JP2023103586A - Maintenance method of liquid discharge device - Google Patents

Abstract

To suppress discharge amounts of liquid in a flushing process.SOLUTION: In a maintenance method of a liquid discharge device, which comprises a nozzle for discharging liquid, a pressure chamber communicated with the nozzle and a driving element that varies pressure of liquid in the pressure chamber and executes a printing process for making the nozzle discharge liquid in a plurality of consecutive control periods of time, an update process for updating a discharge-control value is executed in each of the plurality of control periods of time, and a flushing process, in which the nozzle is made to discharge liquid with amounts corresponding to the discharge-control value updated by the update process in the last control period of time of the plurality of control periods of time, is executed, after a printing process is completed, where the update process in one control period of time is a process in which a first adjusted value predetermined for the one control period of time is added to the discharge-control value and the discharge-control value is updated to a value based on a calculated value from which is subtracted a second adjusted value predetermined in accordance with amounts of liquid discharged from the nozzle in the one control period of time.SELECTED DRAWING: Figure 11

Description

The present invention relates to a maintenance method for a liquid ejection device.

In a liquid ejection apparatus such as an inkjet printer, a piezoelectric element provided in a head unit of the liquid ejection apparatus is driven by a drive signal to displace the ink, etc., filled in a pressure chamber provided in the head unit. liquid is ejected from nozzles to form an image on a medium such as recording paper. In such a liquid ejecting apparatus, for example, the pressure chamber is filled with liquid to suppress deterioration in image quality of an image formed by the liquid ejecting apparatus due to, for example, thickening of the liquid filled in the pressure chamber. liquid must be expelled from the nozzle. For this reason, for example, as described in Japanese Unexamined Patent Application Publication No. 2002-100001, conventionally, there has been proposed a technique related to a liquid ejecting apparatus that periodically performs a flushing process for discharging the liquid filled in the pressure chamber from the nozzle.

JP 2014-233904 A

However, in the prior art, there was a case where the liquid was excessively discharged during the flushing process.

In order to solve the above problems, a maintenance method for a liquid ejecting apparatus according to the present invention includes a nozzle for ejecting liquid, a pressure chamber communicating with the nozzle, and a drive element for varying the pressure of the liquid in the pressure chamber. and performing print processing for forming an image on one or more media by ejecting liquid from the head unit in a plurality of consecutive control periods, the maintenance method comprising: In each of the plurality of control periods during which the printing process is performed, an ejection process is performed in which liquid droplets are ejected from the nozzles and land droplets on a medium by driving the driving element in the printing process. and executing an update process for updating the emission control value, and driving the drive element after the printing process is completed, thereby updating the emission control value in the last control period among the plurality of control periods. and executing a flushing process for discharging from the nozzle an amount of liquid corresponding to the above, and updating the process in one control period among the plurality of control periods, with respect to the discharge control value, with respect to the one control period. to a value calculated by adding a first adjustment value determined in the one control period and subtracting a second adjustment value determined according to the amount of liquid ejected from the nozzle in the one control period, It is characterized in that it is processing for updating the emission control value.

1 is a block diagram showing an example of the configuration of an inkjet printer 1 according to an embodiment of the invention; FIG. 1 is a perspective view showing an example of a schematic internal structure of an inkjet printer 1; FIG. FIG. 4 is a cross-sectional view for explaining an example of the structure of a discharge section D[m]; 3 is a plan view showing an example of arrangement of nozzles N in the head unit 3. FIG. 3 is a block diagram showing an example of the configuration of the head unit 3; FIG. 4 is a timing chart for explaining an example of signals supplied to the head unit 3. FIG. FIG. 4 is an explanatory diagram for explaining an example of an individual designation signal Sd[m]; FIG. 4 is an explanatory diagram for explaining an example of a print job; FIG. FIG. 4 is an explanatory diagram for explaining an example of a reference emission value RK; FIG. 10 is an explanatory diagram for explaining an example of actual ejection values RT[m]; FIG. 5 is an explanatory diagram for explaining an example of an emission control value RS[m]; 4 is a flowchart for explaining an example of the operation of the inkjet printer 1 when the discharge amount determination process is executed; FIG. 5 is an explanatory diagram for explaining an example of an emission control value RS[m]; FIG. 5 is an explanatory diagram for explaining an example of an emission control value RS[m]; FIG. 5 is an explanatory diagram for explaining an example of emission control value RS[m] according to a reference example; FIG. 5 is an explanatory diagram for explaining an example of emission control value RS[m] according to a reference example; FIG. 11 is an explanatory diagram for explaining an example of a reference emission value RK according to modification 1; FIG. 9 is an explanatory diagram for explaining an example of emission control value RS[m] according to modification 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples of the present invention, they are subject to various technically preferable limitations. It is not limited to these forms unless stated otherwise.

<<A. Embodiment>>
In the present embodiment, an inkjet printer that ejects ink to form an image on a recording paper PP is exemplified to explain the liquid ejecting apparatus. In this embodiment, the ink is an example of "liquid" and the recording paper PP is an example of "medium".

<<1. Inkjet printer overview >>
An example of the configuration of an inkjet printer 1 according to the present embodiment will be described below with reference to FIGS. 1 to 4. FIG.

FIG. 1 is a functional block diagram showing an example of the configuration of an inkjet printer 1. As shown in FIG.

As shown in FIG. 1, the inkjet printer 1 is supplied with print data Img representing an image to be formed by the inkjet printer 1 from a host computer such as a personal computer or a digital camera. The inkjet printer 1 executes medium print processing for forming an image indicated by print data Img supplied from a host computer on a recording paper PP.

The inkjet printer 1 includes a control unit 2 for controlling each part of the inkjet printer 1, a head unit 3 provided with an ejection section D for ejecting ink, and a drive signal Com for driving the ejection section D. It includes a generation unit 4, a transport unit 7 for changing the relative position of the recording paper PP with respect to the head unit 3, and a maintenance unit 8 for executing maintenance processing, which will be described later.

In this embodiment, the inkjet printer 1 may include one or more head units 3 and one or more drive signal generation units 4 corresponding to the one or more head units 3 one-to-one. Suppose. Specifically, in this embodiment, the inkjet printer 1 includes four head units 3 and four drive signal generation units 4 corresponding to the four head units 3 one-to-one. Suppose. However, in the following, for convenience of explanation, as shown in FIG. In some cases, the explanation will focus on the provided one drive signal generation unit 4 .

The control unit 2 includes one or more CPUs. However, the control unit 2 may have a programmable logic device such as FPGA instead of or in addition to the CPU. Here, CPU is an abbreviation for Central Processing Unit, and FPGA is an abbreviation for field-programmable gate array. The control unit 2 also includes a memory. Memory includes volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM). Contain one or both.

Although the details will be described later, the control unit 2 generates signals for controlling the operation of each part of the inkjet printer 1, such as the print signal SI and the waveform designation signal dCom.
Here, the waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. Further, the driving signal Com is an analog signal for driving the ejection section D. As shown in FIG. In this embodiment, it is assumed that the drive signal Com includes the drive signal Com-A and the drive signal Com-B. The drive signal generation unit 4 includes a DA conversion circuit and generates a drive signal Com having a waveform defined by the waveform designation signal dCom. The print signal SI is a digital signal that designates the type of operation of the discharge section D. FIG. Specifically, the print signal SI is a signal that designates the type of operation of the discharge section D by designating whether or not to supply the drive signal Com to the discharge section D. FIG.

As shown in FIG. 1, the head unit 3 has a supply circuit 31 and a recording head 32 .

The recording head 32 includes M ejection portions D. As shown in FIG. Here, the value M is a natural number that satisfies "M≧1". Note that, hereinafter, among the M ejection portions D provided in the recording head 32, the m-th ejection portion D may be referred to as an ejection portion D[m]. Here, the variable m is a natural number that satisfies "1≤m≤M". Further, in the following description, when a constituent element or a signal of the inkjet printer 1 corresponds to the ejection section D[m] among the M ejection sections D, the symbol for representing the constituent element or the signal is A subscript [m] may be added.

The supply circuit 31 switches whether to supply the drive signal Com to the ejection section D[m] based on the print signal SI. Note that, hereinafter, among the drive signals Com, the drive signal Com supplied to the ejection section D[m] may be referred to as the supply drive signal Vin[m].

As described above, in the present embodiment, the inkjet printer 1 executes medium print processing. When the medium print process is executed, the control unit 2 generates signals for controlling the head unit 3, such as the print signal SI, based on the print data Img. The control unit 2 also generates signals for controlling the drive signal generation unit 4, such as the waveform designation signal dCom, when the medium printing process is executed. The control unit 2 also generates signals for controlling the transport unit 7 when the media printing process is performed. As a result, in the medium printing process, the control unit 2 controls the transport unit 7 so as to change the relative position of the recording paper PP with respect to the head unit 3. Each part of the inkjet printer 1 is controlled so that an image corresponding to the print data Img is formed on the recording paper PP by adjusting the ink ejection amount, ink ejection timing, and the like.

As described above, in the present embodiment, the inkjet printer 1 executes maintenance processing. Here, the maintenance process is a process for performing maintenance on the ejection section D provided in the head unit 3. In the present embodiment, the flushing process for discharging ink from the ejection section D and the cleaning process near the nozzle N of the ejection section D are performed. a wiping process for wiping off foreign matter such as ink adhering to the discharge section D using a wiper; The maintenance unit 8 includes a discharged ink receiving part 80 for receiving the discharged ink when the ink in the discharge part D is discharged in the flushing process, and a foreign matter such as ink adhering to the vicinity of the nozzle N of the discharge part D. and a tube pump for sucking ink, air bubbles, etc., from the ejection portion D. The discharged ink receiving section 80 will be described later with reference to FIG. Further, the nozzle N will be described later with reference to FIG. Also, wipers and tube pumps are not shown.

The control unit 2 generates signals for controlling the head unit 3, such as the print signal SI, when the flushing process is executed. When the inkjet printer 1 executes the flushing process, the print signal SI is applied to the M ejection portions D provided in the head unit 3 so that the M ejection portions D operate in a predetermined manner. Specifies the behavior of Also, when the flushing process is executed, the control unit 2 generates signals for controlling the drive signal generation unit 4, such as the waveform designation signal dCom, in the same way as when the medium printing process is executed. The control unit 2 also generates a signal for controlling the transport unit 7 so that the head unit 3 moves to a position facing the discharged ink receiving section 80 when the flushing process is executed. Thereby, the control unit 2 controls each part of the inkjet printer 1 so that the ink is discharged from the discharge part D provided in the head unit 3 to the discharged ink receiving part 80 in the flushing process.

FIG. 2 is a perspective view showing an example of the schematic internal structure of the inkjet printer 1. As shown in FIG.

As shown in FIG. 2, in this embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when executing the medium printing process, the inkjet printer 1 transports the recording paper PP in the sub-scanning direction and ejects while reciprocating the head unit 3 in the main scanning direction intersecting the sub-scanning direction. By ejecting ink from the portion D[m], dots Dt corresponding to the print data Img are formed on the recording paper PP.
In the following, the +X direction and the opposite -X direction are collectively referred to as the "X-axis direction", and the +Y direction crossing the X-axis direction and the opposite -Y direction are referred to as the "Y-axis direction". The +Z direction that intersects the X-axis direction and the Y-axis direction and the −Z direction that is the opposite direction thereof are collectively referred to as the “Z-axis direction”. Here, the Y-axis is an example of the "first axis". Also, the X-axis is an example of a "second axis." In this embodiment, as shown in FIG. 2, the +X direction from the upstream side of -X to the downstream side of +X is the sub-scanning direction, and the +Y direction and the -Y direction are the main scanning directions. . In addition, in the present embodiment, as shown in FIG. 2, the +Z direction is set as the ink ejection direction from the ejection section D[m].

As shown in FIG. 2, the inkjet printer 1 according to the present embodiment includes a housing 100, a carriage 110 that can reciprocate in the housing 100 in the Y-axis direction, and on which four head units 3 are mounted. Prepare.
In this embodiment, as shown in FIG. 2, the carriage 110 stores four ink cartridges 120 corresponding to the four colors of cyan, magenta, yellow, and black ink one-to-one. assume. Further, in this embodiment, as described above, the ink jet printer 1 is assumed to include four head units 3 corresponding to the four ink cartridges 120 one-to-one. Each discharge section D[m] is supplied with ink from the ink cartridge 120 corresponding to the head unit 3 in which the discharge section D[m] is provided. As a result, each ejection part D[m] can be filled with the supplied ink and ejected from the nozzle N with the filled ink. Note that the ink cartridge 120 may be provided outside the carriage 110 .

Further, as described above, the inkjet printer 1 according to this embodiment includes the transport unit 7 . As shown in FIG. 2, the transport unit 7 includes a carriage transport mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 76 for supporting the carriage 110 so as to reciprocate in the Y-axis direction, and a recording paper. A medium transport mechanism 73 for transporting PP and a platen 75 provided on the +Z side of the carriage 110 are provided. Therefore, when the medium printing process is executed, the transport unit 7 causes the carriage transport mechanism 71 to reciprocate the head unit 3 together with the carriage 110 in the Y-axis direction along the carriage guide shaft 76, and the medium transport mechanism. 73 conveys the recording paper PP on the platen 75 in the +X direction to change the relative position of the recording paper PP with respect to the head unit 3, thereby enabling ink to land on the entire recording paper PP.
In the following description, the carriage 110 on which the head unit 3 is mounted is moved in the -Y direction from the +Y side end to the -Y side end, and the carriage 110 on which the head unit 3 is mounted is moved to the -Y direction. The process of moving in the +Y direction from the Y-side end to the +Y-side end may be collectively referred to as carriage movement process. Here, the carriage movement process is an example of the "movement process." Further, hereinafter, the process of transporting the recording paper PP on the platen 75 in the +X direction may be referred to as medium transport process. Here, the medium transport process is an example of the "transport process".

FIG. 3 is a schematic partial cross-sectional view of the recording head 32, in which the recording head 32 is cut to include the ejection portions D[m].

As shown in FIG. 3, the ejection section D[m] includes a piezoelectric element PZ[m], a cavity CV filled with ink, a nozzle N communicating with the cavity CV, and a vibration plate 321. . The ejector D[m] ejects the ink in the cavity CV from the nozzle N by driving the piezoelectric element PZ[m] with the supply drive signal Vin[m]. Cavity CV is an example of a “pressure chamber” and is a space defined by cavity plate 324 , nozzle plate 323 having nozzle N formed thereon, and vibration plate 321 . Cavity CV communicates with reservoir 325 via ink supply port 326 . The reservoir 325 communicates via an ink inlet 327 with the ink cartridge 120 corresponding to the ejection section D[m]. The piezoelectric element PZ[m] includes an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. , has The lower electrode Zd[m] is electrically connected to the feeder line Ld set to the potential VBS. Then, when the supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the applied voltage Accordingly, the piezoelectric element PZ[m] is displaced in the +Z direction or the -Z direction, and as a result, the piezoelectric element PZ[m] vibrates. A lower electrode Zd[m] is joined to the diaphragm 321 . Therefore, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] and vibrates, the vibration plate 321 also vibrates. Vibration of the vibration plate 321 changes the volume of the cavity CV and the pressure in the cavity CV, and the ink filled in the cavity CV is ejected from the nozzle N. FIG.

FIG. 4 shows the arrangement of four head units 3 mounted on the carriage 110 and a total of 4M nozzles N provided in the four head units 3 when the inkjet printer 1 is viewed from above in the +Z direction. It is an explanatory view for explaining an example of.

As shown in FIG. 4, each head unit 3 mounted on the carriage 110 is provided with two nozzle rows NL. Here, the nozzle row NL is a plurality of nozzles N arranged to extend in a row in a predetermined direction. In this embodiment, as an example, it is assumed that each nozzle row NL is composed of a plurality of nozzles N arranged so as to extend in the X-axis direction.

Further, hereinafter, of the two nozzle rows NL provided in the head unit 3, one nozzle row NL may be referred to as a nozzle row NL-1, and the other nozzle row NL may be referred to as a nozzle row NL-2. be. More specifically, in this embodiment, the nozzle row NL-1 is composed of a plurality of nozzles N arranged along an axis AX-1 parallel to the X-axis direction, and the nozzle row NL-2 is composed of: It is composed of a plurality of nozzles N provided along an axis AX-2 parallel to the X-axis direction and located in the +Y direction of the axis AX-1. That is, in the present embodiment, the head unit 3 has a total of M nozzles N, including a plurality of nozzles N belonging to the nozzle row NL-1 and a plurality of nozzles N belonging to the nozzle row NL-2.

<<2. Overview of the head unit >>
An outline of the head unit 3 will be described below with reference to FIGS. 5 to 7. FIG.

FIG. 5 is a block diagram showing an example of the configuration of the head unit 3. As shown in FIG.

As shown in FIG. 5, the head unit 3 has a supply circuit 31 and a recording head 32 . The head unit 3 also includes a wiring La to which the drive signal Com-A is supplied from the drive signal generation unit 4 and a wiring Lb to which the drive signal Com-B is supplied from the drive signal generation unit 4 .

As shown in FIG. 5, the supply circuit 31 includes M switches Wa[1] to Wa[M] corresponding to the M ejection portions D[1] to D[M], and M switches Wa[1] to Wa[M]. M switches Wb[1] to Wb[M] in one-to-one correspondence with the ejection units D[1] to D[M] of the above, and a connection state designation circuit 310 for designating the connection state of each switch Prepare.
The connection state designating circuit 310 designates the ON/OFF state of the switch Wa[m] based on at least part of the print signal SI, the latch signal LAT, and the change signal CH supplied from the control unit 2. A designation signal Qa[m] and a connection state designation signal Qb[m] for designating ON/OFF of the switch Wb[m] are generated.
The switch Wa[m] establishes electrical continuity between the wiring La and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the ejection portion D[m] based on the connection state designation signal Qa[m]. and switch non-conducting. In this embodiment, the switch Wa[m] is turned on when the connection state designation signal Qa[m] is at high level, and turned off when it is at low level. When the switch Wa[m] is turned on, the drive signal Com-A supplied to the wiring La is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m].
The switch Wb[m] establishes electrical continuity between the wiring Lb and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal Qb[m]. and switch non-conducting. In this embodiment, the switch Wb[m] is turned on when the connection state designation signal Qb[m] is at high level, and turned off when it is at low level. When the switch Wb[m] is turned on, the drive signal Com-B supplied to the wiring Lb is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the discharge section D[m].

Next, the operation of the head unit 3 will be described with reference to FIGS. 6 and 7. FIG.

In this embodiment, when the inkjet printer 1 performs the medium printing process or the flushing process, one or more unit periods TP are set as the operating period of the inkjet printer 1 . The inkjet printer 1 according to the present embodiment can drive each discharge section D[m] for the medium printing process or the flushing process in each unit period TP. Note that, hereinafter, the unit period TP during which the medium printing process is executed is sometimes referred to as a printing unit period TPP, and the unit period TP during which the flushing process is executed is sometimes referred to as a flushing unit period TPF.

FIG. 6 is a timing chart showing various signals such as the drive signal Com supplied to the head unit 3 in the unit period TP.

As shown in FIG. 6, the control unit 2 outputs a latch signal LAT with pulses PLL. Thereby, the control unit 2 defines the unit period TP as the period from the rise of the pulse PLL to the rise of the next pulse PLL.
The control unit 2 also outputs a change signal CH having a pulse PLC1 and a pulse PLC2 in the unit period TP. The control unit 2 divides the unit period TP into a drive period TQ1 from the rise of the pulse PLL to the rise of the pulse PLC1, a drive period TQ2 from the rise of the pulse PLC1 to the rise of the pulse PLC2, and a pulse from the rise of the pulse PLC2. and a drive period TQ3 until the PLL rises.

The print signal SI according to the present embodiment includes M individual designation signals Sd[1] to Sd[M] corresponding one-to-one with the M ejection units D[1] to D[M]. The individual designation signal Sd[m] designates the driving mode of the discharge section D[m] in each unit period TP when the inkjet printer 1 executes the medium printing process or the flushing process.
As shown in FIG. 6, the control unit 2 connects the print signal SI including M individual designation signals Sd[1] to Sd[M] in synchronization with the clock signal CL prior to each unit period TP. It is supplied to the state specifying circuit 310 . Then, the connection state designation circuit 310 generates the connection state designation signal Qa[m] and the connection state designation signal Qb[m] based on the individual designation signal Sd[m] in the unit period TP.

In this embodiment, during the printing unit period TPP, which is the unit period TP during which the medium printing process is executed, the ejection section D[m] uses a large dot made of ink with an ink amount ξ1 and an ink amount smaller than ξ1. It is assumed that any dot Dt can be formed between a medium dot made of ink with an ink amount ξ2 and a small dot made of ink with an ink amount ξ3 smaller than the ink amount ξ2. In addition, hereinafter, when the unit period TP is the printing unit period TPP, the discharge section D may be referred to as a print discharge section DP.

Also, in this embodiment, it is assumed that the discharge section D[m] can discharge ink of the ink amount ξ4 in the flushing unit period TPF, which is the unit period TP during which the flushing process is performed. In addition, hereinafter, when the unit period TP is the flushing unit period TPF, the ejection section D may be referred to as a flushing target ejection section DF.

FIG. 7 is an explanatory diagram for explaining the individual designation signal Sd[m].

As shown in FIG. 7, in the present embodiment, the individual designation signal Sd[m] causes the discharge section D[m] to form a large dot during the unit period TPP during which the medium print process is executed. A value of "1" for designating the section DP-1, a value of "2" for designating the discharging section D[m] as the medium dot forming discharging section DP-2, and a value of "2" for designating the discharging section D[m] as the small dot forming discharging section DP One of the four values, the value "3" to specify as -3 and the value "4" to specify the discharge section D[m] as the non-dot formation discharge section DP-N can take Here, the large dot formation ejection section DP-1 is the print ejection section DP that forms a large dot in the printing unit period TPP. Also, the medium-dot formation ejection unit DP-2 is a print ejection unit DP that forms a medium dot in the printing unit period TPP. Also, the small dot formation ejection section DP-3 is a print ejection section DP that forms a small dot in the print unit period TPP. Also, the non-dot-forming ejecting portion DP-N is a printing ejecting portion DP that does not form dots in the printing unit period TPP.
In the following description, in the printing unit period TPP, the ejection unit D is driven as a large dot formation ejection unit DP-1, a medium dot formation ejection unit DP-2, or a small dot formation ejection unit DP-3, and The process of ejecting ink from the portion D may be referred to as an ink ejection process. That is, in this embodiment, the media printing process includes one or more ink ejection processes. Note that the ink ejection process is an example of the "ejection process."

As shown in FIG. 7, in the present embodiment, the individual designation signal Sd[m] designates the ejection section D[m] as the ink discharge target ejection section in the flushing unit period TPF, which is the unit period TP during which the flushing process is executed. Select one of two values, the value "5" designated as DF-1 and the value "6" designated as the discharge section D[m] as the ink discharge restricted discharge section DF-N. can take Here, the ink ejection target ejection portion DF-1 is the flushing target ejection portion DF that ejects the ink in the flushing unit period TPF. In addition, the limited ink ejection portion DF-N is a flushing target ejection portion DF that does not eject ink during the flushing unit period TPF.

Returning the description to FIG.
As shown in FIG. 6, in this embodiment, the drive signal Com-A has a waveform PA1 provided in the drive period TQ1, a waveform PA2 provided in the drive period TQ2, and a waveform PA3 provided in the drive period TQ3. and have

Among them, the waveform PA1 is a waveform that returns from the reference potential V0 to the reference potential V0 via the potential VLA1 that is lower than the reference potential V0 and the potential VHA1 that is higher than the reference potential V0. When the supply drive signal Vin[m] having the waveform PA1 is supplied to the ejection section D[m], the waveform PA1 is set so that the ejection section D[m] ejects ink corresponding to the ink amount φ1. Determined.
A waveform PA2 is a waveform that returns from the reference potential V0 to the reference potential V0 via a potential VLA2 that is lower than the reference potential V0 and a potential VHA2 that is higher than the reference potential V0. When the supply drive signal Vin[m] having the waveform PA2 is supplied to the ejection section D[m], the waveform PA2 is set so that the ejection section D[m] ejects ink corresponding to the ink amount φ2. Determined.
A waveform PA3 is a waveform that returns from the reference potential V0 to the reference potential V0 via a potential VLA3 that is lower than the reference potential V0 and a potential VHA3 that is higher than the reference potential V0. When the supply drive signal Vin[m] having the waveform PA3 is supplied to the ejection section D[m], the waveform PA3 is set so that the ejection section D[m] ejects ink corresponding to the ink amount φ3. Determined.
In the following description, waveform PA1, waveform PA2, and waveform PA3 may be collectively referred to as waveform PAA.

In the present embodiment, as an example, when the potential of the supply drive signal Vin[m] supplied to the ejection section D[m] is high, the potential of the ejection section D[m] is higher than when it is low. Assume that the volume of the cavity CV provided is small. Therefore, when the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 or the like, the potential of the supply drive signal Vin[m] changes from a low potential to a high potential, thereby The ink in the portion D[m] is ejected from the nozzle N.

As shown in FIG. 6, in this embodiment, the drive signal Com-B has a waveform PB1 provided in the drive period TQ1, a waveform PB2 provided in the drive period TQ2, and a waveform PB3 provided in the drive period TQ3. and have

Among these waveforms, the waveform PB1 consists of the reference potential V0, a potential VLB1 lower than the reference potential V0 and higher than the potential VLA1, and a potential higher than the reference potential V0 but lower than the potential VHA1. , the waveform returns to the reference potential V0 after passing through the potential VHB1. When the supply drive signal Vin[m] having the waveform PB1 is supplied to the ejection section D[m], the waveform PB1 is set so that the ejection section D[m] ejects ink corresponding to the ink amount φ4. Determined. In this embodiment, it is assumed that the ink amount φ4 is less than the ink amount φ1.
Further, the waveform PB2 is formed from the reference potential V0, a potential VLB2 lower than the reference potential V0 and higher than the potential VLA2, and a potential higher than the reference potential V0 but lower than the potential VHA2. It is a waveform returning to the reference potential V0 via the potential VHB2. When the supply drive signal Vin[m] having the waveform PB2 is supplied to the ejection section D[m], the waveform PB2 is set so that the ejection section D[m] ejects ink corresponding to the ink amount φ5. Determined. In this embodiment, it is assumed that the ink amount φ5 is less than the ink amount φ2.
Further, the waveform PB3 is formed from the reference potential V0, a potential VLB3 lower than the reference potential V0 and higher than the potential VLA3, and a potential higher than the reference potential V0 but lower than the potential VHA3. It is a waveform returning to the reference potential V0 via the potential VHB3. The waveform PB3 is determined so that ink is not ejected from the ejection section D[m] when the supply drive signal Vin[m] having the waveform PB3 is supplied to the ejection section D[m].

In this embodiment, the ink amount ξ1 corresponds to the total amount of the ink amounts φ1, φ2, and φ3, and the ink amount ξ2 corresponds to the total amount of the ink amounts φ1 and φ2. , the ink amount .xi.3 corresponds to the total amount of the ink amounts .phi.4 and .phi.5, and the ink amount .xi.4 corresponds to the total amount of the ink amounts .phi.1, .phi.2 and .phi.3.

As shown in FIG. 7, when the individual designation signal Sd[m] indicates a value "1" for designating the ejection unit D[m] as the large dot formation ejection unit DP-1 in the printing unit period TPP, the connection state is specified. The circuit 310 sets the connection state designation signal Qa[m] to high level during the drive periods TQ1, TQ2, and TQ3. In this case, the switch Wa[m] is turned on for the print unit period TPP. Therefore, the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveforms PA1, PA2, and PA3 in the printing unit period TPP, and the ink amount ξ1 corresponding to the large dot is to dispense.
Further, when the individual designation signal Sd[m] indicates a value “2” for designating the discharge section D[m] as the medium dot formation discharge section DP-2 in the printing unit period TPP, the connection state designation circuit 310 The state designating signal Qa[m] is set to high level during the driving period TQ1 and the driving period TQ2. In this case, the switch Wa[m] is turned on during the driving period TQ1 and the driving period TQ2. Therefore, the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveforms PA1 and PA2 in the printing unit period TPP, and ejects ink of the ink amount ξ2 corresponding to the medium dot.
Further, when the individual designation signal Sd[m] indicates a value "3" for designating the discharge unit D[m] as the small dot formation discharge unit DP-3 in the printing unit period TPP, the connection state designation circuit 310 The state designation signal Qb[m] is set to high level during the drive period TQ1 and the drive period TQ2. In this case, the switch Wb[m] is turned on during the drive period TQ1 and the drive period TQ2. Therefore, the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveforms PB1 and PB2 during the print unit period TPP, and ejects ink in an amount ξ3 corresponding to a small dot.
Further, when the individual designation signal Sd[m] indicates a value "4" for designating the discharge section D[m] as the non-dot-forming discharge section DP-N in the printing unit period TPP, the connection state designation circuit 310 The state designation signal Qa[m] is set to low level for the print unit period TPP, and the connection state designation signal Qb[m] is set to high level during the driving period TQ3. In this case, the switch Wa[m] is turned off during the print unit period TPP, and the switch Wb[m] is turned off during the driving period TQ1 and the driving period TQ2. Therefore, the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveform PB3 in the printing unit period TPP, but does not eject ink.

Further, when the individual designation signal Sd[m] indicates a value “5” that designates the discharge section D[m] as the ink discharge target discharge section DF-1 in the flushing unit period TPF, the connection state designation circuit 310 The state designation signal Qa[m] is set to a high level during the driving periods TQ1, TQ2, and TQ3. In this case, the switch Wa[m] is turned on for the flushing unit period TPF. Therefore, the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveforms PA1, PA2, and PA3 in the flushing unit period TPF, and ejects the ink amount ξ4.
Further, when the individual designation signal Sd[m] indicates a value “5” that designates the discharge section D[m] as the ink discharge limited discharge section DF-N in the flushing unit period TPF, the connection state designation circuit 310 The state designation signal Qa[m] is set to low level for the flushing unit period TPF, and the connection state designation signal Qb[m] is set to high level during the drive period TQ3. Therefore, the ejection section D[m] does not eject ink in the flushing unit period TPF, although it is driven by the supply drive signal Vin[m] having the waveform PB3.

<<3. Print Job >>
A print job according to the present embodiment and a flushing process executed along with execution of the print job will be described below with reference to FIGS. 8 to 14 .

FIG. 8 is an explanatory diagram for explaining an example of a print job according to this embodiment.

Here, a print job is a process including one or more media print processes.
Specifically, in this embodiment, it is assumed that the print job is a process including WJ times of medium print processes. In other words, in the present embodiment, it is assumed that the print job is a process of forming an image indicated by the print data Img on WJ sheets of recording paper PP. Here, the value WJ is a natural number of 1 or more and indicates the number of sheets of recording paper PP on which the image indicated by the print data Img is to be formed. The value WJ may be a value specified by the user of the inkjet printer 1, for example.
In addition, hereinafter, the period during which the print job is executed in the operation period of the inkjet printer 1 may be referred to as the print job period TJ.

Further, in this embodiment, it is assumed that WJ times of medium print processing included in a print job are divided into one or more times of print processing. Here, the print process is a process including K or less unit print processes. Here, the value K is a natural number of 1 or more. A unit print process is a process including L medium print processes. Here, the value L is a natural number of 1 or more. In other words, the print process is a process including K*L or less media print processes.

Hereinafter, the period during which print processing is executed in the print job period TJ may be referred to as a print execution period TT. Also, hereinafter, the period during which the k-th unit print process is executed in the print execution period TT may be referred to as a unit print control period TK(k). Here, the variable k is a natural number that satisfies 1≤k≤K. Note that the unit print control period TK(k) is an example of the "control period".

Also, in this embodiment, it is assumed that the flushing process is executed each time one or more print processes included in a print job are completed. Further, in the present embodiment, it is assumed that maintenance processing including flushing processing is executed before the print job is started and after the print job is finished. Note that in the present embodiment, the flushing process included in the maintenance process executed after the end of the print job also serves as the flushing process executed after the last print process of the print job ends.
Hereinafter, the period during which maintenance processing is performed before the print job is started may be referred to as maintenance period TM1, and the period during which maintenance processing is performed after the print job is finished may be referred to as maintenance period TM2.

In the example shown in FIG. 8, it is assumed that the user of the inkjet printer 1 designates "36" as the value WJ. Further, in this embodiment, as an example, it is assumed that the value L is "2" and the unit print process is composed of two medium print processes. That is, in this embodiment, as an example, it is assumed that an image indicated by the print data Img is formed on two sheets of recording paper PP in the unit print process. Further, in this embodiment, as an example, it is assumed that the value K is "7" and the print process is composed of unit print processes of 7 times or less. That is, in this embodiment, as an example, it is assumed that an image indicated by the print data Img is formed on 14 or less sheets of recording paper PP in the unit printing process.
More specifically, in the example shown in FIG. 8, the print job includes a print process consisting of 7 unit print processes, a print process consisting of 7 unit print processes, and a print process consisting of 4 unit print processes. It is assumed that three print processes are included, including a print process consisting of processes. Hereinafter, the period during which the first print process is executed out of the three print processes is called a print execution period TT(1), and the period during which the second print process is executed is called a print execution period TT(2). , and the period during which the third print process is executed is called a print execution period TT(3). In the example shown in FIG. 8, the print execution period TT(1) includes seven unit print control periods TK(1) to TK( 7), and the print execution period TT(2) includes seven unit print control periods TK(1) to TK(7) corresponding to the seven unit print processes executed in the print execution period TT(2). ), and the print execution period TT(3) includes four unit print control periods TK(1) to TK(4) corresponding to the four unit print processes executed in the print execution period TT(3). consists of

Hereinafter, when the print execution period TT is composed of K unit print control periods TK(1) to TK(K), the print execution period TT may be referred to as a reference print period TTJ. In the example shown in FIG. 8, the print execution period TT(1) and the print execution period TT(2) composed of seven unit print control periods TK(1) to TK(7) correspond to the reference print period TTJ. .
Note that in the present embodiment, the reference printing period TTJ is an example of the "printing period". Also, the value K is an example of the "predetermined number".

Also, hereinafter, the period during which the flushing process is executed after the print process included in the print job is sometimes referred to as a flushing period TF. In the example shown in FIG. 8, the period during which the flushing process is executed after the printing process executed in the printing execution period TT(1) is called a flushing period TF(1), and the printing execution period TT(2) is called a flushing period TF(1). The period during which the flushing process is executed after the end of the print process executed is called a flushing period TF(2), and the flushing process is performed during the maintenance process after the end of the print process executed in the print execution period TT(3). is called a flushing period TF(3). In the example shown in FIG. 8, the flushing period TF(3) is included in the maintenance period TM2.

Hereinafter, the emission amount determination process will be described with reference to FIGS. 9 to 12. FIG.

Here, the discharge amount determination process is a process of determining the discharge control value RS[m] based on the reference discharge value RK and the actual discharge value RT[m].

Among these, the discharge control value RS[m] is a value that defines the amount of ink discharged from the discharge section D[m] in the flushing process. Also, the reference discharge value RK is the amount of ink discharged from the ejection unit D[m] in the flushing process that is executed after the end of the printing process, assuming that no ink is ejected from the ejection part D[m] in the printing process. A value that defines the amount of ink to be printed. In other words, when ink is not ejected from the ejection section D[m] in the printing process and the ink in the ejection section D[m] increases in viscosity, the ink of the reference ejection value RK is ejected from the ejection section D[m]. As a result, the thickened ink in the ejection part [m] is discharged, and the ink in the ejection part [m] is refreshed to the non-thickened ink. Further, the actual ejection value RT[m] is a value that defines the amount of ink ejected from the ejection section D[m] in the printing process.
Specifically, in the present embodiment, the ejection control value RS[m] indicates the number of times the ejection section D[m] is driven as the ink ejection target ejection section DF-1 to eject ink in the flushing process. Further, in the present embodiment, the reference discharge value RK is set so that when it is assumed that no ink is discharged from the discharge portion D[m] in the printing process, the discharge portion D[m] is the ink discharge target discharge portion DF in the flushing process. -1 indicates the number of times it is driven to eject ink. Further, in the present embodiment, the actual ejection value RT[m] is the amount of ink ejected from the ejection section D[m] in the printing process, and the ink ejection target ejection section DF-1 in the flushing process. A value obtained by dividing by the ejected ink amount ξ4 is shown. However, the present invention is not limited to such an aspect. For example, the discharge control value RS[m] may be a value indicating the amount of ink discharged from the ejection section D[m] in the flushing process. Similarly, the reference discharge value RK and the actual discharge value RT[m] may also be values indicating the amount of ink. Note that the number of times the ejection section D[m] is driven as the ink ejection target ejection section DF-1 in the flushing process to eject ink is, for example, the supply drive signal supplied to the ejection section D[m] in the flushing process. It can be the number of flushing unit periods TPF of Vin.

FIG. 9 is an explanatory diagram for explaining the reference emission value RK.

As shown in FIG. 9, in this embodiment, the reference emission value RK(k) is a value obtained by adding the adjusted emission value RC(k) to the initial emission value Rini when k=1. Further, the reference emission value RK(k) is a value obtained by adding the adjustment emission value RC(k) to the reference emission value RK(k-1) when k≧2.

Here, the adjusted discharge value RC(k) is an example of a "first adjustment value" and is a positive real number predetermined for the unit print control period TK(k). Specifically, the adjusted emission value RC(k) is a real number that satisfies "RC(1)>0" when k=1. Further, the adjusted emission value RC(k) is a real number that satisfies "RC(k)>0" and "RC(k)>RC(k-1)" when k≧2. However, the adjusted emission value RC(k) may be a real number that satisfies "RC(k)>0" and "RC(k)≧RC(k-1)" when k≧2.
In this embodiment, as an example, it is assumed that the memory provided in the control unit 2 stores the adjusted discharge values RC(1) to RC(K).

In this embodiment, the reference emission value RK(k) satisfies "RK(1)=Rini+RC(1)" when k=1. Here, the initial discharge value Rini is a real number that satisfies "Rini>0". In this embodiment, as an example, it is assumed that the initial emission value Rini is equal to the minimum emission value Rmin. Here, the minimum discharge value Rmin is a real number that satisfies "Rmin>0" and is the minimum value of the amount of ink discharged from the discharge section D[m] in the flushing process executed after the printing process. For example, the minimum discharge value Rmin may be a value corresponding to the time required for the carriage 110 to move from its position at the end of the printing process to the position corresponding to the discharged ink receiving portion 80 . More specifically, the minimum discharge value Rmin occurs during the period in which the carriage 110 is moving from the position at the end of the printing process to the position corresponding to the discharge ink receiving portion 80. It may be a value that defines the amount of ink discharged from the ejection section D[m], which is necessary to restore the thickened ink inside to a normal state.
Further, in the present embodiment, the reference emission value RK(k) satisfies "RK(k)=RK(k-1)+RC(k)" when k≧2.

FIG. 10 is an explanatory diagram for explaining the actual discharge value RT[m].

As shown in FIG. 10, in the present embodiment, the control unit 2 specifies the actual discharge value RT[m] in each of the unit print control period TK(1) to the unit print control period TK(K). Hereinafter, the actual discharge value RT[m] specified by the control unit 2 in the unit print control period TK(k) will be referred to as the actual discharge value RT[m](k). For example, in the example shown in FIG. 10, the discharge section D[m] is in the unit print control periods TK(2), TK(4), and TK among the unit print control periods TK(1) to TK(7). Ink is ejected in (6), and ink is not ejected in other unit print control periods TK(k). That is, in the example shown in FIG. 10, the actual discharge value RT[m](1) specified in the unit print control period TK(1) satisfies "RT[m](1)=0", and the unit print control period The actual ejection value RT[m](2) specified in TK(2) satisfies "RT[m](2)>0", and the actual ejection value RT[ m](3) satisfies "RT[m](3)=0", and the actual discharge value RT[m](4) specified in the unit print control period TK(4) is "RT[m](4 )>0”, the actual discharge value RT[m](5) specified in the unit print control period TK(5) satisfies “RT[m](5)=0”, and the unit print control period TK( The actual ejection value RT[m](6) specified in 6) satisfies "RT[m](6)>0", and the actual ejection value RT[ m](7) satisfies "RT[m](7)=0". In this embodiment, as an example, the control unit 2, based on a plurality of individual designation signals Sd[m] included in the print signal SI supplied to the head unit 3 in the unit print control period TK(k), It is assumed that the actual discharge value RT[m](k) is specified. Note that, in the present embodiment, the actual ejection value RT[m](k) is an example of the “second adjustment value”.

FIG. 11 is an explanatory diagram for explaining the emission control value RS[m].

As shown in FIG. 11, in this embodiment, the control unit 2 updates the discharge control value RS[m] in each of the unit print control period TK(1) to the unit print control period TK(K).

Specifically, when k=1, the control unit 2 adds the adjusted discharge value RC(k) to the initial discharge value Rini and subtracts the actual discharge value RT[m](k), It is calculated as a provisional calculated value RZ[m](k). Further, when k≧2, the control unit 2 adds the adjusted discharge value RC(k) to the discharge control value RS[m](k-1), and sets the actual discharge value RT[m](k) to The subtracted value is calculated as the provisional calculated value RZ[m](k). Note that, in the present embodiment, the provisional calculated value RZ[m](k) is an example of the "calculated value".
Then, when the provisional calculated value RZ[m](k) is equal to or greater than the minimum emission value Rmin, the control unit 2 determines the provisional calculated value RZ[m](k) as the emission control value RS[m](k). do. On the other hand, when the provisional calculated value RZ[m](k) is less than the minimum emission value Rmin, the control unit 2 determines the minimum emission value Rmin as the emission control value RS[m](k).

In the following, the process of updating the emission control value RS[m] in the unit print control period TK(k) in the emission amount determination process will be referred to as the emission control value updating process. The emission control value update process is an example of "update process". In the following, the initial emission value Rini when k=1 and the emission control value RS[m](k-1) when k≧2 are defined as the pre-update emission control value RP[m](k) may be collectively referred to as That is, hereinafter, the initial emission value Rini is expressed as the pre-update emission control value RP[m](1), and the emission control value RS[m](k-1) is expressed as the pre-update emission control value RP[m] Sometimes expressed as (k). Note that the control unit 2 stores the pre-update emission control value RP[m](k) in the memory.

In this embodiment, when the print execution period TT is the reference print period TTJ, the control unit 2 prints the emission control value RS[m](K) updated in the unit print control period TK(K). It is determined as a value that indicates the amount of ink discharged from the discharge section D[m] in the flushing process that is executed after the execution period TT ends. For example, in the example shown in FIG. 8, the discharge control value RS[m](7) updated in the unit print control period TK(7) of the print execution period TT(1) is executed in the flushing period TF(1). The ejection control value is determined as a value indicating the amount of ink ejected from the ejection unit D[m] in the flushing process, and updated in the unit print control period TK(7) of the print execution period TT(2). RS[m](7) is determined as a value indicating the amount of ink discharged from the ejection portion D[m] in the flushing process executed in the flushing period TF(2).
Further, when the print execution period TT is not the reference print period TTJ, the control unit 2 determines the discharge control value RS[m](k) updated in the last unit print control period TK(k) of the print execution period TT. is determined as a value indicating the discharge amount of ink from the discharge section D[m] in the flushing process executed after the end of the print execution period TT. For example, in the example shown in FIG. 8, the discharge control value RS[m](4) updated in the unit print control period TK(4) of the print execution period TT(3) is executed in the flushing period TF(3). It is determined as a value indicating the discharge amount of ink from the ejection portion D[m] in the flushing process performed.

FIG. 12 is a flow chart showing the operation of the control unit 2 when the discharge amount determination process is executed during the print execution period TT.

As shown in FIG. 12, the control unit 2 first sets "1" to the variable k in the emission amount determination process (S101).
Next, the control unit 2 refers to the memory to specify a predetermined adjusted discharge value RC(k) corresponding to the unit print control period TK(k) (S103).

Next, the control unit 2 sets "1" to the variable m (S105).
Then, based on the individual designation signal Sd[m] included in the print signal SI supplied to the head unit 3 in the unit print control period TK(k), the control unit 2 determines the actual ejection value RT[m](k) is specified (S107).
The control unit 2 also refers to the memory to specify the pre-update emission control value RP[m](k) (S109).

Then, the control unit 2 determines the adjusted discharge value RC(k) specified in step S103, the actual discharge value RT[m](k) specified in step S107, and the pre-update emission control value RP[ m](k), a provisional calculated value RZ[m](k) is calculated (S111).
Specifically, in step S111, when the variable k is "1", the control unit 2 adds the adjusted discharge value RC(1) to the initial discharge value Rini, and adds the actual discharge value RT[m] A provisional calculated value RZ[m](1) is calculated by subtracting (1). Further, in step S111, the control unit 2 adds the adjusted emission value RC(k) to the emission control value RS[m](k-1) when the variable k satisfies "k≧2", and A provisional calculated value RZ[m](k) is calculated by subtracting the actual discharge value RT[m](k).

Next, the control unit 2 determines whether or not the temporary calculated value RZ[m](k) calculated in step S111 is equal to or greater than the minimum discharge value Rmin (S113).
Then, if the result of the determination in step S113 is affirmative, the control unit 2 sets the provisional calculated value RZ[m](k) to the emission control value RS[m](k) so that the emission control value RS[ m] is updated (S115). On the other hand, if the result of determination in step S113 is negative, the control unit 2 updates the emission control value RS[m] by setting the minimum emission value Rmin to the emission control value RS[m](k) ( S117). In this embodiment, the control unit 2 stores the emission control value RS[m](k) updated in step S115 or step S117 in memory as the pre-update emission control value RP[m](k+1). Store.

After that, the control unit 2 determines whether or not the variable m satisfies "m=M" (S119).
Then, when the determination result in step S119 is affirmative, the control unit 2 advances the process to step S123. On the other hand, if the determination result in step S119 is negative, the control unit 2 adds "1" to the variable m (S121), and advances the process to step S107.

After that, the control unit 2 determines whether or not the print job has ended (S123).
Then, when the determination result in step S123 is affirmative, the control unit 2 terminates the emission amount determination process. On the other hand, if the determination result in step S123 is negative, the control unit 2 advances the process to step S125.

After that, the control unit 2 determines whether or not the variable k satisfies "k=K" (S125).
Then, when the result of determination in step S125 is affirmative, the control unit 2 terminates the emission amount determination process. On the other hand, if the result of determination in step S125 is negative, the control unit 2 adds "1" to the variable k (S127), and advances the process to step S103.

Note that the processing of steps S107 to S117 in the emission amount determination processing shown in FIG. 12 corresponds to the emission control value update processing.

A specific example of the emission control value RS[m](k) determined in the emission amount determination process will be described below with reference to FIGS. 13 and 14. FIG.

13 and 14, as in FIGS. 9 to 11, it is assumed that the value WJ is "36", the value L is "2", and the value K is "7". Also, in FIGS. 13 and 14, it is assumed that there are adjusted emission values RC(1) to RC(7) and reference emission values RK(1) to RK(7) similar to those in FIG.

Further, in FIG. 13, among the actual ejection values RT[m](1) to RT[m](7), the actual ejection value RT[m](3) is a specific value RT0, and the actual ejection value RT It is assumed that the values other than [m](3) are "0". In FIG. 13, it is assumed that the provisional calculated value RZ[m](3) is less than the minimum emission value Rmin.
Further, in FIG. 14, among the actual discharge values RT[m](1) to RT[m](7), the actual discharge value RT[m](6) is a specific value RT0, and the actual discharge value RT It is assumed that the values other than [m](6) are "0". In FIG. 14, it is assumed that the provisional calculated value RZ[m](6) is equal to or greater than the minimum emission value Rmin.

As in the example shown in FIG. 13, when the provisional calculated value RZ[m](3) is less than the minimum emission value Rmin, the emission control value RS[m](3) becomes the minimum emission value Rmin. That is, in the example shown in FIG. 13, the amount of decrease of the emission control value RS[m](3) with respect to the emission control value RS[m](2) is a value RT1 smaller than the value RT0. Therefore, in the example shown in FIG. 13, the discharge control value RS[m](7) in the unit print control period TK(7) in which the printing process ends is a value RT1 smaller than the reference discharge value RK(7). RS2.
On the other hand, as in the example shown in FIG. 14, when the provisional calculated value RZ[m](6) is greater than or equal to the minimum emission value Rmin, the emission control value RS[m](6) is the provisional calculated value RZ[m](6). That is, in the example shown in FIG. 14, the reduction width of the emission control value RS[m](6) with respect to the emission control value RS[m](5) is equal to the value RT0. Therefore, in the example shown in FIG. 14, the discharge control value RS[m](7) in the unit print control period TK(7) in which the printing process ends is a value RT0 smaller than the reference discharge value RK(7). RS3. Here, the value RS3 is smaller than the value RS2.

In the examples shown in FIGS. 13 and 14, the length of time from the end of the unit print control period TK(3) in which the print process is executed to the start of the flushing process executed after the end of the print process is It is longer than the length of time from the end of the unit print control period TK(6) during which the process is executed to the start of the flushing process executed after the end of the print process. Therefore, as in the example shown in FIG. 13, when ink corresponding to the value RT0 is ejected in the unit print control period TK(3), as in the example shown in FIG. 14, in the unit print control period TK(6) At the time when the flushing process is started after the end of the printing process, the thickening of the ink in the ejection part D[m] progresses compared to the case where the ink corresponding to the value RT0 is ejected. That is, when ink corresponding to the value RT0 is ejected in the unit print control period TK(3) as in the example shown in FIG. 13, the value In the flushing process after the end of the printing process, it is preferable to discharge more ink from the discharge section D[m] than in the case of discharging ink according to RT0. In other words, as in the example shown in FIG. 14, when ink corresponding to the value RT0 is ejected in the unit print control period TK(6), as in the example shown in FIG. 13, the unit print control period TK(3) , it is possible to reduce the amount of ink discharged from the discharge section D[m] in the flushing process after the end of the printing process, compared to the case where the ink corresponding to the value RT0 is discharged.

Thus, in this embodiment, as in the examples shown in FIGS. 13 and 14, the value RS2 can be made larger than the value RS3. That is, in this embodiment, as in the example shown in FIG. 13, when ink corresponding to the value RT0 is ejected in the unit print control period TK(3), as in the example shown in FIG. 14, the unit print control period TK Compared to the case of ejecting ink according to the value RT0 in (7), it is possible to increase the discharge amount of ink in the flushing process after the printing process is completed. In other words, in the present embodiment, as in the example shown in FIG. 14, when ink corresponding to the value RT0 is ejected in the unit print control period TK(6), as in the example shown in FIG. Compared to the case where ink corresponding to the value RT0 is ejected in the period TK(3), the amount of ink discharged in the flushing process after the end of the printing process can be reduced. Therefore, in the present embodiment, it is possible to discharge in the flushing process an amount of ink corresponding to the degree of thickening of the ink in the discharge section D[m] at the time the flushing process is started. .

A specific example of the emission control value RS[m](k) determined in the emission amount determination process according to the reference example will be described below with reference to FIGS. 15 and 16. FIG.

15 and 16, similar to FIGS. 13 and 14, the value WJ is "36", the value L is "2", and the value K is "7". Suppose.

Further, in the reference examples shown in FIGS. 15 and 16, when the adjusted emission values RC(1) to RC(7) are "0", for example, the reference emission values RK(1) to RK(7) are constant. is the value Rmax of .

Among the reference examples, FIG. 15 shows that among the actual ejection values RT[m](1) to RT[m](7), the actual ejection value RT[m](3) is a specific value RT0, and the actual ejection value RT[m](3) Assume that the values other than the actual value RT[m](3) are "0". In FIG. 15, it is assumed that the provisional calculated value RZ[m](3) is equal to or greater than the minimum emission value Rmin.
Further, in FIG. 16, among the actual ejection values RT[m](1) to RT[m](7), the actual ejection value RT[m](6) is a specific value RT0, and the actual ejection value RT It is assumed that the values other than [m](6) are "0". In FIG. 16, it is assumed that the provisional calculated value RZ[m](6) is equal to or greater than the minimum emission value Rmin.

15, and the emission control value RS[m](5) in the example shown in FIG. 16. The reduction width of the emission control value RS[m](6) with respect to is both the value RT0. For example, the emission control value RS[m](3) in the example shown in FIG. 15 and the emission control value RS[m](6) in the example shown in FIG. 16 are both the value RS4. Therefore, both the emission control value RS[m](7) in the example shown in FIG. 15 and the emission control value RS[m](7) in the example shown in FIG. 16 are the value RS4. However, as shown in FIG. 15, after the amount of ink of a specific value RT0 is ejected in the unit print control period TK(3), the unit print control period TK(4) to the flushing process is repeated in the unit print control period TK(7). The viscosity of the ink in the ejection portion D[m] when the actual ejection values RT[m](4) to RT[m](7) are "0" is shown in FIG. 16 during the unit print control period TK Ejection unit D when the actual ejection value RT[m](7) in the unit print control period TK(7) is "0" after ejecting the amount of ink of the specific value RT0 in (6) until the flushing process Higher than the viscosity of the ink within [m].

Therefore, as in the example shown in FIG. 15, when ink corresponding to the value RT0 is ejected in the unit print control period TK(3), as in the example shown in FIG. Compared to the case of ejecting ink according to RT0, it is not possible to increase the amount of ink ejected from the ejection section D[m] in the flushing process after the end of the printing process. In other words, as in the example shown in FIG. 16, when ink corresponding to the value RT0 is ejected in the unit print control period TK(6), as in the example shown in FIG. 15, the unit print control period TK(3) , the amount of ink discharged from the discharge section D[m] cannot be suppressed in the flushing process after the end of the printing process, compared to the case where the ink corresponding to the value RT0 is discharged. Thus, in the reference example, it is not possible to control the discharge amount of ink in the flushing process that is executed after the end of the printing process according to the timing at which the ink is ejected from the ejection unit D[m] in the printing process. .

On the other hand, in the present embodiment, as described above, the flushing process discharges an amount of ink corresponding to the degree of thickening of the ink in the ejection section D[m] at the time the flushing process is started. It becomes possible to Therefore, according to this embodiment, it is possible to reduce the possibility that an excessive amount of ink is ejected in the flushing process, as compared with the reference example.

<<4. Conclusion of Embodiment>>
As described above, in this embodiment, the head unit 3 has the nozzles N for ejecting ink, the cavities CV communicating with the nozzles N, and the piezoelectric elements PZ[m] for varying the pressure of the ink in the cavities CV. , and executes a printing process of forming an image on K*L pieces of recording paper PP by ejecting ink from the head unit 3 in consecutive unit print control periods TK(1) to TK(K). In the maintenance method 1, in the printing process, by driving the piezoelectric element PZ[m], the ink is ejected from the nozzle N and the ink is ejected to land the dot Dt on the recording paper PP. In each of the unit print control periods TK(1) to TK(K) during which the print process is executed, the discharge control value update process for updating the discharge control value RS[m] is executed. By driving PZ[m], the emission control value RS updated by the emission control value update processing in the last unit print control period TK(K) among the unit print control periods TK(1) to TK(K). Executes a flushing process that discharges an amount of ink corresponding to [m](K) from the nozzle N, and discharges in the unit print control period TK(k) among the unit print control periods TK(1) to TK(K). In the control value update process, the adjustment discharge value RC(k) determined for the unit print control period TK(k) is added to the discharge control value RS[m], and the unit print control period TK( k), the discharge control value RS[ m] is updated.

Therefore, according to the present embodiment, it is possible to discharge in the flushing process an amount of ink corresponding to the ink discharge timing from the discharge section D[m] in the printing process before the flushing process is started. Become. In other words, according to the present embodiment, it is possible to discharge the amount of ink in the flushing process according to the degree of thickening of the ink in the ejection section D[m] at the time the flushing process is started. Become. Therefore, according to the present embodiment, as in the reference example, in the flushing process, the print process before the start of the flushing process is performed without considering the ink ejection timing in the print process before the start of the flushing process. Reduce the possibility of discharging an excessive amount of ink in the flushing process, compared to the mode in which the amount of ink corresponding to the total amount of ink discharged from the discharge part D[m] is discharged in the flushing process. can do.

Further, in the present embodiment, in the discharge control value updating process in the unit print control period TK(k), if the provisional calculated value RZ[m](k) is equal to or greater than the minimum discharge value Rmin larger than 0, the discharge The control value RS[m] is updated to the provisional calculated value RZ[m](k), and if the provisional calculated value RZ[m](k) is less than the minimum emission value Rmin, the emission control value RS[m] is updated to the minimum emission value Rmin.

For this reason, according to the present embodiment, the flushing process discharges an amount of ink that takes into consideration the increase in viscosity that occurs in the ink in the ejection section D[m] during the period from the end of the printing process to the start of the flushing process. becomes possible.

Further, in the present embodiment, among the unit print control periods TK(1) to TK(K), the adjusted discharge value RC(k1) determined for the unit print control period TK(k1) is It is characterized by being smaller than the adjusted discharge value RC(k2) determined for the unit print control period TK(k2) after TK(k1). Here, the values k1 and k2 are natural numbers that satisfy "1≤k1<k2≤K".

Therefore, according to the present embodiment, the thickening of the ink in the ejection section D[m] during the period from the end of the printing process to the start of the flushing process is accurately reflected in the discharge amount of ink in the flushing process. becomes possible.

Further, in the present embodiment, the printing process is a process of forming an image on K*L sheets of recording paper PP, and the unit print control period TK(k) is set to L of the K*L sheets of recording paper PP. It is characterized by being a period during which an image is formed on a sheet of recording paper PP.

Therefore, according to the present embodiment, in the printing process, the ink discharge amount in the flushing process is determined in consideration of the ink ejection amount from the ejection unit D[m] in the unit print control period TK(k). It becomes possible to

In this embodiment, the printing process is repeatedly executed for each reference printing period TTJ consisting of K unit printing control periods TK(1) to TK(K), and the flushing process is performed after the reference printing period TTJ is completed. It is characterized in that it is executed when

Therefore, according to the present embodiment, it is possible to prevent excessive thickening of the ink in the ejection section D[m].

Further, in this embodiment, if the print processing ends before the K unit print control periods TK(1) to TK(K) elapse, the last unit print control period TK( A flushing process is performed after k) is completed.

Therefore, according to the present embodiment, even if the print execution period TT during which the print process is executed is different from the reference print period TTJ, regardless of the end timing of the print process, It is possible to discharge the thickened ink at .

<<B. Modification>>
Each of the above forms can be variously modified. Specific modification modes are exemplified below. Two or more aspects arbitrarily selected from the following examples can be combined as appropriate within a mutually consistent range. It should be noted that, in the modifications illustrated below, the reference numerals referred to in the above description will be used for the elements that have the same actions and functions as those of the embodiment, and the detailed description of each will be omitted as appropriate.

<<Modification 1>>
In the above-described embodiment, the adjusted emission value RC(k) is a real number that satisfies "RC(k)>0" and "RC(k)>RC(k-1)" for k≧2. However, the present invention is not limited to such an embodiment. For example, the adjusted emission value RC(k) may be a real number that satisfies "RC(k)>0" and "RC(k)=RC(k-1)" for k≧2.

FIG. 17 is an explanatory diagram for explaining the reference emission value RK according to Modification 1. As shown in FIG.

As shown in FIG. 17, in this modification, when k=1, the reference emission value RK(k) is obtained by adding the adjustment emission value RC(1) to the initial emission value Rini as in the above-described embodiment. value. Further, in this modification, when k≧2, the reference emission value RK(k) is obtained by adding the adjusted emission value RC(k) to the reference emission value RK(k-1) as in the above-described embodiment. value. Further, in this modified example, the adjusted emission value RC(k) is a real number that satisfies "RC(1)>0" when k=1. Further, in this modification, the adjusted emission value RC(k) is a real number that satisfies "RC(k)>0" and "RC(k)=RC(k-1)" when k≧2.

FIG. 18 is an explanatory diagram for explaining the emission control value RS[m] according to Modification 1. As shown in FIG.

As shown in FIG. 18, in this modification, the control unit 2 updates the discharge control value RS[m] in each of the unit print control period TK(1) to the unit print control period TK(K).
Specifically, when k=1, the control unit 2 adds the adjusted discharge value RC(k) to the initial discharge value Rini and subtracts the actual discharge value RT[m](k), It is calculated as a provisional calculated value RZ[m](k). Further, when k≧2, the control unit 2 adds the adjusted discharge value RC(k) to the discharge control value RS[m](k-1), and sets the actual discharge value RT[m](k) to The subtracted value is calculated as the provisional calculated value RZ[m](k).
Then, when the provisional calculated value RZ[m](k) is equal to or greater than the minimum emission value Rmin, the control unit 2 determines the provisional calculated value RZ[m](k) as the emission control value RS[m](k). do. On the other hand, when the provisional calculated value RZ[m](k) is less than the minimum emission value Rmin, the control unit 2 determines the minimum emission value Rmin as the emission control value RS[m](k).

In this modification, the control unit 2 updates the discharge control value RS[m](K) in the unit print control period TK(K) of the print execution period TT, or the last The discharge control value RS[m](k) updated in the unit print control period TK(k) is used as the discharge amount of ink from the discharge section D[m] in the flushing process executed after the end of the print execution period TT. is determined as a value that indicates For example, in the example shown in FIG. 18, the discharge control value RS[m](7) updated in the unit print control period TK(7) of the print execution period TT is applied to the flushing executed after the end of the print execution period TT. It is determined as a value indicating the amount of ink discharged from the ejection section D[m] in the process.

As described above, according to this modification, the adjusted discharge values RC(1) to RC(K) determined for the unit print control periods TK(1) to TK(K) included in the print execution period TT are equal to each other.

Therefore, according to this modified example, compared with the aspect in which the adjusted emission values RC(1) to RC(K) are different values, the emission control value RS[m] in the emission amount determination process is determined. It is possible to reduce the processing load.

<<Modification 2>>
In the above-described embodiment and modification 1, when a unit print process is composed of L medium print processes, that is, in a unit print control period TK(k) during which the unit print process is executed, L sheets of recording are performed. Although the case where an image is formed on the paper PP has been described as an example, the present invention is not limited to such an aspect. For example, a unit printing process may be composed of L carriage movement processes. That is, the movement of the carriage 110 may be performed L times during the unit print control period TK(k) during which the unit print process is performed.

That is, according to this modification, the printing process includes the ink ejection process, the carriage movement process, and the medium transport process, and the carriage movement process is the process of moving the head unit 3 along the Y-axis. The inkjet printer 1 executes the ink ejection process while executing the carriage movement process, the medium transport process is a process of transporting the recording paper PP along the X axis, and the unit print control period TK(k) is It is characterized by being a period during which the carriage movement process is executed L times.

For this reason, according to this modification, in the printing process, the amount of ink discharged from the ejection unit D[m] in the unit print control period TK(k) is taken into consideration to determine the amount of ink discharged in the flushing process. It becomes possible to

<<Modification 3>>
In the embodiment and Modifications 1 and 2 described above, the driving signal Com-A includes three ejection waveforms, the waveform PA1, the waveform PA2, and the waveform PA3, as ejection waveforms for ejecting ink from the nozzle N, Although the drive signal Com-B includes two ejection waveforms, the waveform PB1 and the waveform PB2, as an example, the present invention is not limited to such an aspect. For example, the drive signal Com may include at least one ejection waveform.

<<Modification 4>>
In the above-described embodiment and Modifications 1 to 3, the drive signal Com includes two signals, the drive signal Com-A and the drive signal Com-B, but the present invention is limited to such an aspect. not something.
For example, the drive signal Com may include only the drive signal Com-A and not the drive signal Com-B.
Further, for example, the drive signal Com may include, in addition to the drive signal Com-A and the drive signal Com-B, a drive signal having a waveform different from that of the drive signal Com-A and the drive signal Com-B.

<<Modification 5>>
In the embodiment and Modifications 1 to 4 described above, the ink jet printer 1 is assumed to have four head units 3, but the present invention is not limited to such an aspect. The inkjet printer 1 may include one or more and three or less head units 3 , or the inkjet printer 1 may include five or more head units 3 .

<<Modification 6>>
Although the above-described embodiment and modified examples 1 to 5 exemplify the case where the inkjet printer 1 is a serial printer, the present invention is not limited to such an aspect. The inkjet printer 1 may be a so-called line printer in which a plurality of nozzles N are provided in the head unit 3 so as to extend wider than the width of the recording paper PP.

REFERENCE SIGNS LIST 1 inkjet printer 2 control unit 3 head unit 4 drive signal generation unit 7 transport unit 8 maintenance unit 31 supply circuit 32 recording head D ejecting section N nozzle .

Claims (8)

a head unit having a nozzle for ejecting a liquid, a pressure chamber communicating with the nozzle, and a drive element for varying the pressure of the liquid in the pressure chamber;
A maintenance method for a liquid ejecting apparatus for executing a print process for forming an image on one or more media by ejecting liquid from the head unit in a plurality of consecutive control periods, the method comprising:
In the printing process, an ejection process is performed in which liquid is ejected from the nozzle by driving the drive element and droplets land on a medium;
executing an update process for updating an emission control value in each of the plurality of control periods in which the print process is executed;
After the printing process is finished, the drive element is driven to discharge the liquid from the nozzle in an amount corresponding to the discharge control value updated by the update process in the last control period among the plurality of control periods. perform the flushing process,
The update process in one control period among the plurality of control periods includes:
A first adjustment value determined for the one control period is added to the discharge control value, and the amount is determined according to the amount of liquid ejected from the nozzle during the one control period. A process of updating the emission control value to a value based on the calculated value obtained by subtracting the second adjustment value,
A maintenance method characterized by: In the update process in the one control period,
updating the emission control value to the calculated value if the calculated value is greater than or equal to a minimum emission value greater than 0;
updating the emission control value to the minimum emission value if the calculated value is less than the minimum emission value;
The maintenance method according to claim 1, characterized by: the plurality of first adjustment values determined for the plurality of control periods are equal to each other;
The maintenance method according to claim 1 or 2, characterized by: A first adjustment value determined for one control period among the plurality of control periods,
smaller than a first adjustment value determined for another control period after the one control period among the plurality of control periods;
The maintenance method according to claim 1 or 2, characterized by: The printing process is a process of forming images on a plurality of media,
The control period is a period during which an image is formed on a predetermined number of media out of the plurality of media.
5. The maintenance method according to any one of claims 1 to 4, characterized in that: The printing process includes
including the ejection process, the movement process, and the transport process,
The moving process includes
A process of moving the head unit along a first axis,
The liquid ejection device is
executing the ejection process while executing the movement process;
The transport process includes
A process of transporting the medium along a second axis that intersects the first axis;
The control period is a period during which the movement process is executed a predetermined number of times.
5. The maintenance method according to any one of claims 1 to 4, characterized in that: The printing process is repeatedly executed for each printing period consisting of a predetermined number of consecutive control periods,
The flushing process is executed when the printing period ends.
The maintenance method according to any one of claims 1 to 6, characterized in that: If the printing process ends before the predetermined number of control periods elapses,
the flushing process is executed after the end of the last control period in which the print process is executed;
The maintenance method according to claim 7, characterized by:

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