JP2017177333A - Liquid discharge device, liquid discharge method in the same, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device capable of suppressing unevenness in discharge among a plurality of head units when a part of the plurality of head units is replaced with another head unit, and a liquid discharge method in the liquid discharge device and a program.SOLUTION: A liquid discharge device has an aging processing section for performing aging processing with respect to a third head unit when the third head unit is attached to the liquid discharge device in lieu of a first head unit after liquid is discharged from a plurality of head units including first and second head units having functions for discharging the liquid. Each head unit comprises: a piezoelectric element; one electrode electrically connected to one end of the piezoelectric element; and the other electrode electrically connected to the other end of the piezoelectric element. The aging processing section supplies a driving signal COM as a first voltage to one electrode of the third head unit, and supplies an aging voltage Vag as a second voltage having polarity different from that of the first voltage to the other electrode.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a liquid ejecting apparatus including an ejecting unit capable of ejecting liquid onto an object such as a relatively moving sheet, a liquid ejecting method in the liquid ejecting apparatus, and a program.

  2. Description of the Related Art Conventionally, as a liquid ejecting apparatus that ejects liquid onto a medium such as paper, an ink jet printer that performs printing on a medium such as paper by ejecting ink as an example of liquid from a nozzle of a head unit is widely known. Yes. The head unit is provided with an ejection portion having a piezoelectric element for each nozzle, and ink droplets are ejected from the nozzle by the ejection pressure generated in the ink chamber by driving the piezoelectric element (for example, Patent Document 1).

  In this type of ink jet printer, a drive signal generation circuit capable of generating a drive signal supplied to the piezoelectric element is provided, and ink droplets are formed in an appropriate size according to the magnitude of the drive signal supplied to the piezoelectric element. Discharged.

  For example, the liquid ejecting apparatus described in Patent Document 1 includes a plurality of head units (heads), and the drive voltage based on the number of ink ejections even when the number of ink ejections increases and the piezoelectric element (piezoelectric actuator) deteriorates. A technique for suppressing the deterioration of image quality by determining the size of the image is disclosed (Patent Document 1, etc.).

JP 2009-184291 A

  Incidentally, in the liquid ejection device described in Patent Document 1, it is necessary to read the ejection number for each head unit before printing. Since it is necessary to correct the drive waveform supplied to the piezoelectric element for each head unit according to the number of ink ejections, the control is complicated, and in the case of a liquid ejection apparatus equipped with a large number of head units, The management of the number of ink ejections and the correction process of the drive signal for each head unit become complicated. It should be noted that this type of problem is generally common to any liquid ejecting apparatus configured to eject a liquid from a nozzle by driving a piezoelectric element, regardless of a printing method such as a serial printer or a line printer.

  An object of the present invention is to provide a liquid ejecting apparatus, a liquid ejecting method in the liquid ejecting apparatus, and a program capable of minimizing variation in ejection between the head units when a part of the plurality of head units is replaced with another head unit. Is to provide.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A liquid ejection apparatus that solves the above problems includes a plurality of head units including a first head unit having a function of ejecting a liquid and a second head unit having a function of ejecting the liquid, and the first head unit. And an aging processing unit that performs an aging process on the third head unit when the third head unit is attached instead of the first head unit after the liquid is discharged from the second head unit. And the first, second and third head units are electrically connected to the piezoelectric element, one electrode electrically connected to one end of the piezoelectric element, and the other end of the piezoelectric element. And the aging treatment unit supplies a first voltage to the one electrode of the third head unit, and the aging processing unit supplies the first voltage to the other electrode. Implementing the aging process by supplying one of the voltage and polarity different second voltage. The first head unit refers to a head unit to be removed among a plurality of head units. The second head unit refers to a head unit that is continuously used before and after the removal of the first head unit among the plurality of head units. The third head unit refers to a head unit attached to the liquid ejection device in place of the removed first head unit.

  According to this configuration, the liquid ejection device ejects liquid from a plurality of head units including the first head unit and the second head unit. For example, among the plurality of head units, the first head unit is removed for reasons of failure, life or maintenance, and the third head unit is attached to the liquid ejection device instead. When the third head unit is attached, the aging processing unit supplies a first voltage to one electrode electrically connected to one end of the piezoelectric element of the third head unit, and the other end of the piezoelectric element The aging process is performed by supplying a second voltage having a polarity different from that of the first voltage to the other electrically connected electrode. Accordingly, the aging process can be performed on the piezoelectric elements of the third head unit to stabilize the ejection characteristics of the piezoelectric elements. Therefore, in the liquid ejection apparatus after the third head unit is attached, the variation in ejection characteristics between the head units is reduced. Can be suppressed.

  In the liquid ejection apparatus, it is preferable that the aging processing unit performs the aging process for aligning the ejection characteristics of the third head unit with the ejection characteristics of the second head unit.

  Note that “alignment” is not limited to strictly matching the two ejection characteristics, but includes cases where the two ejection characteristics are simply brought close to each other so that variations in the quality of the liquid ejection processing are within an allowable range. It is.

  According to this configuration, when the aging processing unit performs the aging process on the third head unit, the ejection characteristics of the third head unit are aligned with the ejection characteristics of the second head unit. For this reason, in the liquid ejection apparatus after the replacement from the first head unit to the third head unit, it is possible to suppress variations in ejection characteristics between the head units.

  The liquid ejection apparatus includes a storage unit that stores liquid ejection history information of the second head unit, and the aging processing unit has a size based on the liquid ejection history information stored in the storage unit. It is preferable to implement.

  According to this configuration, the aging processing unit performs the aging process with a size (processing intensity) based on the liquid ejection history information stored in the storage unit. For this reason, it is possible to suppress variations in ejection characteristics among a plurality of head units. Here, the magnitude of the aging process includes the length of the aging process time, the number of times of the aging process, the magnitude (strength) of the supply voltage during the aging process, a combination thereof, and the like.

  In the liquid ejecting apparatus, at least one of the one electrode and the other electrode of the piezoelectric element constituting the head unit by a liquid ejecting process for ejecting liquid from the plurality of head units and the aging process. A switching circuit for switching a voltage to be supplied to one side, and the aging processing unit switches the switching circuit to supply the first voltage to the one electrode of the piezoelectric element constituting the third head unit, The second voltage is preferably supplied to the other electrode.

  According to this configuration, when the aging process is performed, the voltage supplied to one electrode of the piezoelectric element constituting the third head unit and the voltage supplied to the other electrode are switched by switching the switching circuit. Are switched with respect to the value at the time of the liquid discharge process. Thereby, when an aging process is performed, a 1st voltage can be supplied to one electrode of the piezoelectric element which comprises a 3rd head unit, and a 2nd voltage can be supplied to the other electrode.

  In the liquid ejection device, the voltage supplied to the other electrode is a constant voltage, and the switching circuit can supply different constant voltages to the other electrode in the liquid ejection process and the aging process. The aging processing unit supplies the second voltage to the other electrode electrically connected to the other end of the piezoelectric element constituting the third head unit by switching the switching circuit. It is preferable to do.

  According to this configuration, the aging processing unit switches the switching circuit to switch the constant voltage supplied to the other electrode electrically connected to the other end of the piezoelectric element of the third head unit to the second voltage. Thus, the voltage during the aging process is supplied to the piezoelectric element. Therefore, the aging process for the third head unit can be completed in a relatively short time.

  In the liquid ejecting apparatus, the aging processing unit may be configured such that the first voltage is greater than a voltage difference between a voltage supplied to the one electrode and a voltage supplied to the other electrode during the liquid ejecting process. It is preferable to increase the voltage difference between the second voltage and the second voltage.

  According to this configuration, the aging processing unit has a voltage difference (potential difference) between a voltage (potential) supplied to one electrode and a voltage (potential) supplied to the other electrode during the liquid discharge process, The voltage difference between the first voltage and the second voltage is increased. Therefore, the aging process for the third head unit can be completed in a relatively short time.

  The liquid ejecting apparatus further includes a liquid filling unit that fills the third head unit with a liquid, and the aging processing unit fills the third head unit with a liquid. Before performing, the aging process is performed on the third head unit.

  According to this configuration, the aging process is performed on the third head unit before the liquid is filled in the third head unit. For this reason, it is not necessary to limit the first voltage to a value in a range where liquid is not discharged. Therefore, when the first voltage is set to a value at which, for example, liquid can be ejected, a faster aging process can be realized as compared with a configuration in which the aging process is performed after filling the liquid.

  The liquid ejection apparatus may further include a liquid filling unit that fills the third head unit with a liquid, and the aging processing unit fills the third head unit with the liquid. After that, it is preferable to perform the aging process on the third head unit.

  According to this configuration, the aging process is performed on the third head unit after the third head unit is filled with the liquid. For this reason, even if the piezoelectric element generates heat during the aging process, the filled liquid has a cooling effect, so that it is not necessary to limit the first voltage to a value within a range in which the liquid is not discharged. For this reason, the first voltage can be set to a relatively large value. When the first voltage is set to a value at which liquid can be ejected, for example, a faster aging process can be realized as compared with the configuration in which the aging process is performed before filling the liquid.

  In the liquid ejecting apparatus, it is preferable that the first voltage supplied to the one electrode by the aging processing unit is a voltage value that does not cause the third head unit to eject liquid.

  According to this configuration, the first voltage that the aging processing unit supplies to one electrode of the third head unit is a voltage that does not cause the third head unit to discharge the liquid. Therefore, during the aging process after filling the liquid, A situation in which liquid is unnecessarily discharged from the three head units can be avoided.

  A liquid ejection apparatus that solves the above problems includes a plurality of head units including a first head unit having a function of ejecting a liquid and a second head unit having a function of ejecting the liquid, and the first head unit. And an aging processing unit that performs an aging process on the third head unit when the third head unit is attached instead of the first head unit after the liquid is discharged from the second head unit. And the first, second and third head units are electrically connected to the piezoelectric element, one electrode electrically connected to one end of the piezoelectric element, and the other end of the piezoelectric element. And the aging treatment unit supplies a voltage to be supplied to at least one of the one electrode and the other electrode of the third head unit. Switching to a value different from the voltage supplied during the liquid discharge process, the maximum voltage supplied to the piezoelectric element between the one electrode and the other electrode is larger than the maximum voltage during the liquid discharge process A liquid discharge apparatus characterized by switching to

  According to this configuration, the voltage supplied to at least one of the one electrode and the other electrode of the third head unit is switched to a value different from the voltage supplied during the liquid ejection process by the aging processing unit, The maximum voltage supplied to the piezoelectric element between one electrode and the other electrode is switched to a value larger than the maximum voltage during the liquid discharge process. As a result, during the aging process, a maximum voltage larger than the maximum voltage supplied during the liquid ejection process is supplied to the piezoelectric element. Therefore, high-speed aging processing can be performed on the piezoelectric element of the third head unit.

  A liquid discharge method in a liquid discharge apparatus that solves the above-described problem, wherein the liquid discharge apparatus includes a first head unit having a function of discharging a liquid and a second head unit having a function of discharging the liquid. A plurality of head units, and after the liquid is discharged from the first head unit and the second head unit, the first head unit is removed and a third head unit is attached. A first voltage is supplied to one electrode electrically connected to one end of the piezoelectric element constituting the head unit, and the other electrode electrically connected to the other end of the piezoelectric element is An aging process step of performing an aging process on the third head unit by supplying a second voltage having a polarity different from that of the first voltage; And a liquid ejection process step for discharging liquid by a plurality of head units including said second head unit after managing treatment and the third head unit. According to this method, it is possible to obtain the same effect as that of the liquid ejecting apparatus.

  A program that is executed by a computer provided in a liquid ejection apparatus that solves the above-described problem, wherein the liquid ejection apparatus includes a first head unit that has a function of ejecting liquid and a second head that has a function of ejecting the liquid. A plurality of head units including a unit, and after the liquid is discharged from the first head unit and the second head unit to the computer, the first head unit is removed, and a third head unit is When attached, the first voltage is supplied to one electrode electrically connected to one end of the piezoelectric element constituting the third head unit, and the other voltage is electrically connected to the other end of the piezoelectric element. By supplying a second voltage having a polarity different from that of the first voltage to the other electrode. And aging treatment step of performing ring processing, to perform the liquid ejection processing step of discharging liquid by a plurality of head units including said second head unit after the aging treatment and the third head unit. According to this program, it is possible to obtain the same effects as those of the liquid ejecting apparatus.

1 is a schematic plan view illustrating a schematic configuration of a printer according to an embodiment. 1 is a block diagram showing an electrical configuration of a printing system. The model bottom view which shows a head unit. The schematic side sectional view which shows a discharge part. FIG. 3 is a block diagram showing an electrical configuration of a head controller and a head unit. The graph which shows a drive signal and various signals. FIG. 3 is a block diagram showing an electrical configuration of the head unit. The schematic diagram explaining replacement | exchange of the head unit in a discharge unit. The graph which shows the discharge characteristic of a head unit. Graph showing reference data. The signal waveform diagram explaining a printing process and an aging process. The flowchart which shows an aging process routine. The flowchart which shows the aging process routine in 2nd Embodiment. The signal waveform diagram explaining a printing process and an aging process. The signal waveform diagram explaining the printing process and aging process in a modification. FIG. 3 is a block diagram showing an electrical configuration of a head controller and a head unit.

Hereinafter, an embodiment of a liquid ejection apparatus will be described with reference to the drawings.
As shown in FIG. 1, a printer 11 as an example of a liquid ejection apparatus is an ink jet line printer. The printer 11 includes a transport device 12 that transports a medium P such as paper, and an ejection unit 15 that ejects ink droplets onto the medium P transported in the transport direction Y by the transport device 12 to print an image, a document, or the like. .

  The transport device 12 is wound around a transport motor 20 serving as a power source, a pair of transport rollers 21 and 22 and an idle roller 23 arranged at a predetermined distance in the transport direction Y, and these rollers 21 to 23. An endless transport belt 24 and a feed roller 25 for feeding the medium P onto the transport belt 24 are provided. The transport motor 20 is connected to the transport roller 21 so as to be able to transmit power. When the transport motor 20 is driven, the medium P on the transport belt 24 moves at a constant speed in the transport direction Y with respect to the discharge unit 15. Be transported.

  The discharge unit 15 is disposed at a position at a substantially central position in the transport direction Y of the transport belt 24 with a predetermined gap from the belt surface upward (front side in the direction orthogonal to the paper surface in FIG. 1). The discharge unit 15 extends over a range slightly wider than the assumed maximum width of the medium P along the width direction X intersecting (particularly orthogonal) with the transport direction Y of the transport belt 24. The discharge unit 15 can print on the medium P having a width up to the assumed maximum width during conveyance at a constant speed.

  As shown in FIG. 1, the printer 11 is provided with an encoder 28 having a function of detecting the conveyance speed of the conveyance belt 24. The encoder 28 has a scale portion 28A composed of a plurality of detected portions arranged at a constant pitch along the side edge portion of the conveyor belt 24, and a sensor 28B that detects the detected portions of the scale portion 28A. The encoder 28 may be a rotary encoder that detects the rotation of the transport motor 20 or the rotation of a power transmission system member such as the transport roller 21.

  Next, the configuration of the printing system including the printer 11 will be described with reference to FIG. As shown in FIG. 2, the printing system 90 includes a printer 11 and a host device 100 connected to the printer 11 so as to be communicable. The host device 100 is composed of a personal computer, for example, and includes a main body 101, a monitor 102, and an input device 103. A printer driver 105 is built in the main body 101. The printer driver 105 generates print data PD that can be interpreted by the printer 11 from image data selected as a print target by the user operating the input device 103.

  Specifically, the printer driver 105 performs known processing such as resolution conversion processing, color conversion processing, halftone processing, and rasterization processing on the image data to be printed to generate print image data. Further, the printer driver 105 attaches a header including various commands necessary for print control to the print image data, generates print data PD, and transmits the print data PD to the printer 11. The printer 11 prints an image or the like based on the print data PD received from the host device 100.

  The printer 11 illustrated in FIG. 2 temporarily stores a control unit 30 that controls printing, a communication interface that can communicate with the host device 100 (hereinafter referred to as “communication I / F 31”), and print data PD received from the host device 100. The storage unit 32, the above-described transport device 12, the discharge unit 15, and the discharge control unit 33 that controls the discharge unit 15 are provided. The control unit 30 is electrically connected to a transport motor 20, which is a power source of the transport device 12, an encoder 28, a discharge control unit 33 that controls the discharge unit 15, and the like.

  As shown in FIG. 2, the discharge unit 15 includes a plurality (n (where n is a natural number of 2 or more)) of head units 16 in a predetermined arrangement pattern that can be printed over the entire width of the medium P having the assumed maximum width. This is a so-called multi-head type in which (discharge heads) are arranged. As an example, the n head units 16 are arranged in a zigzag manner in which two rows of head units 16 are shifted by a half pitch in the row direction. Further, the encoder 28 outputs an encoder pulse signal ES including pulses having a number proportional to the transport distance of the medium P (or the transport belt 24) with respect to the discharge unit 15 and a cycle inversely proportional to the transport speed of the medium P.

  As shown in FIG. 2, the discharge controller 33 distributes the print image data in the print data PD to a plurality of print image data DI, and further distributes the print image data DI to a plurality of print image data ND. And a plurality of head controllers 36 for controlling each head unit 16 based on each print image data ND. The storage unit 32 includes a RAM and a nonvolatile memory, and various data such as print data PD and print image data DI and ND are temporarily stored in the RAM, and various programs are stored in the nonvolatile memory. Is remembered.

  For example, the same number (n) of head controllers 36 as the head units 16 are connected to the data controller 35 shown in FIG. A corresponding head unit 16 is connected to each head controller 36 one by one. In this example, the head controller 36 individually controls the corresponding head unit 16. A configuration in which one head controller 36 controls a plurality of head units 16 may be employed. FIG. 2 shows an example in which the number of head units 16 constituting the discharge unit 15 is eight (n = 8), but a predetermined number in the range of 10 to 30 is actually provided. .

  The control unit 30 shown in FIG. 2 interprets the command in the print data PD, and drives and controls the transport motor 20 at a constant speed corresponding to the print mode instructed at that time. Further, the control unit 30 transmits the print image data in the print data PD to the head controller 36 via the distributor 34 and the data controller 35, and generates print data described later to the head controller 36 and the head unit of the print data. 16 is instructed. Further, the control unit 30 instructs the head controller 36 to generate a drive signal COM (see FIG. 6) to be applied to the piezoelectric element 42 and to transmit the drive signal COM to the head unit 16. As described above, the head controller 36 transfers the print control data SIn and the drive signal COM (see FIGS. 5 and 6) necessary for print control to the head unit 16 to the head unit 16 in accordance with instructions from the control unit 30.

  As shown in FIGS. 2 and 3, the nozzle opening surface 16a (bottom surface) of the head unit 16 has m rows (where m is a natural number of 2 or more) of nozzle rows N1, N2,. In the example, m = 4 and N1 to N4) are provided. The plurality of head units 16 are arranged in a zigzag manner in a direction in which the nozzle row direction intersects the transport direction Y, so that the same type (for example, the same ink color) of nozzle rows is arranged in the nozzle row direction (FIG. 2). In the vertical direction). For this reason, the printer 11 can print the full width on the medium P having the assumed maximum width by using the same kind of nozzle row of each head unit 16.

  As shown in FIG. 3, m rows (four rows in FIG. 3) of nozzle rows N <b> 1 to Nm provided on the nozzle opening surface 16 a (bottom surface) of the head unit 16 are nozzle rows that intersect the transport direction Y of the medium P. Each of the nozzles is composed of F nozzles # 1 to #F arranged in a line at a constant nozzle pitch in the direction. The number F of nozzles 17a per nozzle row is a predetermined value within a range of 100 to 500, for example. Further, the arrangement pattern of the nozzles # 1 to #F may be a zigzag shape in which two rows are shifted by a half pitch between the rows.

  In this example, the m nozzle rows N1 to Nm eject ink droplets of different colors or eject ink droplets of the same color. In the former case, in the example of m = 4 shown in the examples of FIGS. 2 and 3, the four nozzle rows N1 to N4 are black (K), cyan (C), magenta (M), and yellow (Y). Four colors of ink can be ejected from each nozzle 17a.

  In the latter case, the nozzles 17a of the m nozzle rows N1 to Nm of the same color are projected nozzles when projected onto the center line (virtual line) of the nozzle row N4 in a direction orthogonal to the nozzle row direction. The pitch is arranged to be 1 / m of the nozzle pitch of each nozzle row, thereby increasing the printing resolution. As another configuration for increasing the printing resolution by setting the pitch of the projection nozzle to 1 / m of the nozzle pitch, a configuration in which the head unit 16 is inclined and arranged in a posture in which the nozzle row obliquely intersects the transport direction Y is provided. Can be mentioned. In the case of this latter configuration, only one discharge unit 15 is shown in FIG. 2, but the same number (for example, four) of discharge units 15 as the number of colors (for example, four colors) are provided.

  In the head unit 16 shown in FIG. 3 according to the present embodiment, four unit head portions 17 each having a nozzle row are arranged on the surface of the head main body 16b on the nozzle opening surface 16a side. The plurality of unit head portions 17 are attached in a direction in which the nozzle rows N1 to Nm are arranged in parallel to each other with respect to the head main body 16b.

  As shown in FIG. 3, the unit head portion 17 includes a piezoelectric element group 41 in which piezoelectric elements 42 corresponding to the nozzles 17a are arranged in the same number as the number of nozzles for each nozzle row. However, in FIG. 3, only a part of the piezoelectric elements 42 corresponding to the nozzles 17 a are schematically illustrated outside the head unit 16. When a drive signal having a predetermined drive waveform is supplied (applied), the piezoelectric element 42 is displaced by electrostriction, and droplets are ejected from the nozzle 17a using the displaced force. As shown in FIG. 3, the unit head unit 17 includes a plurality (F) of ejection units 43 each having a nozzle 17a and a piezoelectric element 42, the same number as the nozzles 17a.

  Next, the configuration of the ejection unit 43 that ejects ink droplets from the nozzles 17a of the head unit 16 will be described with reference to FIG. In FIG. 4, one ejection unit 43 among the ejection units 43 provided in the same number as the plurality of nozzles 17 a in the head unit 16, a reservoir 182 communicating with one ejection unit 43 through the ink supply port 181, and an ink cartridge Alternatively, an ink supply channel 183 for supplying ink from an ink supply source (not shown) including an ink tank or the like to the reservoir 182 is shown. The reservoir 182 communicates in common with each cavity 174 (ink chamber) constituting the plurality of ejection units 43 and the ink supply port 181.

  As shown in FIG. 4, the ejection unit 43 includes a piezoelectric element 42, a cavity 174 filled with ink inside, a nozzle 17 a communicating with the cavity 174, and the cavity 174 and the piezoelectric element 42. And an intervening diaphragm 175. In the ejection unit 43, the piezoelectric element 42 is driven by applying a driving voltage based on the driving signal, and the ink in the cavity 174 is ejected from the nozzle 17a.

  The cavity 174 of the discharge unit 43 is a space defined by a cavity plate 176 formed into a predetermined shape having a recess, a nozzle plate 177 formed with a nozzle 17a, and a vibration plate 175. The cavity 174 communicates with the reservoir 182 through the ink supply port 181. The reservoir 182 communicates with one ink supply source (not shown) through the ink supply channel 183.

  In the present embodiment, a unimorph (monomorph) type as shown in FIG. An individual electrode 45, which is an example of one electrode, is electrically connected to one end of the piezoelectric element 42, and a common electrode 46, which is an example of the other electrode, is electrically connected to the other end of the piezoelectric element 42. . The individual electrode 45 is an electrode individually connected to one end of the plurality of piezoelectric elements 42, and the common electrode 46 is an electrode commonly connected to the other end of the plurality of piezoelectric elements 42. A predetermined reference voltage Vbs is supplied to the common electrode 46, and a drive signal COM (see FIG. 6) is supplied to the individual electrode 45, whereby a voltage is applied to the piezoelectric element 42 between the individual electrode 45 and the common electrode 46. Supplied (applied). In response to the supplied voltage, the piezoelectric element 42 bends and vibrates in the vertical direction in FIG.

  As shown in FIG. 4, the common electrode 46 is bonded to the surface on the opposite side of the cavity 174 side of the diaphragm 175 that closes the upper surface opening of the cavity plate 176. For this reason, when the piezoelectric element 42 is displaced by the electrostrictive action by supplying the drive signal COM, the diaphragm 175 vibrates. A part of the ink filled in the cavity 174 is ejected from the nozzle 17a in the process of decreasing the volume of the cavity 174 due to the vibration of the vibration plate 175. When ink in the cavity 174 decreases due to ink ejection, ink is supplied from the reservoir 182 to the cavity 174. Ink is supplied to the reservoir 182 from an ink supply source through an ink supply channel 183.

  Next, the electrical configuration of the printer 11 will be described with reference to FIG. Since the plurality of head controllers 36 have the same configuration, only one head controller 36 is shown in FIG. Further, since the plurality of head units 16 have the same configuration, only one head unit 16 is shown in FIG. Furthermore, in the head unit 16, since the piezoelectric element 42 and the head drive circuit 60 have the same configuration among a plurality of nozzle rows, only one nozzle row is shown.

  The control unit 30 illustrated in FIG. 5 is configured by a computer including an ASIC (Application Specific IC) including a CPU, for example, and an aging processing unit 38 including software configured by executing a program PR stored in the storage unit 32. Have The ejection characteristics of the head unit 16 are gradually stabilized according to the energization amount (the number of ejections or the ejection time) from the start of use until that time. When a part of the plurality of head units 16 is replaced with a new head unit 16, the aging processing unit 38 changes the ejection characteristics of the new head unit 16 to the other head units 16 that have not been replaced. In order to achieve the same discharge characteristics, an aging process for energizing a new head unit 16 is performed before printing is started. The storage unit 32 stores liquid discharge history information HD related to other head units 16 and reference data RD that is referred to when determining the aging time. The aging processing unit 38 is an aging time that is an execution time for performing the aging process with reference to the reference data RD (see also FIG. 10) based on the liquid ejection history information HD related to the other head unit 16 stored in the storage unit 32. Get Ta. The aging processing unit 38 includes a timer 39 that manages the aging time Ta, and ends the aging process when the time measured by the timer 39 that started measuring at the start of the aging process reaches the aging time Ta.

  As shown in FIG. 5, the head controller 36 includes a data processing circuit 51, a drive signal generation circuit 52, and a switching circuit 53. The head controller 36 receives the print control data SIn from the data processing circuit 51, the drive signal COM generated by the drive signal generation circuit 52, the latch signal LAT, the channel signal CH, and the ground voltage Vg from the switching circuit 53. Is transmitted through wiring such as a flat cable (not shown). The print control data SIn, the drive signal COM, the latch signal LAT, and the channel signal CH are input to the head drive circuit 60, and the ground voltage Vg is supplied to the common electrode 46 connected to the other end of the piezoelectric element 42. The ground voltage Vg can be switched between the reference voltage Vbs used during the printing process (printing operation) and the aging voltage Vag used during the aging process by the switching circuit 53.

  As shown in FIG. 5, the head unit 16 includes a head driving circuit 60 (only one nozzle row is shown in FIG. 5) for each piezoelectric element group 41 corresponding to the nozzle row. The head drive circuit 60 includes a switch circuit 66 including a plurality of analog switches 67 electrically connected to a plurality of individual electrodes 45 connected to one end of the plurality of piezoelectric elements 42.

  The data processing circuit 51 shown in FIG. 5 generates print control data SIn in a format that can be used by the head drive circuit 60 to control the piezoelectric element 42 based on the print image data ND for one nozzle row, and the encoder The print control data SIn is sequentially transferred to the head drive circuit 60 at the transfer timing based on the timing signal generated based on the pulse signal from the control signal 28. That is, the data processing circuit 51 outputs print control data SIn for one nozzle row to the head drive circuit 60 for each print cycle TA, which is a cycle in which the head unit 16 discharges one dot.

  The data processing circuit 51 includes a measurement unit 511. The measuring unit 511 has at least one of a counting function for counting the number of ejections corresponding to the number of dots based on the print image data ND composed of dot data, and a timing function for timing the ejection time. The measuring unit 511 counts the number of ejections of ink droplets ejected by the corresponding head unit 16 or the ejection time of ink droplets for each nozzle row or each head unit 16. The control unit 30 obtains at least one of the ejection number and the ejection time measured by the measurement unit 511 from the data processing circuit 51, and the obtained current measurement value is stored in the storage unit 32 until the previous time. The cumulative value of the measured value is added to obtain the current cumulative value, and the cumulative value of at least one of the current ejection number and the ejection time is written in the storage unit 32 as the liquid ejection history information HD.

  The drive signal generation circuit 52 shown in FIG. 5 includes a so-called class D amplifier (digital amplifier) including a drive waveform generation circuit 54 and a current amplification circuit 55. The drive waveform generation circuit 54 is composed of, for example, a driver IC. The drive waveform generation circuit 54 has a storage unit (not shown) that stores a plurality of waveform data corresponding to a plurality of print modes, and reads out waveform data corresponding to the instructed print mode from the storage unit. The waveform data is composed of a plurality of types of waveform parameters necessary for specifying the waveform of the drive signal COM. The drive waveform generation circuit 54 generates a waveform signal composed of a digital signal based on the read waveform data.

  The current amplification circuit 55 is configured by a DAC (Digital Analog Converter), and includes two transistors 551 and 552, a filter circuit 553, and the like. The transistors 551 and 552 are N-channel MOS transistors, for example. In the current amplifying circuit 55, the drain terminal of the first transistor 551 is connected to a constant voltage power supply voltage Vd (for example, 42V), and the intermediate node between the transistors 551 and 552 is connected to the output terminal of the upstream drive waveform generating circuit 54. In addition to being connected, it is connected to the input terminal of the filter circuit 553 in the downstream stage. The filter circuit 553 is configured by a low-pass filter (LC resonance circuit) including a coil and a capacitor. The source terminal of the second transistor 552 is grounded to the ground. As a result, the current amplification circuit 55 converts the drive signal COM, which is a digital signal input from the drive waveform generation circuit 54, into an analog drive signal COM (FIG. 6), and the drive signal COM made up of an analog signal is sent to the head drive circuit 60. Send. Further, the head controller 36 generates a latch signal LAT and a channel signal CH (see FIG. 6), which will be described later, based on the timing signal, and transmits them to the head drive circuit 60.

  The head drive circuit 60 includes an analog switch 67 that selectively supplies one or two drive pulses DP1 to DP4 (see FIG. 6) included in the drive signal COM to the piezoelectric element 42. The analog switch 67 is turned on / off based on print control data SIn (specifically, print data SI of the print data SI) input to the head drive circuit 60. The output terminal of the analog switch 67 is electrically connected to the individual electrode 45. For this reason, when the analog switch 67 is turned on, the voltage of the drive pulse corresponding to the ON period among the plurality of drive pulses in the drive signal COM is supplied to one end of the piezoelectric element 42 connected to the individual electrode 45. As described above, each analog switch 67 is turned on / off based on the value of the print data SI. When the analog switch 67 is turned on, the drive pulse at the timing of turning on in the drive signal COM is supplied to the piezoelectric element 42. Is not supplied to the piezoelectric element 42.

  The switching circuit 53 shown in FIG. 5 supplies a bias power supply circuit 56 that supplies a reference voltage Vbs and an aging voltage Vag to a ground-side common electrode 46 that is electrically connected to the other end of the piezoelectric element 42. An aging power supply circuit 57 and a first switch element 58 and a second switch element 59 that switch supply voltages output from both power supply circuits 56 and 57 are provided. When the aging processor 38 turns on the first switch element 58 and turns off the second switch element 59, the reference voltage Vbs that is the output of the bias power supply circuit 56 is supplied to the common electrode 46. When the aging processor 38 turns off the first switch element 58 and turns on the second switch element 59, the aging voltage Vag that is the output of the aging power supply circuit 57 is supplied to the common electrode 46.

  The reference voltage Vbs that is the output of the bias power supply circuit 56 is a predetermined voltage that is equal to or lower than the intermediate potential of the drive signal COM, and defines the minimum voltage of the drive pulses DP1 to DP4 that constitute the drive signal COM. Here, the bias power supply circuit 56 is composed of a logic power supply circuit with an output voltage of 5 V, for example, so that the reference voltage Vbs can be adjusted to a desired voltage.

  Further, the aging voltage Vag that is the output of the aging power supply circuit 57 is a predetermined voltage that is lower than the reference voltage Vbs (Vag <Vbs). The aging voltage Vag is set as an example of a second voltage having a different polarity from the voltage of the drive signal COM supplied as the first voltage to the individual electrode 45 electrically connected to one end of the piezoelectric element 42. Yes. That is, the voltage of the drive signal COM is a positive voltage that is not less than the reference voltage Vbs (for example, 5 V) and not more than the waveform maximum voltage Vh (see FIG. 6), and the aging voltage Vag is different from the drive signal COM that takes a positive voltage. It is a negative voltage that takes polarity. The waveform maximum voltage Vh is smaller than the constant voltage power supply voltage Vd due to the influence of the filter circuit 553 (LC resonance circuit) in the drive signal generation circuit 52, and thus takes a value less than the constant voltage power supply voltage Vd.

  Next, a configuration for driving the piezoelectric element 42 in the head unit 16 will be described with reference to FIGS. 6 and 7. First, the electrical configuration of the head unit 16 will be described with reference to FIG. As shown in FIG. 7, from the head controller 36 to the head unit 16, the print control data SIn from the data processing circuit 51, the drive signal COM from the drive signal generation circuit 52, the latch signal LAT and the channel signal CH, The ground voltage Vg from the switching circuit 53 is transferred through wiring such as a flat cable. As shown in FIG. 6, the print control data SIn includes print data SI and definition data SP. The print data SI is composed of upper bit data SIH and lower bit data SIL.

  As shown in FIG. 7, the head drive circuit 60 includes a shift register 61, a latch circuit 62, a control logic 63, a decoder 64, a level shifter 65, and a switch circuit 66. The shift register 61 sequentially stores print data SI and SP transferred from the data processing circuit 51 for each nozzle row. The latch signal LAT from the head controller 36 is input to the latch circuit 62, and the channel signal CH is input to the control logic 63. Further, the drive signal COM from the drive signal generation circuit 52 is input to the switch circuit 66.

  The shift register 61 includes a first shift register, a second shift register, and a third shift register (not shown). The first shift register stores upper bit data SIH of the print data SI, the second shift register stores lower bit data SIL, and the third shift register stores definition data SP.

  The latch circuit 62 holds one bit at a time from the high-order bit data SIH and the low-order bit data SIL constituting the print data SI stored in the shift register 61 in order based on the latch signal LAT. Data SI (HL) is output to the decoder 64 at every timing of the printing cycle TA.

  The definition data SP stored in the third shift register is input to the control logic 63. The control logic 63 stores a translation table that defines translation rules. The control logic 63 outputs a pulse selection signal generated based on the definition data SP and the translation table to the decoder 64.

  The decoder 64 outputs pulse selection information PS corresponding to the value of the input print data SI (HL). The pulse selection information PS has the same number of digits (number of bits) as the number of drive pulses DP1 to DP4, and in this example, consists of 4-digit (4-bit) binary data. The decoder 64 outputs the pulse selection information PS to the level shifter 65 in the order from the upper bit to the lower bit.

  The level shifter 65 functions as a voltage amplifier. When the input bit value is “1”, the level shifter 65 outputs to the switch circuit 66 an electrical signal boosted to a voltage of, for example, several tens of volts that can drive the switch circuit 66. To do. The drive signal COM from the drive signal generation circuit 52 is input to the input terminal of the analog switch 67 constituting the switch circuit 66. The output terminal of the analog switch 67 is connected to one end of the piezoelectric element 42 via the individual electrode 45.

  The analog switch 67 switches on / off based on the input drive signal COM and the pulse selection information PS input from the decoder 64 via the level shifter 65, so that the first to fourth drive pulses DP1 to DP4 are switched. Among them, one or two corresponding to the print data SI (HL) is selected and supplied to the piezoelectric element 42. When the drive pulse from the switch circuit 66 is supplied to the piezoelectric element 42, the piezoelectric element 42 is driven in a vibration mode according to the supplied drive pulse, and from the nozzle 17a in the case other than non-ejection (microvibration). Ink droplets of a size corresponding to the vibration mode are ejected.

  Here, various signals used when the piezoelectric element 42 is driven will be described with reference to FIG. As shown in FIG. 6, the drive signal COM includes a plurality of (four in this example) drive pulses DP1 to DP4 generated in time series during a printing cycle TA which is one cycle for forming one dot. It is a signal that contains. That is, the drive signal COM is a signal in which the first drive pulse DP1, the second drive pulse DP2, the third drive pulse DP3, and the fourth drive pulse DP4 are arranged in time series. The first drive pulse DP1 is a large amplitude pulse generated in the first period T1. The second drive pulse DP2 is a pulse generated in the second period T2 in order to slightly vibrate the ink in the nozzle 17a when there is no dot (no ink droplet ejection). The third drive pulse DP3 is a large amplitude pulse generated in the third period T3. The fourth drive pulse DP4 is a medium amplitude pulse generated in the fourth period T4.

  As shown in FIG. 6, the latch signal LAT is a pulse signal that defines the start timing of the drive signal COM, that is, the timing at which the first drive pulse DP1 is generated. That is, the latch signal LAT includes a pulse generated at the start timing of the drive signal COM.

  As shown in FIG. 6, the channel signal CH is a pulse signal that defines the timing of switching from the previous drive pulse to the next drive pulse in one drive signal COM. That is, the channel signal CH is a pulse generated at a timing when the first driving pulse DP1 is switched to the second driving pulse DP2, a pulse generated at a timing when the second driving pulse DP2 is switched to the third driving pulse DP3, and a third driving pulse. It includes a pulse generated at the timing of switching from DP3 to the fourth drive pulse DP4.

  As shown in FIG. 6, the print control data SIn is transferred to the head drive circuit 60 through a flexible cable in synchronization with the clock signal. The print control data SIn is generated for each ink color by the data processing circuit 51, and a plurality of print control data SIn corresponding to each color of black, cyan, magenta, and yellow is flattened in synchronization with the clock signal within the print cycle TA. The data is transferred in parallel to the head driving circuit 60 through wiring such as a cable. Black print control data SIn is transferred during monochrome printing, and three types of print control data SIn of cyan, magenta, and yellow are transferred during color printing. In the following description, when the colors are not particularly distinguished, they are simply referred to as “print control data SIn”.

  The print control data SIn shown in FIG. 6 includes print data SI and definition data SP. The print data SI is composed of upper bit data SIH and lower bit data SIL. The print data SI is data that defines the size of ink dots formed on the medium P by driving the piezoelectric element 42. Such print data SI is 2-bit data per dot (1 nozzle), and is composed of gradation information representing four gradations including no dots (non-ejection), small dots, medium dots, and large dots. . As shown in FIG. 6, the print data SI includes upper bit data “SIH” (only the upper bits for F nozzles out of the gradation information “HL” for F nozzles (one nozzle row)). F bit) and lower bit data “SIL” (F bit) consisting only of lower bits for F nozzles.

  The 2-bit gradation information (HL) of the print data SI is “00” for non-ejection (slight vibration), “01” for small dots, “10” for medium dots, and “11” for large dots. . Definition data SP defines the correspondence between these 2-bit gradation information (HL) and a plurality of drive pulses DP1, DP2, DP3, DP4 in the drive signal COM. The decoder 64 outputs pulse selection information corresponding to the print data SI (gradation information HL) by translation processing according to the translation rule of the control logic 63 based on the definition data SP. That is, based on the translation rule from the control logic 63, the decoder 64 translates the gradation information HL composed of the combination of the upper bit data SIH and the lower bit data SIL constituting the print data SI, and has a plurality of bits (4 in this example). Bit) of pulse selection information PS is output for the number of nozzles (F).

  When the input print data SI is “00”, the decoder 64 outputs pulse selection information PS = (0100) to select the second drive pulse DP2. Further, when the input print data SI is “01”, the decoder 64 outputs pulse selection information PS = (0010) for selecting the third drive pulse DP3. Further, when the input print data SI is “10”, the decoder 64 outputs pulse selection information PS = (1001) for selecting the first drive pulse DP1 and the fourth drive pulse DP4. Further, when the input print data SI is “11”, the decoder 64 outputs pulse selection information PS = (1010) for selecting the first drive pulse DP1 and the third drive pulse DP3. The 4-digit pulse selection information PS is input to the level shifter 65 in the order from the upper bit to the lower bit.

  The 4-digit pulse selection information PS corresponds to each of the first to fourth drive pulses DP1 to DP4. The switch circuit 66 receives the 4-digit pulse selection information PS and the drive signal COM at the same timing. The switch circuit 66 is turned on when the value of the 4-digit pulse selection information PS is “1”, and is turned off when it is “0”. For this reason, the switch circuit 66 selects the drive pulse input when the value of the 4-digit pulse selection information PS becomes “1” among the four drive pulses DP1 to DP4 constituting the drive signal COM. The drive pulse input when it is output to "0" is not selected. As a result, the drive pulse selected by the switch circuit 66 for each printing cycle TA is supplied to one end of the piezoelectric element 42 via the individual electrode 45. In this way, by controlling the operation of the switch circuit 66 based on the pulse selection information PS, the first to fourth drive pulses DP1 to DP4 are selectively supplied to the piezoelectric element 42.

  Further, as shown in FIG. 7, the common voltage 46 electrically connected to the other end (negative terminal) of the piezoelectric element 42 has a reference voltage Vbs (> 0) during the printing process (liquid ejection process). The aging voltage Vag (<0) is supplied during the aging process. Therefore, during the aging process, the maximum voltage ΔV2 (= Vh−Vag) (greater than the maximum voltage ΔV1 (= Vh−Vbs) supplied during the printing process is applied to both ends (both positive and negative terminals) of the piezoelectric element 42. In either case, see FIG. 11).

  Incidentally, when some of the head units 16 of the plurality of head units 16 constituting the discharge unit 15 shown in FIG. 8 need to be removed due to failure, life or maintenance, the head unit 16 is removed. The head unit 16 is replaced with a new one. For example, before replacement with a new head unit 16, the plurality of head units 16 constituting the discharge unit 15 have a function of discharging ink and a first head unit 161 to be removed by replacement, and the ink. And a second head unit 162 that has a function of discharging and is continuously used without being replaced. Before the replacement of some of the head units 16, both the first head unit 161 and the second head unit 162 are used for printing processing (an example of liquid ejection processing), and the first and second head units 161 and 162 are used. Printing is performed by discharging ink from the nozzles 17a to the medium P. When the number of ejections (the number of ejections) reaches a certain value in a long-term printing process, a failure occurs in which normal ejection is difficult for at least some of the nozzles 17a of the head unit 16 due to deterioration over time or the like. There is. In this case, after the ink is ejected from the first and second head units 161 and 162 used in the printing process, for example, the first head unit 161 needs to be replaced due to a failure, life or maintenance. The third head unit 163 is attached to the printer 11 instead of the first head unit 161.

  As shown in FIG. 8, after the first head unit 161 is replaced with the third head unit 163, the plurality of head units 16 constituting the discharge unit 15 are continuously used before and after the replacement. The second head unit 162 and a newly installed third head unit 163, for example, are included.

  In this way, the ejection characteristics of the ejection section 43 (see FIG. 3) may vary between the second head unit 162 that is continuously used and the third head unit 163 that is attached by replacement. One of the causes is a liquid discharge history (ink discharge history) of the head unit 16. Specifically, as the piezoelectric element 42 is used for printing and the number of energizations approximately proportional to the number of ejections increases, the supply of a voltage in a certain direction is repeated, so that the crystal orientation of the material of the piezoelectric element 42 is aligned. Thus, the voltage-discharge characteristics are gradually stabilized. For this reason, the piezoelectric element 42 has a fluctuation period in which the voltage-discharge characteristics gradually change from the initial stage of start of use until it becomes stable, and a stable period after the voltage-discharge characteristics have been stabilized (see FIG. 9). Therefore, when a new third head unit 163 is replaced, there is a discharge variation due to a difference in discharge characteristics between the second head unit 162 continuously used before and after the replacement. Here, even if the same voltage is supplied to the piezoelectric element 42, the change in the voltage-discharge characteristics differs in the amount of displacement of the piezoelectric element 42, and this also affects the size and discharge speed of the discharged droplet. For this reason, when the second head unit 162 and the third head unit 163 having different voltage-discharge characteristics are mixed in one discharge unit 15, the discharge characteristics vary between the second and third head units 162 and 163. There is a risk that the print quality of the printed matter will deteriorate. In particular, in the present example in which the printer 11 is a line printer, the relative movement speed (medium transport speed) between the head unit 16 and the medium P is higher than that of the serial printer, and thus the second head unit 162 and the third head unit 163. A slight discharge variation in between tends to greatly affect the print quality.

  As a method for reducing the discharge variation between the second and third head units 162 and 163, there is a technique of correcting the voltage of the drive signal supplied to the piezoelectric element 42, but the supply is performed according to the change in the discharge characteristic of the piezoelectric element 42. A correction circuit for correcting the voltage is required, and it is necessary for the piezoelectric element 42 to adjust the supply voltage to the piezoelectric element 42 according to the number of ejections and the ejection time. Further, since the head units 162 and 163 having different replacement times are mixed, it is necessary to adjust the voltage for each head unit, and the voltage correction processing becomes very complicated.

  Therefore, in the present embodiment, the technique for correcting the supply voltage is not a main measure, and an aging process for stabilizing the ejection characteristics is performed on the piezoelectric element 42 of the third head unit 163 attached by replacement. When the first head unit 161 is replaced with the third head unit 163, the aging processing unit 38 uses a new third head in order to reduce variation in ejection characteristics between the second head unit 162 and the third head unit 163. An aging process is performed in which the plurality of piezoelectric elements 42 in the unit 163 are energized to forcibly stabilize the ejection characteristics. By the aging process, the ejection characteristics of the third head unit 163 are stabilized in a short time. After the ejection characteristics are stabilized by the aging process, the dispersion of the ejection characteristics is further reduced by correcting the supply voltage as necessary. For this reason, in the present embodiment, the replaced third head unit 163 is subjected to an aging process.

  Here, when the head unit is replaced, ink filling is performed so that the head unit 16 attached by the replacement is filled by the filling device 37 as an example of the liquid filling unit. However, when the aging process is performed after ink filling, it is necessary to perform the aging process at a voltage level that does not eject ink. On the other hand, if the aging process is performed before ink filling, since there is no ink having a function of dissipating heat generated by driving the piezoelectric element 42, it is necessary to suppress the voltage supplied to the piezoelectric element 42 so as not to overheat. In the present embodiment, the aging process is performed after ink filling, and the aging process is performed by supplying a voltage in a range where ink is not ejected to the piezoelectric element 42.

  As shown in FIG. 9, the ejection characteristics gradually stabilize after a new head unit starts to be used for printing. The ejection characteristics gradually vary as the number of ejections increases until a certain fluctuation period elapses from the start of use of a new head unit. The ejection characteristics are stabilized in the stable period after the fluctuation period is finished. The ejection characteristics of the third head unit 163 replaced with a new one are different from those of the other head unit 16 (162) that has not been replaced. Variations in the ejection characteristics between the head units 162 and 163 cause variations in the landing positions of the ejected ink droplets, resulting in a decrease in print quality. Therefore, in the present embodiment, as indicated by a two-dot chain line in FIG. 9, an aging process for energizing the third head unit 163 is performed before use for printing, and the first aging process is performed within a relatively short time (aging time Ta). The ejection characteristics of the three-head unit 163 are aligned with the ejection characteristics of the second head unit 162 that is continuously used.

  Then, reference data RD shown in FIG. 10 is stored in the storage unit 32 in order to determine the aging time Ta for performing the aging process. As shown in the figure, the aging time Ta corresponding to the ejection number J or the ejection time Tj is set in the reference data RD. The reference data RD is used to obtain the aging time Ta corresponding to the ejection number J or the ejection time Tj of the second head unit 162 when performing the aging process of the third head unit 163. In the present embodiment, the aging processing unit 38 included in the control unit 30 performs an aging process on the third head unit 163 during the aging time Ta.

  Next, the operation of the printer 11 will be described. The computer of the control unit 30 executes the program PR of the aging process routine shown by the flowchart in FIG. Details of the aging process will be described below with reference to FIGS.

  First, the control unit 30 notifies the print mode at that time to the drive signal generation circuit 52 in the head controller 36, and generates the drive signal COM based on the waveform data read from the storage unit. As a result, the drive signal COM is output from the drive signal generation circuit 52 to the head drive circuit 60. Further, the print data PD is distributed into a plurality by the distributor 34 and transmitted to the head controller 36 through the data controller 35. In the head controller 36, the data processing circuit 51 generates print control data SIn based on the print image data ND and transfers it to each head drive circuit 60 for each nozzle row. Then, the head drive circuit 60 discharges by applying or not applying one or two of the drive pulses DP1 to DP4 in the drive signal COM based on the print data SI to the piezoelectric element 42. The portion 43 is controlled to be discharged. Hereinafter, the aging process will be described with reference to the flowchart shown in FIG.

  In step S11, it is determined whether or not the head unit has been replaced. For example, the user operates the input device 103 of the host device 100 to input information (for example, a unit number) that can identify the replaced head unit 16 to notify the host device 100 that the head unit 16 has been replaced. Instructs the start of the aging process. When the computer of the control unit 30 inputs information indicating that the head unit 16 has been replaced and an instruction to start the aging process, the computer determines that the head unit 16 has been replaced and proceeds to step S12. On the other hand, when the information indicating that the head unit has been replaced and the instruction for starting the aging process are not input, the control unit 30 ends the aging process routine.

  In step S12, the liquid discharge history information HD is read. The computer reads the liquid ejection history information HD from the storage unit 32. The liquid ejection history information HD is obtained by the data processing circuit 51 obtaining the ejection number J by counting the number of dots of the print image data ND by the measuring unit 511 or the time during which the ejection unit 15 is ejecting ink. Measurement (time measurement) is performed to obtain the discharge time Tj. Specifically, the current ejection number ΔJ or the ejection time ΔTj is added to the ejection number J or the ejection time Tj that is the cumulative value up to the previous time read from the storage unit 32, and the ejection number that is the cumulative value up to this time. J or the discharge time Tj is acquired and written in the storage unit 32. The control unit 30 reads the ejection number J or the ejection time Tj from the storage unit 32 as an example of the liquid ejection history information HD.

  In step S13, an aging time is set. The computer acquires the reference data RD from the storage unit 32, and sets the aging time Ta according to the liquid discharge history information HD with reference to the reference data RD shown in FIG. 10 based on the liquid discharge history information HD.

In step S14, the voltage of the common electrode 46 is set. The computer sets a voltage to be supplied to the common electrode 46 during the aging process.
In step S15, an aging process is started. The aging processing unit 38 of the control unit 30 starts the aging process. With this start, the aging processing unit 38 starts measuring time by the timer 39. The computer of the control unit 30 switches the switching circuit 53 by turning on and off the switch elements 58 and 59, and supplies the second voltage to be supplied to the common electrode 46 from the reference voltage Vbs for printing processing to the first voltage. The voltage is switched to an aging voltage Vag (<0) as an example of a second voltage having a polarity different from the voltage (≧ Vbs) of the drive signal COM as an example.

  In the next step S16, it is determined whether or not the aging time has elapsed. The aging processing unit 38 determines whether the time measured by the timer 39 has reached the aging time Ta. If the aging time Ta has not elapsed, the process waits until the aging time Ta has elapsed. If the aging time Ta has elapsed, the process proceeds to the next step S17.

  In step S17, the aging process ends. The computer of the control unit 30 stops sending the print data SI for aging processing to the head unit 16 via the data processing circuit 51. Further, the computer switches on / off of the switch elements 58 and 59 of the switching circuit 53 to change the voltage to be supplied to the common electrode 46 from the aging voltage Vag, which is an example of the second voltage, to the reference voltage Vbs for print processing. Switch to.

  In the next step S18, ink filling is performed. The computer of the control unit 30 drives the filling device 37 to fill the third head unit 163 with ink. The filling device 37 includes a cap (not shown) that can contact the nozzle opening surface 16a of the head unit 16 so as to cover all the nozzles 17a, and the nozzle 17a of the third head unit 163 is not shown in the state of capping with the cap. A suction device (for example, a suction pump) is driven using a motor as a power source to suck air to make a negative pressure inside the cap. The filling device 37 forcibly sucks ink from the nozzle 17a by the action of negative pressure in the cap, so that ink from an ink supply source such as an ink tank is used for the ink supply flow path 183, the reservoir 182 and the cavity. Ink filling is performed by filling the ink to 174 and the nozzle 17a.

  When ink filling is completed, a printing process step (an example of a liquid ejection process step) is performed in which ink is ejected from the head units 162 and 163 included in the ejection unit 15 and printing is performed on the medium P.

According to the embodiment described in detail above, the following effects can be obtained.
(1) After the liquid is ejected from the first head unit 161 and the second head unit 162, the printer 11 is replaced with the first head unit 161 for reasons of failure, life or maintenance, and the third head unit 163 is replaced with the printer 11. Is attached to the third head unit 163, the aging processing unit 38 that performs aging processing on the third head unit 163 is provided. The aging processing unit 38 supplies the drive signal COM as the first voltage to the individual electrodes 45 of the third head unit 163, and ages the common electrode 46 as the second voltage having a polarity different from that of the first voltage. An aging process is performed by supplying the voltage Vag. Accordingly, the piezoelectric element 42 of the third head unit 163 can be aged to stabilize the ejection characteristics of the piezoelectric element 42. Therefore, the ejection characteristics between the head units 16 in the printer 11 after the third head unit 163 is attached. The variation of the can be reduced. Therefore, in a liquid ejection apparatus including a plurality of head units, variation in ejection characteristics between the third head unit replaced due to a failure or the like and the second head unit not replaced can be reduced in a short time.

  (2) The aging processing unit 38 performs an aging process for aligning the ejection characteristics of the third head unit 163 with the ejection characteristics of the second head unit 162. Therefore, when the aging processing unit 38 performs the aging process on the third head unit 163, the ejection characteristics of the third head unit 163 are aligned with the ejection characteristics of the second head unit 162. For this reason, in the printer 11 after being replaced from the first head unit 161 to the third head unit 163, the variation in ejection between the head units 16 can be reduced.

  (3) The storage unit 32 stores the liquid discharge history information HD of the head unit 16 (at least the second head unit 162). The aging processing unit 38 performs an aging process with a processing intensity based on the liquid ejection history information HD stored in the storage unit 32. Therefore, it is possible to suppress variations in ejection characteristics among the plurality of head units 16 (162, 163). In particular, since the processing strength of the aging process is adjusted by the length of the aging time, a circuit for adjusting or switching the voltage supplied to the piezoelectric element 42 can be simple.

  (4) A common electrode that is an example of the other electrode of the piezoelectric element that constitutes the head unit by a printing process and an aging process that are examples of a liquid discharge process that discharges ink that is an example of liquid from the plurality of head units 16 A switching circuit 53 for switching the voltage supplied to 46 is provided. The aging processing unit 38 switches the switching circuit 53 to supply a first voltage to the individual electrode 45 electrically connected to one end of the piezoelectric element 42 constituting the third head unit 163, and to the common electrode 46 the second voltage. Supply a voltage of. Therefore, when the aging process is performed, the first voltage can be supplied to the individual electrode 45 of the piezoelectric element 42 constituting the third head unit 163, and the common electrode 46 has a polarity different from the reference voltage Vbs at the time of the printing process. An aging voltage Vag, which is an example of the second voltage, can be supplied.

  (5) The voltage supplied to the common electrode 46 is a constant voltage, and the switching circuit 53 is configured to be able to switch the constant voltage supplied to the common electrode 46 between the printing process and the aging process. The aging processing unit 38 switches the switching circuit 53 and sets an example of the second voltage to the common electrode 46 which is an example of the other electrode electrically connected to the other end of the piezoelectric element 42 constituting the third head unit 163. An aging voltage Vag is supplied. Therefore, the aging processing unit 38 switches the switching circuit 53 to switch the constant voltage supplied to the common electrode 46 of the piezoelectric element 42 of the third head unit 163 from the reference voltage Vbs to the aging voltage Vag, thereby causing the piezoelectric element 42 to change. On the other hand, the voltage Vag at the time of aging processing is supplied. Therefore, the aging process for the third head unit 163 can be completed in a relatively short time.

  (6) The aging processing unit 38 determines the first potential and the second potential from the potential difference (voltage) between the potential supplied to the individual electrode 45 and the potential supplied to the common electrode 46 during the printing process. Increase the potential difference. Therefore, the aging process for the third head unit 163 can be completed in a relatively short time.

  (7) The printer 11 further includes a filling device 37 that fills the third head unit 163 with ink as an example of a liquid. The aging processing unit 38 performs an aging process on the third head unit 163 before the filling device 37 fills the third head unit 163 with ink. For this reason, it is not necessary to limit the first voltage to a value in a range where liquid is not discharged. Therefore, even if the first voltage is set to a relatively high value capable of ejecting liquid such as the first drive pulse DP1, the third drive pulse DP3, and the fourth drive pulse DP4 in the drive signal COM, there is a concern that ink leaks. There is no. Therefore, when the aging process is performed after ink filling, a faster aging process can be realized as compared with the configuration in which the first voltage is kept low in order to avoid ink leakage.

  (8) The first voltage that the aging processing unit 38 supplies to the individual electrode 45 that is an example of one of the electrodes is a voltage value for fine vibration that does not cause the third head unit 163 to discharge the liquid. Therefore, it is possible to avoid a situation where ink is wasted due to leakage of ink from the third head unit 163 during the aging process after ink filling.

  (9) When the third head unit 163 is attached instead of the first head unit 161 after ink is ejected from the first head unit 161 and the second head unit 162, aging is performed on the third head unit 163. An aging processing unit 38 that performs processing is provided. The aging processing unit 38 is a common electrode among the individual electrode 45 electrically connected to one end of the piezoelectric element 42 of the third head unit 163 and the common electrode 46 electrically connected to the other end of the piezoelectric element 42. The voltage supplied to 46 is switched to the aging voltage Vag having a value different from the reference voltage Vbs supplied during the printing process. As a result, the maximum voltage ΔV2 supplied to the piezoelectric element 42 between the individual electrode 45 and the common electrode 46 can be switched to a value larger than the maximum voltage ΔV1 during the printing process. Therefore, during the aging process, a maximum voltage ΔV2 larger than the maximum voltage ΔV1 supplied during the printing process can be supplied to the piezoelectric element 42. Therefore, the piezoelectric element 42 of the third head unit 163 can be subjected to a high-speed aging process, and the ejection characteristics of the second and third head units 162 and 163 can be aligned in a relatively short time.

  (10) The present invention is also applied to the ink ejection method in the printer 11. The printer 11 configures the third head unit 163 when the first head unit 161 is removed and the third head unit 163 is attached after ink is ejected from the first head unit 161 and the second head unit 162. The first voltage is supplied to the individual electrode 45 electrically connected to one end of the piezoelectric element 42 and the first voltage is applied to the common electrode 46 electrically connected to the other end of the piezoelectric element 42. Aging processing is performed on the third head unit 163 by supplying a second voltage having a polarity different from that of the third head unit 163 (aging processing step). Then, after the aging process, ink is ejected by a plurality of head units 16 including the second head unit 162 and the third head unit 163 (liquid ejection process step). Therefore, according to this ink ejection method, when a part of the plurality of head units 16 is replaced with another third head unit 163, the variation in ejection between the head units 16 can be reduced.

  (11) The present invention is also applied to a program PR executed by a computer provided in the printer 11. The program PR causes the computer to execute an aging process step and a liquid ejection process step. That is, when ink is ejected from the first head unit 161 and the second head unit 162, the first head unit 161 is removed, and the third head unit 163 is attached, the piezoelectrics constituting the third head unit 163. A first voltage is supplied to the individual electrode 45 electrically connected to one end of the element 42. Further, an aging process is performed on the third head unit 163 by supplying a second voltage having a polarity different from that of the first voltage to the common electrode 46 electrically connected to the other end of the piezoelectric element 42. (Aging process step). Then, after the aging process, a printing process for ejecting ink onto the medium P is performed by the plurality of head units 16 including the second head unit 162 and the third head unit 163 (liquid ejection process step). By causing the computer to execute the program PR, it is possible to reduce the discharge variation between the head units 16 when a part of the plurality of head units 16 is replaced with another third head unit 163.

(Second Embodiment)
Next, the aging process in the second embodiment will be described with reference to FIGS. In this embodiment, the aging process is performed after ink replacement after replacing the head unit. Since the configuration of the printer 11 is the same as that of the first embodiment, the contents of aging processing that are particularly different will be described. The storage unit 32 stores an aging processing program PR shown in the flowchart of FIG. The computer of the control unit 30 performs the aging process by executing the program PR. Hereinafter, the aging process will be described with reference to FIGS. 13 and 14.

  First, as shown in FIG. 8, the first head unit 161 is removed from the plurality of head units due to a failure or the like, and the third head unit 163 is attached instead of the first head unit 161. The third head unit 163 is replaced. The aging process described below is different in that ink filling (step S22) for filling the third head unit 163 with ink is performed before the aging process (steps S26 to S28). In the aging process, the first voltage is the voltage of the micro-vibration driving pulse DP2 that does not eject the liquid, and the second voltage is the aging voltage Vag having a polarity different from that of the driving pulse DP2. For this reason, the processes in steps S21 to S28 in FIG. 13 are basically the same as the processes in steps S11, S18, and S12 to S17 in FIG. 12 described in the first embodiment.

  In step S21, it is determined whether or not the head unit has been replaced. If the head unit has been replaced, the process proceeds to step S22. If the head unit has not been replaced, the routine ends.

In step S22, ink filling is performed. The computer of the control unit 30 drives the filling device 37 to fill the third head unit 163 with ink.
In the next step S23, the liquid discharge history information is read. The computer of the control unit 30 reads the liquid discharge history information HD from the storage unit 32. As the liquid ejection history information HD, at least one of the ejection number J and the ejection time Tj is acquired.

  In step S24, an aging time is set. The computer of the control unit 30 acquires the aging time Ta by referring to the reference data RD based on the liquid discharge history information HD, and sets the acquired aging time Ta. The aging time Ta of the present embodiment is the voltage of the micro-vibration driving pulse DP2 that does not cause the liquid to be ejected. Therefore, when the liquid ejection history information is the same, the aging time Ta is compared with the first embodiment. A slightly longer aging time Ta is set.

  In step S25, a voltage to be supplied to the common electrode 46 is set. The computer of the control unit 30 turns off the switch element 58 of the switching circuit 53 and turns on the switch element 59. As a result, the aging voltage Vag is supplied to the common electrode 46 that is electrically connected to the other end of the piezoelectric element 42.

  In step S26, an aging process is started. The computer of the control unit 30 causes the head controller 36 to start generating the drive signal COM, and also reads out print image data for aging processing from the storage unit 32 and transmits it to the data processing circuit 51. As a result, as shown in FIG. 14, in the aging process, the drive signal COM including the slightly oscillating drive pulse DP <b> 2 is supplied to the individual electrode 45. In this aging process, the maximum voltage ΔV3 supplied between the electrodes 45 and 46 on both sides of the piezoelectric element 42 is larger than the maximum voltage ΔV1 during the printing process (an example of the liquid discharge process).

Then, when the time measured by the timer 39 that has started timing with the start of the aging process reaches the aging time Ta (Yes in S16), the aging process is terminated (S28).
As shown in FIG. 14, during the aging process, a drive pulse DP2 for fine vibration is supplied as an example of the first voltage to the individual electrode 45, which is an example of one of the electrodes. A negative aging voltage Vag (<0) is supplied to the common electrode 46, which is an example of the other electrode, as an example of a second voltage smaller than the positive reference voltage Vbs (> 0) supplied during the printing process. . In this aging process, a maximum voltage ΔV3 larger than the maximum voltage ΔV1 supplied during the printing process is supplied to both ends of the piezoelectric element 42.

  Further, in the aging process, since the micro-vibration drive pulse DP2 is supplied to the individual electrode 45, even if the aging process is performed after the ink filling is completed, the nozzle 17a of the third head unit 163 is wasted during the aging process. Ink can be prevented from being ejected or leaking out. For this reason, overheating of the third head unit 163 due to heat generation by the aging process can be prevented by the cooling effect by the ink filled in the third head unit 163 while suppressing unnecessary discharge of the ink by the aging process.

  When the aging process is finished, a printing process step (an example of a liquid ejection process step) is performed in which ink is ejected from the head units 162 and 163 included in the ejection unit 15 and printing is performed on the medium P.

  (12) The printer 11 further includes a filling device 37 that fills the third head unit 163 with ink as an example of a liquid. The aging processing unit 38 performs aging processing on the third head unit 163 after the filling device 37 performs ink filling on the third head unit 163. Therefore, even if the piezoelectric element 42 generates heat during the aging process, the filled ink has a cooling effect for cooling the piezoelectric element 42 and the head drive circuit 60, and thus the heat generation of the piezoelectric element 42 and the head drive circuit 60 during the aging process. Can be suppressed. Further, since the first voltage is the voltage of the micro-vibration drive pulse DP2 that does not eject ink, leakage of ink during the aging process can be avoided.

In addition, the said embodiment can also be changed into the following forms.
As shown in FIG. 16, the first voltage to be supplied to the individual electrode 45, which is an example of one electrode electrically connected to one end of the piezoelectric element 42, may be switched during the aging process. In the head controller 36, a switch element 71 is provided between the output terminal of the drive signal generation circuit 52 and the head unit 16. One end of the switch element 71 is connected to the constant voltage power supply voltage Vd, and the other end is connected to a signal line between the output terminal of the drive signal generation circuit 52 and the head unit 16 in the head controller 36. The control unit 30 transmits the drive signal COM to the head unit 16 by turning off the switch element 71 during the printing process. The aging processing unit 38 in the control unit 30 turns off the transistors 551 and 552 and turns on the switch element 71 at the time of aging processing. As a result, during the aging process, the constant voltage power supply voltage Vd is supplied as an example of the first voltage to the individual electrode 45 that is an example of one of the electrodes connected to one end of the piezoelectric element 42. In the example shown in FIG. 16, a bias power supply circuit 56 that can output the reference voltage Vbs as a bias voltage is provided instead of the switching circuit 53. In this case, during the aging process, the constant voltage power supply voltage Vd, which is an example of the first voltage, is supplied to the individual electrode 45, and the second electrode having the same polarity as the constant voltage power supply voltage Vd is supplied to the common electrode 46, which is an example of the other electrode. A reference voltage Vbs (for example, 5 V), which is an example of the voltage, is supplied. According to this configuration, as shown in FIG. 15, during the aging process, a voltage Vd (> Vh) larger than the waveform maximum voltage Vh of the drive signal COM during the printing process can be supplied to the individual electrode 45. Therefore, at the time of aging processing, the maximum voltage ΔV4 larger than the maximum voltage ΔV1 (= Vh−Vbs) supplied at the time of printing processing can be supplied to the replaced new third head unit 163. Therefore, the piezoelectric element 42 of the third head unit 163 can be subjected to a high-speed aging process, and the ejection characteristics of the second and third head units 162 and 163 can be aligned in a relatively short time.

  The electrode that switches the voltage supplied during the aging process may be at least one of the individual electrode 45 that is an example of one electrode and the common electrode 46 that is an example of the other electrode. That is, only the second voltage supplied to the common electrode 46 on the low potential side may be switched as in the first and second embodiments, or on the high potential side as in the modification examples shown in FIGS. Only the voltage supplied to the individual electrode 45 may be switched, or both voltages supplied to both the individual electrode 45 and the common electrode 46 may be switched together. Thus, in the aging process, it is sufficient to switch the voltage supplied to at least one of the one electrode and the other electrode.

  In the second embodiment in which the aging process is performed after ink filling, drive pulses other than those for fine vibration may be supplied to the piezoelectric element 42. For example, the cooling effect by the ink filled in the third head unit 163 eliminates the need to limit the first voltage to a value that does not cause the liquid to be ejected, so even if leakage of ink during the aging process is allowed. If it is good, the first voltage may be a relatively large value that allows the liquid to be discharged. In this case, ink is wasted due to the aging process, but since the aging process is performed with the ink filled, efficient aging process can be performed while suppressing overheating of the head unit 163 due to heat generation. . When the first potential is set to a value that allows ink leakage, at least the nozzle opening surface 16a of the third head unit 163 is capped with a cap provided in the filling device 37, and the ink leaked from the nozzle 17a is received by the cap. It is desirable to have a configuration. In this case, the waste ink collected in the cap is collected in the waste liquid tank in the printer 11 from the cap through a tube line such as a tube by driving the suction device.

  In each of the embodiments, the aging processing unit 38 performs the aging process in which the ejection characteristics of the third head unit 163 are aligned with the ejection characteristics of the second head unit 162. However, the second head unit 162 and the third head unit It is not necessary to exactly match the discharge characteristics with 163. For example, the discharge characteristics of the second and third head units may be brought close to each other so that variations in the quality of the liquid discharge process are within an allowable range.

-All head units may be subjected to an aging process.
In addition to the aging process, the voltage supplied to the piezoelectric element 42 during the printing process may be corrected.

  It is not essential that the aging process is aligned with the ejection characteristics of the other head units 162, and it is only necessary to perform an aging process that only reduces variations in ejection characteristics. For example, a uniform aging process may be performed on the third head unit 163 regardless of the number of ejections or the ejection time.

  In each of the above embodiments, the processing strength of the aging process is adjusted according to the length of the aging time Ta, but the present invention is not limited to this, and at least two of the aging time, the number of aging processes, the magnitude of the aging supply voltage, Two combinations or the like may be employed.

  In a multi-head type in which a plurality of head units 16 are arranged, each head unit is arranged in a state where the nozzle row direction is inclined in a direction that obliquely intersects the transport direction Y of the medium P, thereby The pitch in the direction orthogonal to the transport direction Y may be shortened to increase the printing resolution. In this case, a configuration in which a plurality of nozzle rows are arranged in a state in which the nozzles of the other nozzle row are located between the pitches in the direction orthogonal to the nozzle transport direction of the nozzle row to obtain higher resolution. Also good.

  The line printer is not limited to a multi-head type in which a plurality of head units are arranged, and nozzles are arranged at a constant pitch over the entire print area in the width direction X that intersects the conveyance direction Y of the medium P. The structure provided with the one elongate line head which has several nozzle row which becomes. In this case, in the case of a configuration in which a plurality of unit head portions are replaceably provided in one line head, the unit head portion corresponds to an example of a head unit. Thus, the unit head part which is an example of a head unit should just be the structure which can be replaced | exchanged.

  -The gradation of dots formed by ejecting liquid by the head unit is not limited to four gradations (large dots, medium dots, small dots, no ejection), but three gradations (large dots, small dots, ejection) None) or two gradations (with or without ejection). Furthermore, a gradation of 5 gradations or more may be adopted.

  The aging process performed by the control unit 30 is realized by software by a computer that executes a program, for example, by hardware such as an electronic circuit such as an FPGA (field-programmable gate array) or an ASIC (Application Specific IC), It may be realized by cooperation of software and hardware.

  -The liquid ejection device is not limited to a line printer. The liquid ejection apparatus may be a liquid ejection system (for example, an inkjet system) including a plurality of piezoelectric head units. For example, a plurality of head units are mounted on a carriage so as to be movable together with a carriage that can move in a main scanning direction that intersects the medium conveyance direction Y, and main scanning by movement of the head unit and sub-scanning by medium conveyance are substantially alternately performed. It is also possible to use a serial printer that goes to step 1 and prints on a medium. Further, a lateral type printer in which a plurality of head units move in both the main scanning direction and the sub-scanning direction and print on a medium may be used.

  The liquid ejecting apparatus is not limited to an ink jet printer as long as it includes a plurality of head units, and may be an apparatus that ejects liquid other than ink. For example, even a liquid ejection device that ejects a liquid material that contains functional materials such as electrode materials and color materials (pixel materials) used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, and surface-emitting displays. Good. Moreover, the liquid discharge apparatus which discharges the biological organic substance used for biochip manufacture, and the liquid discharge apparatus which discharges the liquid used as a precision pipette as a sample may be sufficient. Further, a liquid ejection device for ejecting a transparent resin liquid such as a thermosetting resin on a substrate to form a micro hemispherical lens (optical lens) used for an optical communication element or the like, an acid or an alkali to etch the substrate, etc. A liquid discharge apparatus that discharges the etching liquid and a liquid discharge apparatus that discharges a fluid such as a gel (for example, physical gel) may be used. In this way, the “liquid” discharged by the liquid discharge device includes a liquid such as an inorganic solvent, an organic solvent, a solution, a liquid resin, a liquid metal (metal melt), or a solid such as particles of a functional material. Also included are fluid fluids and fluids such as gels. In addition, liquid discharge devices discharge liquids such as paper, resin films, laminate films, woven fabrics, non-woven fabrics, metal foils, metal films, and ceramic sheets, as well as elements and wiring. A medium such as a substrate formed by ejection is also included. Furthermore, the object is not limited to a medium serving as a base when the discharged liquid is landed to form a discharge formed object. Further, the discharge formation is not limited to a flat shape, and the liquid discharge device may be, for example, a 3D printer that manufactures a three-dimensional molded product as a discharge formation on an object by an inkjet method.

  DESCRIPTION OF SYMBOLS 11 ... Printer as an example of a liquid discharge apparatus, 12 ... Conveyance apparatus, 14 ..., 15 ... Discharge unit, 16 ... Head unit, 16a ... Nozzle opening surface, 17 ... Unit head part, 17a ... Nozzle, 20 ... Conveyance motor, DESCRIPTION OF SYMBOLS 30 ... Control part, 32 ... Memory | storage part, 34 ... Distributor, 35 ... Data controller, 36 ... Head controller, 37 ... Filling apparatus as an example of a liquid filling part, 38 ... Aging process part, 42 ... Piezoelectric element, 43 ... Discharge unit, 45 ... individual electrode as an example of one electrode, 46 ... common electrode as an example of the other electrode, 51 ... data processing circuit, 511 ... measurement unit, 52 ... drive signal generation circuit, 53 ... switching circuit, 54: Drive waveform generation unit, 55: Current amplification circuit, 60: Head drive circuit, 61: Shift register, 62: Latch circuit, 63: Control logic, 6 Decoder, 65 ... Level shifter, 66 ... Switch circuit, 67 ... Analog switch, 71 ... Switch element, 100 ... Host device, 101 ... Main body, 102 ... Monitor, 103 ... Input device, 105 ... Printer driver, 161 ... First Head unit 162 ... second head unit 163 ... third head unit N1-N4 ... nozzle array, PD ... print data, SIn ... print control data, SI ... print data, SP ... definition data, PS ... pulse selection information , P ... medium, TA ... printing cycle, COM ... drive signal, DP1 ... first drive pulse, DP2 ... second drive pulse, DP3 ... third drive pulse, DP4 ... fourth drive pulse, Vbs ... reference voltage, Vag ... Aging voltage, Vh: Maximum voltage, Vd: Constant voltage power supply voltage, PR: Program, HD: Liquid discharge history information , RD ... reference data, Ta ... aging time, J ... ejections number, Tj ... discharge time, ΔV1~ΔV4 ... maximum voltage, X ... width direction, Y ... conveyance direction.

Claims (12)

A first head unit having a function of discharging liquid;
A second head unit having a function of discharging the liquid;
A plurality of head units including:
After the liquid is discharged from the first head unit and the second head unit, when a third head unit is attached instead of the first head unit, an aging process is performed on the third head unit. An aging processing unit,
The first, second and third head units are
A piezoelectric element;
One electrode electrically connected to one end of the piezoelectric element;
The other electrode electrically connected to the other end of the piezoelectric element,
The aging processing unit supplies a first voltage to the one electrode of the third head unit, and supplies a second voltage having a polarity different from that of the first voltage to the other electrode. A liquid ejecting apparatus that performs the aging process.   2. The liquid ejecting apparatus according to claim 1, wherein the aging processing unit performs the aging process for aligning the ejection characteristics of the third head unit with the ejection characteristics of the second head unit. 3. A storage unit for storing liquid discharge history information of the second head unit;
3. The liquid ejection apparatus according to claim 1, wherein the aging processing unit performs the aging processing with a size based on liquid ejection history information stored in the storage unit. A voltage to be supplied to at least one of the one electrode and the other electrode of the piezoelectric element constituting the head unit by a liquid discharge process for discharging liquid from a plurality of the head units and the aging process. A switching circuit for switching,
The aging processing unit supplies the first voltage to the one electrode of the piezoelectric element constituting the third head unit by switching the switching circuit, and supplies the second voltage to the other electrode. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The voltage supplied to the other electrode is a constant voltage,
The switching circuit is switched so that a different constant voltage can be supplied to the other electrode in the liquid ejection process and the aging process,
The aging processing unit supplies the second voltage to the other electrode that is electrically connected to the other end of the piezoelectric element constituting the third head unit by switching the switching circuit. The liquid ejection device according to claim 4.   The aging processing unit is configured to determine whether the first voltage and the second voltage are higher than a voltage difference between a voltage supplied to the one electrode and a voltage supplied to the other electrode during the liquid discharge process. The liquid discharge apparatus according to claim 5, wherein a voltage difference between the first and second liquids is increased. A liquid filling unit for filling the third head unit with a liquid;
7. The aging processing unit performs the aging processing on the third head unit before the liquid filling unit performs liquid filling on the third head unit. The liquid ejection apparatus according to any one of the above. A liquid filling unit for filling the third head unit with a liquid;
The aging processing unit performs the aging processing on the third head unit after the liquid filling unit performs liquid filling on the third head unit. The liquid ejection apparatus according to any one of the above.   The liquid ejecting apparatus according to claim 8, wherein the first voltage supplied to the one electrode by the aging processing unit is a voltage value that does not cause the third head unit to eject liquid. A first head unit having a function of discharging liquid;
A second head unit having a function of discharging the liquid;
A plurality of head units including:
After the liquid is discharged from the first head unit and the second head unit, when a third head unit is attached instead of the first head unit, an aging process is performed on the third head unit. An aging processing unit,
The first, second and third head units are
A piezoelectric element;
One electrode electrically connected to one end of the piezoelectric element;
The other electrode electrically connected to the other end of the piezoelectric element,
The aging processing unit switches the voltage supplied to at least one of the one electrode and the other electrode of the third head unit to a value different from the voltage supplied during the liquid ejection process, A liquid ejection apparatus, wherein the maximum voltage supplied to the piezoelectric element between the electrode and the other electrode is switched to a value larger than the maximum voltage during the liquid ejection process. A liquid discharge method in a liquid discharge apparatus,
The liquid ejecting apparatus includes a plurality of head units including a first head unit having a function of ejecting a liquid and a second head unit having a function of ejecting the liquid.
After the liquid is discharged from the first head unit and the second head unit, when the first head unit is removed and the third head unit is attached, the piezoelectric elements constituting the third head unit A first voltage is supplied to one electrode electrically connected to one end, and the polarity is different from that of the first voltage to the other electrode electrically connected to the other end of the piezoelectric element. An aging process step of performing an aging process on the third head unit by supplying a second voltage;
A liquid discharge method in a liquid discharge apparatus, comprising: a liquid discharge process step of discharging liquid by a plurality of head units including the second head unit and the third head unit after the aging process. There is a program executed by a computer provided in the liquid ejection device,
The liquid ejecting apparatus includes a plurality of head units including a first head unit having a function of ejecting a liquid and a second head unit having a function of ejecting the liquid.
On the computer,
After the liquid is discharged from the first head unit and the second head unit, when the first head unit is removed and the third head unit is attached, the piezoelectric elements constituting the third head unit A first voltage is supplied to one electrode electrically connected to one end, and the polarity is different from that of the first voltage to the other electrode electrically connected to the other end of the piezoelectric element. An aging process step of performing an aging process on the third head unit by supplying a second voltage;
A program for executing a liquid discharge processing step of discharging liquid by a plurality of head units including the second head unit and the third head unit after the aging process.

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