the subsequent drive pulse is set so that a subsequent drive pulse generated next to the pulse is applied to the pressure generating unit.
The drive signal for recovery of the injection capacity in the first injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. The interval between the preceding drive pulse and the subsequent drive pulse is set so as to be close to the apex of.

According to this configuration, in the first injection capacity recovery process, the meniscus in the nozzle moves from the pressure chamber side to the injection side in response to the pressure vibration generated by applying the preceding drive pulse to the pressure generating means. The subsequent drive pulse is applied to the pressure generating means. As a result, the liquid jet pressure can be increased by resonating (synthesizing) the reaction of the meniscus drawn back to the pressure chamber side to return to the original position and the pressure fluctuation caused by the subsequent drive pulse. It is possible to easily eject the liquid that has become difficult to swing from the nozzle. As a result, it is possible to more effectively recover the jetting ability of the liquid jet head that has been lowered due to the thickening of the liquid. Further, it is possible to discharge the thickening liquid while stabilizing the meniscus by suppressing the pressure fluctuation more than in the first jetting capacity recovery process.
That is, in the initial stage of the ejection capacity recovery process, the liquid can be ejected with a higher pressure fluctuation and the thickened liquid can be discharged, and in the later stage of the ejection capacity recovery process, the liquid ejection time is higher than in the initial stage. The stability of the meniscus can be ensured by keeping the pressure fluctuation low. Thereby, it is possible to quickly shift to the process of jetting the liquid to the jetting target by converging the meniscus vibration as quickly as possible while enhancing the effect of restoring the jetting ability. In addition, since it is possible to perform the ejection capacity recovery process using a drive pulse whose main purpose is to eject liquid toward the ejection target medium without changing the waveform, a drive pulse dedicated to the ejection capacity recovery process is separately provided. There is no need to provide it.

In the present invention, the timing at which the subsequent drive pulse is applied to the pressure generating means in the first injection capacity recovery process is −0 from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating means. It is suitable when it is set in the range of .2Tc to + 0.2Tc.
According to this configuration, the subsequent drive is performed at the timing when the meniscus in the nozzle moves from the deeply drawn state to the pressure chamber side to the injection side in accordance with the pressure vibration generated by applying the preceding drive pulse to the pressure generating unit. A pulse is applied to the pressure generating means. As a result, the liquid jet pressure can be increased by resonating (synthesizing) the reaction of the meniscus drawn back to the pressure chamber side to return to the original position and the pressure fluctuation caused by the subsequent drive pulse. It is possible to easily eject the liquid that has become difficult to swing from the nozzle.

2 is a plan view illustrating a configuration of a printer. FIG. FIG. 3 is a cross-sectional view of a main part of the recording head. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is a wave form diagram explaining the structure of the ejection pulse contained in the drive signal for recording. It is a wave form diagram explaining the composition of the drive signal for injection capacity recovery containing a plurality of injection pulses. It is a schematic diagram explaining the movement of the meniscus at the time of supplying an injection pulse. It is a flowchart explaining the flow of flushing. It is a table | surface which shows the difference in each flushing period in other embodiment.

  The best mode for carrying out the present invention will be described below 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 this embodiment, an ink jet recording apparatus (hereinafter referred to as “printer”) is taken as an example of the liquid ejecting apparatus, and an ink jet recording head (hereinafter referred to as “recording head”) is taken as an example of the liquid ejecting head. I will explain.

  FIG. 1 is a perspective view illustrating the configuration of the printer 1, and FIG. 2 is a cross-sectional view of the main part of the recording head 3. In the printer 1, a recording head 3 which is a kind of liquid ejecting head is attached inside a housing 2, and a carriage 5 to which an ink cartridge 4 for storing ink (corresponding to the liquid in the present invention) is detachably attached. The platen 6 disposed below the recording head 3 and the carriage 5 (recording head 3) are reciprocated in the paper width direction of the recording paper 7 (corresponding to the ejected medium in the present invention), that is, in the main scanning direction. A carriage moving mechanism 8 and a paper feeding mechanism 9 that conveys the recording paper 7 in the sub-scanning direction that is a direction orthogonal to the main scanning direction are schematically configured. A configuration in which the ink cartridge 4 is mounted on the housing 2 side of the printer 1 and is supplied to the recording head 3 via an ink supply tube may be employed.

  The carriage 5 is attached while being supported by a guide rod 10 installed in the main scanning direction, and is configured to move in the main scanning direction along the guide rod 10 by the operation of the carriage moving mechanism 8. ing. The position of the carriage 5 in the main scanning direction is detected by the linear encoder 11, and the detection signal, that is, the encoder pulse is transmitted to the control unit 56 (see FIG. 3) of the printer controller. Thereby, the control unit 56 can control the recording operation (jetting operation) and the like by the recording head 3 while recognizing the scanning position of the carriage 5 (recording head 3) based on the encoder pulse from the linear encoder 11. .

  A home position serving as a scanning base point is set in an end area outside the recording area within the moving range of the carriage 5 (on the right side in FIG. 1). The home position in the present embodiment includes a capping member 12 (corresponding to a region other than the ejection target in the present invention) that seals the nozzle formation surface (nozzle plate 32: see FIG. 2) of the recording head 3, and the nozzle formation surface. A wiper member 13 for wiping is disposed. The printer 1 moves forward when the carriage 5 (recording head 3) moves from the home position toward the opposite end, and when the carriage 5 returns from the opposite end to the home position. In other words, so-called bidirectional recording is possible in which characters and images are recorded on the recording paper 7 in both directions. The capping member 12 is a tray-like member having an open top surface, and is made of an elastic member such as rubber or elastomer, and has a liquid-absorbing member made of a liquid-absorbing material such as felt or sponge that can absorb ink therein. (Not shown) is laid. The capping member 12 configured in this manner will be described later for eliminating (removing) thickened ink and bubbles remaining in the ink by ejecting (discarding) ink droplets (a kind of ink). Used as an ink receiving portion for receiving ink droplets in flushing (a type of ejection capability recovery process).

  As shown in FIG. 2, the recording head 3 in this embodiment can accommodate a vibrator unit 25 in which a piezoelectric vibrator group 22, a fixing plate 23, a flexible cable 24, and the like are unitized, and the vibrator unit 25. A head case 26 and a flow path unit 27 that forms a series of ink flow paths from a reservoir (common ink chamber) 36 through a pressure chamber (pressure generation chamber) 38 to a nozzle opening 35 (corresponding to the nozzle in the present invention). It is configured with.

  First, the vibrator unit 25 will be described. A piezoelectric vibrator 30 (a kind of pressure generating means in the present invention) constituting the piezoelectric vibrator group 22 is formed in a comb-like shape elongated in the vertical direction, and is cut into an extremely narrow width of about several tens of μm. . The piezoelectric vibrator 30 is configured as a longitudinal vibration type piezoelectric vibrator that can expand and contract in the vertical direction. Each piezoelectric vibrator 30 is fixed in a so-called cantilever state in which a fixed end portion is joined to the fixing plate 23 so that the free end portion protrudes outward from the tip edge of the fixing plate 23. The distal end of the free end portion of each piezoelectric vibrator 30 is joined to an island portion 44 that constitutes the diaphragm portion 42 of the flow path unit 27, as will be described later. The flexible cable 24 is electrically connected to the piezoelectric vibrator 30 on the side surface of the fixed end opposite to the fixed plate 23. In addition, the fixing plate 23 that supports each piezoelectric vibrator 30 is configured by a metal plate material having rigidity capable of receiving a reaction force from the piezoelectric vibrator 30. In this embodiment, it is made of a stainless steel plate having a thickness of about 1 mm.

  The head case 26 is a hollow box-like member made of, for example, an epoxy-based resin, and a flow path unit 27 is fixed to the front end surface (lower surface) of the head case 26 in an accommodation space 28 formed inside the case. Accommodates a vibrator unit 25 which is a kind of actuator. A case channel 29 is formed inside the head case 26 so as to penetrate the height direction. The case flow path 29 is a flow path for supplying ink from the ink cartridge 4 side to the reservoir 36.

  Next, the flow path unit 27 will be described. The flow path unit 27 includes a nozzle plate 32, a flow path forming substrate 33, and a vibration plate 34. The nozzle plate 32 is on one surface of the flow path forming substrate 33, and the vibration plate 34 is opposite to the nozzle plate 32. Each of the flow path forming substrates 33 is arranged and laminated on the other surface of the flow path forming substrate 33 and integrated by adhesion or the like.

  The nozzle plate 32 is a thin plate made of stainless steel in which a plurality of nozzle openings 35 are opened in a row at a pitch corresponding to the dot formation density. In the present embodiment, for example, 180 nozzle openings 35 are formed in a row, and the nozzle rows are configured by these nozzle openings 35. And this nozzle row is provided side by side and four rows.

  The flow path forming substrate 33 is a plate-like member that forms a series of ink flow paths including a reservoir 36, an ink supply port 37, and a pressure chamber 38. Specifically, a plurality of the flow path forming substrates 33 are formed in a state where the empty portions that become the pressure chambers 38 are partitioned by the partition walls corresponding to the respective nozzle openings 35, and the empty spaces that become the ink supply ports 37 and the reservoirs 36. It is the plate-shaped member which formed the part. The flow path forming substrate 33 of the present embodiment is produced by etching a silicon wafer. The pressure chamber 38 is formed as a long and narrow chamber in a direction orthogonal to the direction in which the nozzle openings 35 are arranged (nozzle row direction), and the ink supply port 37 communicates between the pressure chamber 38 and the reservoir 36. It is formed as a narrowed portion with a narrow channel width. The reservoir 36 is a chamber for supplying ink stored in the ink cartridge 4 to each pressure chamber 38, and communicates with the corresponding pressure chamber 38 through the ink supply port 37.

  The vibration plate 34 is a composite plate material having a double structure in which a resin film 41 such as PPS (polyphenylene sulfide) is laminated on a metal support plate 40 such as stainless steel, and seals one opening surface of the pressure chamber 38. This is a member having a diaphragm portion 42 for stopping and changing the volume of the pressure chamber 38 and a compliance portion 43 for sealing one opening surface of the reservoir 36. Then, the diaphragm portion 42 performs an etching process on a portion of the support plate 40 corresponding to the pressure chamber 38, removes the portion in an annular shape, and joins the free end portion of the piezoelectric vibrator 30 to the island portion 44. It is comprised by forming. Similar to the planar shape of the pressure chamber 38, the island portion 44 has a block shape elongated in a direction orthogonal to the direction in which the nozzle openings 35 are arranged, and the resin film 41 around the island portion 44 functions as an elastic film. To do. Further, the portion functioning as the compliance portion 43, that is, the portion corresponding to the reservoir 36 is only the resin film 41 by removing the support plate 40 by etching processing following the opening shape of the reservoir 36.

  Since the tip end surface of the piezoelectric vibrator 30 is joined to the island portion 44, the volume of the pressure chamber 38 can be changed by expanding and contracting the free end of the piezoelectric vibrator 30. A pressure fluctuation occurs in the ink in the pressure chamber 38 along with the volume fluctuation. The recording head 3 ejects ink droplets from the nozzle openings 35 using this pressure fluctuation.

Next, the electrical configuration of the printer 1 will be described.
FIG. 3 is a block diagram illustrating an electrical configuration of the printer 1. The printer 1 in the present embodiment is schematically configured by a printer controller 50 and a print engine 51. The printer controller 50 stores an external interface (external I / F) 52 that receives print data from an external device such as a host computer, a RAM 53 that stores various data, and a control program for various controls. ROM 54, a control unit 56 that performs overall control of each unit in accordance with a control program stored in ROM 54, an oscillation circuit 57 that generates a clock signal, and a drive signal that generates a drive signal COM to be supplied to recording head 3 A generation circuit 58 (corresponding to drive signal generation means) and an internal interface (internal I / F) for outputting dot pattern data, drive signals, etc. obtained by developing print data for each dot to the recording head 3 59 and a timer circuit 60 that functions as a time measuring means and performs a time measuring operation. The print engine 51 includes a recording head 3, a carriage moving mechanism 8, a paper feed mechanism 9, and an ink cartridge attachment detection unit 61 that detects that the ink cartridge 4 is attached to the carriage 5. . The ink cartridge mounting detection unit 61 detects that the ink cartridge 4 is mounted for the first time, and outputs a detection signal to the control unit 56. Based on this detection signal, the control unit 56 executes an initial filling process for filling the ink flow path of the recording head 3 with the ink of the ink cartridge 4. In addition, the timer circuit 60 counts the mounting time of the ink cartridge 4 from the time when the ink is first filled, the elapsed time from the last recording process (printing process) to the next recording process, In other words, the time for which the ink is not continuously ejected is measured. The ink cartridge mounting detection unit 61 may be any device that can detect mounting of the ink cartridge 4 such as an electrical detection unit or a mechanical detection unit.

  The control unit 56 controls ejection of ink droplets by the recording head 3 and other units of the printer 1 in accordance with an operation program stored in the ROM 54. The control unit 56 outputs a head control signal for controlling the operation of the recording head 3 to the recording head 3 and outputs a control signal for generating the driving signal COM to the driving signal generating circuit 58. The head control signal is, for example, a transfer clock CLK, pixel data SI, a latch signal LAT, and a change signal CH1. These latch signals and change signals define the supply timing of each pulse constituting the drive signal COM. The control unit 56 converts print data input from an external device via the external I / F 52 into ejection data used for ejecting ink droplets in the recording head 3. The converted ejection data is transferred to the recording head 3 through the internal I / F 59, and the recording head 3 controls the supply of the drive signal COM to the piezoelectric vibrator 30 based on the ejection data, thereby ejecting ink droplets. That is, a recording operation (jetting operation) is performed. Further, the control unit 56 performs flushing described later based on the elapsed time measured by the timer circuit 60.

  The drive signal generation circuit 58 drives the piezoelectric vibrator 30 to eject ink from the nozzle openings 35 toward the recording paper 7 within a period (one ejection period or one recording period) T for one pixel, that is, One or a plurality of ejection drive pulses DP (corresponding to the drive pulses in the present invention) whose main purpose is to eject ink to record an image or the like on the recording paper 7 or drive pulses having other waveforms In addition, a recording drive signal COM1 is generated with this as a repeating unit. In addition, the drive signal generation circuit 58 generates an ejection capability recovery drive signal COM2 including a plurality of ejection drive pulses DP used for flushing, which will be described later, based on the elapsed time counted by the timer circuit 60. Then, the drive signal generation circuit 58 supplies the drive signals COM1 and COM2 to the recording head 3 side via the internal I / F 56, respectively.

  Here, the thickening of the ink in the ink flow path of the recording head 3 will be described. In the printer 1, the meniscus (free surface) exposed from the nozzle openings 35 is exposed to air with the passage of time, and the ink solvent is evaporated to increase the viscosity of the ink. That is, the viscosity of the ink is higher than that at the time of manufacture. There is a case. Then, when the viscosity of the ink is increased in this way, there is a possibility that the ink is not ejected from the nozzle opening 35, so that ejection failure such as so-called dot omission or flying bending may occur. For this reason, the printer 1 uses the recording drive signal COM1 including the ejection drive pulse DP to eject ink onto the recording paper 7 and prints text, images, and the like or after the recording process (printing process). In the state where the recording head 3 is moved to a position for receiving ink called a flushing point provided on the capping member 12 or the platen at the home position and is opposed to the ink receiving portion at regular intervals during Flushing is executed as a recovery process. In the flushing, by repeatedly applying the ejection capability recovery drive signal COM2 including a plurality of ejection drive pulses DP to the piezoelectric vibrator 30, thickened ink and bubbles mixed in the ink are forcibly removed.

FIG. 4 is a waveform diagram illustrating the configuration of the ejection drive pulse DP1 included in the recording drive signal COM1 generated by the drive signal generation circuit 58 having the above configuration. In FIG. 4, the vertical axis represents the potential of the ejection drive pulse DP, and the horizontal axis represents time [μs].
The ejection drive pulse DP1 included in the recording drive signal COM1 is an example of a drive pulse generally used for recording an image or the like in a conventional printer, and has the largest size among ink droplets that can be ejected in this type of printer. This is an ejection driving pulse for ejecting a large ink droplet. The recording drive signal COM1 is configured to include one ejection drive pulse DP1 within a unit period divided by the LAT signal. In addition, the injection drive pulse DP1 in the present invention is not limited to the illustrated waveform, and may include other elements.

  The ejection drive pulse DP1 has an expansion element p1 that expands the pressure chamber 38 by changing the potential from the reference potential VB to the expansion potential VH and expands the pressure chamber 38, an expansion maintaining element p2 that maintains the expansion potential VH for a certain time, and an expansion potential VH. From the contraction potential VL to the contraction potential VL, the contraction element p3 for rapidly contracting the pressure chamber 38 by the potential changing to the minus side, the contraction maintaining (vibration hold) element p4 for maintaining the contraction potential VL for a certain time, and the reference from the contraction potential VL And a return element p5 for returning the potential to the potential VB.

  When the ejection drive pulse DP1 is supplied to the piezoelectric vibrator 30, it operates as follows. First, when the expansion element p1 is supplied to the piezoelectric vibrator 30, the piezoelectric vibrator 30 contracts, and accordingly, the pressure chamber 38 increases from the reference volume corresponding to the reference potential VB to the maximum volume corresponding to the maximum potential VH. Expands to Thereby, the meniscus exposed to the nozzle opening 35 is drawn to the pressure chamber 38 side. The expansion state of the pressure chamber 38 is kept constant throughout the supply period of the expansion maintaining element p2.

  When the contraction element p3 is supplied to the piezoelectric vibrator 30 subsequent to the expansion maintaining element p2, the piezoelectric vibrator 30 expands, so that the pressure chamber 38 extends from the maximum volume to the minimum volume corresponding to the minimum potential VL. Shrinks rapidly. The ink in the pressure chamber 38 is pressurized by the rapid contraction of the pressure chamber 38, and thereby, several pl to several tens pl of ink is ejected from the nozzle opening 35. The contraction state of the pressure chamber 38 is maintained for a short time over the supply period of the contraction maintaining element p4, and then the return element p5 is supplied to the piezoelectric vibrator 30 so that the pressure chamber 38 has a volume corresponding to the lowest potential VL. To the reference volume corresponding to the reference potential VB.

FIG. 5 is a waveform diagram illustrating the configuration of the drive signal COM2 including a plurality of ejection drive pulses DP generated by the drive signal generation circuit 58. In FIG. 5, the vertical axis represents the potential of the ejection drive pulse DP, and the horizontal axis represents time [μs].
Further, the printer 1 in the first embodiment is configured to perform flushing by using the ejection drive pulse DP as it is without changing the waveform and devising an interval between the ejection drive pulses DP as described later. ing. The printer 1 is configured to generate, from the drive signal generation circuit 58, an ejection capability recovery drive signal COM2 that includes two ejection drive pulses DP within one ejection cycle T in flushing. Specifically, the injection drive pulse DP included in the injection capacity recovery drive signal COM2 includes a preceding injection drive pulse DP2 (corresponding to a preceding drive pulse in the present invention) generated earlier and a preceding injection drive pulse DP2. It consists of a subsequent injection drive pulse DP3 (corresponding to the subsequent drive pulse in the present invention) generated later. The preceding ejection drive pulse DP2 and the subsequent ejection drive pulse DP3 are drive pulses having the same waveform as the ejection drive pulse DP1 included in the recording drive signal COM1, and thus description thereof is omitted. The ejection capacity recovery drive signal COM2 including these ejection drive pulses DP2 and DP3 drives the piezoelectric vibrator 30 for the purpose of recovery of the ejection capacity, that is, the area other than the recording paper 7 from the nozzle opening 35, that is, the present embodiment. In the embodiment, it is a drive signal for ejecting ink toward the capping member 12 facing the nozzle formation surface. In the flushing using the ejection capacity recovery drive signal COM2 including the ejection drive pulses DP2 and DP3 of the present invention, the ejection drive pulse DP is continuously applied to the piezoelectric vibrator 30 at a predetermined frequency (for example, several kHZ). Thus, ink is discharged from the nozzle openings 35 by the number of ejection drive pulses DP applied. In this case, injection from one shot to a certain shot (for example, 10 shots) is a flushing unit [seg] (flushing segment). In the flushing in the present embodiment, the ejection drive pulse DP is repeatedly applied (supplied) to the piezoelectric vibrator 30 by a predetermined number of flushing segments (for example, a total of several tens to several thousand segments), so that Ink is discharged from the nozzle opening 35.

  Next, flushing using the ejection capability recovery drive signal COM2 including the ejection drive pulses DP2 and DP3 configured as described above will be described. The printer 1 of the present invention moves the recording head 3 to the home position side when the normal printing mode for printing text, images, etc. on the recording paper 7 is switched to the flushing mode for flushing. The nozzle forming surface 3 and the upper surface open side of the capping member 12 are made to face each other. The printer 1 according to the present invention performs flushing by interrupting the recording process at predetermined intervals while the recording process of an image or the like is being performed on a recording medium such as the recording paper 7. When it is time to execute the configured flushing, the control unit 56 is switched to the flushing mode in order to cause the drive signal generating circuit 58 to generate the ejection capability recovery drive signal COM2, and in this flushing mode, as described above. In addition, by repeatedly applying the ejection drive pulse DP (DP2, DP3) to the piezoelectric vibrator 30 with the recording head 3 facing the capping member 12, ink is discarded from the nozzle opening 35 with respect to the cap member 12. Strike.

  FIG. 6 is a schematic diagram for explaining the meniscus vibration that occurs when the ejection drive pulse DP2 is independently applied to the piezoelectric vibrator 30 from the ejection capacity recovery drive signal COM2 and ink is ejected from the nozzle openings 35. FIG. . 6, the horizontal axis indicates time t [μs], and the vertical axis indicates that the position of the free surface (meniscus) of the ink in the nozzle opening 35 is positive from the pressure chamber 38 side toward the ejection side. It is shown as follows. Further, the origin of the coordinate axis is a time point corresponding to the start end of the expansion element p1 of the ejection drive pulse DP2, and is a timing at which the driving of the piezoelectric vibrator 30 is started by the ejection drive pulse DP2, and a time point indicated by a symbol A. This is a time corresponding to the vicinity of the end of the expansion maintaining element p2 of the ejection drive pulse DP2, and is a time when the pressure chamber 38 expands to the maximum volume corresponding to the maximum potential VH and ink ejection is started. Furthermore, the time indicated by the symbol Mm1 is the time corresponding to the vicinity of the end of the contraction maintaining element p4 of the ejection drive pulse DP2.

  Here, when the printer 1 according to the present invention is switched from the normal printing mode to the flushing mode, the first ejection capacity recovery process (first flushing) and the second ejection capacity recovery process (second flushing) are sequentially performed. Is configured to run. In these flushing, the structure of the drive signal for recovering the injection capacity to be used is different. In the first flushing, the first injection capacity recovery drive signal COM2a is used, and in the second flushing, the second injection is performed. The ability recovery drive signal COM2b is used. The difference in configuration of these drive signals will be described later. That is, in the flushing in the present embodiment, one set of applying the ejection drive pulse DP for a predetermined shot (for example, 10 shots) to the piezoelectric vibrator 30 using the first ejection capacity recovery drive signal COM2a, By performing this for a predetermined set (for example, 5 sets), a first flushing period in which the first flushing is performed by performing this, and then a predetermined shot (for example, 100 shots) using the second injection capacity recovery drive signal COM2b Including a second flushing period in which the second flushing is executed by performing a predetermined set (for example, 10 sets) of applying the ejection drive pulse DP of the minute to the piezoelectric vibrator 30 as a set. It is.

FIG. 7 is a flowchart for explaining the flow of flushing.
Specifically, first, when it is determined that flushing is necessary during recording processing (image mode) of a recording medium such as the recording paper 7 (in the printing mode) (S1). (S2: YES), the printing mode is switched to the flushing mode, and the first flushing is executed using the first ejection capability recovery drive signal COM2a (S3). Then, after the first flushing is executed, the second flushing is executed using the second ejection capacity recovery drive signal COM2b (S4). If it is not determined that flushing is necessary (S2: NO), the printing mode is continuously set.

  Here, the second ejection capacity recovery drive signal COM2b in the second flushing is a maximum point MX1 (main) of residual vibration generated by applying the preceding ejection drive pulse DP2 that is generated first to the piezoelectric vibrator 30. This corresponds to the apex of the residual vibration in the invention.) The preceding injection drive pulse DP2 and the subsequent injection drive pulse are applied so that the start end tb of the expansion element p1 of the subsequent injection drive pulse DP3 is applied to the piezoelectric vibrator 30 at a timing deviated from the peak. An interval ph with respect to DP3 is set. More specifically, the timing at which the subsequent drive pulse DP3 is applied to the piezoelectric vibrator 30 is farther from the maximum point of the residual vibration due to the preceding injection drive pulse DP2 than in the case of the first injection capability recovery drive signal COM2a. In this manner, the interval between the preceding injection driving pulse DP2 and the subsequent injection driving pulse DP3 in the second injection capacity recovery driving signal COM2b is set. In one flushing segment, the ejection drive pulse DP3 of the second ejection capacity recovery drive signal COM2b generated earlier and the ejection drive of the second ejection capacity recovery drive signal COM2b generated next. The interval with the pulse DP2 is set similarly. In this case, the injection drive pulse DP3 of the second injection capability recovery drive signal COM2b generated first is the preceding injection drive pulse, and the injection drive pulse DP2 of the second injection capability recovery drive signal COM2b generated next. Corresponds to the subsequent injection driving pulse.

  In contrast, the first ejection capacity recovery drive signal COM2a in the first flushing is performed when the timing at which the subsequent ejection drive pulse DP3 is applied to the piezoelectric vibrator 30 is the second ejection capacity recovery drive signal COM2b. Further, the distance ph between the preceding injection driving pulse DP2 and the subsequent injection driving pulse DP3 is set so as to be closer to the maximum point MX1 of the residual vibration due to the preceding injection driving pulse DP2. Note that the interval between the first ejection capacity recovery drive signal DP2a of the first ejection capacity recovery drive signal COM2a and the next ejection path driving pulse DP2 of the first ejection capacity recovery drive signal COM2a, It is set similarly. In this case, the injection drive pulse DP3 of the first injection capability recovery drive signal COM2a generated first is the preceding injection drive pulse, and the injection drive pulse DP2 of the second injection capability recovery drive signal COM2b generated next. Corresponds to the subsequent injection driving pulse.

  That is, in the first flushing according to the present invention, the meniscus is moved to the pressure chamber 38 side according to the pressure vibration of the vibration cycle Tc generated in the ink in the pressure chamber 38 by applying the preceding ejection drive pulse DP2 to the piezoelectric vibrator 30. The subsequent ejection drive pulse DP3 is applied to the piezoelectric vibrator 30 while moving from the nozzle opening 35 to the outside of the nozzle opening 35, that is, the ejection side. Accordingly, the reaction of the meniscus drawn into the pressure chamber 38 returning to the original position and the pressure fluctuation caused by the subsequent ejection drive pulse DP3 can be resonated (synthesized), and the ink ejection pressure is increased to increase the viscosity. As a result, it is possible to easily eject the ink that has become difficult to swing and the air bubbles mixed in the ink from the nozzle opening 35. As a result, it is possible to more effectively recover the jetting ability of the recording head 3 that has been lowered due to the increased viscosity of the ink. In addition, since the jetting capacity can be recovered in a shorter time, the time required for flushing can be shortened. Further, in the past, when the above-mentioned standing time exceeded, for example, one month, it was difficult to recover the jetting ability even when flushing was performed, whereas in the printer according to the present invention, the thickened ink in flushing was difficult to recover. Since the discharge effect is higher than before, it is possible to further extend the time that can be left.

In the second flushing, after the ink thickened near the meniscus is ejected by the first flushing, the flushing is performed using the second ejection capability recovery drive signal COM2b. In the second flushing, it is possible to discharge the thickened ink while stabilizing the meniscus by suppressing the pressure fluctuation as compared with the first flushing.
As a result, in the initial stage of flushing, ink can be ejected with a higher pressure fluctuation and the thickened ink can be discharged more effectively.In the latter stage of flushing, the pressure fluctuation during ejection is more than in the initial stage. Can be kept low and the stability of the meniscus can be ensured. As a result, the meniscus vibration can be converged as quickly as possible and the recording process on the recording paper 7 can be shifted promptly while enhancing the effect of restoring the jetting ability. Further, since it is possible to perform flushing using a drive pulse used for recording an image or the like without changing the waveform, it is not necessary to separately provide a drive pulse dedicated to flushing.

  Regarding the timing at which the subsequent ejection drive vibration DP3 in the first flushing is applied to the piezoelectric vibrator 30, the maximum point MX1 of the residual vibration generated by applying the preceding ejection drive pulse DP2 to the piezoelectric vibrator 30 is -0. It is desirable to set in the range of 2 Tc to +0.2 Tc. In this case, the meniscus in the nozzle opening 35 moves deeper toward the pressure chamber 38 from the state where it has been drawn deeper into the pressure chamber 38 according to the pressure vibration generated by applying the preceding ejection drive pulse DP2 to the piezoelectric vibrator 30. At the timing, the subsequent ejection drive pulse DP3 is applied to the piezoelectric vibrator 30. As a result, the ink ejection pressure can be increased by resonating (synthesizing) the reaction of the meniscus drawn back to the pressure chamber 38 to return to the original position and the pressure fluctuation caused by the subsequent ejection drive vibration DP3. It is possible to easily eject the ink that has become sticky and does not easily swing from the nozzle opening 35.

The natural vibration period Tc is a value determined by the shape of the nozzle opening 35 and the pressure chamber 38, and the vibration period Tc of the ink in the pressure chamber 38 can be expressed by the following equation (1).
Tc = 2π√ [[(Mn × Ms) / (Mn + Ms)] × Cc] (1)
In the formula (A), Mn is an inertance at the nozzle opening 35, Ms is an inertance at the ink supply port 37 communicating with the pressure chamber 38, and Cc is a compliance of the pressure chamber 38 (volume change per unit pressure, degree of softness) Is shown.) In the above equation (1), inertance M indicates the ease of ink movement in the ink flow path, and is the mass of ink per unit cross-sectional area. Then, assuming that the density of the ink is ρ, the cross-sectional area of the surface orthogonal to the ink flow direction of the flow path is S, and the length of the flow path is L, the inertance M can be expressed by the following equation (2). it can.
Inertance M = (density ρ × length L) / cross-sectional area S (2)
Further, Tc is not limited to the above formula (2), and may be any vibration cycle that the pressure chamber 38 has.

By the way, the present invention is not limited to the above embodiment, and various modifications can be made based on the description of the scope of claims.
In the first embodiment, the control unit 56 may control the timing for switching from the first flushing to the second flushing according to the ink leaving time counted by the timer circuit 60. That is, the control unit 56 in the present invention functions as a switching control unit. Specifically, the longer the leaving time measured by the timer circuit 60, the slower the timing of switching from the first flushing to the second flushing, while the shorter the ink leaving time measured by the timer circuit 60, The timing for switching from the first flushing to the second flushing may be advanced. As a result, it is possible to achieve both recovery of the jetting ability and suppression of ink consumption. That is, the longer the time during which ink is not ejected, the higher the possibility that the viscosity of the ink is higher. Therefore, the thickened ink can be discharged more reliably by executing the first flushing longer. On the other hand, the shorter the time during which ink is not ejected, the higher the possibility that the viscosity of the ink is relatively low. Therefore, the first flushing execution time is shortened and the process proceeds to the second flushing at an early stage. Consumption can be suppressed. Therefore, it is possible to perform flushing without excess or deficiency according to the viscosity of the ink.

FIG. 8 is a table showing the difference in each flushing period in the second embodiment.
The printer 1 according to the second embodiment performs the third flushing after the first flushing is performed and before the second flushing is performed (corresponding to the third ejection capability recovery process in the present invention). The point which is comprised so that may be performed differs from the said 1st Embodiment. The ejection capability recovery drive signal COM2c generated by the drive signal generation circuit 58 in the third flushing is farther from the maximum point MX1 of the residual vibration due to the preceding ejection drive pulse DP2 than in the first flushing, and the second The interval between the preceding injection driving pulse DP2 and the subsequent injection driving pulse DP3 is set so as to be closer to the maximum point MX1 of the residual vibration due to the preceding injection driving pulse DP2 than in the case of the flushing (for example, 1.3 Tc). That is, in the flushing (injection capacity recovery process) in the second embodiment, the first flushing period in which the first injection capacity recovery process is executed and the second flushing period in which the second injection capacity recovery process is executed. During this period, there is a third flushing period in which the ejection capacity recovery drive signal COM2c for a predetermined shot (for example, 100 shots) is applied to the piezoelectric vibrator 30 for a predetermined set (for example, 5 sets) and the third flushing is performed. It may be included. With this configuration, it is possible to execute the ejection capability recovery process using the ejection capability recovery drive signal corresponding to the ink viscosity.

  In each of the above embodiments, the viscosity is 10 to 30 millipascals and is higher than that of conventional inks, such as a photocurable ink that is cured by irradiation with light energy such as ultraviolet rays. This is suitable when ink (high viscosity liquid) is ejected or when natural thickening of the ink is promoted. In this case, the ink is less likely to oscillate due to pressure fluctuations than the low-viscosity ink such as the conventional water-based ink, and when performing flushing for this high-viscosity ink, the conventional water-based ink However, if the flushing is performed using the ejection recovery drive signal COM2, the pressure chamber 38 is expanded by the preceding ejection drive pulse DP2. The reaction that contracts later and the pressure fluctuation of the subsequent ejection drive pulse DP3 can be resonated (combined), and the liquid ejection pressure can be increased to facilitate the ejection of the thickened ink from the nozzle openings 35.

  Moreover, in the said embodiment, although the injection drive pulse DP shown in FIG. 4, FIG. 5 was mentioned as an example of the injection drive pulse DP in this invention, the shape of a pulse is not restricted to what was illustrated, In 2nd flushing The ejection capacity recovery drive signal COM2b is expanded at the timing deviated from the maximum point MX1 of the residual vibration generated by applying the preceding ejection drive pulse DP2 generated earlier to the piezoelectric vibrator 30. An interval (indicated by reference numeral ph in FIG. 6) between the preceding injection driving pulse DP2 and the subsequent injection driving pulse DP3 is set so that the starting end tb of the element p1 is applied to the piezoelectric vibrator 30. The ejection capacity recovery drive signal COM2a in the flushing of the second flushing timing is the timing at which the subsequent ejection drive pulse DP3 is applied to the piezoelectric vibrator 30. As long as the interval ph between the preceding injection driving pulse DP2 and the subsequent injection driving pulse DP3 is set so as to be closer to the maximum point MX1 of the residual vibration due to the preceding injection driving pulse DP2 than in the case of Sing, it has an arbitrary waveform Can be used. For example, the ejection capacity recovery drive signal COM2 may include three or more ejection drive pulses DP, and in this case, the interval between adjacent pulses is set in the same manner as in each exemplary embodiment. The number of flashing segments can be set to an arbitrary value.

  In the above-described embodiment, the so-called longitudinal vibration mode piezoelectric vibrator 30 is exemplified as the pressure generating element, but the pressure generating element is not limited thereto. For example, the present invention can also be applied when using a so-called flexural vibration mode piezoelectric vibrator or heating element. When this flexural vibration mode piezoelectric vibrator is employed, the waveform of the ejection drive pulse DP shown in FIGS. 4 and 5 is inverted upside down.

  The present invention is not limited to a printer as long as it is a liquid ejecting apparatus that can perform ejection control using a plurality of drive signals, and other than various ink jet recording apparatuses such as a plotter, a facsimile machine, a copying machine, and a recording apparatus. The present invention can also be applied to a liquid ejecting apparatus such as a display manufacturing apparatus, an electrode manufacturing apparatus, and a chip manufacturing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 3 ... Recording head, 7 ... Recording paper, 12 ... Capping member, 30 ... Piezoelectric vibrator, 35 ... Nozzle opening, 38 ... Pressure chamber, 56 ... Control part, 58 ... Drive signal generation circuit, 60 ... Timer circuit

Claims (8)

A liquid ejecting head that applies pressure fluctuation to the pressure chamber by the operation of the pressure generating means, and ejects the liquid filled in the pressure chamber from the nozzle;
A drive signal generating unit capable of generating a drive signal including a drive pulse whose main purpose is to drive the pressure generating unit to eject liquid from the nozzle toward the ejection medium. There,
An ejection capability recovery mode is performed in which the liquid is ejected from a plurality of drive modes for driving the pressure generating means toward an area other than the ejection target medium to perform an ejection capability recovery process for the purpose of restoring the ejection capability. When set, the drive signal generating means generates an ejection capability recovery drive signal including a plurality of the drive pulses,
In the injection capacity recovery process, the second injection capacity recovery process is executed after at least the first injection capacity recovery process is executed,
The drive signal for recovering the injection capability in the second injection capability recovery process is the timing at which the preceding drive is deviated from the apex of the residual vibration generated by applying the preceding drive pulse generated previously to the pressure generating means. An interval between the preceding drive pulse and the subsequent drive pulse is set so that a subsequent drive pulse generated next to the pulse is applied to the pressure generating unit.
The drive signal for recovery of the injection capacity in the first injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. An interval between the preceding drive pulse and the subsequent drive pulse is set so as to be close to the apex of the liquid ejecting apparatus.   The timing at which the subsequent drive pulse in the first injection capacity recovery process is applied to the pressure generating means is from -0.2 Tc to +0 from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating means. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is set in a range of .2Tc. Time measuring means for measuring the time during which the liquid ejecting head is not continuously ejecting the liquid;
2. A switching control means for controlling timing for switching from the first injection capacity recovery process to the second injection capacity recovery process according to the time measured by the time measuring means. Alternatively, the liquid ejecting apparatus according to claim 2.   The switching control means delays the timing of switching from the first injection capacity recovery process to the second injection capacity recovery process as the time measured by the time measuring means is longer, while being timed by the time measuring means. The liquid ejecting apparatus according to claim 3, wherein the timing for switching from the first ejection capacity recovery process to the second ejection capacity recovery process is advanced as the time is shorter. In the injection ability recovery process executed by the drive signal generating means, the third injection ability recovery process is performed after the first injection ability recovery process is executed and before the second injection ability recovery process is executed. Executed,
The drive signal for recovering the injection capacity in the third injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse as compared with the case of the first injection capacity recovery process. The interval between the preceding drive pulse and the subsequent drive pulse is set so as to be far from the top of the nozzle and further closer to the vertex of the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.   The liquid ejecting apparatus according to claim 1, wherein the liquid has a viscosity of 10 millipascal seconds or more and 30 millipascal seconds or less. The pressure generating means causes a pressure variation in the pressure chamber, and a liquid ejecting head for ejecting the liquid filled in the pressure chamber from the nozzle, and the pressure generating means to drive the liquid from the nozzle toward the ejected medium. And a drive signal generating means capable of generating a drive signal including a drive pulse whose main purpose is to inject the liquid,
An ejection capability recovery mode is performed in which the liquid is ejected from a plurality of drive modes for driving the pressure generating means toward an area other than the ejection target medium to perform an ejection capability recovery process for the purpose of restoring the ejection capability. When set, the drive signal generating means generates a drive signal for recovering the injection capability including a plurality of the drive pulses. In the injection capability recovery process, the second is performed after at least the first injection capability recovery process is executed. The injection capacity recovery process of
The drive signal for recovering the injection capability in the second injection capability recovery process is the timing at which the preceding drive is deviated from the apex of the residual vibration generated by applying the preceding drive pulse generated previously to the pressure generating means. An interval between the preceding drive pulse and the subsequent drive pulse is set so that a subsequent drive pulse generated next to the pulse is applied to the pressure generating unit.
The drive signal for recovery of the injection capacity in the first injection capacity recovery process is such that the timing at which the subsequent drive pulse is applied to the pressure generating means is the residual vibration due to the preceding drive pulse than in the case of the second injection capacity recovery process. A method for controlling a liquid ejecting apparatus, wherein an interval between the preceding drive pulse and the subsequent drive pulse is set so as to be close to a vertex of the liquid crystal.   The timing at which the subsequent drive pulse in the first injection capacity recovery process is applied to the pressure generating means is from -0.2 Tc to +0 from the top of the residual vibration generated by applying the preceding drive pulse to the pressure generating means. The method for controlling a liquid ejecting apparatus according to claim 7, wherein the control method is set in a range of .2Tc.

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