JP2018001560A - Liquid discharge device and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an occurrence of discharge abnormality which is unrecoverable even by maintenance processing when complementary printing is performed.SOLUTION: A liquid discharge device comprises: a plurality of discharge sections discharging liquid; a first recording head provided with a first discharge section; a second recording head provided with a second discharge section; a determination section determining discharge states of the liquid in the plurality of discharge sections; and a control section controlling the plurality of discharge sections. When the determination section determines a discharge state of the liquid in one discharge section provided on the first recording head to be abnormal, the control section can perform control by a first control mode for controlling the plurality of discharge sections so as to cause the liquid to be discharged from the first discharge section instead of discharging of the liquid from one discharge section until a first time period elapses from determination, and by a second control mode for controlling the plurality of discharge sections so as to cause the liquid to be discharged from the second discharge section instead of the discharging of the liquid from one discharge section until a second time period elapses from the determination. The first time period is shorter than the second time period.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a liquid ejection apparatus and a control method for the liquid ejection apparatus.

  A liquid ejection apparatus such as an ink jet printer performs a printing process for ejecting a liquid such as ink from each of a plurality of ejection units provided in a head unit and forming an image on a recording medium. In such a liquid ejecting apparatus, there is a case in which ejection abnormalities in which the liquid cannot be ejected normally from the ejecting unit may occur due to the viscosity of the liquid in the ejecting unit. When the ejection abnormality occurs, the dots that are scheduled to be formed on the recording medium cannot be accurately formed by the liquid ejected from the ejection unit, and the image quality of the image formed on the recording medium in the printing process is degraded. In order to prevent such deterioration in image quality due to an abnormal discharge, when a discharge abnormality occurs in one discharge unit, the ink is discharged from another discharge unit instead of discharging the ink from the one discharge unit. Various techniques related to so-called complementary printing, in which dots are formed by ejecting the ink, have been proposed (for example, Patent Document 1).

JP 2004-174816 A

  By the way, as described above, in the complementary printing, the ejection of the liquid from the ejection unit where the ejection abnormality has occurred is stopped. For this reason, for example, if complementary printing is performed when a discharge abnormality has occurred due to the increase in the viscosity of the liquid in the discharge unit, the degree of the increase in the viscosity of the liquid in the discharge unit in which the discharge abnormality has occurred progresses, and flushing In some cases, it may be difficult to recover from abnormal discharge even by the maintenance process.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a technique for preventing the occurrence of a discharge abnormality that cannot be recovered even by maintenance processing when performing complementary printing.

  In order to solve the above-described problems, a liquid ejection apparatus according to the present invention includes a plurality of ejection units that eject liquid, and a first recording head provided with a first ejection unit among the plurality of ejection units. A second recording head provided with a second ejection unit among the plurality of ejection units, a determination unit that determines a liquid ejection state in the ejection unit, and a control unit that controls the plurality of ejection units. When the determination unit determines that the liquid discharge state of the one discharge unit provided in the first recording head is abnormal, the control unit includes a first time from the determination. From the determination, a first control mode for controlling the plurality of ejection units so that liquid is ejected from the first ejection unit instead of ejecting liquid from the one ejection unit until the time elapses. Until the second time elapses, the one discharge unit The plurality of ejection units can be controlled by a second control mode for controlling the plurality of ejection units so that liquid is ejected from the second ejection unit instead of ejecting liquid, The time 1 is shorter than the second time.

  In the present invention, since complementary printing is performed only during the first time or the second time from the determination of the liquid discharge state in the discharge unit, even after the first time or the second time has elapsed since the determination. Compared with the case where the complementary printing is continued, it is possible to reduce the possibility that the liquid discharge state in one discharge portion is deteriorated.

  In the liquid ejection apparatus described above, when the control unit controls the plurality of ejection units in the first control mode, after the first time has elapsed from the determination, the control unit controls the liquid in the one ejection unit. In the case where the plurality of discharge units are controlled so as to execute a recovery operation for recovering the discharge state normally, and the plurality of discharge units are controlled in the second control mode, the second time from the determination is determined. After a lapse of time, the plurality of ejection units may be controlled so that the recovery operation is executed.

  According to this aspect, since the recovery operation is performed after the first time or the second time has elapsed from the determination of the liquid discharge state in the discharge unit, the first time or the second time has elapsed since the determination. It is possible to reduce the possibility that the discharge state of the liquid in one discharge portion will deteriorate compared to the case where the discharge of the liquid from the discharge portion is continued thereafter.

  In the liquid ejection apparatus described above, the recovery operation may be an operation in which the plurality of ejection units eject liquid.

  According to this aspect, since the liquid is discharged from the plurality of discharge units including the one discharge unit, in the case where the discharge state abnormality due to the thickening of the liquid occurs in the one discharge unit, the discharge state It is possible to eliminate the abnormality.

  The liquid ejection apparatus described above includes a first drive signal that drives the ejection unit so that liquid is ejected from the ejection unit, and a first drive signal that drives the ejection unit so that no liquid is ejected from the ejection unit. A drive signal generator that generates two drive signals, and a switch that switches whether to supply the first drive signal to the ejection unit, and a switch that switches whether to supply the second drive signal to the ejection unit. And when the determination unit determines that the discharge state of the liquid in the one discharge unit is abnormal, the control unit sets the plurality of discharge units to the first control mode or the first control mode. During the control in the second control mode, the switching unit may be controlled so that the first drive signal and the second drive signal are not supplied to the one ejection unit.

  According to this aspect, in the case where an abnormality in the ejection state due to the thickening of the liquid occurs in one ejection unit, the thickened liquid is prevented from diffusing inside the one ejection unit. be able to.

  The control method of the liquid ejection apparatus according to the present invention includes a plurality of ejection units that eject liquid, a first recording head provided with a first ejection unit among the plurality of ejection units, and the plurality of the plurality of ejection units. A control method for a liquid ejection apparatus, comprising: a second recording head provided with a second ejection unit among the ejection units; and a determination unit for determining a liquid ejection state in the ejection unit, comprising: When the determination unit determines that the liquid discharge state in the one discharge unit provided in the first recording head is abnormal, the first time period from the determination until the first time elapses. A first control mode for controlling the plurality of ejection units so that a liquid is ejected from the first ejection unit instead of ejecting a liquid from the ejection unit, and a period until a second time elapses from the determination. In the meantime, instead of discharging the liquid from the one discharge part Among the second control modes for controlling the plurality of ejection units so that liquid is ejected from the second ejection unit, the plurality of ejection units are controlled in one control mode, and the first The time is shorter than the second time.

  In the present invention, since complementary printing is performed only during the first time or the second time from the determination of the liquid discharge state in the discharge unit, even after the first time or the second time has elapsed since the determination. Compared with the case where the complementary printing is continued, it is possible to reduce the possibility that the liquid discharge state in one discharge portion is deteriorated.

1 is a block diagram illustrating a configuration of an inkjet printer 1 according to the present invention. 1 is a perspective view showing a schematic internal structure of an ink jet printer 1. FIG. FIG. 6 is an explanatory diagram for explaining the structure of a discharge unit D. 6 is an explanatory diagram for explaining an ink ejection operation in the ejection section D. FIG. It is a top view which shows the example of arrangement | positioning of the nozzle N in the head module HM. 4 is a flowchart for explaining the operation of the inkjet printer 1. It is a block diagram which shows the structure of the head unit HU. It is a timing chart for explaining printing processing and discharge state judging processing. It is a timing chart for explaining printing processing and discharge state judging processing. 3 is a block diagram showing a configuration of a connection state designation circuit 11. FIG. It is explanatory drawing which shows the decoding content of decoder DC. It is explanatory drawing for demonstrating the determination information Stt. FIG. 10 is an explanatory diagram for explaining a normal printing process. It is explanatory drawing for demonstrating discharge abnormality. It is explanatory drawing for demonstrating a complementary printing process. It is explanatory drawing for demonstrating a complementary printing process. FIG. 10 is a block diagram illustrating a configuration of an inkjet printer 1 according to Modification 7.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the size and scale of each part are appropriately changed from the actual ones. Further, since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are attached thereto. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

<< A. Embodiment >>
In the present embodiment, the liquid ejecting apparatus will be described by exemplifying an ink jet printer that ejects ink (an example of “liquid”) to form an image on a recording paper P (an example of “medium”).

<< 1. Overview of inkjet printers >>
The configuration of the inkjet printer 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a functional block diagram illustrating an example of the configuration of the inkjet printer 1 according to the present embodiment. FIG. 2 is a perspective view showing an example of a schematic internal structure of the ink jet printer 1.

  The inkjet printer 1 is supplied with print data Img indicating an image to be formed by the inkjet printer 1 and information indicating the number of copies of the image to be formed by the inkjet printer 1 from a host computer such as a personal computer or a digital camera. Is done. The ink jet printer 1 executes a printing process for forming an image indicated by the print data Img supplied from the host computer on the recording paper P.

As illustrated in FIG. 1, the inkjet printer 1 includes a head module HM including a head unit HU provided with a discharge unit D that discharges ink, a control unit 6 that controls the operation of each unit of the inkjet printer 1, and A drive signal generation circuit 2 (an example of a “drive signal generation unit”) that generates a drive signal Com for driving the ejection unit D, and a transport mechanism 7 for changing the relative position of the recording paper P with respect to the head module HM. The discharge state determination circuit 9 (“determination unit”) determines the ink discharge state in the discharge unit D (hereinafter sometimes referred to as “discharge state determination”) and outputs determination information Stt indicating the result of the discharge state determination. In the storage module 5 for storing the control program of the inkjet printer 1 and other information, and the ejection unit D. Includes a maintenance unit 4 for performing a kick maintenance is successfully recover the ink ejection state of the discharge portion D if the discharge state of ink becomes abnormal processing (an example of the "recovery operation"), a.
In the present embodiment, as illustrated in FIG. 1, the head module HM includes four head units HU, and the determination module CM includes four ejection states corresponding to the four head units HU. Assume that the determination circuit 9 is provided.

In the present embodiment, each head unit HU includes a recording head HD including M ejection units D, a switching circuit 10 (an example of a “switching unit”), and a detection circuit 20 (in the present embodiment). , M is a natural number satisfying 2 ≦ M).
Hereinafter, in order to distinguish each of the M ejection portions D provided in each recording head HD, they may be referred to as “first stage, second stage,..., M stage” in order. In addition, the m stages of ejection portions D may be referred to as ejection portions D [m] (the variable m is a natural number satisfying 1 ≦ m ≦ M). In addition, when the components, signals, etc. of the ink jet printer 1 correspond to the number of stages m of the discharge section D [m], the codes for representing the components, signals, etc. correspond to the number of stages m. May be expressed with a subscript [m].

The switching circuit 10 switches whether to supply the drive signal Com output from the drive signal generation circuit 2 to each ejection unit D. In addition, the switching circuit 10 switches whether to electrically connect each ejection unit D and the detection circuit 20.
Based on the detection signal Vout [m] detected from the discharge unit D [m] driven by the drive signal Com, the detection circuit 20 drives the discharge unit D [m] after the discharge unit D [m] is driven. A residual vibration signal NES [m] indicating residual vibration (hereinafter referred to as “residual vibration”) is generated.

Based on the residual vibration signal NES [m], the discharge state determination circuit 9 generates determination information Stt [m] indicating the result of the discharge state determination of the discharge unit D [m].
In the following description, the discharge part D that is the target of the discharge state determination by the discharge state determination circuit 9 may be referred to as a determination target discharge part D-H.
In addition, a series of processes executed in the ink jet printer 1 including the discharge state determination performed by the discharge state determination circuit 9 and the preparation process for the discharge state determination circuit 9 to execute the discharge state determination are performed as the discharge state determination. This is called processing.

  In the present embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, the ink jet printer 1 performs the printing process by ejecting ink from the ejection unit D while transporting the recording paper P in the sub scanning direction and moving the head module HM in the main scanning direction. In this embodiment, as shown in FIG. 2, the + Y direction and the −Y direction (hereinafter, the + Y direction and the −Y direction are collectively referred to as “Y-axis direction”) are the main scanning direction, and the + X direction (hereinafter, + X The direction and the opposite -X direction are collectively referred to as “X-axis direction”).

  As illustrated in FIG. 2, the inkjet printer 1 according to the present embodiment includes a housing 200 and a carriage 100 that can reciprocate in the housing 200 in the Y-axis direction and mounts the head module HM.

The transport mechanism 7 changes the relative position of the recording paper P with respect to the head module HM by reciprocating the carriage 100 in the Y-axis direction and transporting the recording paper P in the + X direction when printing processing is executed. As a result, the ink can land on the entire recording paper P.
Specifically, as shown in FIG. 1, the transport mechanism 7 includes a transport motor 71 serving as a drive source for reciprocating the carriage 100 in the Y-axis direction, and a motor driver 72 for driving the transport motor 71. , A paper feed motor 73 serving as a drive source for transporting the recording paper P and a motor driver 74 for driving the paper feed motor 73 are provided. Further, as shown in FIG. 2, the transport mechanism 7 is stretched between a carriage guide shaft 76 extending in the Y-axis direction, a pulley 711 that is rotationally driven by the transport motor 71, and a rotatable pulley 712. And a timing belt 710 extending in the Y-axis direction. The carriage 100 is supported reciprocally in the Y-axis direction by a carriage guide shaft 76 and is fixed to a predetermined portion of the timing belt 710 via a fixture 101. Therefore, the transport mechanism 7 can move the head module HM mounted on the carriage 100 in the Y-axis direction along the carriage guide shaft 76 by rotating the pulley 711 by the transport motor 71.
As shown in FIG. 2, the transport mechanism 7 is a platen provided on the lower side of the carriage 100, that is, in the −Z direction (hereinafter, the −Z direction and the opposite + Z direction are collectively referred to as “Z-axis direction”). 75, a sheet feeding roller (not shown) that rotates according to the driving of the sheet feeding motor 73 and supplies the recording paper P one by one onto the platen 75, and a platen that rotates according to the driving of the sheet feeding motor 73. And a paper discharge roller 730 for transporting the recording paper P on 75 to a paper discharge port. For this reason, the transport mechanism 7 can transport the recording paper P on the platen 75 from the −X direction (upstream side) to the + X direction (downstream side).

  The maintenance unit 4 includes a cap 40 for covering each head unit HU so that the nozzles N of the discharge unit D are sealed, and paper dust or the like attached in the vicinity of the nozzles N (see FIG. 3 described later) of the discharge unit D. A wiper (not shown) for wiping off foreign matter, a tube pump (not shown) for sucking ink and bubbles in the discharge part D, and ink discharged when discharging the ink in the discharge part D And a discharged ink receiving unit 41 for receiving. In the present embodiment, the aspect in which the cap 40 is attached to the housing 200 is illustrated, but the present invention is not limited to such an aspect, and the cap 40 is attached to the carriage 100. May be.

Further, in this embodiment, as illustrated in FIG. 2, there is a one-to-one correspondence with four color (CMYK) inks of cyan (CY), magenta (MG), yellow (YL), and black (BK). Assume that four corresponding ink cartridges 31 are stored in the carriage 100. FIG. 2 is merely an example, and the ink cartridge 31 may be provided outside the carriage 100.
In the present embodiment, four head units HU and four ink cartridges 31 are provided in a one-to-one correspondence. Each ejection unit D receives ink supplied from the ink cartridge 31 corresponding to the head unit HU provided with the ejection unit D. Thereby, each discharge part D can fill the supplied ink inside, and can discharge the filled ink from the nozzle N. That is, a total of 4M ejection portions D included in the head module HM can eject inks of four colors CMYK as a whole.

  The storage unit 5 includes a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). , And stores various information such as print data Img supplied from a host computer and a control program for the inkjet printer 1.

  The control unit 6 includes a CPU (Central Processing Unit). However, the control unit 6 may include a programmable logic device such as an FPGA (field-programmable gate array) instead of the CPU.

  The control unit 6 is a drive control that controls the drive signal generation circuit 2, the head module HM, and the transport mechanism 7 by a CPU provided in the control unit 6 operating according to a control program stored in the storage unit 5. A unit 61, a maintenance control unit 62 that controls the maintenance unit 4 (an example of a “recovery control unit”), and a time measuring unit 63 that measures the time since the determination of the ink discharge state in the discharge unit D is made. Function.

The drive control unit 61 generates a print signal SI for controlling the head module HM, a waveform designation signal dCom for controlling the drive signal generation circuit 2, and a signal for controlling the transport mechanism 7.
Here, the waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the ejection unit D. The drive signal generation circuit 2 includes a DA conversion circuit, and generates a drive signal Com having a waveform defined by the waveform designation signal dCom. In the present embodiment, it is assumed that the drive signal Com includes the drive signal Com-A and the drive signal Com-B.
The print signal SI is a digital signal for designating the type of operation of the ejection unit D. Specifically, the print signal SI specifies the type of operation of the ejection unit D by designating whether or not to supply the drive signal Com to the ejection unit D. Here, the designation of the type of operation of the ejection part D is, for example, whether or not the ejection part D is to be driven or whether ink is ejected from the ejection part D when the ejection part D is driven. Or specifying the amount of ink ejected from the ejection unit D when the ejection unit D is driven.

  When the printing process is executed, the drive control unit 61 first stores the print data Img supplied from the host computer in the storage unit 5. Next, based on various data such as print data Img stored in the storage unit 5, the drive control unit 61 generates a print signal SI, a waveform designation signal dCom, a signal for controlling the transport mechanism 7, and the like. Various control signals are generated. The drive control unit 61 controls the transport mechanism 7 so as to change the relative position of the recording paper P with respect to the head module HM based on various control signals and various data stored in the storage unit 5. The head module HM is controlled so that the discharge part D is driven. Accordingly, the drive control unit 61 adjusts the presence / absence of ink ejection from the ejection unit D, the ink ejection amount, the ink ejection timing, and the like, and forms an image corresponding to the print data Img on the recording paper P. Controls execution of print processing.

As described above, the inkjet printer 1 according to the present embodiment determines whether or not the ejection state of the ink from each ejection unit D is normal, that is, whether or not ejection abnormality has occurred in each ejection unit D. A discharge state determination process for determining is executed.
Here, the ejection abnormality is a state in which ink cannot be ejected according to a mode defined by the drive signal Com even if the ejection unit D is driven by the drive signal Com to eject ink from the ejection unit D. Here, the ink ejection mode defined by the drive signal Com is an ejection mode in which the ejection unit D ejects an amount of ink defined by the waveform of the drive signal Com, and the ejection unit D is ejected by the waveform of the drive signal Com. Ink is ejected at a speed. That is, the state in which ink cannot be ejected due to the ink ejection mode defined by the drive signal Com is a state in which the ink cannot be ejected from the ejection unit D, as well as an amount less than the ink ejection amount defined by the drive signal Com. The state in which ink is ejected from the ejection part D, the state in which a larger amount of ink is ejected from the ejection part D than the ejection amount defined by the drive signal Com, or the state of the ink defined by the drive signal Com This includes a state in which ink cannot be landed on a desired landing position on the recording paper P because ink is ejected at a speed different from the ejection speed.

  In the ejection state determination process, the inkjet printer 1 first selects the determination target ejection unit D-H from the M ejection units D provided in each head unit HU by the drive control unit 61, and Second, driving the determination target discharge unit D-H under the control of the drive control unit 61 causes residual vibration in the determination target discharge unit D-H. Third, the determination is performed by the detection circuit 20. A residual vibration signal NES is generated based on the detection signal Vout detected from the target discharge part D-H. Fourth, the discharge state determination circuit 9 determines the determination target discharge part D-H based on the residual vibration signal NES. A target discharge state determination is performed, determination information Stt indicating the determination result is generated, and fifthly, the control unit 6 performs a series of processes of storing the determination information Stt in the storage unit 5.

As described above, the ink jet printer 1 according to the present embodiment executes the maintenance process for normally recovering the ink ejection state in the ejection section D that has caused ejection abnormality.
More specifically, the maintenance process includes a flushing process for discharging ink from the ejection part D, a wiping process for wiping off foreign matters such as paper dust attached to the vicinity of the nozzle N of the ejection part D with a wiper, and the inside of the ejection part D. This is a general term for processes for returning the ink discharge state of the discharge part D to normal, such as a pumping process for sucking ink or bubbles by a tube pump.

In the flushing process, the inkjet printer 1 firstly moves the head module HM to the upper side (+ Z direction) of the discharged ink receiving unit 41 under the control of the drive control unit 61, and secondly, the drive control unit 61. Under the control of the above, by driving 4M ejection portions D provided in the head module HM, the discharged ink receiving portion 41 is caused to eject ink.
In the wiping process, the ink jet printer 1 firstly moves the head module HM to the upper side of the wiper under the control of the drive control unit 61, and secondly, under the control of the maintenance control unit 62, The foreign matter adhering to each discharge part D is wiped off by driving the wiper.
In the pumping process, the inkjet printer 1 firstly moves the head module HM to the upper side of the tube pump under the control of the drive control unit 61, and secondly, under the control of the maintenance control unit 62. Then, by driving the tube pump, the ink in the 4M ejection portions D provided in the head module HM is sucked.

  Further, the inkjet printer 1 according to the present embodiment causes the recording paper P to be ejected from the ejection unit D in which the ejection state is normal instead of the ejection unit D in which the ejection state becomes abnormal as a printing process. There is a case where a complementary printing process for forming an image corresponding to the print data Img on the recording paper P is executed.

  More specifically, the complementary printing process refers to another ejection different from the one ejection unit D instead of ejecting ink from the one ejection unit D when ejection abnormality occurs in one ejection unit D. This is a printing process in which the role of one ejection part D is replaced (complemented) by another ejection part D by increasing the ejection amount of ink from the part D. Hereinafter, a printing process other than the complementary printing process, that is, a printing process in which any ejection unit D is executed without complementing another ejection unit D may be referred to as a normal printing process.

In the complementary printing process, the drive control unit 61 first selects another ejection unit D that can complement the one ejection unit D when the ejection abnormality occurs in the one ejection unit D. Secondly, the switching circuit 10 is controlled so as to stop the supply of the drive signal Com to the one ejection unit D, and the ejection amount of the ink from the other ejection unit D is increased to increase the other ejection unit. The switching circuit 10 is controlled so that one discharge part D is complemented by D. As a result, even if a discharge abnormality occurs in one discharge unit D, it is possible to continue the print process without stopping the print process and performing the maintenance process.
In the case where one ejection unit D is complemented by another ejection unit D, “increasing the ejection amount of ink from the other ejection unit D” means that if normal printing processing is performed, the ink is discharged. This includes the case where another ejection unit D that was not intended to eject ink ejects ink by executing the complementary printing process.
In the following, since a discharge abnormality has occurred, the discharge part D that needs to be complemented by another discharge part D in the printing process is referred to as an abnormal discharge part D-F. In the complementary printing process, the abnormal discharge part D-F is referred to as an abnormal discharge part D-F. The complementary discharge part D may be referred to as a complementary discharge part D-Q.

<< 2. Overview of recording head and discharge section >>
With reference to FIGS. 3 to 5, the recording head HD and the ejection portion D provided in the recording head HD will be described.

FIG. 3 is a schematic partial cross-sectional view of the recording head HD in which the recording head HD is cut so as to include the ejection portion D.
As shown in FIG. 3, the ejection part D includes a piezoelectric element PZ, a cavity 320 filled with ink inside (an example of a “pressure chamber”), a nozzle N communicating with the cavity 320, a vibration plate 310, Is provided. The ejection part D ejects ink in the cavity 320 from the nozzles N when the drive signal Com is supplied to the piezoelectric element PZ and the piezoelectric element PZ is driven by the drive signal Com. The cavity 320 is a space defined by the cavity plate 340, the nozzle plate 330 in which the nozzles N are formed, and the vibration plate 310. The cavity 320 communicates with the reservoir 350 via the ink supply port 360. The reservoir 350 communicates with the ink cartridge 31 corresponding to the ejection unit D via the ink intake port 370.
In the present embodiment, a unimorph (monomorph) type as shown in FIG. 3 is adopted as the piezoelectric element PZ. The piezoelectric element PZ is not limited to a unimorph type, but may be a bimorph type or a laminated type.
The piezoelectric element PZ includes an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm provided between the upper electrode Zu and the lower electrode Zd. The lower electrode Zd is electrically connected to a power supply line LHd (see FIG. 7) set at the potential VBS, and the drive signal Com is supplied to the upper electrode Zu, so that the upper electrode Zu and the lower electrode Zd are connected. When a voltage is applied to the piezoelectric element PZ, the piezoelectric element PZ is displaced in the + Z direction or the −Z direction according to the applied voltage, and as a result, the piezoelectric element PZ vibrates.
A diaphragm 310 is installed in the upper surface opening of the cavity plate 340. A lower electrode Zd is joined to the vibration plate 310. For this reason, when the piezoelectric element PZ is driven by the drive signal Com and vibrates, the diaphragm 310 also vibrates. Then, the volume of the cavity 320 is changed by the vibration of the vibration plate 310, and the ink filled in the cavity 320 is ejected from the nozzle N. Ink is supplied from the reservoir 350 when the ink in the cavity 320 decreases due to ink ejection.

  FIG. 4 is an explanatory diagram for explaining an example of the ink ejection operation in the ejection unit D. As illustrated in FIG. 4, the drive control unit 61 changes the electric potential of the drive signal Com supplied to the piezoelectric element PZ included in the ejection unit D in the Phase-1 state, thereby the piezoelectric element PZ. Generates a distortion that displaces in the + Z direction, and bends the diaphragm 310 of the discharge unit D in the + Z direction. Thereby, the volume of the cavity 320 of the said discharge part D expands compared with the state of Phase-1 like the state of Phase-2 shown in FIG. Next, the drive control unit 61 changes the potential indicated by the drive signal Com to generate a distortion that causes the piezoelectric element PZ to be displaced in the −Z direction, and causes the diaphragm 310 of the discharge unit D to be −Z. Bend in the direction. Thereby, as in the state of Phase-3 shown in FIG. 4, the volume of the cavity 320 is rapidly contracted, and a part of the ink filling the cavity 320 is formed as ink droplets from the nozzle N communicating with the cavity 320. Discharged. After the piezoelectric element PZ and the vibration plate 310 are driven by the drive signal Com and displaced in the Z-axis direction, residual vibration occurs in the discharge portion D including the vibration plate 310.

FIG. 5 shows four recording heads HD provided in the head module HM and a total of 4M pieces provided on the four recording heads HD when the inkjet printer 1 is viewed in plan from the + Z direction or the −Z direction. 5 is an explanatory diagram for explaining an example of an arrangement of nozzles N. FIG.
As shown in FIG. 5, each recording head HD provided in the head module HM is provided with a plurality of nozzle rows Ln. Here, the nozzle row Ln is a plurality of nozzles N provided so as to extend in a row in a predetermined direction. In the present embodiment, it is assumed that each nozzle row Ln is configured by arranging M nozzles N so as to extend in a row in the X-axis direction.
Hereinafter, as shown in FIG. 5, the four nozzle rows Ln provided in the head module HM are referred to as nozzle rows Ln-BK, Ln-CY, Ln-MG, and Ln-YL. Here, the nozzle row Ln-BK is a nozzle row Ln in which the nozzles N of the discharge portion D that discharges black ink are arranged, and the nozzle row Ln-CY is the nozzle N of the discharge portion D that discharges cyan ink. Are arranged in a nozzle row Ln, the nozzle row Ln-MG is a nozzle row Ln in which the nozzles N of the ejection unit D that ejects magenta ink are arranged, and the nozzle row Ln-YL ejects yellow ink. This is a nozzle row Ln in which the nozzles N of the discharge part D are arranged.

  FIG. 5 is an example, and the M nozzles N belonging to each nozzle row Ln may be arranged with a predetermined width in a direction intersecting with the extending direction of the nozzle row Ln. That is, in each nozzle row Ln, the M nozzles N belonging to each nozzle row Ln are, for example, staggered so that the positions of the even-numbered nozzles N and the odd-numbered nozzles N in the Y-axis direction are different from the + X side. It may be arranged. Each nozzle row Ln may extend in a direction different from the X-axis direction. Further, in this embodiment, the case where the number of nozzle rows Ln provided in each print head HD is “1” is illustrated, but each print head HD is provided with two or more nozzle rows Ln. May be.

<< 3. Overview of inkjet printer operations >>
Hereinafter, the outline of the operation of the inkjet printer 1 will be described with reference to FIG.

FIG. 6 is a flowchart illustrating an example of the operation of the inkjet printer 1 when the printing process is executed.
FIG. 6 illustrates the case where the inkjet printer 1 executes the ejection state determination process before executing the printing process. The case where the ejection state determination process is executed before the printing process is, for example, the case where the printing process is the first printing process after power-on of the inkjet printer 1 or the printing process is executed first. For example, when the printing process is executed after a lapse of a certain time, or when the printing process is executed after a lapse of a certain time from the discharge state determination process.

  In the example illustrated in FIG. 6, the inkjet printer 1 performs an ejection state determination process prior to the printing process (S10). Next, the control unit 6 of the ink jet printer 1 determines whether or not there is an abnormal ejection unit D-F determined as ejection abnormality in the ejection state determination process executed in step S10 (S20). Then, if the determination result in step S20 is negative, that is, if there is no abnormal ejection part D-F, the inkjet printer 1 executes normal printing processing (S30) and ends the processing shown in FIG.

  On the other hand, if the determination result in step S20 is affirmative, that is, if there is an abnormal ejection portion DF, the control unit 6 of the inkjet printer 1 determines whether or not complementary printing processing is possible (S40). Specifically, in step S40, for example, the control unit 6 includes, for example, a complementary discharge unit that has a predetermined number (or a predetermined ratio) or less of abnormal discharge units D-F and can complement the abnormal discharge units D-F. When DQ exists, it is determined that complementary printing processing is possible. And the control part 6 of the inkjet printer 1 advances a process to step S80, when the determination result of step S40 is negative (ie, when a complementary printing process is not possible).

  Moreover, the control part 6 of the inkjet printer 1 starts the count (time count) of the elapsed time from the determination (discharge state determination) in step S10, when the determination result of step S40 is affirmative (S50). Here, the elapsed time from the discharge state determination is the first determination information Stt among the times when the control unit 6 acquires 4M pieces of determination information Stt corresponding to the 4M discharge units D from the determination module CM. It may be the elapsed time from the acquired time, may be the elapsed time from the time when the last determination information Stt was acquired, or may be the elapsed time from the average time at which 4M pieces of determination information Stt are acquired. There may be. The elapsed time from the discharge state determination is the first determination information Stt out of the estimated time when the determination module CM outputs 4M determination information Stt corresponding to the 4M discharge units D. It may be the elapsed time from the estimated time, the elapsed time from the estimated time when the last determination information Stt was output, or 4M pieces of determination information Stt were output. It may be an elapsed time from the average time estimated.

  Then, after step S50, the inkjet printer 1 performs a complementary printing process (S60).

  Further, the control unit 6 of the inkjet printer 1 determines whether or not the elapsed time from the ejection state determination in step S10 has passed a predetermined time (S70). Note that the process of step S70 may be executed in parallel with the process of step S60. The control unit 6 functions as the time measuring unit 63 by executing the processes of step S50 and step S70.

And the inkjet printer 1 performs a maintenance process, when the determination result of step S70 is affirmative (S80). Specifically, in step S80, the inkjet printer 1 controls each unit of the inkjet printer 1 so that the flushing process is executed by the drive control unit 61.
However, the present invention is not limited to such an embodiment, and the inkjet printer 1 is configured so that the wiping process is executed by the drive control unit 61 and the maintenance control unit 62 in step S80. Each unit may be controlled, or each unit of the inkjet printer 1 may be controlled by the drive control unit 61 and the maintenance control unit 62 so that the pumping process is executed.
Further, in step S80, the control unit 6 of the ink jet printer 1 performs the ink jet printer so that one or more processes corresponding to the processing result of step S10 are executed among the flushing process, the wiping process, and the pumping process. Each part of 1 may be controlled. For example, the control unit 6 of the inkjet printer 1 determines in step S80 if an abnormal ejection unit DF in which ejection abnormality due to ink thickening has occurred is detected in the ejection state determination process in step S10. Each part of the ink jet printer 1 may be controlled so that the flushing process or the pumping process is executed. Further, for example, the control unit 6 of the ink jet printer 1 determines in step S80 if an abnormal ejection unit DF in which ejection abnormality due to air bubbles is present is detected in the ejection state determination process in step S10. In this case, each part of the inkjet printer 1 may be controlled so that the flushing process or the pumping process is executed. For example, the control unit 6 of the ink jet printer 1 determines that in step S80, in the discharge state determination process, if an abnormal discharge portion DF in which discharge abnormality due to adhesion of foreign matter has occurred is detected, in step S80. What is necessary is just to control each part of the inkjet printer 1 so that a wiping process may be performed.
In addition, the control unit 6 of the inkjet printer 1 determines the number of abnormal ejection units DF determined to be ejection abnormal in the ejection state determination process in step S <b> 10 or 4M ejection units provided in the inkjet printer 1. Depending on the ratio of the abnormal ejection part D-F to D, the process to be executed in step S80 may be determined. For example, the control unit 6 of the ink jet printer 1 is a case where an abnormal ejection unit D-F in which an ejection abnormality due to ink thickening has occurred is detected in the ejection state determination process in step S10. If the number of ejection parts D-F is less than the first reference number, or if the ratio of abnormal ejection parts D-F is less than the first reference value, the inkjet printer is configured so that the flushing process is executed in step S80. 1 is controlled, and when the number of abnormal ejection portions D-F is equal to or greater than the first reference number, or when the ratio of abnormal ejection portions D-F is equal to or greater than the first reference value, the pumping process is performed in step S80. Each part of the ink jet printer 1 may be controlled so that is executed. Further, for example, the control unit 6 of the inkjet printer 1 is a case where, in the discharge state determination process in step S10, an abnormal discharge unit D-F in which a discharge abnormality due to mixing of bubbles is detected is detected. If the number of abnormal ejection portions D-F is less than the second reference number, or if the ratio of abnormal ejection portions D-F is less than the second reference value, the inkjet is performed so that the flushing process is executed in step S80. If each part of the printer 1 is controlled and the number of abnormal ejection parts D-F is equal to or greater than the second reference number, or the ratio of abnormal ejection parts D-F is greater than or equal to the second reference value, pumping is performed in step S80. You may control each part of the inkjet printer 1 so that a process may be performed.

  And the control part 6 of the inkjet printer 1 advances a process to step S60, when the determination result of step S70 is negative, and continues a complementary printing process.

  Then, after step S80, the control unit 6 of the inkjet printer 1 determines whether or not the printing process based on the print data Img has been completed (S90). Then, if the determination result in step S90 is affirmative, the inkjet printer 1 ends the process shown in FIG. 6, while if the determination result in step S90 is negative, the process proceeds to step S10.

<< 4. Head unit configuration >>
Hereinafter, the configuration of each head unit HU will be described with reference to FIG.

  FIG. 7 is a block diagram showing an example of the configuration of the head unit HU. As described above, the head unit HU includes the recording head HD, the switching circuit 10, and the detection circuit 20. Further, the head unit HU includes an internal wiring LHa to which the drive signal Com-A is supplied from the drive signal generation circuit 2, an internal wiring LHb to which the drive signal Com-B is supplied from the drive signal generation circuit 2, and an ejection unit D. And an internal wiring LHs for supplying the detection signal Vout detected from the detection circuit 20 to the detection circuit 20.

As shown in FIG. 7, the switching circuit 10 includes M switches SWa (SWa [1] to SWa [M]), M switches SWb (SWb [1] to SWb [M]), and M switches. Switch SWs (SWs [1] to SWs [M]) and a connection state designating circuit 11 for designating the connection state of each switch. As each switch, for example, a transmission gate can be adopted.
The connection state designating circuit 11 switches SWa [1] to SWa [based on at least a part of the print signal SI, the latch signal LAT, the change signal CH, and the period designating signal Tsig supplied from the control unit 6. Connection state designation signals SLa [1] to SLa [M] for designating ON / OFF of M] and connection status designation signals SLb [1] to SLb [M] for designating ON / OFF of switches SWb [1] to SWb [M] And connection state designation signals SLs [1] to SLs [M] for designating ON / OFF of the switches SWs [1] to SWs [M].
The switch SWa [m] is connected between the internal wiring LHa and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the ejection part D [m] in response to the connection state designation signal SLa [m]. Switch between conduction and non-conduction. For example, the switch SWa [m] is turned on when the connection state designation signal SLa [m] is at a high level and turned off when it is at a low level.
The switch SWb [m] is connected between the internal wiring LHb and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the ejection part D [m] in response to the connection state designation signal SLb [m]. Switch between conduction and non-conduction. For example, the switch SWb [m] is turned on when the connection state designation signal SLb [m] is at a high level and turned off when it is at a low level.
Of the drive signals Com-A and Com-B, a signal actually supplied to the piezoelectric element PZ [m] of the discharge section D [m] via the switch SWa [m] or SWb [m] It may be referred to as a supply drive signal Vin [m].
The switch SWs [m] is connected between the internal wiring LHs and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the discharge part D [m] in response to the connection state designation signal SLs [m]. Switch between conduction and non-conduction. For example, the switch SWs [m] is turned on when the connection state designation signal SLs [m] is at a high level and turned off when it is at a low level.

  A detection signal Vout [m] output from the piezoelectric element PZ [m] of the discharge unit D [m] driven as the determination target discharge unit D-H is supplied to the detection circuit 20 via the internal wiring LHs. The Then, the detection circuit 20 generates a residual vibration signal NES based on the detection signal Vout [m].

<< 5. Head unit operation >>
Hereinafter, the operation of each head unit HU will be described with reference to FIGS.

In the present embodiment, the operation period of the inkjet printer 1 includes one or a plurality of unit periods Tu. The inkjet printer 1 according to the present embodiment has one of driving of each discharge unit D in the printing process, driving of the determination target discharge unit D-H in the discharge state determination process, and detection of residual vibration in each unit period Tu. Assuming that However, the present invention is not limited to such an embodiment, and in each unit period Tu, driving of each discharge unit D in the printing process and driving and remaining of the determination target discharge unit D-H in the discharge state determination process It may be possible to perform both vibration detection.
In general, the inkjet printer 1 repeatedly executes printing processing over a plurality of continuous or intermittent unit periods Tu to discharge ink one or more times from each discharge unit D, thereby printing data. An image indicated by Img is formed. In addition, the inkjet printer 1 according to the present embodiment performs M ejection state determination processes in M unit periods Tu provided continuously or intermittently, thereby performing M ejection units D [1. ] To D [M], the discharge state determination process is performed with the determination target discharge unit D-H.

FIG. 8 is a timing chart for explaining the operation of the inkjet printer 1 in the unit period Tu.
As shown in FIG. 8, the control unit 6 outputs a latch signal LAT having a pulse PlsL and a change signal CH having a pulse PlsC. Thereby, the control unit 6 defines the unit period Tu as a period from the rising of the pulse PlsL to the rising of the next pulse PlsL. Further, the control unit 6 divides the unit period Tu into two control periods Tu1 and Tu2 by the pulse PlsC.
The print signal SI includes individual designation signals Sd [1] to Sd [M] that designate the driving mode of the ejection units D [1] to D [M] in each unit period Tu. Then, when at least one of the printing process and the ejection state determination process is performed in the unit period Tu, the drive control unit 61 of the control unit 6 individually performs prior to the start of the unit period Tu as shown in FIG. The print signal SI including the designation signals Sd [1] to Sd [M] is supplied to the connection state designation circuit 11 in synchronization with the clock signal CL. In this case, the connection state designation circuit 11 generates connection state designation signals SLa [m], SLb [m], and SLs [m] based on the individual designation signal Sd [m] in the unit period Tu.

  Note that the individual designation signal Sd [m] according to the present embodiment ejects an amount of ink corresponding to a large dot (a large amount) to the ejection unit D [m] in each unit period Tu (“ May be referred to as "large dot formation"), an amount of ink corresponding to a medium dot (medium amount) (may be referred to as "medium dot formation"), and an amount corresponding to a small dot (small) Ink ejection (sometimes referred to as “small dot formation”), non-ejection of ink, and drive as a determination target in the discharge state determination process (“determination target discharge unit D-H as This is a signal designating any one of the five driving modes. In the present embodiment, as an example, it is assumed that the individual designation signal Sd [m] is a 3-bit digital signal (see FIG. 11).

  As shown in FIG. 8, the drive signal generation circuit 2 outputs a drive signal Com-A having a waveform PX provided in the control period Tu1 and a waveform PY provided in the control period Tu2. In the present embodiment, the waveform PX and the waveform PY are determined so that the potential difference between the highest potential VHX and the lowest potential VLX of the waveform PX is larger than the potential difference between the highest potential VHY and the lowest potential VLY of the waveform PY. Specifically, when the ejection portion D [m] is driven by the drive signal Com-A having the waveform PX, the waveform PX has a waveform so that a medium amount of ink is ejected from the ejection portion D [m]. Determine. Further, when the ejection unit D [m] is driven by the drive signal Com-A having the waveform PY, the waveform PY is determined so that a small amount of ink is ejected from the ejection unit D [m]. In the waveforms PX and PY, the potential at the start and end is set to the reference potential V0.

When the individual designation signal Sd [m] designates the formation of large dots for the ejection part D [m], the connection state designation circuit 11 sends the connection state designation signal SLa [m] to the control period Tu1. The high level is set in Tu2, and the connection state designation signals SLb [m] and SLs [m] are set to low level in the unit period Tu. In this case, the ejection unit D [m] is driven by the drive signal Com-A having the waveform PX in the control period Tu1 and ejects a medium amount of ink, and the drive signal Com− having the waveform PY in the control period Tu2. Driven by A, a small amount of ink is ejected. Accordingly, the ejection unit D [m] ejects a large amount of ink in total in the unit period Tu, and a large dot is formed on the recording paper P.
When the individual designation signal Sd [m] designates the formation of medium dots for the ejection part D [m], the connection state designation circuit 11 sends the connection state designation signal SLa [m] in the control period Tu1. The connection state designation signals SLb [m] and SLs [m] are set to a low level in the unit period Tu. In this case, the ejection part D [m] ejects a medium amount of ink in the unit period Tu, and medium dots are formed on the recording paper P.
In addition, when the individual designation signal Sd [m] designates the formation of small dots for the ejection part D [m], the connection state designation circuit 11 sends the connection state designation signal SLa [m] in the control period Tu1. The connection state designation signals SLb [m] and SLs [m] are set to a low level in the unit period Tu. In this case, the ejection unit D [m] ejects a small amount of ink in the unit period Tu, and small dots are formed on the recording paper P.
When the individual designation signal Sd [m] designates non-ejection of ink to the ejection part D [m], the connection state designation circuit 11 generates the connection state designation signals SLa [m] and SLb [m]. SLs [m] is set to a low level in the unit period Tu. In this case, the ejection unit D [m] does not eject ink and does not form dots on the recording paper P in the unit period Tu.

As shown in FIG. 8, the drive signal generation circuit 2 outputs a drive signal Com-B having a waveform PS provided in the unit period Tu. In the present embodiment, the waveform PS is determined so that the potential difference between the highest potential VHS and the lowest potential VLS of the waveform PS is smaller than the potential difference between the highest potential VHY and the lowest potential VLY of the waveform PY. Specifically, when the drive signal Com-B having the waveform PS is supplied to the ejection unit D [m], the ejection unit D [m] is driven to the extent that no ink is ejected from the ejection unit D [m]. Next, the waveform PS is determined. In the waveform PS, the potential at the start and end is set to the reference potential V0.
Further, the control unit 6 outputs a period designation signal Tsig having a pulse PlsT1 and a pulse PlsT2. Thereby, the control unit 6 determines the unit period Tu from the start of the pulse PlsL to the start of the pulse PlsT1, the control period TSS2 from the start of the pulse PlsT1 to the start of the pulse PlsT2, and the start of the pulse PlsT2. The control period TSS3 until the start of the next pulse PlsL is divided.

When the individual designation signal Sd [m] designates the ejection part D [m] as the determination target ejection part D-H, the connection state designation circuit 11 sends the connection state designation signal SLa [m] to the unit period Tu. The connection state designation signal SLb [m] is set to the high level in the control periods TSS1 and TSS3, and the connection state designation signal SLs [m] is set to the low level in the control period TSS2. The low level is set in the periods TSS1 and TSS3, and the high level is set in the control period TSS2.
In this case, the determination target discharge unit DH is driven by the drive signal Com-B having the waveform PS in the control period TSS1. Specifically, the piezoelectric element PZ included in the determination target discharge unit DH is displaced by the drive signal Com-B having the waveform PS in the control period TSS1. As a result, vibration is generated in the determination target discharge portion DH, and this vibration remains even in the control period TSS2. In the control period TSS2, the upper electrode Zu included in the piezoelectric element PZ of the determination target discharge unit DH changes the potential according to the residual vibration generated in the determination target discharge unit DH. In other words, in the control period TSS2, the upper electrode Zu of the piezoelectric element PZ of the determination target discharge unit DH is caused to generate an electromotive force of the piezoelectric element PZ due to residual vibration generated in the determination target discharge unit DH. The corresponding potential is shown. The potential of the upper electrode Zu can be detected as the detection signal Vout in the control period TSS2.

FIG. 9 is an explanatory diagram for explaining the operation of the switching circuit 10 in the unit period Tu. Hereinafter, the switches SWa, SWb, and SWs provided corresponding to the determination target discharge unit D-H may be referred to as switches SWa-H, SWb-H, and SWs-H, respectively. Hereinafter, the discharge unit D driven in the printing process is referred to as a print drive discharge unit DP, and the switches SWa, SWb, SWs provided corresponding to the print drive discharge unit DP are respectively referred to as the switch SWa. -P, SWb-P, SWs-P.
As shown in FIG. 9, when the discharge section D [m] operates as the print drive discharge section DP in the unit period Tu, the discharge section D [m] is driven in accordance with the individual designation signal Sd [m], and print processing is performed. It will be used for
As shown in FIG. 9, when the discharge unit D [m] operates as the determination target discharge unit D-H in the unit period Tu, the switch SWa [m], which is the switch SWa-H, is turned off over the unit period Tu. The switch SWb [m], which is the switch SWb-H, is turned on in the control period TSS1 and the control period TSS3, and the switch SWs [m], which is the switch SWs-H, is turned on in the control period TSS2. In this case, in the control period TSS1, the piezoelectric element PZ [m] included in the discharge unit D [m] which is the determination target discharge unit DH is driven and displaced by the drive signal Com-B, and in the control period TSS2 A state in which residual vibration is generated in D [m] is created. In the control period TSS2, the detection signal Vout [m] based on the residual vibration in the discharge part D [m] is supplied to the detection circuit 20 via the internal wiring LHs.

FIG. 10 is a diagram illustrating an example of the configuration of the connection state designating circuit 11 according to the present embodiment. As shown in FIG. 10, the connection state designation circuit 11 receives connection state designation signals SLa [1] to SLa [M], SLb [1] to SLb [M], and SLs [1] to SLs [M]. Generate.
Specifically, the connection state designating circuit 11 includes transfer circuits SR [1] to SR [M] and a latch circuit LT [M] so as to correspond one-to-one with the discharge units D [1] to D [M]. 1] to LT [M] and decoders DC [1] to DC [M]. Among these, the individual designation signal Sd [m] is supplied to the transfer circuit SR [m]. In this figure, the individual designation signals Sd [1] to Sd [M] are supplied serially. For example, the individual designation signal Sd [m] corresponding to m stages is transferred from the transfer circuit SR [1] to the transfer circuit SR. A case is illustrated in which [m] is sequentially transferred in synchronization with the clock signal CL. The latch circuit LT [m] latches the individual designation signal Sd [m] supplied to the transfer circuit SR [m] at the timing when the pulse PlsL of the latch signal LAT rises to a high level. The decoder DC [m] is connected to the connection designation signals SLa [m], SLb [m], and the individual designation signal Sd [m], the latch signal LAT, the change signal CH, and the period designation signal Tsig. , SLs [m] is generated.

FIG. 11 is an explanatory diagram for explaining the generation of connection state designation signals SLa [m], SLb [m], and SLs [m] in the decoder DC [m]. The decoder DC [m] decodes the individual designation signal Sd [m] according to FIG. 11, and generates connection state designation signals SLa [m], SLb [m], and SLs [m].
As shown in FIG. 11, the individual designation signal Sd [m] according to the present embodiment has a value (1, 1, 0) that designates the formation of large dots and a value (1, 0, 0) that designates the formation of medium dots. 0), a value (0, 1, 0) designating the formation of small dots, a value (0, 0, 0) designating non-ejection of ink, or the drive as the determination target ejection unit D-H is designated. Indicates one of the values (1, 1, 1). When the individual designation signal Sd [m] indicates (1, 1, 0), the decoder DC [m] sets the connection state designation signal SLa [m] to the high level in the control periods Tu1 and Tu2, and the individual designation signal Sd [m] When Sd [m] indicates (1, 0, 0), the connection state designation signal SLa [m] is set to the high level during the control period Tu1, and the individual designation signal Sd [m] indicates (0, 1, 0). In this case, when the connection state designation signal SLa [m] is set to the high level in the control period Tu2 and the individual designation signal Sd [m] indicates (1, 1, 1), the connection state designation signal SLb [ m] is set to the high level, and the connection state designation signal SLs [m] is set to the high level in the control period TSS2, and each signal is set to the low level when not corresponding to the above.

As described above, the detection circuit 20 generates the residual vibration signal NES based on the detection signal Vout. The residual vibration signal NES is obtained by shaping the detection signal Vout into a waveform suitable for processing in the discharge state determination circuit 9 by amplifying the amplitude of the detection signal Vout and removing a noise component from the detection signal Vout. Signal.
The detection circuit 20 includes, for example, a negative feedback amplifier for amplifying the detection signal Vout, a low-pass filter for attenuating the high frequency component of the detection signal Vout, and a residual vibration signal having a low impedance by converting impedance. A configuration including a voltage follower that outputs NES may be used.

<< 6. Discharge state determination circuit >>
Next, the discharge state determination circuit 9 will be described.

Generally, the residual vibration generated in the ejection part D has a natural vibration frequency determined by the shape of the nozzle N, the weight of the ink filled in the cavity 320, the viscosity of the ink filled in the cavity 320, and the like. .
In general, when there is a discharge abnormality in the discharge part D because the bubbles are mixed in the cavity 320 of the discharge part D, compared to the case where no bubbles are mixed in the cavity 320, The frequency of residual vibration increases. Also, in general, when foreign matter such as paper dust adheres near the nozzle N of the discharge part D, the discharge abnormality occurs in the discharge part D, compared with the case where no foreign matter adheres. Thus, the frequency of residual vibration is lowered. In general, when the ink filled in the cavity 320 of the discharge part D is thickened, an abnormality in the discharge of the discharge part D occurs compared to the case where the ink is not thickened. Thus, the frequency of residual vibration is lowered. In general, when the ink filled in the cavity 320 of the discharge part D is thickened and discharge abnormality occurs in the discharge part D, paper dust or the like near the nozzle N of the discharge part D Compared with the case where the foreign matter adheres, the frequency of the residual vibration is lowered. Further, in general, when there is a discharge abnormality in the discharge part D because the cavity 320 of the discharge part D is not filled with ink, or when the piezoelectric element PZ fails and cannot be displaced, the discharge is performed in the discharge part D. When an abnormality has occurred, the amplitude of the residual vibration becomes small.

  As described above, the residual vibration signal NES indicates a waveform corresponding to the residual vibration occurring in the determination target discharge unit DH. Specifically, the residual vibration signal NES indicates a frequency corresponding to the frequency of the residual vibration generated in the determination target discharge unit DH, and corresponds to the amplitude of the residual vibration generated in the determination target discharge unit DH. Frequency. For this reason, the discharge state determination circuit 9 can perform discharge state determination for determining the ink discharge state in the determination target discharge portion D-H based on the residual vibration signal NES.

In the discharge state determination, the discharge state determination circuit 9 measures the time length NTc of one cycle of the residual vibration signal NES and generates period information Info-T indicating the measurement result.
Further, the discharge state determination circuit 9 generates amplitude information Info-S indicating whether or not the residual vibration signal NES has a predetermined amplitude in the discharge state determination. Specifically, the discharge state determination circuit 9 determines that the potential of the residual vibration signal NES is the potential Vth at the amplitude center level of the residual vibration signal NES during the period in which the time length NTc of one cycle of the residual vibration signal NES is measured. It is determined whether or not the threshold potential Vth-O is higher than -C and lower than the threshold potential Vth-U lower than the potential Vth-C. If the result of the determination is affirmative, a value indicating that the residual vibration signal NES has a predetermined amplitude, for example “1”, is set in the amplitude information Info-S, and the result of the determination Is negative, a value indicating that the residual vibration signal NES does not have a predetermined amplitude, for example, “0” is set in the amplitude information Info-S.
Then, the ejection state determination circuit 9 generates determination information Stt indicating the determination result of the ink ejection state in the determination target ejection unit DH based on the period information Info-T and the amplitude information Info-S.

FIG. 12 is an explanatory diagram for explaining generation of the determination information Stt in the discharge state determination circuit 9.
As shown in this figure, the discharge state determination circuit 9 compares the time length NTc indicated by the cycle information Info-T with a part or all of the threshold value Tth1, the threshold value Tth2, and the threshold value Tth3 to thereby determine the determination target discharge part D. The ejection state at -H is determined, and determination information Stt indicating the result of the determination is generated.
Here, the threshold value Tth1 is a time length of one cycle of residual vibration when the discharge state of the determination target discharge unit DH is normal, and a time length of one cycle of residual vibration when bubbles are mixed into the cavity 320. Is a value for indicating the boundary between and. The threshold value Tth2 is a time length of one cycle of residual vibration when the discharge state of the determination target discharge unit D-H is normal, and a time length of one cycle of residual vibration when foreign matter adheres near the nozzle N. Is a value for indicating the boundary between and. The threshold value Tth3 is a time length of one period of residual vibration when a foreign substance adheres to the vicinity of the nozzle N of the determination target discharge unit DH, and one period of residual vibration when the ink in the cavity 320 is thickened. It is a value for indicating the boundary between the time length of The threshold values Tth1 to Tth3 satisfy “Tth1 <Tth2 <Tth3”.

As shown in FIG. 12, in this embodiment, the value of the amplitude information Info-S is “1” and the time length NTc indicated by the period information Info-T satisfies “Tth1 ≦ NTc ≦ Tth2”. Assumes that the ink ejection state in the determination target ejection unit D-H is normal. In this case, the discharge state determination circuit 9 sets a value “1” indicating that the discharge state of the determination target discharge portion D-H is normal in the determination information Stt.
Further, when the value of the amplitude information Info-S is “1” and the time length NTc indicated by the period information Info-T satisfies “NTc <Tth1”, the determination target discharge unit D-H is caused by bubbles. Assume that a discharge abnormality has occurred. In this case, the discharge state determination circuit 9 sets the determination information Stt to a value “2” indicating that a discharge abnormality due to bubbles has occurred in the determination target discharge portion DH.
Further, when the value of the amplitude information Info-S is “1” and the time length NTc indicated by the period information Info-T satisfies “Tth2 <NTc ≦ Tth3”, the determination target ejection unit D-H It is considered that a discharge abnormality has occurred due to foreign matter adhesion. In this case, the discharge state determination circuit 9 sets the determination information Stt to a value “3” indicating that a discharge abnormality due to adhesion of foreign matter has occurred in the determination target discharge portion DH.
Further, when the value of the amplitude information Info-S is “1” and the time length NTc indicated by the period information Info-T satisfies “Tth3 <NTc”, the viscosity is increased in the determination target discharge unit DH. It is considered that an abnormal discharge has occurred. In this case, the discharge state determination circuit 9 sets the determination information Stt to a value “4” indicating that a discharge abnormality due to thickening has occurred in the determination target discharge portion DH.
Further, even when the value of the amplitude information Info-S is “0”, it is considered that a discharge abnormality has occurred in the determination target discharge unit DH. In this case, the discharge state determination circuit 9 sets the determination information Stt to a value “5” indicating that a discharge abnormality has occurred in the determination target discharge portion DH.
As described above, the ejection state determination circuit 9 generates the determination information Stt based on the period information Info-T and the amplitude information Info-S.
Then, the control unit 6 causes the storage unit 5 to store the determination information Stt generated by the discharge state determination circuit 9 in association with the stage number m of the determination target discharge unit DH corresponding to the determination information Stt. Thereby, the control unit 6 manages the determination information Stt [1] to Stt [M] corresponding to the discharge units D [1] to D [M].
In the present embodiment, the case where the determination information Stt is quinary information from “1” to “5” is illustrated, but the determination information Stt has a time length NTc of “Tth1 ≦ NTc ≦ Tth2”. It may be binary information indicating whether or not the above is satisfied. At least the determination information Stt may include information indicating whether or not the ink discharge state in the determination target discharge portion D-H is normal.

<< 7. Normal printing process and complementary printing process >>
Hereinafter, the complementary printing process will be described with reference to FIGS.

In FIG. 13, when the discharge states of the five discharge portions D [1] to D [5] having the nozzles N belonging to the nozzle row Ln-BK are normal, the normal printing process is executed, and the five A case where five medium dots Dt1 to Dt5 are formed by the discharge portions D [1] to D [5] is illustrated.
In FIG. 14, the normal printing process as illustrated in FIG. 13 is executed, and five medium dots Dt1 to Dt5 are formed by the five discharge parts D [1] to D [5]. D [3] is the abnormal ejection part DF, the medium dot that was to be formed by the ink ejected from the ejection part D [3], failing to eject ink from the ejection part D [3] The case where Dt3 is not formed is illustrated.

FIG. 15 illustrates a case where the complementary printing process is executed instead of the normal printing process in the example shown in FIG. In particular,
In the complementary printing process shown in FIG. 15, the nozzles N belonging to the same nozzle row Ln as the abnormal discharge part D-F are used as the complementary discharge part D-Q that complements the discharge part D [3] that is the abnormal discharge part D-F. The discharge part D [2] and the discharge part D [4], which are discharge parts D adjacent to the abnormal discharge part D-F, are employed. In other words, in the complementary printing process illustrated in FIG. 15, the discharge portion D adjacent to the abnormal discharge portion DF in the sub-scanning direction (X-axis direction in the present embodiment) is employed as the complementary discharge portion D-Q. To do. In the complementary printing process shown in FIG. 15, compared with the normal printing process shown in FIG. 14, the ejection amount of ink from the ejection unit D [2] and the ejection unit D [4] which are the complementary ejection unit DQ. And the supply of the drive signal Com to the discharge part D [3], which is the abnormal discharge part DF, is stopped to stop the drive of the discharge part D [3]. Thus, in the complementary printing process shown in FIG. 15, large dots DtQ2 and large dots DtQ4 are formed instead of the medium dots Dt2 and Dt4 formed in the normal printing process shown in FIG. For this reason, in the complementary printing process shown in FIG. 15, compared to the normal printing process shown in FIG. 14, even when the dot Dt <b> 3 formation fails and a dot dropout occurs, the original printing process shown in FIG. 13 is formed. It is possible to form dots Dt in a manner close to a plurality of power dots Dt, and it is possible to reduce the degree of deterioration of image quality due to ejection abnormality.

  In the complementary printing process shown in FIG. 15, the case where the nozzle N of the abnormal discharge portion DF and the nozzle N of the complementary discharge portion D-Q belong to the nozzle row Ln-BK is illustrated, but this is only an example. First, the nozzle N of the abnormal ejection part DF and the complementary ejection part D-Q nozzle N may belong to a nozzle array Ln other than the nozzle arrays Ln-BK.

  Further, in the complementary printing process shown in FIG. 15, the two ejection units adjacent to the abnormal ejection unit D-F are the ejection units D having the nozzles N belonging to the same nozzle row Ln as the abnormal ejection unit D-F. D is adopted as the complementary discharge portion DQ, but the present invention is not limited to such an embodiment, and there may be one complementary discharge portion DQ, or the complementary discharge portion D-Q may be a discharge unit D having nozzles N belonging to a nozzle row Ln different from the abnormal discharge unit D-F.

  FIG. 16 illustrates the case where the complementary printing process is executed instead of the normal printing process in the example shown in FIG. Specifically, in the complementary printing process shown in FIG. 16, as the complementary discharge unit D-Q that complements the discharge unit D [3], which is the abnormal discharge unit DF corresponding to the nozzle row Ln-BK, the abnormal discharge unit A discharge unit D [6] corresponding to the nozzle row Ln-CY and a discharge unit D [7 corresponding to the nozzle row Ln-MG, which are the discharge units D having the nozzles N belonging to the nozzle row Ln different from DF. ] And the discharge section D [8] corresponding to the nozzle row Ln-YL are illustrated. In other words, in the complementary printing process illustrated in FIG. 16, the discharge unit D positioned in the main scanning direction or the opposite direction (Y-axis direction in the present embodiment) as viewed from the abnormal discharge unit D-F is used as the complementary discharge unit. Adopted as D-Q. In the complementary printing process shown in FIG. 16, compared with the normal printing process shown in FIG. 14, the ejection unit D [6], the ejection unit D [7], and the ejection unit D [8, which are complementary ejection units DQ. ] And the supply of the drive signal Com to the ejection part D [3], which is the abnormal ejection part DF, is stopped to stop the ejection part D [3] from being driven. Accordingly, in the complementary printing process shown in FIG. 16, instead of the medium dot Dt3 that should originally be formed with black ink, the medium dot DtQ6 formed with cyan ink and the medium dot formed with magenta ink are used. DtQ7 and medium dots DtQ8 formed with yellow ink are formed. For this reason, in the complementary printing process shown in FIG. 16, compared to the normal printing process shown in FIG. 14, even if the formation of the dot Dt <b> 3 fails, an aspect close to the dot Dt that should be originally formed shown in FIG. 13. Thus, the dot Dt can be formed, and the degree of deterioration of the image quality due to the ejection abnormality can be reduced.

<< 8. Conclusion of embodiment >>
As described above, according to the present embodiment, since the complementary printing process can be executed even when there is a discharge unit D having an abnormal discharge, the complementary printing process is performed after the abnormal discharge is detected. The convenience of the user of the inkjet printer 1 can be improved as compared with the case where the maintenance process is executed immediately without executing it.

  Further, according to the present embodiment, when there is an ejection portion D with abnormal ejection, the time for which the complementary printing process is performed is limited to a predetermined time or less, for example, ejection due to ink thickening In the ejection portion D where abnormality has occurred, it is possible to prevent the occurrence of a serious ejection abnormality that cannot be recovered even by maintenance processing, such as the degree of ink thickening progressing and ink fixing.

<< B. Modification >>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other. In addition, about the element which an effect | action and a function are equivalent to embodiment in the modification illustrated below, the code | symbol referred by the above description is diverted and each detailed description is abbreviate | omitted suitably.

<< Modification 1 >>
In the embodiment described above, the control unit 6 executes the maintenance process when a predetermined time has elapsed from the discharge state determination. However, the present invention is not limited to such an aspect, and the control unit 6 Depending on the processing result of the discharge state determination process, the time from the discharge state determination to the start of the maintenance process may be determined.
For example, when the abnormal discharge portion D-F in which the discharge abnormality due to ink thickening has occurred is detected, the control unit 6 detects the abnormal discharge portion D in which the discharge abnormality due to mixing of bubbles has occurred. Compared to the case where only -F is detected and the case where only the abnormal discharge part D-F where the discharge abnormality due to the adhesion of foreign matter has occurred is detected, from the discharge state determination to the start of the maintenance process The time may be lengthened. In addition, for example, the control unit 6 has the number (or ratio) of abnormal ejection portions D-F in which ejection abnormalities due to ink thickening occur are equal to or greater than the first reference number (or greater than the first reference value). In this case, the time from the discharge state determination to the start of the maintenance process may be lengthened as compared with the case of less than the first reference number (or less than the first reference value).

<< Modification 2 >>
In the embodiment and the modification described above, the drive signal Com includes the waveform PX and the waveform PY, which are ejection waveforms for driving the ejection unit D so that ink is ejected from the ejection unit D. However, the drive signal Com may include a micro-vibration waveform PBS that is a non-ejection waveform for driving the ejection unit D to the extent that ink is not ejected from the ejection unit D.
In this case, the control unit 6 (drive control unit 61) according to this modification supplies the fine vibration waveform PBS to the discharge unit D to which the waveform PX or the waveform PY is not supplied in each unit period Tu of the normal printing process. May be. In addition, the control unit 6 (drive control unit 61) according to the present modified example is a unit other than the abnormal ejection unit D-F among the ejection units D to which the waveform PX or the waveform PY is not supplied in each unit period Tu of the complementary printing process. The fine vibration waveform PBS may be supplied to the discharge part D. That is, the control unit 6 (drive control unit 61) according to the present modification example has the waveform PX, the waveform PY, and the minute vibration waveform for the abnormal ejection unit DF in each unit period Tu of the complementary printing process. It is preferable to control the switching circuit 10 so that no waveform of PBS is supplied.
Of the drive signal Com, the signal including the ejection waveform such as the waveform PX and the waveform PY is an example of the “first drive signal”, and the drive signal Com includes the non-ejection waveform such as the micro vibration waveform PBS. The signal is an example of a “second drive signal”.

<< Modification 3 >>
In the embodiment and the modification described above, the control unit 6 performs the maintenance process when a predetermined time has elapsed from the discharge state determination or when a time corresponding to the processing result of the discharge state determination process has elapsed from the discharge state determination. However, the present invention is not limited to such an embodiment, and the control unit 6 is configured such that the nozzle N of the abnormal discharge unit DF and the nozzle N of the complementary discharge unit D-Q are the same. Depending on whether it belongs to the nozzle row Ln, the time from the discharge state determination to the start of the maintenance process may be determined.
For example, the control unit 6 compares the case where the nozzle N of the abnormal discharge unit DF and the nozzle N of the complementary discharge unit D-Q belong to the same nozzle row Ln as compared to the case where they belong to different nozzle rows Ln. Thus, the time from the discharge state determination to the start of the maintenance process may be shortened. According to this aspect, for example, when there is a discharge abnormality due to ink thickening in the abnormal discharge portion DF, the complementary discharge portions adjacent in the same nozzle row Ln (the same print head HD). The vibration accompanying the drive of D-Q propagates to the abnormal ejection part DF, so that the thickened ink filled in the abnormal ejection part DF diffuses to the deep part of the abnormal ejection part DF. In addition, the thickened ink can be prevented from diffusing into the reservoir 350 via the ink supply port 360.

The control unit 6 includes a shape priority printing mode for giving priority to the accuracy of the position or shape of the image formed on the recording paper P over the accuracy of the color of the image formed on the recording paper P, and the recording. It is possible to control the printing process by the color priority printing mode for giving priority to the accuracy of the color of the image formed on the recording paper P over the accuracy of the position or shape of the image formed on the paper P. May be.
When the control unit 6 performs the complementary printing process in the shape priority printing mode, the complementary discharge unit DQ is a discharge unit having nozzles N belonging to a nozzle row Ln different from the abnormal discharge unit D-F. It is preferable to select from D. Further, when the complementary printing process is executed in the color priority printing mode, the complementary discharge unit DQ is selected from the discharge units D having the nozzles N belonging to the same nozzle row Ln as the abnormal discharge unit D-F. It is preferable.
Furthermore, when the complementary printing process is executed in the color priority printing mode, the control unit 6 compares the discharge state determination to the start of the maintenance process as compared with the case where the complementary printing process is executed in the shape priority printing mode. You may shorten the time. As a result, when the complementary printing process is executed in the color priority printing mode and the ejection abnormality due to the thickening of the ink occurs in the abnormal ejection part D-F, the adjacent nozzles Ln are adjacent to each other. It is possible to prevent the thickened ink from diffusing due to the vibration accompanying the driving of the complementary complementary discharge section DQ being propagated to the abnormal discharge section DF.

In the complementary printing process, when the nozzle N of the complementary discharge unit DQ and the nozzle N of the abnormal discharge unit DF belong to the same nozzle row Ln, for example, the complementary discharge unit DQ and the abnormal discharge unit The case where DF is provided in the same recording head HD is referred to as complementary printing processing in the same column complementary mode (an example of “first control mode”).
In the complementary printing process, when the nozzle N of the complementary discharge unit DQ and the nozzle N of the abnormal discharge unit DF belong to different nozzle rows Ln, for example, the complementary discharge unit DQ and the abnormal discharge unit D The case where it is provided in a recording head HD different from -F is referred to as complementary printing processing in the other column complementary mode (an example of “second control mode”).
In the present modification, when the complementary printing process is executed in the same column complementing mode, the control unit 6 uses the first time, which is the time from the discharge state determination to the start of the maintenance process, as the other column complementing. When the complementary printing process is executed depending on the mode, control is performed so as to be shorter than the second time, which is the time from the discharge state determination to the start of the maintenance process.

<< Modification 4 >>
In the embodiment and the modification described above, the ink jet printer 1 is provided so that the four head units HU and the four ink cartridges 31 correspond to each other in one-to-one. The ink jet printer 1 is not limited to the above, and the ink jet printer 1 only needs to include one or more head units HU and one or more ink cartridges 31.
Further, in the above-described embodiment and modification, the inkjet printer 1 is provided with four ejection state determination circuits 9 corresponding to the four head units HU on a one-to-one basis. The ink jet printer 1 may be provided with one ejection state determination circuit 9 for the plurality of head units HU, and the plurality of ejections for one head unit HU. A state determination circuit 9 may be provided.

<< Modification 5 >>
In the embodiment and the modification described above, the discharge state determination circuit 9 is provided as a separate circuit from the control unit 6, but the present invention is not limited to such a mode, and the discharge state determination circuit 9 Some or all of them may be implemented as functional blocks realized by the CPU of the control unit 6 operating according to the control program.

<< Modification 6 >>
In the embodiment and the modification described above, the timing unit 63 is implemented as a functional block realized by the control unit 6 operating according to the control program, but the present invention is not limited to such a mode. The timer unit 63 may be implemented as a circuit or hardware separate from the control unit 6.
For example, the time measuring unit 63 is provided outside the head module HM separately from the control unit 6, and the timing at which the discharge state determination circuit 9 outputs the determination information Stt or the residual vibration signal NES to the discharge state determination circuit 9. The time from the timing at which is supplied may be counted. Then, it is determined whether or not the timing for starting the maintenance process has arrived on the basis of the time when the timing is started, and when the timing for starting the maintenance process has arrived, the control unit 6 Can be notified.

Further, in the above-described embodiments and modifications, the inkjet printer 1 includes one timekeeping unit 63, but the present invention is not limited to such an aspect, and the inkjet printer 1 includes, for example, four Four timing units 63 may be provided so as to correspond one-to-one with the head unit HU or the four discharge state determination circuits 9.
For example, the timer 63 may be provided for each head unit HU in the head module HM. For example, each of the four head units HU may include a timer unit 63. In this case, each of the four timing units 63 provided in the head module HM determines whether or not the timing for starting the maintenance process has arrived, for example, based on the timing at which the detection circuit 20 outputs the residual vibration signal NES. If it is time to start the maintenance process, the control unit 6 may be notified of this. In this case, the timing at which the detection circuit 20 outputs the residual vibration signal NES may be regarded as the timing at which the discharge state determination circuit 9 outputs the determination information Stt.
Further, for example, the timer 63 may be provided for each discharge state determination circuit 9 in the determination module CM. That is, each of the four discharge state determination circuits 9 may include a timer unit 63. In this case, each of the four timing units 63 provided in the determination module CM supplies, for example, the timing when the discharge state determination circuit 9 outputs the determination information Stt or the residual vibration signal NES to the discharge state determination circuit 9. It is determined whether or not the timing for starting the maintenance process has arrived on the basis of the timing to be performed, and when the timing for starting the maintenance process has arrived, the control unit 6 may be notified accordingly.
In these cases, since the timing of the maintenance process can be individually determined for each head unit HU, there is a possibility that a serious discharge abnormality that cannot be recovered even by the maintenance process occurs in each head unit HU. It is possible to make recommendations.

<< Modification 7 >>
In the embodiment and the modification described above, the inkjet printer 1 may include a clock 630 as illustrated in FIG. Specifically, the timepiece 630 is, for example, a radio timepiece, and acquires information about the time from the outside of the RTC (real-time clock) and the inkjet printer 1 and corrects the time of the RTC based on the acquired information. And a function for generating information related to time. Here, the information related to the time may be information related to the time used outside the ink jet printer 1 such as a standard time. In addition, the function of obtaining time information from the outside of the inkjet printer 1 includes, for example, a function of receiving time information from a GPS (Global Positioning System) satellite, a function of obtaining time information from the Internet, and the like as appropriate. Adopt it.
In the present modification, the timing unit 63 refers to the clock 630 at the timing when the discharge state determination is performed, and then periodically refers to the clock 630 to arrive at a timing at which the maintenance process should be started. What is necessary is just to determine whether or not. That is, the time measuring unit 63 determines whether or not the time for starting the maintenance process has arrived based on the difference between the reference time and the current time, with the time when the discharge state determination is made as a reference. When it is time to start the maintenance process, the control unit 6 may be notified of this.
FIG. 17 illustrates the case where the timepiece 630 is provided separately from the timekeeping unit 63, but the timepiece 630 may be provided in the timekeeping unit 63. That is, the time measuring unit 63 may include the clock 630.

<< Modification 8 >>
In the above-described embodiments and modifications, it is assumed that the ink jet printer 1 is a serial printer. However, the present invention is not limited to such a mode, and the ink jet printer 1 includes a plurality of head modules HM. A so-called line printer may be used in which the nozzles N are provided so as to extend wider than the width of the recording paper P.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Drive signal generation circuit, 4 ... Maintenance unit, 5 ... Memory | storage part, 6 ... Control part, 7 ... Conveyance mechanism, 9 ... Discharge state determination circuit, 10 ... Switching circuit, 20 ... Detection circuit, 61 DESCRIPTION OF SYMBOLS ... Drive control part 62 ... Maintenance control part 63 ... Timing part, CM ... Determination module, D ... Discharge part, HD ... Recording head, HM ... Head module, HU ... Head unit.

Claims (5)

A plurality of ejection units for ejecting liquid;
A first recording head provided with a first ejection unit among the plurality of ejection units;
A second recording head provided with a second ejection unit among the plurality of ejection units;
A determination unit for determining a liquid discharge state in the discharge unit;
A control unit for controlling the plurality of discharge units;
With
The controller is
When the determination unit determines that the liquid discharge state in one discharge unit provided in the first recording head is abnormal,
Until the first time elapses from the determination, the first ejection unit controls the plurality of ejection units to eject the liquid from the first ejection unit instead of ejecting the liquid from the one ejection unit. Control mode,
A second control unit that controls the plurality of ejection units to eject liquid from the second ejection unit instead of ejecting liquid from the one ejection unit until a second time elapses from the determination; Control mode,
The plurality of discharge units can be controlled by
The first time is shorter than the second time;
A liquid discharge apparatus characterized by that. The controller is
When controlling the plurality of ejection units according to the first control mode,
After the first time has elapsed from the determination,
In order to perform a recovery operation to normally recover the liquid discharge state in the one discharge unit,
Controlling the plurality of ejection units;
When controlling the plurality of discharge units in the second control mode,
After the second time has elapsed from the determination, the recovery operation is executed.
Controlling the plurality of ejection units;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The recovery operation is
The plurality of ejection units are operations for ejecting liquid.
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A first drive signal for driving the ejection unit so that liquid is ejected from the ejection unit; and
A second drive signal for driving the ejection unit so that liquid is not ejected from the ejection unit;
A drive signal generator for generating
Switching whether to supply the first drive signal to the ejection unit;
A switching unit that switches whether to supply the second drive signal to the ejection unit;
With
The controller is
When the determination unit determines that the liquid discharge state in the one discharge unit is abnormal,
While controlling the plurality of discharge units in the first control mode or the second control mode,
The first drive signal and the second drive signal are not supplied to the one ejection unit.
Controlling the switching unit;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A plurality of ejection units for ejecting liquid;
A first recording head provided with a first ejection unit among the plurality of ejection units;
A second recording head provided with a second ejection unit among the plurality of ejection units;
A determination unit for determining a liquid discharge state in the discharge unit;
A method for controlling a liquid ejection apparatus comprising:
With
When the determination unit determines that the liquid discharge state in one discharge unit provided in the first recording head is abnormal,
Until the first time elapses from the determination, the first ejection unit controls the plurality of ejection units to eject the liquid from the first ejection unit instead of ejecting the liquid from the one ejection unit. Control mode,
A second control unit that controls the plurality of ejection units to eject liquid from the second ejection unit instead of ejecting liquid from the one ejection unit until a second time elapses from the determination; Control mode,
Control the plurality of discharge units in one of the control modes,
The first time is shorter than the second time;
A control method for a liquid ejection apparatus.

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