JP2016182718A - Liquid discharge device, control method for liquid discharge device, and control program for liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance accuracy for determining a discharge state of an ink from a discharge section.SOLUTION: A liquid discharge device includes: a recording head including M (M is an integer of 2 or more) pieces of discharge sections for discharging liquid; a driving section for driving the M pieces of discharge sections; a detection section for detecting residual vibration generated in the one discharge section driven by the driving section; a characteristic information generation section for generating characteristic information showing the characteristic of the residual vibration generated in the one discharge section on the basis of the detection result of the detection section; a cleaning mechanism for cleaning the M pieces of discharge sections; a rank determination section for classifying the M pieces of discharge sections to α (α is a natural number satisfying 2≤α<M) pieces of ranks on the basis of the M pieces of characteristic information corresponding to the M pieces of discharge sections and determining a rank to which each discharge section belongs according to the classification result after the cleaning mechanism performs cleaning of the discharge sections; a discharge state determination section for determining a discharge state of liquid in the one discharge section on the basis of rank reference information fixed according to the characteristic information corresponding to the one discharge section and the rank to which the one discharge section belongs.SELECTED DRAWING: Figure 22

Description

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

A liquid discharge apparatus such as an ink jet printer drives a discharge portion provided in a recording head by a drive signal, and discharges a liquid such as ink filled in a cavity (pressure chamber) of the discharge portion onto a recording medium. Form an image. In such a liquid ejecting apparatus, there is a case in which ejection abnormality that prevents the liquid from being ejected normally from the ejecting unit may occur due to thickening of the liquid, mixing of bubbles in the cavity, or the like. When the ejection abnormality occurs, the dots that are to be formed on the medium cannot be accurately formed by the liquid ejected from the ejection unit, and the image quality of the image formed by the liquid ejection device is degraded.
Patent Document 1 proposes a technique for preventing a deterioration in image quality due to abnormal ejection by determining a liquid ejection state in the ejection unit based on residual vibration generated in the ejection unit after driving the ejection unit. .

JP 2004-276544 A

  By the way, the characteristic of the residual vibration generated in the ejection unit varies due to the position of the ejection unit in the recording head, the manufacturing error of the ejection unit, and the like. For this reason, if the determination criterion used in the determination of the discharge state is determined without considering the variation, for example, it may be erroneously determined that a discharge abnormality has occurred in a discharge unit having a normal discharge state. On the other hand, if the determination criterion is relaxed so as to allow variation, it may be erroneously determined that the discharge state is normal with respect to a discharge unit having an abnormal discharge state. As described above, there is a case where the discharge state cannot be normally determined due to the variation in the characteristic of the residual vibration caused by the manufacturing error of the discharge unit.

The present invention has been made in view of the above-described circumstances, and even when there is variation in the characteristics of residual vibration generated in the discharge unit, the determination of the discharge state of the liquid from the discharge unit is highly accurate. One of the problems to be solved is to provide a technology that can be executed in

  In order to solve the above problems, a liquid ejection apparatus according to the present invention includes a recording head including M ejection units (M is a natural number satisfying 2 ≦ M) that ejects liquid, and the M ejection units. A drive unit capable of driving the discharge unit, a detection unit capable of detecting residual vibration generated in the one discharge unit when one of the M discharge units is driven by the drive unit, and the detection A characteristic information generating unit for generating characteristic information corresponding to the one ejection unit indicating a characteristic of residual vibration generated in the one ejection unit based on a detection result of the unit, and a cleaning for cleaning the M ejection units Based on the mechanism and M characteristic information corresponding to the M discharge units on a one-to-one basis, the M discharge units are classified into α ranks (α is a natural number satisfying 2 ≦ α <M). Before the cleaning mechanism cleans the discharge part. According to the result of the classification, according to the rank determination unit that determines the rank to which each of the M discharge units belongs, the characteristic information corresponding to the one discharge unit, and the rank to which the one discharge unit belongs A discharge state determination unit that determines a discharge state of the liquid in the one discharge unit based on determined rank reference information.

According to the present invention, based on the characteristic information indicating the characteristic of residual vibration generated in the discharge unit, the process of dividing the M discharge units into a plurality of ranks (hereinafter, this process may be referred to as “ranking”). ). Also, rank reference information is provided for each of the α ranks set by the rank division. Then, based on the characteristic information corresponding to the ejection unit and the rank reference information corresponding to the rank to which the ejection unit belongs, the ejection state of the ejection unit is determined. For this reason, compared with the case where the discharge state is determined using a single reference information common to the M discharge units, the discharge is performed with high accuracy in consideration of the variation in the residual vibration characteristics between the discharge units. The state can be determined.
In addition, according to the present invention, the rank to which each discharge unit belongs is determined based on the result of ranking performed after cleaning the discharge unit. That is, the rank to which each discharge unit belongs is determined based on the result of ranking performed after the discharge abnormality caused by bubbles mixed into the cavity of the discharge unit is eliminated. For this reason, it is possible to prevent rank determination based on the characteristic information corresponding to the ejection unit having an ejection failure, and to prevent generation of rank reference information that is likely to cause an erroneous determination. This reduces the possibility of misjudgment of the discharge state and accurately determines the discharge state of each discharge unit, compared to the case where the rank is determined based on the characteristic information corresponding to the discharge unit with abnormal discharge. It becomes possible.

  In the above-described liquid ejecting apparatus, the rank determining unit may determine that the M number of ejection units is β (β is a natural number satisfying 2 ≦ β <M) before the cleaning mechanism cleans the ejection unit. First, the first classification information indicating a result of the classification is generated, and after the cleaning mechanism cleans the ejection unit, the M ejection units are classified into the α ranks, Based on the first section information and the second section information, the second section information belongs to each of the M discharge sections based on the first section information and the second section information. A classification information determination unit that determines whether or not the classification information is appropriate classification information, and when the determination result of the classification information determination unit is affirmative, the second classification information indicates The M based on the classification result Discharge unit determines the rank belongs, it may be characterized in that.

In general, the characteristic of residual vibration generated in a discharge part in which the discharge state is normal is stable. Therefore, when the discharge states of the M discharge units are normal, the change in the residual vibration characteristics before and after cleaning is small as compared with the case where there are discharge units with abnormal discharge.
According to this aspect, the first classification information indicating the result of the ranking performed before cleaning the ejection unit, and the second classification information indicating the result of the ranking performed after cleaning the ejection unit. Based on this, it is determined whether or not the second classification information is appropriate classification information suitable for determining the rank. Therefore, when the second classification information indicates the result of ranking performed based on the M pieces of characteristic information corresponding to the M number of ejection units having normal ejection states, the second classification information is It can be determined that the classification information is appropriate. As a result, it is possible to prevent the rank from being determined based on the characteristic information corresponding to the ejection portion having the ejection abnormality, and to reduce the possibility of erroneous determination of the ejection state.

  Further, in the liquid ejecting apparatus described above, the classification information determination unit includes a distribution of the M ejection units belonging to the β ranks indicated by the first classification information and the α number indicated by the second classification information. The second classification information is determined to be the appropriate classification information when the degree of similarity with the distribution of the M ejection units belonging to the rank is higher than a predetermined similarity. Also good.

In general, the characteristic of residual vibration generated in a discharge part in which the discharge state is normal is stable. For this reason, when the discharge states of the M discharge units are normal, the M discharges belonging to the β ranks indicated by the first classification information are compared with the case where there are discharge abnormal discharge units. The degree of similarity between the distribution shape of the portion and the distribution shape of the M ejection portions belonging to the α ranks indicated by the second classification information is high.
According to this aspect, based on the degree of similarity between the first classification information and the second classification information, it is determined whether or not the second classification information is appropriate classification information suitable for determining the rank. Therefore, when the second classification information indicates the result of ranking performed based on the M pieces of characteristic information corresponding to the M number of ejection units having normal ejection states, the second classification information is It can be determined that the classification information is appropriate. As a result, it is possible to prevent the rank from being determined based on the characteristic information corresponding to the ejection portion having the ejection abnormality, and to reduce the possibility of erroneous determination of the ejection state.

  Further, in the liquid ejecting apparatus described above, the classification information generation unit includes the position in the β ranks of the rank to which the most ejection units among the β ranks indicated by the first classification information belong, When the degree of error between the rank of the α ranks indicated by the second classification information and the position of the rank to which the most discharge units belong in the α ranks is smaller than a predetermined allowable error, the first rank It is good also as determining that 2 division information is the said appropriate division information.

As in the above-described aspect, the distribution shape of M ejection units belonging to β ranks indicated by the first division information and the distribution of M ejection units belonging to α ranks indicated by the second division information When the degree of similarity with the shape is high, the mode value in the distribution of the M ejection units belonging to the β ranks indicated by the first division information and the α ranks indicated by the second division information There is a high possibility that the mode value in the distribution of the M ejection units to which it belongs is substantially the same. That is, when the discharge states of the M discharge units are normal, the mode value to which the most discharge units belong to the β ranks indicated by the first classification information in the distribution shape of the M discharge units. There is a high possibility that the rank and the mode rank to which the largest number of ejection units belong among the α ranks indicated by the second classification information are substantially the same position.
According to this aspect, the second classification information is used to determine the rank based on the degree of error in the position of the mode rank between the first classification information and the second classification information in the distribution shape of the M ejection units. It is determined whether or not the appropriate classification information is appropriate. Therefore, when the second classification information indicates the result of ranking performed based on the M pieces of characteristic information corresponding to the M number of ejection units having normal ejection states, the second classification information is It can be determined that the classification information is appropriate. As a result, it is possible to prevent the rank from being determined based on the characteristic information corresponding to the ejection portion having the ejection abnormality, and to reduce the possibility of erroneous determination of the ejection state.

  The method for controlling a liquid ejection apparatus according to the present invention can drive a recording head including M ejection units (M is a natural number satisfying 2 ≦ M) that ejects liquid, and the M ejection units. A drive unit, a detection unit capable of detecting residual vibration generated in the one discharge unit when one of the M discharge units is driven by the drive unit, and a detection result of the detection unit A characteristic information generating unit that generates characteristic information corresponding to the one ejection unit indicating a characteristic of residual vibration generated in the one ejection unit, and a cleaning mechanism that cleans the M ejection units. A control method of a liquid ejection apparatus provided, wherein the number of M ejection units is α (α is 2 ≦ α <M based on M characteristic information corresponding to the M ejection units on a one-to-one basis. Natural number), and the cleaning mechanism In accordance with the result of the classification performed after cleaning the section, the rank to which each of the M ejection sections belongs is determined, the characteristic information corresponding to the one ejection section, and the one ejection section It is characterized in that the liquid discharge state in the one discharge unit is determined based on rank reference information determined according to the rank to which it belongs.

According to this invention, the M discharge units are divided into a plurality of ranks, and the discharge state of the discharge units is determined based on the rank reference information provided for each rank. Therefore, compared to the case where the discharge state is determined based on the reference information common to the M discharge units, it is possible to determine the discharge state with higher accuracy in consideration of variations in the residual vibration characteristics between the discharge units. It becomes.
In addition, according to the present invention, the rank to which each discharge unit belongs is determined based on the result of ranking performed after cleaning the discharge unit. For this reason, it is possible to prevent the rank from being determined on the basis of the characteristic information corresponding to the ejection portion having the ejection abnormality, and to reduce the possibility of erroneous determination of the ejection state.

  The control program for the liquid ejection apparatus according to the present invention can drive a recording head including M ejection units (M is a natural number satisfying 2 ≦ M) for ejecting liquid, and the M ejection units. A drive unit, a detection unit capable of detecting residual vibration generated in the one discharge unit when one of the M discharge units is driven by the drive unit, and a detection result of the detection unit A characteristic information generating unit that generates characteristic information corresponding to the one ejection unit indicating characteristics of residual vibration generated in the one ejection unit, a cleaning mechanism that cleans the M ejection units, and a computer A control program for a liquid ejection apparatus comprising: the computer, the M ejection units based on M characteristic information corresponding to the M ejection units on a one-to-one basis, α is a natural number satisfying 2 ≦ α <M A rank determining unit that determines a rank to which each of the M discharge units belongs according to a result of the division after the cleaning mechanism cleans the discharge unit, and the one discharge unit And a discharge state determination unit that determines the discharge state of the liquid in the one discharge unit based on the characteristic information corresponding to the rank and rank reference information determined according to the rank to which the one discharge unit belongs. It is characterized by that.

According to this invention, the M discharge units are divided into a plurality of ranks, and the discharge state of the discharge units is determined based on the rank reference information provided for each rank. Therefore, compared to the case where the discharge state is determined based on the reference information common to the M discharge units, it is possible to determine the discharge state with higher accuracy in consideration of variations in the residual vibration characteristics between the discharge units. It becomes.
In addition, according to the present invention, the rank to which each discharge unit belongs is determined based on the result of ranking performed after cleaning the discharge unit. For this reason, it is possible to prevent the rank from being determined on the basis of the characteristic information corresponding to the ejection portion having the ejection abnormality, and to reduce the possibility of erroneous determination of the ejection state.

1 is a block diagram illustrating a configuration of a printing system 100 according to an embodiment of the present invention. 1 is a schematic partial cross-sectional view of an inkjet printer 1. 2 is a schematic cross-sectional view of a recording head 3. FIG. 3 is a plan view showing an example of arrangement of nozzles N in the recording head 3. FIG. It is explanatory drawing which shows the change of the cross-sectional shape of the discharge part D when the drive signal Vin is supplied. 3 is a circuit diagram showing a simple vibration model representing residual vibration in a discharge section D. FIG. 4 is a graph showing a relationship between an experimental value and a calculated value of residual vibration in the discharge section D. It is explanatory drawing which shows the state of the discharge part D when a bubble mixes in the discharge part D inside. 4 is a graph showing experimental values and calculated values of residual vibration in the discharge section D. FIG. 6 is an explanatory diagram illustrating a state of a discharge unit D when ink near a nozzle N is fixed. 4 is a graph showing experimental values and calculated values of residual vibration in the discharge section D. It is explanatory drawing which shows the state of the discharge part D when paper dust adheres. 4 is a graph showing experimental values and calculated values of residual vibration in the discharge section D. 3 is a block diagram illustrating a configuration of a drive signal generation unit 51. FIG. It is explanatory drawing which shows the decoding content of decoder DC. 5 is a timing chart showing the operation of a drive signal generation unit 51. 5 is a timing chart showing the operation of a drive signal generation unit 51. It is a timing chart which shows the waveform of drive signal Vin. 4 is an explanatory diagram for explaining a connection relationship between a connection unit 53 and a detection unit 8. FIG. 4 is a timing chart showing an operation of a period information generation unit 41. It is explanatory drawing for demonstrating determination information RS. It is a flowchart which shows a rank determination process. It is a flowchart which shows a division information generation process. It is a figure which shows the data structure of rank reference | standard information table TBL1. It is a figure which shows the data structure of the affiliation rank information table TBL2. It is a flowchart which shows a division information determination process.

  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 printing system >>
The configuration of the inkjet printer 1 according to the present embodiment will be described with reference to FIGS. 1 and 2.

FIG. 1 is a functional block diagram illustrating a configuration of a printing system 100 including an inkjet printer 1. The printing system 100 includes a host computer 9 such as a personal computer or a digital camera, and the inkjet printer 1.
The host computer 9 outputs print data Img indicating an image to be formed by the ink jet printer 1 and information indicating the number of copies of the image to be formed by the ink jet printer 1.
The ink jet printer 1 executes a printing process in which an image indicated by the print data Img supplied from the host computer 9 is formed on the recording paper P in a required number of copies. In the present embodiment, the case where the inkjet printer 1 is a line printer will be described as an example.

As shown in FIG. 1, the inkjet printer 1 includes a head unit 10 provided with a discharge unit D that discharges ink, a determination unit 4 that determines a discharge state of ink from the discharge unit D, and a recording sheet for the head unit 10. A transport mechanism 7 for changing the relative position of P, a control unit 6 that controls the operation of each unit of the inkjet printer 1, a storage unit 20 that stores a control program of the inkjet printer 1 and other information, and an ejection unit D When a discharge abnormality is detected, the cleaning mechanism 21 that executes a cleaning process (maintenance process) that normally restores the ink discharge state in the discharge unit D, and a liquid crystal display, an LED lamp, and the like are included. Display unit for displaying error messages, etc., and inkjet printer Comprising a display operation unit 1 of the user comprises an operation unit for inputting various commands to the inkjet printer 1 (not shown), a.
In addition, although mentioned later for details, in this embodiment, the case where the inkjet printer 1 is provided with the some head unit 10 and the some determination unit 4 is assumed.

FIG. 2 is a partial cross-sectional view illustrating the outline of the internal configuration of the inkjet printer 1.
As shown in FIG. 2, the inkjet printer 1 includes a mounting mechanism 32 that mounts the head unit 10. In addition to the head unit 10, four ink cartridges 31 are mounted on the mounting mechanism 32. The four ink cartridges 31 are provided in one-to-one correspondence with four colors (CMYK) of black (BK), cyan (CY), magenta (MG), and yellow (YL). Each ink cartridge 31 is filled with ink of a color corresponding to the ink cartridge 31. Each ink cartridge 31 may be provided in another place of the inkjet printer 1 instead of being mounted on the mounting mechanism 32.

In the present embodiment, the inkjet printer 1 is provided with four head units 10 so as to correspond to the four ink cartridges 31 on a one-to-one basis, as shown in FIG. In the present embodiment, the inkjet printer 1 is provided with four determination units 4 so as to correspond to the four ink cartridges 31 on a one-to-one basis.
In the following, when the head unit 10 and the determination unit 4 are described, one head unit 10 and one unit provided corresponding to any one of the four ink cartridges 31. The determination unit 4 will be described below, but the description also applies to the other three head units 10 and the three determination units 4.

  As shown in FIG. 1, the transport mechanism 7 includes a transport motor 71 serving as a drive source for transporting the recording paper P, and a motor driver 72 for driving the transport motor 71. Further, as shown in FIG. 2, the transport mechanism 7 includes a platen 74 provided below the mounting mechanism 32 (the −Z direction in FIG. 2), a transport roller 73 that rotates by the operation of the transport motor 71, and FIG. , A guide roller 75 provided to be rotatable around the Y axis, and a storage portion 76 for storing the recording paper P in a rolled state. When the inkjet printer 1 executes a printing process, the transport mechanism 7 feeds the recording paper P from the storage unit 76 and follows a transport path defined by the guide roller 75, the platen 74, and the transport roller 73. In the figure, the sheet is conveyed at a conveyance speed Mv in the + X direction (the direction from the upstream side to the downstream side).

The storage unit 20 is necessary for executing various processes such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), which is a kind of nonvolatile semiconductor memory for storing the print data Img supplied from the host computer 9, and a printing process. RAM (Random Access Memory) for temporarily storing control data for temporarily storing various data such as printing processing and executing various processing such as printing processing, and a control program for controlling each part of the inkjet printer 1 And a PROM which is a kind of nonvolatile semiconductor memory to be stored.
The storage unit 20 stores a rank reference information table TBL1 and an affiliation rank information table TBL2. These various tables will be described later.

The control unit 6 includes a CPU (Central Processing Unit), an FPGA (field-programmable gate array), and the like, and the CPU and the like operate according to a control program stored in the storage unit 20, whereby the inkjet printer 1. Control the operation of each part.
Then, the control unit 6 controls the head unit 10 and the transport mechanism 7 based on the print data Img supplied from the host computer 9 to form an image corresponding to the print data Img on the recording paper P. Control execution of processing.

Specifically, the control unit 6 first stores the print data Img supplied from the host computer 9 in the storage unit 20.
Next, the control unit 6 controls the operation of the head unit 10 based on various data stored in the storage unit 20 such as the print data Img, and the print signal SI and the drive waveform for driving the ejection unit D. A signal such as the signal Com is generated.
Further, the control unit 6 generates signals for controlling the operation of the motor driver 72 based on the print signal SI and various data stored in the storage unit 20, and outputs the generated various signals. Although details will be described later, the drive waveform signal Com according to the present embodiment includes drive waveform signals Com-A and Com-B.
The drive waveform signal Com is an analog signal. Therefore, the control unit 6 includes a DA conversion circuit (not shown), converts a digital drive waveform signal generated by a CPU or the like provided in the control unit 6 into an analog drive waveform signal Com, and outputs the converted signal.

  As described above, the control unit 6 drives the transport motor 71 so as to transport the recording paper P in the + X direction through the control of the motor driver 72, and the discharge unit D through the control of the head unit 10. The presence / absence of ink ejection, the ink ejection amount, the ink ejection timing, and the like are controlled. Thereby, the control unit 6 adjusts the dot size and the dot arrangement formed by the ink ejected on the recording paper P, and controls the execution of the printing process for forming the image corresponding to the print data Img on the recording paper P. .

  Although details will be described later, the control unit 6 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. The execution of the discharge state determination process is controlled.

  Here, the ejection abnormality means that the ink ejection state in the ejection part D becomes abnormal. In other words, the ink is accurately discharged from the nozzle N (see FIGS. 3 and 4 described later) provided in the ejection part D. This is a generic term for a state in which ejection is not possible. More specifically, the ejection abnormality means that the image indicated by the print data Img is formed because the amount of ink ejected is small even when the ejection unit D cannot eject ink, and even when ink can be ejected from the ejection unit D. In a state where the ejection unit D cannot eject an amount of ink necessary to perform, a state where an amount of ink more than that necessary for forming the image indicated by the print data Img is ejected from the ejection unit D, an ejection from the ejection unit D This includes a state in which the ink to be landed at a position different from the landing position planned for forming the image indicated by the print data Img.

  When a discharge abnormality occurs in the discharge portion D, the ink discharge state in the discharge portion D is normally recovered by the cleaning process by the cleaning mechanism 21. Here, the cleaning process is a flushing process for preliminarily ejecting ink from the ejection unit D, a pumping process for sucking thickened ink or bubbles in the ejection unit D by a tube pump (not shown), and the like. In this process, the ink inside D is discharged, and new ink is supplied from the ink cartridge 31 to the discharge unit D, thereby returning the ink discharge state in the discharge unit D to normal.

  As shown in FIG. 1, each head unit 10 includes a recording head 3 including M ejection portions D and a head driver 5 that drives each ejection portion D included in the recording head 3 (this embodiment). In the embodiment, M is a natural number satisfying 2 ≦ M). Hereinafter, in order to distinguish each of the M ejection portions D, they may be referred to as “first stage, second stage,..., M stage” in order. In the following description, the m stages of ejection units D may be expressed as ejection units D [m] (the variable m is a natural number that satisfies 1 ≦ m ≦ M).

  Each of the M ejection portions D receives ink from the ink cartridge 31 corresponding to the head unit 10 provided with the M ejection portions D. Each ejection part D can be filled with ink supplied from the ink cartridge 31 and eject the filled ink from a nozzle N included in the ejection part D. Specifically, each ejection unit D records dots for constituting an image by ejecting ink onto the recording paper P at a timing when the transport mechanism 7 transports the recording paper P onto the platen 74. Form on paper P. Then, full-color printing is realized by ejecting four colors of CMYK ink as a whole from the 4M ejection portions D provided in the four head units 10.

As shown in FIG. 1, the head driver 5 includes a drive signal supply unit 50 (“drive unit”) that supplies a drive signal Vin for driving each of the M ejection units D included in the recording head 3 to each ejection unit D. And a detection unit 8 (an example of “detection unit”) that detects residual vibration generated in the discharge unit D after the discharge unit D is driven by the drive signal Vin.
In the following description, among the M ejection units D, the ejection unit D that is the target of residual vibration detection by the detection unit 8 may be referred to as a target ejection unit Dtg. Although the details will be described later, the target discharge portion Dtg is designated from the M discharge portions D by the control unit 6.

The drive signal supply unit 50 includes a drive signal generation unit 51 and a connection unit 53.
The drive signal generation unit 51 drives each of the M ejection units D included in the recording head 3 based on signals supplied from the control unit 6 such as the print signal SI, the clock signal CL, and the drive waveform signal Com. A drive signal Vin for generating the signal is generated.
The connection unit 53 electrically connects each ejection unit D to either the drive signal generation unit 51 or the detection unit 8 based on the connection control signal Sw supplied from the control unit 6. The drive signal Vin generated in the drive signal generation unit 51 is supplied to the ejection unit D via the connection unit 53. When the drive signal Vin is supplied, each discharge unit D is driven based on the supplied drive signal Vin, and can discharge the ink filled therein onto the recording paper P.

The detection unit 8 detects a residual vibration signal Vout indicating a residual vibration generated in the discharge section D after the discharge section D designated as the target discharge section Dtg is driven by the drive signal Vin.
Then, the detection unit 8 generates a shaped waveform signal Vd by performing processing such as removing noise components and amplifying the signal level on the detected residual vibration signal Vout, and the generated shaped waveform signal. Vd is output. In the present embodiment, the drive signal supply unit 50 and the detection unit 8 are mounted as an electronic circuit on a substrate provided in the head unit 10, for example.

The determination unit 4 determines the ink discharge state in the discharge portion D designated as the target discharge portion Dtg based on the shaped waveform signal Vd output from the detection unit 8 when the discharge state determination processing is executed. Determination information RS indicating the determination result is generated.
Specifically, the determination unit 4 firstly, based on the shaped waveform signal Vd output from the detection unit 8, an example of period information NTc (an example of “characteristic information”) indicating a time Tc for one period of the shaped waveform signal Vd. ) Is generated. Next, the determination unit 4 determines the ink discharge state in the discharge unit D based on the period information NTc and the reference information STth generated by the control unit 6, and generates determination information RS indicating the determination result. To do. In the present embodiment, the determination unit 4 is mounted as an electronic circuit on a substrate provided at a location different from the head unit 10, for example.

  The discharge state determination process is a process in which a discharge unit D designated as the target discharge unit Dtg is driven by the drive signal supply unit 50 under the control of the control unit 6 and residual vibration generated in the discharge unit D is detected by the detection unit. The determination unit 4 generates the determination information RS based on the shaped waveform signal Vd detected by the detection unit 8 that detects the residual vibration and the reference information STth output by the control unit 6. It is a series of processes executed by the inkjet printer 1.

In addition, the inkjet printer 1 according to the present embodiment is a process that generates reference information STth indicating a reference value Tth that is a determination reference used when determining the discharge state of the discharge unit D prior to the execution of the discharge state determination process. A certain rank determination process is executed.
More specifically, in the rank determination process, the M ejection units D are divided into a plurality of ranks, and the rank to which each of the M ejection units D belongs is determined. On the other hand, this is a series of processes executed by the ink jet printer 1 to define a reference value Tth that is a criterion for determining the ink ejection state in the ejection unit D and to generate reference information STth indicating the reference value Tth. The reference information STth in the present embodiment is an example of “rank reference information”.

As described above, due to the position of the ejection part D in the recording head 3, the manufacturing error of the ejection part D, and the like, the residual vibration characteristics may vary among the M ejection parts D. For example, the ejection portion D provided at the end of the recording head 3 may have a longer time Tc, which is a period of residual vibration generated in the ejection portion D, than the ejection portion D provided at the central portion of the recording head 3. is there. For this reason, when determining the ink ejection state in the ejection unit D based on the residual vibration characteristics such as the period of the residual vibration generated in the ejection unit D, the determination is performed without considering the variation in the residual vibration characteristics. If the determination criterion used for the determination is determined, there is a high possibility of erroneous determination in the determination.
Therefore, in the present embodiment, M discharge units D are divided into a plurality of ranks based on period information NTc indicating the period of residual vibration, which is one of the characteristics of residual vibration generated in the discharge unit D. After determining the rank to which the discharge unit D belongs, a reference value Tth is determined for each of the plurality of ranks. Then, the ink ejection state in each ejection unit D is determined using a reference value Tth determined according to the rank to which each ejection unit D belongs as a criterion. Thereby, compared with the case where the common reference value Tth is determined for the M ejection units D, it is possible to reduce the probability of occurrence of erroneous determination due to the variation existing between the M ejection units D. Become.

In the rank determination process, the process of dividing the M ejection units D into a plurality of ranks and generating the classification information Info indicating the result of the classification is referred to as a classification information generation process.
In the rank determination process, a process for determining whether or not the classification information Info generated by the classification information generation process is suitable for final determination of the rank to which each of the M ejection units D belongs. This is referred to as segment information determination processing.

  The control unit 6 functions as the rank determination unit 60 when the CPU of the control unit 6 controls the execution of the rank determination process according to the control program. Moreover, the control part 6 functions as the division information generation part 61 by controlling execution of the division information generation process in the rank determination process. Moreover, the control part 6 functions as the division information determination part 62 by performing a division information determination process in a rank determination process. That is, as shown in FIG. 1, the rank determination unit 60 includes a division information generation unit 61 and a division information determination unit 62.

  Hereinafter, the period information NTc indicating the period of the residual vibration in the discharge unit D [m] is expressed as period information NTc [m], and the time Tc indicated by the period information NTc [m] is expressed as time Tc [m]. In addition, the discharge unit D [m] is denoted by reference numerals indicating components and information corresponding to the discharge unit D [m], for example, the determination information RS indicating the ink discharge state is expressed as the determination information RS [m]. In some cases, a subscript [m] indicating the number m of stages of D [m] is attached.

<< 2. Configuration of recording head >>
The recording head 3 and the ejection part D provided in the recording head 3 will be described with reference to FIGS.

  FIG. 3 is an example of a schematic partial cross-sectional view of the recording head 3. In this figure, for convenience of illustration, one ejection unit D among the M ejection units D of the recording head 3 communicates with the one ejection unit D via the ink supply port 360. A reservoir 350 and an ink intake 370 for supplying ink from the ink cartridge 31 to the reservoir 350 are shown.

  As shown in FIG. 3, the ejection unit D includes a piezoelectric element 300, a cavity 320 (an example of a “pressure chamber”) filled with ink, a nozzle N communicating with the cavity 320, a vibration plate 310, Is provided. The ejection unit D ejects ink in the cavity 320 from the nozzles N when the piezoelectric element 300 is driven by the drive signal Vin. The cavity 320 of the discharge part D is a space defined by a cavity plate 340 formed into a predetermined shape having a recess, a nozzle plate 330 on which a nozzle N is formed, and a vibration plate 310. The cavity 320 communicates with the reservoir 350 via the ink supply port 360. The reservoir 350 communicates with one ink cartridge 31 through the ink intake port 370.

In the present embodiment, for example, a unimorph (monomorph) type as shown in FIG. The piezoelectric element 300 is not limited to a unimorph type but may be a bimorph type or a laminated type.
The piezoelectric element 300 includes a lower electrode 301, an upper electrode 302, and a piezoelectric body 303 provided between the lower electrode 301 and the upper electrode 302. Then, when the potential of the lower electrode 301 is set to a predetermined reference potential VSS and the drive signal Vin is supplied to the upper electrode 302, the voltage is applied between the lower electrode 301 and the upper electrode 302. The piezoelectric element 300 bends (displaces) in the vertical direction in the figure in accordance with the applied voltage, and as a result, the piezoelectric element 300 vibrates.

  A diaphragm 310 is installed in the upper surface opening of the cavity plate 340, and the lower electrode 301 is joined to the diaphragm 310. For this reason, when the piezoelectric element 300 vibrates by the drive signal Vin, the vibration plate 310 also vibrates. Then, the volume of the cavity 320 (pressure in 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. Ink is supplied to the reservoir 350 from the ink cartridge 31 through the ink intake 370.

  FIG. 4 shows an example of the arrangement of M nozzles N provided in each of the four recording heads 3 mounted on the mounting mechanism 32 when the inkjet printer 1 is viewed in plan from the + Z direction or the −Z direction. It is explanatory drawing for demonstrating.

  As shown in FIG. 4, each recording head 3 is provided with a nozzle row Ln composed of M nozzles N. In other words, the inkjet printer 1 has four nozzle rows Ln. Specifically, the inkjet printer 1 has four nozzle rows Ln including a nozzle row Ln-BK, a nozzle row Ln-CY, a nozzle row Ln-MG, and a nozzle row Ln-YL. Here, each of the plurality of nozzles N belonging to the nozzle row Ln-BK is a nozzle N provided in the ejection unit D that ejects black (BK) ink, and the plurality of nozzles N belonging to the nozzle row Ln-CY. Each of the nozzles N is provided in a discharge unit D that discharges cyan (CY) ink, and each of the plurality of nozzles N belonging to the nozzle row Ln-MG discharges magenta (MG) ink. Each of the plurality of nozzles N belonging to the nozzle row Ln-YL is a nozzle N provided in the ejection unit D that ejects yellow (YL) ink. In this embodiment, each of the four nozzle rows Ln extends in the + Y direction or the −Y direction (hereinafter, the + Y direction and the −Y direction are collectively referred to as “Y-axis direction”) when viewed in plan. It is provided to exist. A range YNL in which each nozzle row Ln extends in the Y-axis direction is a recording sheet P (more precisely, the recording sheet P has a maximum width that can be printed by the inkjet printer 1 in the Y-axis direction). When printing the paper P), the recording paper P has a range YP or more in the Y-axis direction.

As shown in FIG. 4, in the plurality of nozzles N constituting each nozzle row Ln, the positions of the even-numbered nozzles N and the odd-numbered nozzles N in the X-axis direction are different from each other from the left side (−Y side). In addition, they are arranged in a so-called staggered pattern. In each nozzle row Ln, the interval (pitch) between the nozzles N in the Y-axis direction can be appropriately set according to the printing resolution (dpi: dot per inch).
In the present embodiment, in the recording head 3, M nozzles N are arranged in stages such as nozzles N [1], N [2],..., N [M] from the −Y direction to the + Y direction in the drawing. Arranged in order of young. In other words, in the recording head 3, M ejection portions D are arranged in order of the number of stages, such as ejection portions D [1], D [2], ..., D [M].

  As an example, the printing process according to the present embodiment is performed as follows. As shown in FIG. 4, the recording paper P has a plurality of print areas (for example, an A4 size rectangle in the case of printing an A4 size image on the recording paper P). When a plurality of images corresponding to a plurality of print areas are formed after being divided into areas and labels on a label sheet) and blank areas for partitioning each of the plurality of print areas. Is assumed.

<< 3. Discharge unit operation and residual vibration >>
Next, the ink ejection operation from the ejection unit D and the residual vibration generated in the ejection unit D will be described with reference to FIGS.

  FIG. 5 is an explanatory diagram for explaining an ink ejection operation from the ejection unit D. FIG. In the state shown in FIG. 5A, when the drive signal Vin is supplied from the head driver 5 to the piezoelectric element 300 included in the ejection unit D, the piezoelectric element 300 responds to the electric field applied between the electrodes. Distortion occurs, and the diaphragm 310 of the discharge part D bends upward in the drawing. Thereby, compared with the initial state shown in FIG. 5A, as shown in FIG. 5B, the volume of the cavity 320 of the discharge section D is enlarged. In the state shown in FIG. 5B, when the potential indicated by the drive signal Vin is changed, the diaphragm 310 is restored by its elastic restoring force, and goes downward in the figure beyond the position of the diaphragm 310 in the initial state. As a result, the volume of the cavity 320 rapidly contracts as shown in FIG. At this time, due to the compression pressure generated in the cavity 320, a part of the ink filling the cavity 320 is ejected as an ink droplet from the nozzle N communicating with the cavity 320.

  As shown in FIG. 5, the vibration plate 310 of the discharge unit D vibrates after being driven by the drive signal Vin and displaced in the vertical direction. This vibration remains even after the ejection part D is driven by the drive signal Vin. Such residual vibrations remaining in the ejection part D after the ejection part D is driven by the drive signal Vin are the acoustic resistance Res due to the shape of the nozzle N and the ink supply port 360 or the viscosity of the ink, and the ink weight in the flow path. Is assumed to have a natural vibration frequency determined by the inertance Int and the compliance Cm of the diaphragm 310. Hereinafter, a calculation model of residual vibration generated in the diaphragm 310 of the discharge unit D based on the assumption will be described.

FIG. 6 is a circuit diagram showing a calculation model of simple vibration assuming residual vibration of diaphragm 310. Thus, the calculation model of the residual vibration of the diaphragm 310 can be expressed by the sound pressure Prs, the above-described inertance Int, compliance Cm, and acoustic resistance Res. When the step response when the sound pressure Prs is applied to the circuit of FIG. 6 is calculated for the volume velocity Uv, the following equation is obtained.
Uv = {Prs / (ω · Int)} e− ^γt · sin (ωt)
ω = {1 / (Int · Cm) −γ ² } ^1/2
γ = Res / (2 ・ Int)

The calculation result (calculated value) obtained from this equation is compared with the experimental result (experimental value) in the residual vibration experiment of the discharge section D performed separately. The residual vibration experiment is an experiment for detecting residual vibration generated in the vibration plate 310 of the ejection unit D after ejecting ink from the ejection unit D in which the ink ejection state is normal.
FIG. 7 is a graph showing the relationship between experimental values and calculated values of residual vibration. As can be seen from the graph shown in FIG. 7, when the ink ejection state in the ejection part D is normal, the two waveforms of the experimental value and the calculated value are almost the same.

  Now, in spite of the ejection part D performing the ink ejection operation, the ink ejection state in the ejection part D is abnormal and the ink droplets are not ejected normally from the nozzles N of the ejection part D, that is, ejection Abnormalities may occur. The cause of this ejection abnormality is (1) mixing of bubbles into the cavity 320, (2) thickening or fixing of ink in the cavity 320 due to drying of the ink in the cavity 320, and (3). Examples include adhesion of foreign matters such as paper dust to the vicinity of the outlet of the nozzle N.

  As described above, the ejection abnormality typically means that ink cannot be ejected from the nozzle N, that is, a non-ejection phenomenon of ink appears. In this case, pixel missing in the image printed on the recording paper P is lost. Arise. Further, as described above, in the case of abnormal ejection, even if ink is ejected from the nozzle N, the amount of ink is too small, or the flight direction (ballistic) of the ejected ink droplets is deviated. It will appear as a missing dot in the pixel.

  In the following, based on the comparison result shown in FIG. 7, at least one of the acoustic resistance Res and inertance Int is set so that the calculated value of the residual vibration and the experimental value are substantially matched for each cause of the discharge abnormality occurring in the discharge portion D. Adjust the value of.

First, (1) the mixing of bubbles into the cavity 320, which is one of the causes of ejection abnormalities, will be examined. FIG. 8 is a conceptual diagram for explaining a case where bubbles are mixed in the cavity 320. As shown in FIG. 8, when bubbles are mixed in the cavity 320, it is considered that the total weight of the ink filling the cavity 320 is reduced and the inertance Int is reduced. Further, when bubbles are attached in the vicinity of the nozzle N, it is considered that the diameter of the nozzle N is increased by the size of the diameter, and the acoustic resistance Res is considered to decrease.
Therefore, the acoustic resistance Res and the inertance Int are set to be small compared with the case where the ink ejection state as shown in FIG. 7 is normal, and matched with the experimental value of the residual vibration when the bubbles are mixed. A graph like 9 was obtained. As shown in FIGS. 7 and 9, when a discharge abnormality occurs due to bubbles mixed in the cavity 320, the frequency of residual vibration is higher than when the discharge state is normal. In addition, the attenuation rate of the amplitude of the residual vibration is reduced due to the decrease in the acoustic resistance Res, and it can be confirmed that the residual vibration is slowly decreasing the amplitude.

Next, (2) thickening or fixing of ink in the cavity 320, which is one of the causes of ejection abnormalities, will be examined. FIG. 10 is a conceptual diagram for explaining a case where ink near the nozzle N of the cavity 320 is fixed by drying. As shown in FIG. 10, when the ink near the nozzle N is dried and fixed, the ink in the cavity 320 is confined in the cavity 320. In such a case, it is considered that the acoustic resistance Res increases.
Therefore, compared with the case where the ink ejection state as shown in FIG. 7 is normal, the acoustic resistance Res is set large, and the experimental value of the residual vibration when the ink near the nozzle N is fixed or thickened By matching, a graph as shown in FIG. 11 was obtained. The experimental values shown in FIG. 11 indicate the residual vibration of the diaphragm 310 provided in the ejection unit D in a state where the ejection unit D is left without the cap (not shown) attached for several days and the ink near the nozzle N is fixed. It is measured. As shown in FIGS. 7 and 11, when the ink in the vicinity of the nozzle N in the cavity 320 is fixed, the residual vibration frequency is extremely low and the residual vibration is lower than when the ejection state is normal. A characteristic waveform in which is overdamped is obtained. This is because, when the vibration plate 310 is drawn in the + Z direction (upward) to discharge ink, the vibration plate 310 moves in the −Z direction (downward) after ink flows from the reservoir into the cavity 320. In addition, since there is no escape path for ink in the cavity 320, the vibration plate 310 cannot vibrate rapidly (because it is overdamped).

Next, (3) adhesion of foreign matters such as paper dust near the outlet of the nozzle N, which is one of the causes of ejection abnormalities, will be examined. FIG. 12 is a conceptual diagram for explaining the case where paper dust adheres to the vicinity of the nozzle N outlet. As shown in FIG. 12, when paper dust adheres to the vicinity of the outlet of the nozzle N, the ink oozes out from the cavity 320 through the paper powder, and ink cannot be ejected from the nozzle N. When paper dust adheres to the vicinity of the outlet of the nozzle N and the ink oozes out from the nozzle N, the amount of ink that oozes out from the cavity 320 when viewed from the diaphragm 310 is greater than when the ejection state is normal. The increase in inertance is thought to increase the inertance Int. Further, it is considered that the acoustic resistance Res is increased by the fiber of the paper powder attached near the outlet of the nozzle N.
Therefore, in comparison with the case where the ink ejection state as shown in FIG. 7 is normal, the inertance Int and the acoustic resistance Res are set larger, and the residual vibration when the paper dust adheres to the vicinity of the nozzle N outlet is tested. By matching the values, a graph as shown in FIG. 13 was obtained. As can be seen from the graphs of FIGS. 7 and 13, when paper dust adheres near the outlet of the nozzle N, the frequency of residual vibration is lower than when the ejection state is normal.
From the graphs shown in FIGS. 11 and 13, (3) the case where foreign matter such as paper dust adheres to the vicinity of the outlet of the nozzle N is compared with the case of (2) the thickening of the ink in the cavity 320. It can be seen that the frequency of the residual vibration is high.

  Here, in both (2) the case of ink thickening and (3) the case of paper dust adhering to the vicinity of the nozzle N outlet, the residual vibration is higher than in the case where the ink ejection state is normal. The frequency is low. The causes of these two ejection abnormalities can be distinguished by comparing the residual vibration waveform, specifically, the frequency or period of the residual vibration with a predetermined threshold.

  As is clear from the above description, the ejection state of the ejection unit D can be determined based on the waveform of the residual vibration generated when the ejection unit D is driven, particularly the frequency or cycle of the residual vibration. More specifically, based on the frequency or period of the residual vibration, whether or not the discharge state in the discharge part D is normal, and the cause of the discharge abnormality when the discharge state in the discharge part D is abnormal It can be determined as to which of (1) to (3) described above corresponds. The ink jet printer 1 according to the present embodiment executes a discharge state determination process for analyzing a residual vibration and determining a discharge state.

<< 4. Configuration and operation of head driver and determination unit >>
Next, the head driver 5 (the drive signal generation unit 51, the detection unit 8, and the connection unit 53) and the determination unit 4 will be described with reference to FIGS.

<< 4.1. Drive signal generator >>
FIG. 14 is a block diagram illustrating a configuration of the drive signal generation unit 51 in the head driver 5.
As illustrated in FIG. 14, the drive signal generation unit 51 corresponds to a set of the shift register SR, the latch circuit LT, the decoder DC, and the switching unit TX so as to correspond to the M ejection units D on a one-to-one basis. Have M. Hereinafter, each element constituting the M sets may be referred to as a first stage, a second stage,...

  The drive signal generator 51 is supplied with a clock signal CL, a print signal SI, a latch signal LAT, a change signal CH, and a drive waveform signal Com (Com-A, Com-B) from the controller 6.

The drive waveform signal Com (Com-A, Com-B) is a signal including a plurality of waveforms for driving the ejection part D.
The print signal SI designates the waveform of the drive waveform signal Com to be supplied to each ejection part D, and accordingly, whether or not ink is ejected from each ejection part D and each ejection part D should eject. This is a digital signal that specifies the amount of ink. The print signal SI includes print signals SI [1] to SI [M]. Among these, the print signal SI [m] indicates whether or not ink is ejected from the ejection unit D [m] and the amount of ink to be ejected by the ejection unit D [m]. Specify in bits.
Specifically, the print signal SI [m] is used when the ink jet printer 1 is performing a printing process, with respect to the ejection unit D [m]. Either one of ink ejection corresponding to a dot, ink ejection corresponding to a small dot, or non-ink ejection is designated (see FIG. 15A). On the other hand, the print signal SI [m] is generated when the inkjet printer 1 is performing the discharge state determination process or the rank determination process, and the occurrence of residual vibration for the discharge state inspection in the discharge unit D [m]. Alternatively, one of the occurrences of fine vibrations for preventing ink thickening in the ejection unit D [m] is designated (see FIG. 15B).
The drive signal generation unit 51 supplies a drive signal Vin having a waveform specified by the print signal SI [m] to the ejection unit D [m]. Hereinafter, the drive signal Vin having a waveform specified by the print signal SI [m] among the drive signals Vin and supplied to the ejection unit D [m] is referred to as a drive signal Vin [m].

  The shift register SR temporarily holds the serially supplied print signal SI (SI [1] to SI [M]) for every 2 bits corresponding to each ejection unit D. Specifically, the shift register SR has a configuration in which M shift registers SR of 1 stage, 2 stages,..., M stages corresponding to M ejection units D on a one-to-one basis are cascade-connected to each other. The serially supplied print signal SI is sequentially transferred to the subsequent stage according to the clock signal CL. When the print signal SI is transferred to all of the M shift registers SR, each of the M shift registers SR maintains a state in which data for 2 bits corresponding to itself is held in the print signal SI. To do. Hereinafter, the m-stage shift register SR may be referred to as a shift register SR [m].

  Each of the M latch circuits LT simultaneously latches the print signal SI [m] for 2 bits corresponding to each stage held in each of the M shift registers SR at the timing when the latch signal LAT rises. To do. That is, the m-stage latch circuit LT latches the print signal SI [m] held by the shift register SR [m].

  By the way, the operation period, which is a period in which the inkjet printer 1 executes at least one of the printing process, the ejection state determination process, or the rank determination process, includes a plurality of unit periods Tu. In this embodiment, the unit period Tu includes a unit printing period Tu-P (see FIG. 16) that is a unit period Tu in which the printing process is executed, and a unit period in which the discharge state determination process or the rank determination process is executed. The unit determination period Tu-T (see FIG. 17), which is Tu, is classified into two types of unit periods Tu.

As described above, the inkjet printer 1 according to the present embodiment divides the long recording paper P into a plurality of printing regions and a margin region for partitioning each of the plurality of printing regions, One image is formed for the print area.
For this reason, the control unit 6 determines a period in which at least a part of the print area of the recording paper P is located below the recording head 3 (−Z side) among the plurality of unit periods Tu constituting the operation period. The printing period Tu-P is classified, and the operation of each unit of the inkjet printer 1 is controlled so that the printing process is executed in the unit printing period Tu-P.
Note that the unit determination period Tu-T may be set as appropriate during the operation period, excluding the unit printing period Tu-P. For example, the control unit 6 is a period in which an area other than the printing area of the recording paper P is located below the recording head 3 among the plurality of unit periods Tu constituting the operation period, or below the recording head 3. The period in which the recording paper P does not exist is classified as a unit determination period Tu-T, and the operation of each part of the inkjet printer 1 is controlled so that the ejection state determination process or the rank determination process is executed in the unit determination period Tu-T. May be.

The control unit 6 supplies the print signal SI to the drive signal generation unit 51 every unit period Tu, and the latch circuit LT latches the print signal SI [m] every unit period Tu. A signal LAT is supplied.
Specifically, in the unit printing period Tu-P, the control unit 6 supplies a printing process drive signal Vin for executing the printing process to each ejection unit D [m]. The drive signal generator 51 is controlled. Here, the drive signal Vin for printing processing means that the ejection unit D ejects an amount of ink corresponding to a large dot, ejects an amount of ink corresponding to a medium dot, and ejects an amount of ink corresponding to a small dot. Or a drive signal Vin for driving the ejection unit D so as to execute either non-ejection of ink.
In addition, the control unit 6 supplies a drive signal Vin for discharge state determination processing for executing discharge state determination processing or rank determination processing to each discharge unit D [m] in the unit determination period Tu-T. Thus, the drive signal generation unit 51 is controlled. Here, the drive signal Vin for the discharge state determination process is a drive signal Vin for driving the discharge unit D so that residual vibration or fine vibration is generated in the discharge unit D.

  In the present embodiment, the control unit 6 divides the unit period Tu into a control period Ts1 and a control period Ts2 based on the change signal CH. The control periods Ts1 and Ts2 have the same time length. Hereinafter, the control periods Ts1 and Ts2 may be collectively referred to as a control period Ts.

The decoder DC decodes the print signal SI [m] latched by the latch circuit LT and outputs selection signals Sa [m] and Sb [m].
FIG. 15 is an explanatory diagram showing the decoding contents of the decoder DC in each unit period Tu. Among these, FIG. 15A shows the contents of decoding by the m-stage decoder DC in the unit printing period Tu-P, and FIG. 15B shows the contents of the m-stage decoder DC in the unit determination period Tu-T. Decode contents are shown.

  As shown in FIGS. 15A and 15B, in the unit printing period Tu-P and the unit determination period Tu-T, the m-stage decoder DC receives the selection signal Sa [m in the control periods Ts1 and Ts2. ] And Sb [m] are output. For example, in the unit print period Tu-P, when the print signal SI [m] is (b1, b2) = (1, 0) (see FIG. 15A2), the m-stage decoder DC is in the control period. In Ts1, the selection signal Sa [m] is set to the high level H and the selection signal Sb [m] is set to the low level L. In the control period Ts2, the selection signal Sb [m] is set to the high level H and the selection signal Sa. [m] is set to the low level L, respectively.

As illustrated in FIG. 14, the drive signal generation unit 51 includes M switching units TX so as to correspond to the M ejection units D on a one-to-one basis. The m-stage switching unit TX [m] is turned on when the selection signal Sa [m] is at H level and turned off when the selection signal Sa [m] is at L level, and the selection signal Sb [m] is at H level. And a transmission gate TGb [m] that is turned on at the time of L and turned off at the L level.
For example, when the print signal SI [m] indicates (1, 0) in the unit print period Tu-P (see FIG. 15A2), the transmission gate TGa [m] is turned on in the control period Ts1, and the transmission The gate TGb [m] is turned off, and the transmission gate TGa [m] is turned off and the transmission gate TGb [m] is turned on in the control period Ts2.

As shown in FIG. 14, the drive waveform signal Com-A is supplied to one end of the transmission gate TGa [m], and the drive waveform signal Com-B is supplied to one end of the transmission gate TGb [m]. The other ends of the transmission gates TGa [m] and TGb [m] are electrically connected to the m-stage output terminal OTN.
As shown in FIG. 15, in each control period Ts, the switching unit TX [m] is controlled such that one of the transmission gates TGa [m] and TGb [m] is turned on and the other is turned off. That is, in each control period Ts, the switching unit TX [m] discharges either the drive waveform signal Com-A or Com-B as the drive signal Vin [m] via the m-stage output terminals OTN. Supply to part D [m].

<< 4.2. Drive waveform signal >>
16 and 17 are timing charts for explaining various signals supplied to the drive signal generation unit 51 by the control unit 6 in each unit period Tu and the operation of the drive signal generation unit 51 in each unit period Tu. is there. 16 shows an example of the operation of the drive signal generation unit 51 and the signal supplied to the drive signal generation unit 51 in the unit printing period Tu-P, and FIG. 17 shows the unit determination period Tu-T. 2 is an example of the operation of the drive signal generation unit 51 and the signal supplied to the drive signal generation unit 51. 16 and 17 exemplify a case where M = 4 for convenience of illustration.

As shown in FIGS. 16 and 17, the unit period Tu is divided by a pulse Pls-L included in the latch signal LAT output from the control unit 6, and the control periods Ts1 and Ts2 are output from the control unit 6. It is divided by the pulse Pls-C included in the change signal CH.
Prior to the start of each unit period Tu, the controller 6 supplies the print signal SI to the drive signal generator 51 in synchronization with the clock signal CL. Then, the shift register SR of the drive signal generation unit 51 sequentially transfers the supplied print signal SI [m] to the subsequent stage according to the clock signal CL.

As shown in FIGS. 16 and 17, in the present embodiment, the waveform of the drive waveform signal Com-A output from the control unit 6 differs between the unit printing period Tu-P and the unit determination period Tu-T.
Hereinafter, among the drive waveform signals Com-A, a signal output by the control unit 6 in the unit printing period Tu-P is referred to as a printing drive waveform signal Com-AP (see FIG. 16). Of the drive waveform signal Com-A, a signal output by the control unit 6 in the unit determination period Tu-T is referred to as a determination drive waveform signal Com-AT (see FIG. 17).

As illustrated in FIG. 16, the printing drive waveform signal Com-AP output by the control unit 6 during the unit printing period Tu-P is an ejection waveform PA1 (hereinafter referred to as “waveform PA1”) provided during the control period Ts1. And a discharge waveform PA2 (hereinafter referred to as “waveform PA2”) provided in the control period Ts2.
The waveform PA1 is such that when a drive signal Vin [m] having the waveform PA1 is supplied to the ejection part D [m], a medium amount of ink corresponding to a medium dot is ejected from the ejection part D [m]. It is a simple waveform.
The waveform PA2 is such that when a drive signal Vin [m] having the waveform PA2 is supplied to the ejection part D [m], a small amount of ink corresponding to a small dot is ejected from the ejection part D [m]. It is a simple waveform.
For example, the potential difference between the lowest potential Va11 and the highest potential Va12 of the waveform PA1 is determined to be larger than the potential difference between the lowest potential Va21 and the highest potential Va22 of the waveform PA2.

As illustrated in FIGS. 16 and 17, the drive waveform signal Com-B output by the control unit 6 in the unit period Tu of both the unit printing period Tu-P and the unit determination period Tu-T is the fine vibration waveform PB ( (Hereinafter referred to as “waveform PB”).
The waveform PB is a waveform in which ink is not ejected from the ejection part D [m] when the drive signal Vin [m] having the waveform PB is supplied to the ejection part D [m]. That is, the waveform PB is a waveform for preventing the ink from thickening by giving a slight vibration to the ink inside the ejection portion D. For example, the potential difference between the lowest potential Vb11 and the highest potential (reference potential V0 in this example) of the waveform PB is determined to be smaller than the potential difference between the lowest potential Va21 and the highest potential Va22 of the waveform PA2.

As illustrated in FIG. 17, the determination drive waveform signal Com-AT output by the control unit 6 in the unit determination period Tu-T has a test waveform PT (hereinafter referred to as “waveform PT”).
The waveform PT includes a waveform PT1 for vibrating the discharge portion D and a waveform PT2 for maintaining residual vibration of the discharge portion D after being driven by the waveform PT1.
The waveform PT1 is a waveform such that ink is not ejected from the ejection part D [m] when the drive signal Vin [m] having the waveform PT1 is supplied to the ejection part D [m]. For example, the potential difference between the lowest potential VcL and the highest potential (detected potential VcH in this example) of the waveform PT1 is determined to be smaller than the potential difference between the lowest potential Va21 and the highest potential Va22 of the waveform PA2. That is, the discharge state determination process according to the present embodiment determines the ink discharge state in the discharge unit D based on the residual vibration generated in the discharge unit D when the discharge unit D is driven so as not to discharge ink. A case of so-called “non-ejection inspection” is assumed. However, the waveform PT1 may be a waveform in which ink is ejected from the ejection part D [m] when the drive signal Vin [m] having the waveform PT1 is supplied to the ejection part D [m]. . That is, the ejection state determination process may be executed as “ejection inspection”.
The waveform PT2 is a flat waveform maintained at the detection potential VcH. Immediately after the discharge unit D [m] is driven by the drive signal Vin [m] having the waveform PT1, the drive unit Vin [m] having the waveform PT2 is supplied, thereby causing discharge due to the drive by the waveform PT1. It is possible to maintain the residual vibration generated in the part D [m], and it is possible to accurately detect the residual vibration.

The detection unit 8 is supplied with the waveform PT2 to the discharge unit D [m] during the unit determination period Tu-T in which the determination drive waveform signal Com-AT is supplied to the discharge unit D [m], and the drive signal. In the detection period Td included in the period in which Vin [m] maintains the detection potential VcH, the residual vibration generated in the discharge section D [m] is detected as the residual vibration signal Vout.
In the present embodiment, the detection period Td is defined as a period in which the detection period designation signal Tsig output from the control unit 6 is at a predetermined potential VHigh, as shown in FIG. In the present embodiment, the detection period Td is provided before the start of the period in which the clock signal CL is supplied and the shift register SR transfers the print signal SI [m].

<< 4.3. Drive signal >>
Next, the drive signal Vin output from the drive signal generation unit 51 in the unit period Tu will be described.

  First, the drive signal Vin for print processing output by the drive signal generation unit 51 in the unit printing period Tu-P will be described with reference to FIG.

  When the print signal SI [m] supplied in the unit print period Tu-P indicates (1, 1), the switching unit TX [m] selects the drive waveform signal Com-A in the control period Ts1 and selects the waveform PA1. Drive signal Vin [m] is output, the drive waveform signal Com-A is selected in the control period Ts2, and the drive signal Vin [m] having the waveform PA2 is output (see FIG. 15A1). Therefore, in this case, as shown in FIG. 18, the drive signal Vin [m] supplied to the ejection unit D [m] in the unit printing period Tu-P includes a waveform PA1 and a waveform PA2. As a result, the ejection unit D [m] ejects a medium amount of ink based on the waveform PA1 and a small amount of ink based on the waveform PA2 in the unit printing period Tu-P. Large dots are formed on the recording paper P by the ink discharged over time.

  When the print signal SI [m] supplied in the unit print period Tu-P indicates (1, 0), the switching unit TX [m] selects the drive waveform signal Com-A in the control period Ts1. The drive signal Vin [m] having the waveform PA1 is output, the drive waveform signal Com-B is selected in the control period Ts2, and the drive signal Vin [m] having the waveform PB is output (see FIG. 15A2). Therefore, in this case, as shown in FIG. 18, the drive signal Vin [m] supplied to the discharge section D [m] in the unit printing period Tu-P includes a waveform PA1 and a waveform PB. As a result, the ejection unit D [m] ejects a medium amount of ink based on the waveform PA1 during the unit printing period Tu-P, and forms medium dots on the recording paper P.

  When the print signal SI [m] supplied in the unit print period Tu-P indicates (0, 1), the switching unit TX [m] selects the drive waveform signal Com-B in the control period Ts1. The drive signal Vin [m] having the waveform PB is output, the drive waveform signal Com-A is selected in the control period Ts2, and the drive signal Vin [m] having the waveform PA2 is output (see FIG. 15 (A3)). Therefore, in this case, as shown in FIG. 18, the drive signal Vin [m] supplied to the discharge section D [m] in the unit printing period Tu-P includes a waveform PA2. As a result, the ejection unit D [m] ejects a small amount of ink based on the waveform PA2 in the unit printing period Tu-P to form small dots on the recording paper P.

  When the printing signal SI [m] supplied in the unit printing period Tu-P indicates (0, 0), the switching unit TX [m] selects the driving waveform signal Com-B in the control periods Ts1 and Ts2. Then, the drive signal Vin [m] having the waveform PB is output (see FIG. 15 (A4)). That is, in this case, as shown in FIG. 18, the drive signal Vin [m] supplied to the discharge section D [m] in the unit printing period Tu-P includes a waveform PB. As a result, the ejection unit D [m] does not eject ink during the unit printing period Tu-P, and no dots are formed on the recording paper P (non-recording).

  Next, the drive signal Vin for discharge state determination processing output from the drive signal generation unit 51 in the unit determination period Tu-T will be described.

First, when the print signal SI [m] supplied in the unit determination period Tu-T indicates (1, 1), the switching unit TX [m] selects the drive waveform signal Com-A in the control periods Ts1 and Ts2. Then, the drive signal Vin [m] having the waveform PT is supplied to the discharge section D [m] (see FIG. 15 (B1)).
When the print signal SI [m] supplied in the unit determination period Tu-T indicates (0, 0), the switching unit TX [m] selects the drive waveform signal Com-B in the control periods Ts1 and Ts2. Then, the drive signal Vin [m] having the waveform PB is supplied to the discharge section D [m] (see FIG. 15 (B2)).

When the control unit 6 designates the discharge unit D [m] as the target discharge unit Dtg that is the target of residual vibration detection in the discharge state determination process or rank determination process in one unit determination period Tu-T, In one unit determination period Tu-T, the value of the print signal SI [m] is set to (1, 1) so that the drive signal Vin [m] having the waveform PT is supplied to the ejection part D [m]. Set to.
Further, when the discharge unit D [m] is not designated as the target discharge unit Dtg in one unit determination period Tu-T, the control unit 6 discharges the discharge unit D [m] in the one unit determination period Tu-T. The value of the print signal SI [m] is set to (0, 0) so that the drive signal Vin [m] having the waveform PB is supplied.

<< 4.4. Connection section >>
FIG. 19 is a block diagram illustrating the configuration of the connection unit 53, the configuration of the determination unit 4, and the connection relationship between the recording head 3, the connection unit 53, the detection unit 8, and the determination unit 4.
As illustrated in FIG. 19, the connection unit 53 includes 1 to M stages of M connection circuits Ux (Ux [1], Ux [2],... Corresponding to the M ejection units D on a one-to-one basis. , Ux [M]). The m-stage connection circuit Ux [m] includes either the m-stage output terminal OTN provided in the drive signal generation unit 51 or the detection unit 8 with the upper electrode 302 of the piezoelectric element 300 of the ejection unit D [m]. Electrically connect to
Hereinafter, a state in which the connection circuit Ux [m] electrically connects the ejection unit D [m] and the m-stage output end OTN of the drive signal generation unit 51 is referred to as a first connection state. The state in which the connection circuit Ux [m] electrically connects the discharge part D [m] and the detection unit 8 is referred to as a second connection state.

The control unit 6 outputs a connection control signal Sw for controlling the connection state of each connection circuit Ux to each connection circuit Ux.
Specifically, the control unit 6 connects the connection control signal such that the connection circuit Ux [m] maintains the first connection state throughout the unit printing period Tu-P in the unit printing period Tu-P. Sw [m] is supplied to the connection circuit Ux [m]. For this reason, the drive signal Vin [m] is supplied from the drive signal generation unit 51 to the ejection unit D [m] over the entire period of the unit printing period Tu-P.

Further, in the unit determination period Tu-T, when the discharge unit D [m] is designated as the target discharge unit Dtg, the control unit 6 determines that the connection circuit Ux [m] is included in the unit determination period Tu-T. The connection control signal Sw [m] that supplies the first connection state during the period other than the detection period Td and the second connection state during the detection period Td is supplied to the connection circuit Ux [m]. For this reason, when the discharge unit D [m] is designated as the target discharge unit Dtg in the unit determination period Tu-T, the drive signal generation unit 51 outputs the unit determination period Tu-T in a period other than the detection period Td. The drive signal Vin [m] is supplied to the discharge unit D [m], and the residual vibration signal Vout is output from the discharge unit D [m] to the detection unit 8 in the detection period Td in the unit determination period Tu-T. Is supplied.
In addition, in the unit determination period Tu-T, when the discharge unit D [m] is not designated as the target discharge unit Dtg, the control unit 6 causes the connection circuit Ux [m] to be in the entire unit determination period Tu-T. A connection control signal Sw [m] that maintains the first connection state is supplied to the connection circuit Ux [m].

  In the present embodiment, as shown in FIG. 19, the inkjet printer 1 includes one detection unit 8 for M ejection units D, and each detection unit 8 has one unit period. In Tu, it is assumed that only residual vibration generated in one ejection part D can be detected. That is, the control unit 6 according to the present embodiment designates one ejection unit D among the M ejection units D as the target ejection unit Dtg in one unit determination period Tu-T.

<< 4.5. Detection unit >>
The detection unit 8 shown in FIG. 19 generates the shaped waveform signal Vd based on the residual vibration signal Vout as described above. As described above, the shaped waveform signal Vd is suitable for processing in the determination unit 4 by amplifying the amplitude of the residual vibration signal Vout and removing a noise component from the residual vibration signal Vout. This signal is shaped into a waveform.

  The detection unit 8 is, for example, a negative feedback type amplifier for amplifying the residual vibration signal Vout, a low-pass filter for attenuating the high frequency component of the residual vibration signal Vout, and shaping the low impedance by converting the impedance. A configuration including a voltage follower that outputs the waveform signal Vd may be used.

<< 4.6. Judgment unit >>
The determination unit 4 determines the ink ejection state in the ejection part D based on the shaped waveform signal Vd output from the detection unit 8, and generates determination information RS indicating the result of the determination.

  As shown in FIG. 19, the determination unit 4 includes a cycle information generation unit 41 that generates cycle information NTc, and a discharge state determination unit that determines an ink discharge state in the discharge unit D based on the cycle information NTc and the reference information STth. 42. The period information generation unit 41 that generates the period information NTc, which is an example of the characteristic information, is an example of a “characteristic information generation unit”. Hereinafter, details of the cycle information generation unit 41 and the discharge state determination unit 42 will be described.

As described in FIG. 1, the cycle information generation unit 41 is supplied with the shaped waveform signal Vd from the detection unit 8, and is supplied with the threshold potential signal SVth and the mask signal Msk from the control unit 6.
Here, the threshold potential signal SVth is a signal indicating a threshold potential Vth1, which is a potential at the amplitude center level of the shaped waveform signal Vd, a signal indicating a threshold potential Vth2 higher than the threshold potential Vth1, and a threshold potential Vth1. And a signal indicating a low potential threshold potential Vth3 (see FIG. 20).

  FIG. 20 is a timing chart showing the operation of the period information generation unit 41. As shown in this figure, the period information generation unit 41 compares the potential indicated by the shaped waveform signal Vd with the threshold potential Vth1, and becomes high level when the potential indicated by the shaped waveform signal Vd is equal to or higher than the threshold potential Vth1. Then, the comparison signal Cmp1 that is low level when the potential is lower than the threshold potential Vth1 is generated. Further, the period information generation unit 41 compares the potential indicated by the shaped waveform signal Vd with the threshold potential Vth2, and becomes high when the potential indicated by the shaped waveform signal Vd is equal to or higher than the threshold potential Vth2, and is lower than the threshold potential Vth2. In this case, a comparison signal Cmp2 that is at a low level is generated. Further, the period information generation unit 41 compares the potential indicated by the shaped waveform signal Vd with the threshold potential Vth3, and becomes high when the potential indicated by the shaped waveform signal Vd is less than the threshold potential Vth3. In this case, a comparison signal Cmp3 that is at a high level is generated.

  The period information generation unit 41 starts the potential indicated by the shaped waveform signal Vd from the time t1 when the potential indicated by the shaped waveform signal Vd is first equal to the threshold potential Vth1 after the mask signal Msk falls to the low level. Is measured for a time Tc until time t2, which is the timing when becomes equal to the threshold potential Vth1, and period information NTc indicating the time Tc is generated. The mask signal Msk is a signal that is at a high level only for a predetermined period Tmsk after the supply of the shaped waveform signal Vd from the detection unit 8 is started. In addition, the period information generation unit 41 measures the time Ta during which the shaped waveform signal Vd is equal to or higher than the threshold potential Vth2 during the period from time t1 to time t2, and the comparison signal Cmp2 is at the high level. In addition, the period information generation unit 41 measures a time Tb during which the shaped waveform signal Vd is less than the threshold potential Vth3 and the comparison signal Cmp3 is at a high level in the period from time t1 to time t2.

  When the time Ta satisfies “Ta0 ≦ Ta” and the time Tb satisfies “Tb0 ≦ Tb”, the period information generation unit 41 uses the value of the validity flag Flag as the amplitude of the shaped waveform signal Vd. A value indicating that it falls within a predetermined range, for example, “1” is set. Here, Ta0 is a real number satisfying “0 <Ta0”, and Tb0 is a real number satisfying “0 <Tb0”. On the other hand, when the time Ta is “Ta <Ta0” or when the time Tb is “Tb <Tb0”, the period information generation unit 41 sets the value of the validity flag Flag of the shaped waveform signal Vd. A value indicating that the amplitude is not included in the predetermined range, for example, “0” is set.

As exemplified by the broken line Vd ′ in FIG. 21, when the amplitude of the shaped waveform signal Vd is small without causing the residual vibration of the amplitude corresponding to the drive signal Vin in the ejection unit D, the cause is the ink from the cavity 320. It is assumed that some trouble has occurred in the discharge part D, such as a ooze out or a failure of the discharge part D.
In the present embodiment, the validity flag Flag indicating whether or not the shaped waveform signal Vd has an appropriate amplitude is generated. For this reason, it becomes possible to grasp | ascertain the discharge abnormality which arises in the discharge part D resulting from the failure of the discharge part D, etc.
In the present embodiment, the time Ta, the time Tb, and the time Tc are measured after the elapse of the period Tmsk in which the mask signal Msk is at a high level. For this reason, the influence of the noise component superimposed immediately after the start of the residual vibration can be reduced, and highly accurate periodic information NTc can be obtained.

  The discharge state determination unit 42 includes three reference values Tth1 and Tth2 indicated by the cycle information NTc [m] and the validity flag Flag supplied from the cycle information generation unit 41 and the reference information STth supplied from the control unit 6. Based on Tth3, determination information RS [m] indicating the ink ejection state in the ejection section D [m] is generated.

FIG. 21 is an explanatory diagram for explaining the content of the determination in the discharge state determination unit 42. As shown in this figure, the discharge state determination unit 42 sets the time Tc [m] indicated by the cycle information NTc [m] to three reference values Tth1, Tth2, and Tth3, or one of these three reference values. Compare with the reference value of the part.
Here, the reference value Tth1 is a time length of one period of residual vibration when bubbles are generated in the cavity 320 and the frequency of residual vibration is high, and 1 of residual vibration when the discharge state is normal. This is a value for indicating the boundary with the time length of the period. Further, the reference value Tth2 is a value that represents a time length longer than the reference value Tth1, and is 1 of residual vibration when a foreign matter such as paper dust adheres to the vicinity of the nozzle N outlet and the frequency of the residual vibration becomes low. This is a value for indicating the boundary between the time length of the period and the time length of one period of the residual vibration when the ejection state is normal. Further, the reference value Tth3 is a threshold value representing a longer time length than the reference value Tth2, and the residual vibration is further increased as compared with the case where foreign matter such as paper dust adheres due to thickening or fixing of ink near the nozzle N. A value for indicating the boundary between the time length of one cycle of residual vibration when the frequency is low and the time length of one cycle of residual vibration when foreign matter such as paper dust adheres to the vicinity of the nozzle N outlet. is there. In the present embodiment, the reference values Tth1, Tth2, and Tth3 may be collectively referred to as the reference value Tth.

As shown in FIG. 21, the discharge state determination unit 42 indicates that the value of the validity flag Flag is “1” and the time Tc [m] indicated by the period information NTc [m] is “Tth1 ≦ Tc [m]”. If “≦ Tth2” is satisfied, it is determined that the ink discharge state in the discharge portion D [m] is normal, and the determination information RS [m] has a value indicating that the discharge state is normal, for example, “1”. "Is set.
Further, the discharge state determination unit 42 has the value of the validity flag Flag “1” and the time Tc [m] indicated by the period information NTc [m] satisfies “Tc [m] <Tth1”. Determines that a discharge abnormality has occurred due to the bubble generated in the cavity 320, and sets a value indicating that a discharge abnormality has occurred due to the bubble, for example, “2”, for example, in the determination information RS [m].
Further, the discharge state determination unit 42 has the value of the validity flag Flag “1”, and the time Tc [m] indicated by the period information NTc [m] satisfies “Tth2 <Tc [m] ≦ Tth3”. In this case, it is determined that a discharge abnormality has occurred due to a foreign substance such as paper dust attached near the nozzle N outlet, and the determination information RS indicates that a discharge abnormality has occurred due to the attachment of a foreign substance such as paper powder. For example, “3” is set.
Further, the discharge state determination unit 42 has the value of the validity flag Flag “1” and the time Tc [m] indicated by the period information NTc [m] satisfies “Tth3 <Tc [m]”. Is determined that an ejection abnormality has occurred due to the thickening of ink in the cavity 320, and a value indicating that an ejection abnormality has occurred due to the thickening of ink, for example “4”, is set in the determination information RS. To do.
Further, when the value of the validity flag Flag is “0”, the ejection state determination unit 42 indicates that there is some problem in the ejection unit D such as ink bleeding or failure of the ejection unit D in the determination information RS [m]. For example, “5” is set as a value indicating that the error occurs.
As described above, the discharge state determination unit 42 determines the discharge state in the discharge unit D [m] based on the period information NTc [m] and the validity flag Flag, and the determination information RS [m] indicating the determination result. ] Is generated.

  The control unit 6 stores the determination information RS [m] output from the discharge state determination unit 42 in the storage unit 20 in association with the stage number m of the discharge unit D [m] corresponding to the determination information RS [m]. Let For this reason, it becomes possible to grasp which ejection part D has the ejection abnormality among the M ejection parts D. Accordingly, it is possible to execute the cleaning process at an appropriate timing in consideration of the number of ejection portions D in which ejection abnormality has occurred, the position of the ejection portion D in which ejection abnormality has occurred, and the like. Therefore, it is possible to prevent the image quality formed in the printing process from being deteriorated due to the ejection abnormality in the ejection part D.

<< 5. Rank determination process >>
Hereinafter, the rank determination process will be described with reference to FIGS.

<< 5.1. Overview of rank determination process >>
FIG. 22 is a flowchart illustrating an example of the operation of the inkjet printer 1 when rank determination processing is executed.
As described above, in the rank determination process, a plurality of division information generation processes and one or a plurality of division information determination processes are executed. Specifically, as shown in FIG. 22, during the period from the start to the end of the rank determination process, w times of division information generation processing, (w−1) times of division information determination processing, and (w−1) ) Cleaning processes are performed (w is a natural number satisfying 2 ≦ w. However, in steps S100 and S200 described later, w = 1 is assumed).

As illustrated in FIG. 22, in the rank determination process, the control unit 6 of the inkjet printer 1 initializes a variable w indicating the number of division information generation processes to “1” (S100).
Next, the control unit 6 controls the execution of the classification information generation process (S200). Specifically, in step S200, the control unit 6 classifies the M ejection units D into Q [w] ranks, and generates segment information Info [w] indicating the result of the segment. The operation of each part of the inkjet printer 1 is controlled. Here, Q [w] is a natural number satisfying 2 ≦ Q [w] <M. Since the variable w is “1” in step S200, the control unit 6 classifies the M ejection units D into Q [1] ranks, and the segment information Info [ 1] will be generated.

As shown in FIG. 22, the control unit 6 controls the execution of the cleaning process (S300), and adds “1” to the variable w (S400).
And the control part 6 controls execution of a division | segmentation information generation process (S500). In step S500, as in step S200, the control unit 6 classifies the M ejection units D into Q [w] ranks, and generates segment information Info [w] indicating the result of the segment. In addition, the operation of each part of the inkjet printer 1 is controlled.
Next, the control part 6 performs a division information determination process (S600). Specifically, in step S600, the control unit 6 determines whether it is appropriate to determine the rank to which each of the M ejection units D belongs according to the classification information Info [w] generated in step S500. judge.

If the determination result in step S600 is affirmative, the control unit 6 determines the rank to which each of the M ejection units D belongs according to the classification information Info [w] generated in step S500 (S700). Then, the rank determination process shown in FIG. 22 is terminated.
Further, when the determination result in step S600 is negative, the control unit 6 determines whether or not the variable w is equal to or greater than the maximum number of executions Wmax of the category information generation process (Wmax is a natural number satisfying 2 ≦ Wmax). (S800). Then, when the determination result in step S800 is affirmative, the control unit 6 ends the rank determination process illustrated in FIG. 22 without determining the rank to which each of the M ejection units D belongs. Moreover, the control part 6 advances a process to step S300, when the determination result in step S800 is negative.

<< 5.2. Classification information generation processing >>
Next, the classification information generation process in the rank determination process will be described.

  FIG. 23 is a flowchart illustrating an example of the operation of the inkjet printer 1 when the classification information generation process is executed. As described above, the classification information generation process shown in FIG. 23 is a process executed in step S200 or step S500 in the rank determination process shown in FIG.

As shown in FIG. 23, in the classification information generation process, the control unit 6 prints the print signal SI so as to designate the discharge units D [1] to D [M] as the target discharge unit Dtg in order, for example, every unit period Tu. Is generated to control the operation of the head driver 5 so that the determination unit 4 can output the period information NTc [1] to NTc [M] (S510).
Next, the control unit 6 specifies the maximum value TcMax and the minimum value TcMin from the times Tc [1] to Tc [M] indicated by the period information NTc [1] to NTc [M] (S520).
Next, the control unit 6 acquires the rank width ΔTq, which is the width of the time Tc in each rank, from the storage unit 20 (S530). In the present embodiment, it is assumed that the rank width ΔTq is a predetermined value.
Next, the control unit 6 determines the number Q [w] of ranks by dividing the value obtained by subtracting the minimum value TcMin from the maximum value TcMax by the rank width ΔTq (S540). That is, in the present embodiment, the number of ranks into which M ejection units D are classified in the w-th division information generation process is expressed as Q [w].

Next, the control unit 6 theoretically relates to a time Tc indicating a period of residual vibration generated in the discharge unit D that can belong to the rank q (the variable q is a natural number satisfying 1 ≦ q ≦ Q [w]). A maximum value TcMax [q] and a minimum value TcMin [q] are calculated, and a reference value Tth [q] that is a reference value Tth corresponding to the rank q is determined based on the calculation result (S550). In other words, the control unit 6 determines the reference values Tth1 [q] to Tth3 [q] that are the reference values Tth1 to Tth3 corresponding to the rank q.
Specifically, in step S550, the control unit 6 first determines the maximum value TcMax [q] of the time Tc corresponding to the rank q as “TcMax [q] = TcMax− (q−1) * ΔTq”. The minimum value TcMin [q] of the time Tc corresponding to the rank q is defined as “TcMin [q] = TcMax−q * ΔTq”. However, the minimum value TcMin [Q] of the time Tc corresponding to the rank Q [w] is defined as “TcMin [Q] = TcMin”. That is, the control unit 6 determines the range of the time Tc in each rank so that the rank number increases for each rank width ΔTq as the time Tc that is the period of the residual vibration becomes shorter.
In step S550, the control unit 6 then sets a value obtained by subtracting the predetermined margin value ΔTc1 from the minimum value TcMin [q] as the reference value Tth1 [q], and sets the predetermined margin value ΔTc2 to the maximum value TcMax [q]. The added value is set as a reference value Tth2 [q], and a value obtained by adding a predetermined margin value ΔTc3 to the reference value Tth2 [q] is set as a reference value Tth3 [q], thereby calculating the reference value Tth [q].

The control unit 6 stores the reference value Tth [q] calculated in step S550 in the rank reference information table TBL1.
FIG. 24 is a diagram illustrating an example of a data structure of the rank reference information table TBL1. As shown in this figure, the rank reference information table TBL1 includes the number “q” of rank q and the reference value Tth [q] (Tth1 [q] to Tth3 [q]) calculated corresponding to the rank q. Are stored in association with each other.
In the rank determination process, when the classification information generation process is executed twice or more and the rank reference information table TBL1 stores the calculation result of the previously executed classification information generation process, it is newly executed. What is necessary is just to overwrite with the calculation result of the classification information generation process. That is, in this embodiment, the latest classification information generation process result is stored in the rank reference information table TBL1.

Next, the control unit 6 assigns the discharge units D [m] to any one of the ranks 1 to Q [w], thereby assigning the discharge units D [1] to D [M] to Q. [w] Divide into ranks (S560). Specifically, in step S560, the control unit 6 determines that the time Tc [m] indicating the period of residual vibration generated in the discharge unit D [m] is “TcMin [q] ≦ Tc [m] <TcMax [q]. The discharge part D [m] is assigned to the rank q satisfying “. In the following, the rank q to which the ejection unit D [m] is assigned in the w-th division information generation process in step S560 is expressed as rank Rk [m] [w]. In other words, the rank Rk [m] [w] to which the discharge unit D [m] is assigned in the w-th division information generation process is:
The rank satisfies “TcMin [Rk [m] [w]] ≦ Tc [m] <TcMax [Rk [m] [w]]”.

  Next, the control unit 6 stores the classification information Info [w] indicating the result of the classification of the discharge units D [1] to D [M] into ranks 1 to Q [w] in step S560 in the storage unit 20. It is stored in the affiliation rank information table TBL2 (S570). The classification information Info [w] is assigned ranks Rk [1] [w] to Rk [M] [w] to which the ejection units D [1] to D [M] are assigned in the wth classification information generation process. Show.

FIG. 25 is a diagram showing an example of the data structure of the affiliation rank information table TBL2. As shown in this figure, the affiliation rank information table TBL2 includes the rank m to which the ejection unit D [m] is assigned in the stage number m of the ejection unit D [m] and the first to wth division information generation processing. Rk [m] [1] to Rk [m] [w] are stored in association with each other. That is, as shown in this figure, the rank Rk [m] [w] is a rank to which the ejection unit D [m] is assigned in the w-th division information generation process,
Any one of ranks 1 to Q [w].

  In addition, the control part 6 functions as the division | segmentation information generation part 61 by performing a one part or all part process from step S510-S570.

<< 5.3. Classification information judgment processing >>
Next, the classification information determination process in the rank determination process will be described.

  FIG. 26 is a flowchart illustrating an example of the operation of the control unit 6 when the classification information determination process is executed. As described above, the classification information determination process shown in FIG. 26 is a process executed in step S600 in the rank determination process shown in FIG.

As shown in FIG. 26, in the classification information determination process, the control unit 6 calculates the difference dMD between the mode value rank RkMD [w] and the mode value rank RkMD [w-1] (S610).
As described above, in the w-th division information generation process, each of the ejection units D [1] to D [M] is assigned to any one rank q among the ranks 1 to Q [w]. In this case, of ranks 1 to Q [w], the rank number to which the most discharge units D are assigned is the mode rank RkMD [w]. The difference dMD calculated in step S610 is the rank to which the largest number of ejection units D are allocated among the Q [w] ranks in which M ejection units D are segmented in the w-th segment information generation process. The most frequent value rank RkMD [w] and the number [Q] [w-1] ranks in which the M discharge sections D are divided in the (w-1) th division information generation process. The difference from the mode rank RkMD [w-1], which is the rank number to which the discharge unit D is assigned, is shown.

Next, the control unit 6 determines whether or not the difference dMD is greater than or equal to a predetermined allowable error ΔRkMD (S620).
Next, when the determination result of step S620 is affirmative, the controller 6 determines that the difference between the rank Rk [m] [w] and the rank Rk [m] [w-1] is different from the difference dMD. It is determined whether or not the discharge unit D [m] exists (S630).
Next, when the determination result of step S630 is affirmative, the controller 6 determines w times Tc indicated by w pieces of period information NTc [m] acquired in the first to w-th division information generation processing. The difference value between the maximum value MaxTc [m] in [m] and the time Tc [m] indicated by the period information NTc [m] acquired in the w-th division information generation process is greater than or equal to a predetermined threshold ΔMaxTc It is determined whether or not there is a discharge portion D [m] that satisfies (S640).

When the determination result of step S640 is affirmative, it is inappropriate for the control unit 6 to determine the rank to which the discharge units D [1] to D [M] belong according to the classification result indicated by the classification information Info [w]. (S650). Such classification information Info [w] that is not suitable for determining the rank to which the discharge units D [1] to D [M] belong may be referred to as “inappropriate classification information”.
On the other hand, the control unit 6 corresponds to at least one of a case where the determination result of step S620 is negative, a case where the determination result of step S630 is negative, or a case where the determination result of step S620 is negative. When determining, it is determined that it is appropriate to determine the rank to which the ejection units D [1] to D [M] belong according to the classification result indicated by the classification information Info [w] (S660). Such classification information Info [w] suitable for determining the rank to which the discharge units D [1] to D [M] belong may be referred to as “appropriate classification information”.

  In addition, the control part 6 functions as the division | segmentation information determination part 62 by performing a one part or all part process from step S610-S660.

<< 6. Conclusion of embodiment >>
As described above, the ink jet printer 1 according to the present embodiment has each of the M ejection units D according to the segment information Info [w] generated in the segment information generation process executed after the cleaning process. Determine the rank to which it belongs.
There is a high possibility that air bubbles are mixed in the cavity 320 and the time Tc is shortened in the ejection part D before the cleaning process is performed, compared to the ejection part D after the cleaning process is performed. Then, the classification result into M ranks of the M ejection units D indicated by the segment information Info [w] generated based on the residual vibration detected from the ejection unit D having an abnormal ejection state is as follows. It is highly possible that the variation does not reflect the variation among the M discharge portions D, but is merely affected by the discharge abnormality in the discharge portions D. That is, the rank to which each of the M ejection units D belongs is determined based on the classification information Info [w] generated before the cleaning process is performed, and the reference information STth corresponding to each rank is determined. However, there is a high possibility that an erroneous determination will occur in the discharge state determination process.
On the other hand, in the present embodiment, the cleaning process is executed in step S300, and after the discharge abnormality such as the mixing of bubbles is eliminated, the classification information Info [w] generated in the classification information generation process in step S500 is used. Thus, the rank to which each discharge unit D belongs is determined, and reference information STth corresponding to each rank is generated. For this reason, according to the present embodiment, compared to the case where the rank to which each discharge unit D belongs is determined based on the classification information Info [w] generated before the execution of the cleaning process, an error occurs in the discharge state determination process. The possibility that the determination will occur can be reduced.

In general, when the ink ejection state in the ejection part D is normal, the characteristic of residual vibration detected from the ejection part D is stable, and the characteristic of residual vibration before and after the cleaning process is executed. The fluctuation of is small. On the other hand, when a discharge abnormality occurs in the discharge part D, generally, the characteristic of the residual vibration detected from the discharge part D becomes unstable, and the characteristic of the residual vibration before and after the cleaning process is executed. The fluctuation of becomes large.
In this embodiment, in the category information determination process, the category information Info [w-1] generated in the category information generation process executed before the cleaning process and the category information generation process executed after the cleaning process are generated. Based on the classification information Info [w], it is determined whether or not the classification information Info [w] is appropriate classification information suitable for determining the rank to which each ejection unit D belongs. For this reason, in the present embodiment, the rank to which each ejection unit D belongs is determined based on the classification information Info [w] generated in the classification information generation process that is performed when the ejection abnormality occurs in each ejection unit D. It is possible to prevent the determination. That is, in the present embodiment, the ink is generated by the classification information generation process executed when the ink discharge state in each discharge unit D is normal and the characteristics of the residual vibration detected from each discharge unit D are stable. Based on the sorting information Info [w], the rank to which each of the M ejection portions D belongs can be determined. For this reason, in this embodiment, it becomes possible to determine accurately the discharge state in each discharge part D in discharge state determination processing.

In addition, when the discharge state of the ink in each discharge unit D is normal and the variation in the characteristic of residual vibration generated in each discharge unit D is small before and after the cleaning process is performed, discharge abnormality occurs in the discharge unit D. Compared to the case, the M discharge units D belonging to the rank of Q [w-1] indicated by the division information Info [w-1] generated in the division information generation process executed before the cleaning process. The distribution shape of the discharge units and the distribution of the discharge units of the M discharge units D belonging to the rank of Q [w] indicated by the division information Info [w] generated in the division information generation process executed after the cleaning process The degree of similarity with the shape increases. Then, when the distribution shape of the M ejection portions D indicated by the division information Info [w-1] is similar to the distribution shape of the M ejection portions D indicated by the division information Info [w], it is compared with the case where they are not similar. Thus, there is a high possibility that the mode rank RkmD [w-1] and the mode rank RkmD [w] are close ranks.
In the present embodiment, in step S620 of the classification information determination process, it is determined whether or not the difference dMD between the mode rank RkmD [w] and the mode rank RkMD [w-1] is smaller than the allowable error ΔRkmD. I do. For this reason, the distribution information Info [w-1] when the distribution shape of the M ejection portions D indicated by the division information Info [w-1] is similar to the distribution shape of the M ejection portions D indicated by the division information Info [w]. Based on w], the rank to which each of the M ejection portions D belongs can be determined. In other words, based on the classification information Info [w] generated when the ink ejection state in each ejection unit D is normal and the variation in the characteristics of residual vibration generated in each ejection unit D is small, M The rank to which each of the discharge units D belongs can be determined. For this reason, in this embodiment, it becomes possible to determine accurately the discharge state in each discharge part D in discharge state determination processing.
The difference dMD between the mode rank RkmD [w] and the mode rank RkmD [w-1] is the position of the mode rank RkmD [w] in Q [w] ranks and Q [w- 1] is an example of the degree of error from the position of the mode rank RkmD [w-1] in ranks. Here, the position of the mode rank RkMD [w] is information that can define the position of the mode rank RkMD [w] in the distribution of the M ejection portions D indicated by the division information Info [w]. For example, it may be a value obtained by dividing the number of the mode rank RkMD [w] by the number of ranks Q [w], or the mode rank RkMD [w]. And a median value or an average value in the distribution of the M ejection portions D may be used.

In the present embodiment, when the difference dMD between the mode rank RkmD [w] and the mode rank RkMD [w−1] is equal to or larger than the allowable error ΔRkMD, the classification information determination process in step S630. Then, it is determined whether or not the difference between the rank Rk [m] [w] and the rank Rk [m] [w-1] is equal to the difference dMD.
Thereby, for example, noise is superimposed on the residual vibration detected from the discharge unit D corresponding to the maximum value TcMax, and the maximum value TcMax [1] corresponding to rank 1 is affected by the noise, whereby each rank q Even when the maximum value TcMax [q] and the minimum value TcMin [q] are values that are slid by the amount corresponding to the noise, M discharge units D indicated by the classification information Info [w-1] It is possible to determine whether or not the distribution shape of each of the M ejection portions D indicated by the classification information Info [w] is similar.

In the present embodiment, when the difference dMD between the mode rank RkmD [w] and the mode rank RkMD [w−1] is equal to or larger than the allowable error ΔRkMD, the classification information determination process in step S640. Then, it is determined whether or not the difference between the maximum value MaxTc [m] and the time Tc [m] is smaller than a predetermined threshold value ΔmaxTc.
As a result, when the discharge state changes from normal to abnormal due to, for example, air bubbles mixed into the discharge unit D [m] while repeating the w division information generation process, based on the result of the division information generation process. Thus, it is possible to prevent the rank to which each of the M ejection portions D belongs.

When the rank to which each of the M ejection units D belongs is determined based on the classification information Info [w] generated in the w-th classification information generation process, the (w−1) -th classification information. The section information Info [w-1] generated in the generation process is an example of the first section information generated before the last cleaning process before the rank is determined, and is generated in the w-th section information generation process. The sorting information Info [w] is an example of the second sorting information generated after the last cleaning process before the rank is determined.
Further, for convenience of description, Q [w-1] ranks indicated by the category information Info [w-1], which is an example of the first category information, may be expressed as “β ranks”. The Q [w] ranks indicated by the category information Info [w], which is an example of the category information, may be expressed as “α ranks”.

<< 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 number of ranks Q [w] is a variable value calculated based on the result of subtracting the minimum value TcMin from the maximum value TcMax in step S540 of the classification information generation process. The number of ranks Q [w] is not limited to such an aspect, and may be a predetermined value.
In the above-described embodiment, the rank width ΔTq is a predetermined value. However, the present invention is not limited to such a mode, and the rank width ΔTq is the maximum in the segment information generation process. It may be a variable value calculated based on at least one of the difference value between the value TcMax and the minimum value TcMin, or the number of ranks Q [w].

<Modification 2>
In the embodiment and the modification described above, the rank to which the discharge unit D [m] belongs is determined based on the cycle information NTc [m]. However, the present invention is not limited to such a mode. The rank to which the ejection unit D [m] belongs may be determined based on NTc [m] and information other than the period information NTc [m]. For example, the rank to which the ejection unit D [m] belongs may be determined based on the position of the ejection unit D [m] in the recording head 3 and the period information NTc [m].

<Modification 3>
In the embodiment described above, the period information NTc indicating the time Tc for one period of the shaped waveform signal Vd has been exemplified and described as the characteristic information. However, the present invention is not limited to such an aspect, and the characteristic information The information may be any information as long as the information indicates the characteristic of residual vibration. For example, the characteristic information may be one or a plurality of information selected from the period, amplitude, and phase of the residual vibration signal Vout or the shaped waveform signal Vd.

<Modification 4>
In the embodiment described above, the rank determination process includes w division information generation process, (w-1) cleaning process, and (w-1) division information determination process. Is not limited to such a mode, and the rank determination process includes at least one cleaning process and one classification information generation process executed after the cleaning process. Good.
That is, the rank determination process only needs to include at least the process shown in step S300, the process shown in step S500, and the process shown in step S700 in the flowchart shown in FIG.
In other words, in the embodiment and the modification described above, the rank determination unit 60 includes the segment information generation unit 61 and the segment information determination unit 62, but the rank determination unit 60 includes at least the segment information generation unit 61. Good.

<Modification 5>
In the embodiment and the modification described above, the discharge state determination process is executed in the unit determination period Tu-T. However, the present invention is not limited to such a mode, and the discharge state determination is performed in the unit print period Tu-P. Processing may be executed. That is, the printing process and the discharge state determination process may be executed in the same unit period Tu.
For example, in the unit printing period Tu-P shown in FIG. 16, the waveform PA1 included in the printing drive waveform signal Com-AP may have a role for detecting residual vibration (a role as the waveform PT). In this case, the residual vibration of the discharge section D caused by the driving by the waveform PA1 may be detected by setting a part of the period during which the potential of the waveform PA1 is maintained at the maximum potential Va12 as the detection period Td. .
The waveform for detecting the residual vibration may be a waveform for ejecting ink, such as the waveform PA1 or the waveform PA2, or may be a waveform that does not eject ink, such as the waveform PB. Good.

<Modification 6>
The inkjet printer 1 according to the embodiment and the modification described above includes four detection units 8 and four determination units 4 with respect to the four recording heads 3. The present invention is not limited to this mode, and four recording heads 3 may be provided with five or more detection units 8 and five or more determination units 4, or conversely, four recording heads 3. The recording head 3 may be configured to include three or less detection units 8 and three or less determination units 4.

<Modification 7>
The inkjet printer 1 according to the embodiment and the modification described above is a line printer in which the nozzle row Ln is provided so that the range YNL includes the range YP, but the present invention is not limited to such an aspect. The ink jet printer 1 may be a serial printer in which the recording head 3 reciprocates in the Y-axis direction to execute print processing.

<Modification 8>
The inkjet printer 1 according to the embodiment and the modification described above can eject four colors of CMYK ink, but the present invention is not limited to such an aspect, and the inkjet printer 1 has at least one color. It is sufficient that the above ink can be ejected, and the ink color may be a color other than CMYK.
In addition, the inkjet printer 1 according to the embodiment and the modification described above includes four nozzle rows Ln, but may be any as long as it includes at least one nozzle row Ln.

<Modification 9>
In the embodiment and the modification described above, the drive waveform signal Com includes two systems of drive waveform signals Com-A and Com-B, but the present invention is not limited to such a mode, and the drive The waveform signal Com only needs to include one or more system signals. That is, the drive waveform signal Com may be a signal of one system, for example, a signal including only the drive waveform signal Com-A, or three or more signals, for example, the drive waveform signals Com-A, Com-B, and Com-C. A signal including
In the embodiment and the modification described above, the unit period Tu includes two control periods Ts1 and Ts2. However, the present invention is not limited to such a mode, and the unit period Tu has a single control period. It may consist of a period Ts or may include three or more control periods Ts.
In the embodiment and the modification described above, the print signal SI [m] is a 2-bit signal, but the number of bits of the print signal SI [m] is included in the gradation to be displayed and the unit period Tu. What is necessary is just to determine suitably according to the number of the control periods Ts, the number of signal systems included in the drive waveform signal Com, and the like.

<Modification 10>
In the embodiment and the modification described above, the ejection state determination unit 42 is implemented as an electronic circuit, but may be implemented as a functional block realized by the CPU of the control unit 6 operating according to a control program.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 3 ... Recording head, 4 ... Determination unit, 5 ... Head driver, 6 ... Control part, 7 ... Conveyance mechanism, 8 ... Detection unit, 9 ... Host computer, 10 ... Head unit, 20 ... Storage part, DESCRIPTION OF SYMBOLS 21 ... Cleaning mechanism, 41 ... Period information generation part, 42 ... Discharge state determination part, 50 ... Drive signal supply part, 51 ... Drive signal generation part, 53 ... Connection part, 60 ... Rank determination part, 61 ... Classification information generation part 62 ... Classification information determination unit, 100 ... Printing system, 300 ... Piezoelectric element, 320 ... Cavity, D ... Discharge unit, N ... Nozzle, TX ... Switching unit.

Claims (6)

A recording head having M (M is a natural number satisfying 2 ≦ M) ejection units that eject liquid;
A drive unit capable of driving the M ejection units;
A detection unit capable of detecting residual vibration generated in the one ejection unit when one ejection unit among the M ejection units is driven by the driving unit;
Based on the detection result of the detection unit, a characteristic information generation unit that generates characteristic information corresponding to the one ejection unit indicating a characteristic of residual vibration generated in the one ejection unit;
A cleaning mechanism for cleaning the M ejection units;
Based on the M pieces of characteristic information corresponding to the M discharge units on a one-to-one basis,
The M discharge units are divided into α ranks (α is a natural number satisfying 2 ≦ α <M),
A rank determining unit that determines a rank to which each of the M ejection units belongs according to a result of the division after the cleaning mechanism has cleaned the ejection unit;
Characteristic information corresponding to the one ejection unit, and
Based on rank reference information determined according to the rank to which the one discharge unit belongs,
A discharge state determination unit that determines a discharge state of the liquid in the one discharge unit;
Comprising
A liquid discharge apparatus characterized by that. The rank determining unit
Before the cleaning mechanism cleans the discharge part,
The M discharge units are divided into β ranks (β is a natural number satisfying 2 ≦ β <M),
Generating first division information indicating the result of the division;
After the cleaning mechanism cleans the discharge part,
Dividing the M discharge parts into the α ranks,
A section information generating unit that generates second section information indicating the result of the section;
Based on the first segment information and the second segment information,
A classification information determination unit that determines whether the second classification information is appropriate classification information that is information suitable for determining a rank to which each of the M ejection units belongs;
With
When the determination result of the classification information determination unit is affirmative,
Determining a rank to which the M discharge units belong based on a classification result indicated by the second classification information;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The classification information determination unit
A distribution of the M ejection units belonging to the β ranks indicated by the first classification information;
A distribution of the M ejection units belonging to the α ranks indicated by the second classification information;
The degree of similarity of
If it is higher than a certain degree of similarity,
Determining that the second category information is the appropriate category information;
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The division information generation unit
Of the ranks of the β ranks indicated by the first classification information, the rank to which the most discharge units belong,
The position in the β ranks;
Of the ranks of the α ranks indicated by the second classification information, the rank to which the most discharge units belong,
A position in the α ranks;
The degree of error is
If it is less than the predetermined tolerance,
Determining that the second category information is the appropriate category information;
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A recording head having M (M is a natural number satisfying 2 ≦ M) ejection units that eject liquid;
A drive unit capable of driving the M ejection units;
A detection unit capable of detecting residual vibration generated in the one ejection unit when one ejection unit among the M ejection units is driven by the driving unit;
Based on the detection result of the detection unit, a characteristic information generation unit that generates characteristic information corresponding to the one ejection unit indicating a characteristic of residual vibration generated in the one ejection unit;
A cleaning mechanism for cleaning the M ejection units;
A method for controlling a liquid ejection apparatus comprising:
Based on the M pieces of characteristic information corresponding to the M discharge units on a one-to-one basis,
The M discharge units are divided into α ranks (α is a natural number satisfying 2 ≦ α <M),
In accordance with the result of the classification performed after the cleaning mechanism has cleaned the discharge unit, determine a rank to which each of the M discharge units belongs,
Characteristic information corresponding to the one ejection unit, and
Based on rank reference information determined according to the rank to which the one discharge unit belongs,
Determining a liquid discharge state in the one discharge unit;
A method for controlling a liquid ejection apparatus, comprising: A recording head having M (M is a natural number satisfying 2 ≦ M) ejection units that eject liquid;
A drive unit capable of driving the M ejection units;
A detection unit capable of detecting residual vibration generated in the one ejection unit when one ejection unit among the M ejection units is driven by the driving unit;
Based on the detection result of the detection unit, a characteristic information generation unit that generates characteristic information corresponding to the one ejection unit indicating a characteristic of residual vibration generated in the one ejection unit;
A cleaning mechanism for cleaning the M ejection units;
A computer,
A control program for a liquid ejection device comprising:
The computer,
Based on the M pieces of characteristic information corresponding to the M discharge units on a one-to-one basis,
The M discharge units are divided into α ranks (α is a natural number satisfying 2 ≦ α <M),
A rank determining unit that determines a rank to which each of the M ejection units belongs according to a result of the division after the cleaning mechanism has cleaned the ejection unit;
Characteristic information corresponding to the one ejection unit, and
Based on rank reference information determined according to the rank to which the one discharge unit belongs,
A discharge state determination unit that determines a discharge state of the liquid in the one discharge unit;
Function as
A control program for a liquid ejecting apparatus.

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