JP7293732B2 - Inkjet recording apparatus and complementary setting method for defective ejection nozzles - Google Patents

Description

The present invention relates to an inkjet recording apparatus and a complementary setting method for ejection failure nozzles.

2. Description of the Related Art There are inkjet recording apparatuses that record images, thin films, and/or three-dimensional structures by ejecting ink from a plurality of nozzles. In recent years, inkjet recording apparatuses have a large number of nozzles, and ejection failures tend to occur in some of them. Ejection failure may occur not only when ink is not ejected, but also in ejection amount and/or ejection direction. 2. Description of the Related Art Conventionally, there has been known a technique of supplementing ink for which ejection failure occurs by ejecting ink from nozzles in the vicinity of the ejection failure nozzle when the ejection failure nozzle occurs.

In addition, the ink droplets that have landed on the recording medium may move peculiar to liquid, such as liquid drift and penetration, before being fixed on the recording medium. Japanese Patent Application Laid-Open No. 2002-200001 discloses a technique for changing a criterion for determining whether or not to supplement ink ejection from a nozzle having a defect in the ejection direction, taking into consideration the liquid deviation according to the ejection timing. .

JP 2014-43076 A

However, there are various causes for ejection direction defects, and among these, deviations in the ejection direction that do not pose a problem during normal image printing can occur in many nozzles. As a result, there is a problem that when a nozzle used for supplementing the ejection failure has a minute ejection failure, the print quality may not be appropriately maintained as a result of the simple compensation process.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet printing apparatus and a complementary setting method for ejection failure nozzles, which can more reliably maintain printing quality.

In order to achieve the above object, the invention according to claim 1,
a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
The control unit compensates for the ejection failure of the first nozzle with a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure. A first set value related to the amount of ink droplets to be ejected from the first nozzle is added to a second set value related to the amount of ink droplets to be ejected from the second nozzle. No. 2 nozzles are caused to eject ink in an amount corresponding to the added second set value.
This inkjet recording apparatus is characterized by:

Further, according to the invention of claim 2, in the ink jet recording apparatus of claim 1,
a storage unit that stores ejection information related to the landing position of the ink ejected from the nozzle;
The control unit may specify a distance between the landing position and the reference position based on the ejection information.

Further, according to the invention of claim 3 , in the ink jet recording apparatus of claim 1 or 2 ,
When the second set value becomes larger than a predetermined maximum set value as a result of the addition, the control unit calculates the difference between the second set value and the maximum set value for another nozzle different from the second nozzle. A set value relating to the amount of ink droplets to be ejected from the other nozzle is assigned to the nozzle.

Further, according to the invention of claim 4 , in the inkjet recording apparatus of claim 3 ,
The control unit adds the difference to a third set value relating to the amount of droplets of ink to be ejected by a third nozzle that lands ink at a position second closest to the reference position. The set value is the maximum set value.

Further, according to the invention of claim 5 , in the inkjet recording apparatus of claim 4 ,
When the third set value becomes larger than the predetermined maximum set value as a result of the addition and the ejection failure of the first nozzle is a landing position failure, the control unit sets the third set value and A difference from the maximum set value is discharged from the first nozzle, and the third set value is set as the maximum set value.

Further, the invention according to claim 6 is the ink jet recording apparatus according to any one of claims 1 to 5 ,
The control unit is characterized in that the second nozzles are specified including defective nozzles that are causing ejection failures related to ink landing positions.

Further, the invention according to claim 7 is the inkjet recording apparatus according to any one of claims 3 to 5 ,
The control unit is characterized by specifying the other nozzles including the defective nozzle that is causing the ejection failure related to the landing position of the ink.

Further, the invention according to claim 8 is the ink jet recording apparatus according to claim 6 or 7 ,
The control unit determines whether or not to cause the specified nozzle to perform the supplementation according to whether or not a set value related to the amount of ink droplets ejected by the specified nozzle is equal to or greater than a predetermined first reference value. characterized by
Further, the invention according to claim 9 is
a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit
determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle;
identifying the second nozzles including defective nozzles that are causing ejection failures related to ink landing positions;
Depending on whether or not the set value related to the amount of ink droplets to be ejected by the identified nozzle is equal to or greater than a predetermined first reference value, it is determined whether or not to cause the nozzle to perform the complement.
This inkjet recording apparatus is characterized by:

Further, the invention according to claim 10 is the inkjet recording apparatus according to any one of claims 1 to 9,
The controller determines that a set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value, and a deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval. , the nozzle is not used as the second nozzle.
Further, the invention according to claim 11,
a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit
determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle;
When the set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value and the deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval, Do not use the nozzle as the second nozzle
This inkjet recording apparatus is characterized by:

Further, the invention according to claim 12 is the ink jet recording apparatus according to any one of claims 1 to 11 ,
The recording operation section is characterized in that it performs a recording operation on the fabric.

Further, the invention according to claim 13 is the inkjet recording apparatus according to any one of claims 1 to 12 , wherein
a storage unit that stores ejection information related to the landing position of the ink ejected from the nozzle;
The control unit causes the recording operation unit to eject ink from each of the nozzles to land on a recording medium in a predetermined arrangement to print a predetermined test pattern, and based on the landing positions of the ink in the test pattern. to generate the ejection information.

Further, according to the fourteenth aspect of the invention, there is provided the ink jet recording apparatus according to the thirteenth aspect,
The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
The control unit is characterized in that the test pattern is printed by ejecting the second smallest droplet amount or more among the plurality of stages.

Further, according to the fifteenth aspect of the invention, there is provided the inkjet recording apparatus of the thirteenth or fourteenth aspect,
Equipped with a reading unit that reads the surface of the recording medium,
The control unit causes the reading unit to read the test pattern to specify the landing position.

Further, the invention according to claim 16 is the inkjet recording apparatus according to any one of claims 13 to 15 ,
A transport unit for transporting a recording medium is provided,
The control unit causes the recording operation unit to eject ink onto the recording medium while moving the recording medium in a predetermined conveying direction by the conveying unit;
The test pattern is characterized in that lines of ink ejected from each nozzle extending in the transport direction are arranged so as to be identifiable.

Further, the invention according to claim 17 is the inkjet recording apparatus according to any one of claims 1 to 16 ,
The control unit is characterized in that the landing position is calculated according to the distance between the recording medium and the opening of the nozzle.
Further, the invention according to claim 18,
a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit compensates for the ejection failure of the first nozzle with a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure. defined as a nozzle,
calculating the landing position according to the distance between the recording medium and the opening of the nozzle;
This inkjet recording apparatus is characterized by:

Further, the invention according to claim 19 is the ink jet recording apparatus according to claim 17 or 18 ,
An input reception unit that receives input of settings related to the type of the recording medium,
The control unit is characterized by setting the interval based on the type.

Further, the invention according to claim 20 is the inkjet recording apparatus according to any one of claims 1 to 19 , wherein
The recording operation unit has a recording head in which a plurality of nozzles are arranged two-dimensionally,
The impact position includes a systematic deviation amount corresponding to an installation error of the recording head.

Further, the invention according to claim 21 ,
A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
In the setting step,
A first set value related to the amount of ink droplets to be ejected from the first nozzle is added to a second set value related to the amount of ink droplets to be ejected from the second nozzle. It is determined to eject ink in a droplet amount corresponding to the second set value to which the addition is made.
It is characterized by
Further, the invention according to claim 22,
A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step,
identifying the second nozzles including defective nozzles that are causing ejection failures related to ink landing positions;
Depending on whether or not the set value related to the amount of ink droplets to be ejected by the identified nozzle is equal to or greater than a predetermined first reference value, it is determined whether or not to cause the nozzle to perform the complement.
It is characterized by
Further, the invention according to claim 23,
A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step,
When the set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value and the deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval, Do not use the nozzle as the second nozzle
It is characterized by
Further, the invention according to claim 24,
A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step, the landing position is calculated according to the distance between the recording medium and the opening of the nozzle.
A complementary setting method for an ejection failure nozzle, characterized by:
It is characterized by

According to the present invention, there is an effect that the recording quality can be maintained more reliably.

1 is an overall perspective view of an inkjet recording apparatus; FIG. 4 is a bottom view showing a surface of the head unit facing the transport surface; FIG. 1 is a block diagram showing the functional configuration of an inkjet recording apparatus; FIG. FIG. 10 is a diagram illustrating selection of alternative nozzles; FIG. 4 is a chart showing setting patterns of alternative nozzles; FIG. FIG. 5 is a diagram showing an example of a test image for acquiring information on ink landing positions and information on ink ejection failure; 5 is a flowchart showing a control procedure of ink ejection state identification processing; 4 is a flowchart showing a control procedure of image data adjustment processing; 4 is a flowchart showing a control procedure of image data adjustment processing; 7 is a flowchart showing a control procedure of alternative nozzle identification processing called in image data adjustment processing; FIG. 10 is a diagram illustrating the arrangement of nozzles in a print head 211 of a modified example;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall perspective view of an inkjet recording apparatus 100 according to an embodiment of the invention.

This inkjet recording apparatus 100 has a plurality of line heads, here eight line heads, and is capable of recording a color image by ejecting ink in a single pass method. It includes a recording operation unit 20, an ink supply unit 30, an imaging unit 42 (reading unit), and the like.

The transport unit 10 includes a drive roller 11, a transport drive unit 12, a transport belt 14 (placement member), and the like. The transport drive unit 12 has a rotary motor that rotates the drive roller 11 at a predetermined speed. An endless conveying belt 14 is wound around the driving roller 11 together with a driven roller (not shown). Using the outer surface of the transport belt 14 as a transport surface, the transport unit 10 places a recording medium in a predetermined range on the transport surface, and moves the recording medium in a circular movement direction as the transport belt 14 rotates. (the moving direction of the recording medium during transportation, that is, the transportation direction). The type of recording medium here is a continuous fabric or the like. The conveying unit 10 can, for example, sequentially send out roll-shaped cloths, place them on the conveying surface, and convey them.

The recording operation section 20 includes a head unit 21 (see FIG. 2), a carriage 22, a carriage lifting section 23, and the like. The recording operation unit 20 is provided in a number corresponding to the number of ink colors (eight sets in this case). Each of the carriages 22 extends in a direction intersecting the transport direction of the transport unit 10 in a plane parallel to the transport surface, here, in a width direction perpendicular to the transport surface, above the transport surface of the recording medium by the transport unit 10. (height direction). The carriage 22 supplies ink from the openings of a plurality of nozzles N (see FIG. 2) over the entire width of the recording medium being conveyed (the width that can be recorded in the width direction; there may be some margins at both ends or at one end). A head unit 21 is fixed so as to be able to eject droplets of . The recording elements 26 (see FIG. 3) of each of the eight (plural) head units 21, here, nozzles N, ink flow paths (ink chambers), and a configuration for ejecting ink from each of the nozzles N (an electro-mechanical transducer, which will be described later). The number of the elements 252 (see FIG. 3) is appropriately determined according to the recording resolution, the size of the recording medium on which the ink jet recording apparatus 100 can record, and the like. A plurality of carriages 22, that is, the recording operation section 20, are provided at different positions in the transport direction. The carriage 22 is provided so that its position in the height direction can be changed by a carriage elevating section 23, and the distance of the head unit 21 from the conveying surface (the distance from the conveying surface) is changed as the carriage 22 moves. When the recording elements 26 each perform a recording operation (eject ink), ink is ejected from the nozzles to record (form) an image on the recording medium.

The carriage lifter 23 changes the distance of the carriage 22 from the conveying surface. The carriage lifting section 23 includes a lifting motor 232, an electromagnetic brake 233, a beam member 234, a support section 235, and the like.
Two beam members 234 are provided substantially parallel to each other in a direction intersecting the conveying direction (here, a direction orthogonal to the conveying direction, that is, a width direction) above the conveying belt 14 (on the conveying surface side of the recording medium). A support portion 235 is fixed to each end of the . The lifting motor 232 , the electromagnetic brake 233 and the carriage 22 are attached to the supporting portion 235 .
The carriage 22 is moved up and down according to the operation of an elevating motor 232 and an electromagnetic brake 233 which are driven based on a control signal from the control section 50 (see FIG. 3) to determine its position.

The lifting motor 232 moves the carriage 22 at a predetermined lifting speed. As the lifting motor 232, for example, a servo motor or a stepping motor is used.

The electromagnetic brake 233 maintains the fixed state of the carriage 22 , and when the fixed state is released in response to a drive signal, the carriage 22 can be temporarily moved by the lift motor 232 . That is, the electromagnetic brake 233 fixes the carriage 22 in a normal state including when the power supply is cut off. A disc brake, for example, is used as the electromagnetic brake 233 .

The ink supply unit 30 stores ink of each color used for image recording, and supplies the ink to the head unit 21 . Here, the ink storage tanks 31 for each color are arranged in a dedicated rack 32 and connected to the head unit 21 for ejecting each color ink through piping such as a tube. The ink of each color is not particularly limited, but eight different colors are used here, including C (cyan), M (magenta), Y (yellow) and K (black). P (pink), S (sky), G (gray), and O (orange) inks (at least part of which is a different color than the other part) can be supplied. The ink of each color is ejected as fine dots from the nozzles of the supplied head units 21 and lands on the recording medium, and is represented by a density or a combination thereof depending on the number of fine dots and the size of the dots (volume of droplets). A mixed color image is recorded. Further, the color of the ink stored in the ink storage tank 31 and supplied to the head unit 21 may be exchangeable.

The image capturing unit 42 is provided downstream of the recording operation unit 20 in the conveying direction, and captures and reads the surface of the recording medium on which the image has been recorded by the recording operation unit 20 (or has passed without being recorded). . The imaging unit 42 may include an illumination unit (not shown). The illumination unit illuminates the imaging surface (surface of the recording medium) of the imaging unit 42 substantially uniformly.

The imaging unit 42 has, for example, a one-dimensional imaging sensor. Here, the one-dimensional imaging sensor has a plurality of imaging elements arranged over the width of the conveying belt 14 at least in the width direction. By moving the recording medium in the conveying direction by the operation of the conveying unit 10, the imaging unit 42 can two-dimensionally image the recording medium. As the imaging sensor, a CCD sensor (Charge Coupled Device), a CMOS sensor (Complementary Metal Oxide Semiconductor), or the like is used. These image pickup sensors perform an image pickup operation in which each image pickup element outputs a charge amount or a voltage corresponding to the amount of light input from the surface of a recording medium to a light receiving element via an optical system (lens). Here, the imaging sensor is capable of imaging in each wavelength band (a plurality of wavelength bands) of RGB, and the imaging unit 42 can acquire a color read image. It should be noted that the imaging unit 42 may have a variable distance from the transport surface, similar to the carriage 22 .

FIG. 2 is a bottom view showing a surface of the head unit 21 facing the transport surface.
Here, since the head units 21 for each color have the same shape and configuration, any one of them will be described.

Eight recording heads 211 are fixed to the head unit 21 here. On the bottom surface of each recording head 211, a plurality of (plurality of) nozzle openings N are arranged at a predetermined nozzle pitch in the width direction. The opening positions of the nozzles N may be different in the transport direction as long as they are arranged at predetermined intervals in the width direction. Here, in the print head 211, the openings of the nozzles N are arranged in a houndstooth pattern. The numbers and sizes of the openings of the nozzles N shown in this figure are for explanation purposes only. is sufficiently small compared to the width of

The eight recording heads 211 included in one head unit 21 are arranged in a zigzag pattern at different positions. Along with this, the arrangement ranges of the nozzles N in the width direction of the openings of the respective recording heads 211 are positioned differently from each other, and accordingly, images can be recorded in mutually different recording ranges. The ends of the arrangement ranges of the nozzles N in the width direction of the adjacent recording heads 211 slightly overlap. Therefore, in the head unit 21, by combining the recording ranges in the width direction of each of the eight recording heads 211, the above nozzle pitch is achieved over the entire width of the recording medium in the width direction (there may be some margins at both ends). , ink can be ejected from a plurality of nozzles divided into each of the recording heads 211 .

FIG. 3 is a block diagram showing the functional configuration of the inkjet recording apparatus 100. As shown in FIG.

The inkjet recording apparatus 100 includes a transport section 10, a recording operation section 20, a detection section 40, a control section 50, a storage section 60, a communication section 70, a display section 81, an operation reception section 82, and a bus 90. etc. The transport section 10 has the transport driving section 12 described above. The detection unit 40 includes the imaging unit 42 described above.

The recording operation unit 20 includes a carriage driving unit 24, a head driving unit 25, and the like in addition to the components described above. The carriage drive unit 24 outputs a drive signal to the above-described lift motor 232, electromagnetic brake 233, and the like to operate or fix them. The recording element 26 includes the electromechanical transducer element 252 and the nozzle N, as described above.

The head drive section 25 includes a recording control section 251 . The recording control unit 251 outputs a drive signal for causing pressure fluctuations in the ink in the ink flow path communicating with each nozzle N of the recording head 211 under the control of the control unit 50 . For example, an electromechanical conversion element 252 (here, a piezoelectric element) is used as a configuration for generating pressure fluctuation, and the electromechanical conversion element 252 generates deformation according to the applied voltage, that is, the output voltage of the drive signal. , the ink flow path, and in particular, the pressure chamber, which is sized and shaped to appropriately generate pressure fluctuations, is deformed. As the drive signal, a voltage waveform pattern is determined in advance, and the electromechanical conversion element 252 corresponding to each nozzle is subjected to a voltage waveform pattern according to the control signal from the control unit 50 or drive data (halftone image data). Whether or not to output the drive signal in the voltage waveform pattern is determined. An appropriate amount of ink pushed out from the nozzle N by the deformation operation of the electromechanical conversion element 252 (printing operation of the printing element 26) due to the drive signal is separated from the ink in the ink flow path and ejected as ink droplets. . Here, the ink discharge amount (droplet amount) can be set in a plurality of stages, for example, in three stages. A voltage waveform pattern is determined according to the set ejection amount.

The detection unit 40 has an encoder 43 in addition to the imaging unit 42 described above. The encoder 43 detects the rotation of the drive motor of the transport drive unit 12 or the drive roller 11, and outputs a signal corresponding to the direction of rotation for each rotation of a predetermined angle.

The control unit 50 centrally controls the overall operation of the inkjet recording apparatus 100 . The control unit 50 includes a CPU 51 (Central Processing Unit), a RAM 52 (Random Access Memory), and the like. The control unit 50 performs various processes related to image recording based on image data, status signals and clock signals of each unit, and the like. Further, the control unit 50 performs processing such as operation adjustment related to ink ejection from each nozzle N, processing related to detection of a defective state of ejection operation and its response, and processing such as detection and adjustment of image quality deterioration.

The CPU 51 performs various kinds of arithmetic processing, and controls the conveyance of the recording medium, the supply of ink, the ejection of ink, and the reading operation of the recorded image in the inkjet recording apparatus 100 . The CPU 51 performs calculations and controls related to the above processes according to programs read from the storage unit 60 .

The RAM 52 provides working memory space for the CPU 51 and stores temporary data. The storage area for the temporary data may be appropriately shared with the DRAM area of the storage unit 60 .

The storage unit 60 stores a program 61, various setting data, job data 64 relating to image recording commands, and the like. The job data 64 includes image data to be recorded, its processed data, information related to operation settings, and the like. The program 61 includes a program for specifying defective ejection nozzles that are causing defective ink ejection, various image processing programs, and programs for complementary processing of defective ejection nozzles. The setting data includes an ejection failure nozzle list 62 indicating the positions of nozzles that have ejection failures (ejection failure nozzles) and ejection position information 63 (ejection information) relating to the ink ejection direction of each nozzle N. be

The storage unit 60 includes volatile memory such as DRAM and non-volatile memory here. Temporary data, such as job data and process data, may be stored in volatile memory for high speed processing and erased after the image recording operation is completed. Programs, setting data, and the like are held in a nonvolatile memory and held even while power is not supplied to the inkjet printing apparatus 100 . Some programs and setting data, such as initial data and core programs, may be stored in a non-erasable ROM or the like instead of the non-volatile memory.

The communication unit 70 is a communication interface that controls communication operations with external devices. The communication interface includes, for example, one or a plurality of network cards such as LAN cards that support various communication protocols. Under the control of the control unit 50, the communication unit 70 acquires image data to be recorded and job data including image recording settings from the external device, and can transmit status information and the like to the external device. can.

The display unit 81 displays the status of the inkjet recording apparatus 100 and an operation menu on the display screen according to the control signal from the control unit 50 . Examples of the display screen include a liquid crystal screen. In addition, the display unit 81 may include an LED lamp or the like for warning the presence or absence of power supply and/or an error.

The operation accepting unit 82 accepts a user's operation and outputs it to the control unit 50 . The operation reception unit 82 has, for example, a touch sensor. The touch sensor may be provided over the display screen of the display unit 81 and used as a touch panel. The control unit 50 outputs information on the position and type of the touch operation detected by the touch sensor to the control unit 50 . Also, the operation reception unit 82 may have a push button switch and/or a numeric keypad.

The bus 90 is a path that electrically connects the control unit 50 and each component that exchanges signals with the control unit 50 and transmits the signals.

Next, the control of the ink ejection operation of this embodiment will be described.
The inkjet recording apparatus 100 records a two-dimensional image by ejecting ink from each nozzle N while conveying the recording medium. Whether or not ink is ejected and the amount of ink ejected at a pixel position according to each timing during transport and the combination of each nozzle N is determined by a halftone image.

As described above, some of the many nozzles N may have an ink ejection failure. The ejection failure includes ink ejection failure, ejection amount abnormality (mainly decrease), ejection speed abnormality, and ejection direction abnormality. Causes of ejection failure include an abnormality in a drive circuit including an electromechanical conversion element, clogging of nozzles, adhesion of foreign matter in the vicinity of nozzle openings, and the like. Clogging of nozzles and adhesion of foreign matter are many abnormalities that occur over time during use.

Of the ejection failures, the abnormality in the ejection direction gradually changes according to the degree of clogging of the nozzle N and the amount and position of foreign matter adhering to the vicinity of the opening. The determination of the presence or absence of an ejection failure is made, for example, by comparing the difference between the landing position of the ejected ink and the reference position with a predetermined reference distance (for example, a predetermined number of times the nozzle interval). In a predetermined ejection direction, the difference depends on the ejection direction and the distance between the opening of the nozzle N and the recording medium. Since the position of the carriage 22 can be moved in the inkjet recording apparatus 100, the interval can be changed according to the characteristics of the surface of the recording medium, for example, the size of fluff. Here, by calculating the interval according to the type of printing medium, the determination of whether or not there is an ejection failure may differ for each type. Alternatively, the presence or absence of ejection failure may be determined according to the angle of the ink ejection direction. Information about the set ejection failure nozzles is stored in the ejection failure nozzle list 62 . The information on the type of recording medium may be acquired by an input operation accepted by the operation acceptance unit 82 or may be included in the job data 64 acquired via the communication unit 70 . The operation reception unit 82 and the communication unit 70 constitute an input reception unit in the inkjet recording apparatus 100 of this embodiment.

If the difference in ink landing positions (or the amount of angular deviation) is less than or equal to the reference distance, it is considered normal ejection even if the ejection direction deviates slightly from the reference position. Information on the ink landing position or ink ejection angle from each nozzle N is stored in the ejection position information 63 .

When there is an ejection failure nozzle, the ink ejection setting from the ejection failure nozzle is complemented by replacing it with the surrounding normal nozzles. As the surrounding nozzles, nozzles adjacent to each other in the width direction (on both sides) are usually selected. Currently, the ink coverage width when the ink ejected from each nozzle lands on the recording medium is larger than the nozzle interval (for example, 2 to 3 times), so the ink is ejected from adjacent nozzles. However, it is difficult to cause a large deterioration in image quality. However, in an image of uniform density, a thin line (white streak) of low density is likely to occur at the position of the ejection failure nozzle, and such density unevenness is likely to be conspicuous.

In the inkjet recording apparatus 100 of the present embodiment, when this complementary ejection is set, among the two nozzles adjacent to the defective ejection nozzle (first nozzle) in the width direction, the original landing position (reference The second nozzle (that is, normally, the nozzle at the ink landing position closest to the reference position) that actually lands at a position closer to the position) is used as an alternative nozzle (a nozzle that complements the first nozzle). In other words, the ink ejected from the alternative nozzle in a complementary manner and landed on the recording medium tends to spread toward the ejection failure nozzle side of the alternative nozzle, and is adjacent to the ejection failure nozzle on the opposite side of the replacement nozzle. The former suppresses the above-mentioned white streaks, and the latter suppresses the occurrence of black streaks due to a local increase in density due to overlap.

FIG. 4 is a diagram for explaining selection of alternative nozzles. In practice, the amount of deviation of the landing position is sufficiently small with respect to the flight distance of the ink. there is
As shown in FIG. 4A, out of the nozzles N1 to N10 arranged in the width direction, nozzles N3 and N9 are defective in discharge. Further, as shown in FIG. 4B, among the remaining nozzles, the ink landing position of nozzle N6 is in a direction perpendicular to the nozzle opening surface (here in the vertical direction) is offset by +2.8 nozzle intervals. Therefore, this nozzle N6 is set as an ejection failure nozzle.

The landing positions of the nozzles N2 and N4 on both sides of the nozzle N3 having an ejection failure due to ejection failure are ±0.0 and -0.4, respectively. In other words, the ink landing position from the nozzle N4 is slightly biased toward the original ink landing position from the nozzle N3 with respect to the nozzle N2 where the ink lands in a normal position. Therefore, nozzle N4 is preferentially set as the alternative nozzle. Similarly, the nozzle N5 is preferentially set as the alternative nozzle for the nozzle N6, and the nozzle N10 is preferentially set as the alternative nozzle for the nozzle N9. Note that even if the displacement of the impact positions is equal to or less than the reference distance, the order of the impact positions may be changed depending on the relative relationship.

FIG. 5 is a chart showing alternative nozzle setting patterns. Here, the numerical values in the upper row are the set values (three levels as described above) corresponding to the ink discharge amount originally set in the halftone image, and the numerical values in the lower row are the set values for the halftone image after the complementary setting. be.

As shown in FIG. 5A, nozzles N4, N5, and N10, which are preferentially set as substitute nozzles for ejection failure nozzles N3, N6, and N9, do not eject ink. In some cases, the ink ejection settings for nozzles N3, N6, and N9 may simply be changed to nozzles N4, N5, and N10. This applies mainly to images with low gradation (low ink ejection amount and high brightness).

As shown in FIG. 5(b), if the nozzles N4, N5, and N10 have already been set to discharge ink (here, the original set value of the nozzles N4 and N10 is "1"), the nozzle N3 , N6 and N9 (first set values) are added to the set values (second set values) of nozzles N4, N5 and N10. Here, the set values of nozzles N4 and N10 are "2". This applies mainly to low to medium gradation (medium ink ejection volume) images.

As shown in FIG. 5(c), when the addition of the setting value related to the ejection amount of the ejection failure nozzle results in a value greater than the settable maximum value (predetermined maximum setting value) of “3”, More than the maximum set value (the difference between the set value after addition and the maximum set value) is assigned to the nozzle on the opposite side, that is, the nozzle (third nozzle) whose landing position is second closest to the landing position of the defective nozzle. be done. Here, when the set value "2" of the nozzle N3 with ejection failure is added to the nozzle N4 originally set to "2", the result is "4", which exceeds the maximum set value. Therefore, the maximum set value of "3" is set for nozzle N4, and the remaining "1" is added to the set value (third set value) of nozzle N2 on the opposite side. In addition, since the ejection amount of "2" of the nozzle N9 cannot be additionally assigned to the nozzle N10 originally set to "3", the set value of "2" is assigned to the nozzle N8. Such a situation applies mainly to medium to high gradation images (high ink discharge amount and low brightness).

Here, the nozzle closest to the original landing position of the nozzle N9 is actually the nozzle N6. Therefore, as shown in FIG. 5(d), this nozzle N6 may be used as a substitute nozzle for the nozzle N9. That is, if there is no problem with the ink ejection amount and ejection speed, nozzles other than those on both sides of the ejection failure nozzle, in particular, nozzles set as ejection failure nozzles due to poor landing positions (defective nozzles) can be used for other ejection failure nozzles. Complementary ejection may be performed. Further, such complementary ejection by a defective nozzle may be limited to a case where the density of the image (ejection frequency and ejection amount of each nozzle) is equal to or higher than a predetermined reference value. If the size of the ink droplet is small, the deviation of the landing position is large, and the longer the flight distance, the more likely the flight becomes unstable. The set value may be set according to whether it is equal to or greater than a predetermined reference value (first reference value), for example, "2".

FIG. 6 is a diagram showing an example of a test image for acquiring information on ink landing positions and information on ink ejection failures.

The detection of ink landing positions and ink ejection failures, and the generation and updating of the ejection position information 63 and the ejection failure nozzle list 62 are performed by a test in which ink is ejected individually from each nozzle N and landed on a printing medium in a predetermined arrangement. This is performed based on the result of reading the image (predetermined test pattern) by the imaging unit 42 . Here, as shown in FIG. 6A, each nozzle prints an independent (separable and identifiable) straight line extending in the transport direction on the print medium. Since the landing position of the ink ejected from each nozzle N can be shifted by several times the nozzle interval, in order to identify which nozzle N is the straight line of the ink ejected, the number of adjacent straight lines must be the above number. It is necessary to separate them by more than two times, that is, by about 5 to 10 nozzles. The straight lines formed by the nozzles N in between are printed at different positions in the transport direction. Here, straight lines L formed by eight consecutive nozzles N are recorded at different positions in the transport direction, and the position in the transport direction is determined in a cycle of eight lines.

As shown in FIG. 6B, the nozzles N corresponding to the areas V1 and V2 in which straight lines are not drawn are determined to be defective in ink ejection. If the straight line T1 that is thinner than it should be is drawn, it is determined that the ink ejection amount is insufficient. Also, the straight line F1, which has a relatively large deviation from the drawing position of the surrounding straight lines, is determined to be an inaccurate ejection direction.

As described above, even the straight lines formed by the nozzles N other than the ejection-defective nozzles may have slight positional deviations. By specifying the positions of these straight lines, the displacement amount of each nozzle N in the ejection direction can be obtained. Here, these straight lines alone do not specify the displacement of the entire ejection position due to the positional displacement of the print head 211 or the like. Here, for example, the reference position where the straight line of the nozzle N is assumed to be drawn is determined by the average position of a predetermined number of straight lines in the width direction for the straight line of the target nozzle N. stipulate. Alternatively, the average position in the width direction of a predetermined part or all of the straight lines may be obtained, and the position corresponding to a constant multiple of the nozzle interval (determined by the positional relationship of each nozzle) from this average position may be determined as the reference position. good.

Such a test image is generated at the time of initial start-up, at the time of resuming power supply to the inkjet recording apparatus 100, and/or at the timing when the inkjet recording apparatus 100 has completed all image recording operations in response to an image recording command and has shifted to a standby state. Alternatively, the defective ejection nozzle list 62 and the ejection position information 63 may be updated by recording at a timing before a new image recording command is acquired and the image recording operation is started.

FIG. 7 is a flow chart showing the control procedure by the control unit 50 for the ink ejection state specifying process. When the ink ejection state specifying process is started, the control unit 50 (CPU 51) operates the recording operation unit 20 (head driving unit 25) to record the test image on the recording medium (step S101). At this time, the control unit 50 may set the amount of ink droplets to be ejected from each nozzle N to the second or higher stage from the smaller side of the three stages. As described above, with a nozzle having a poor landing position, if the droplet volume is small, the flight direction of the droplet becomes unstable, and the landing position may fluctuate. Also, even with nozzles within a normal range, a slight deviation in the landing position may occur. The control unit 50 causes the test image recorded by the imaging unit 42 to be read (step S102).

The control unit 50 specifies the position and density in the width direction of the straight line corresponding to each nozzle N based on the read test image. The control unit 50 stores and updates the specified recording positions as the ejection position information 63 for the nozzles N on which the straight line is drawn (step S103).

The control unit 50 identifies the ejection failure nozzle. The control unit 50 specifies, as faulty ejection nozzles, nozzles in which no straight line is recorded, the density of the straight line is insufficient, and the position of the straight line is displaced by a reference distance or more. It is stored (step S104). Then, the control unit 50 ends the ink ejection state specifying process.

8 and 9 are flowcharts showing control procedures by the control unit 50 for image data adjustment processing. This image data adjustment process includes the complementary setting method of the ejection failure nozzle of the present embodiment, and converts the data of the image to be recorded into driving image data based on the image recording command and outputs the data to the head driving section 25 . , which is started when the image recording command is obtained. Note that in the following processing, two defective ejection nozzles are adjacent to each other, and a plurality of defective ejection nozzles exist among the nozzles that can serve as substitute nozzles (that is, there are three or more nozzles including the target defective ejection nozzle). ) is not expected. In these cases, it is necessary to clean the nozzle N or replace the recording head 211, and a separate process corresponding to these needs to be performed.

When the image data adjustment process is started, the control unit 50 (CPU 51) generates driving halftone image data according to the image data to be recorded (step S151). In the halftone image data generated here, each pixel corresponds to the nozzle N, and as described above, there are multiple stages corresponding to the number of steps (three stages) of the amount of ink droplets that can be ejected by the nozzle N. (Here, four levels from 0 to 3) are indicated by set values (that is, pixel values). The control unit 50 sets the first (one end) pixel in the first row of the generated halftone image as the target pixel (step S152).

The control unit 50 determines whether or not the nozzle N corresponding to the target pixel is an ejection failure nozzle based on the ejection failure nozzle list 62 (step S153). If it is determined that the nozzle is not an ejection failure nozzle ("NO" in step S153), the process of the control unit 50 proceeds to step S175 (A).

If it is determined that the nozzle is defective in ejection ("YES" in step S153), the control unit 50, based on the ejection position information 63, adjusts the reference position related to the landing of ink from the defective ejection nozzle. An alternative nozzle identifying process for identifying alternative nozzles in the order in which ink lands in the closest position is called and executed (step S154). The control unit 50 identifies the first alternative nozzle, the second alternative nozzle, and the third alternative nozzle in order of impact position closer to the reference position. The control unit 50 determines whether the first alternative nozzle is an ejection failure nozzle related to an abnormality in the ejection direction, or whether the difference between its own reference position and the landing position is equal to or greater than the reference interval (step S155). If it is determined that the nozzle is not an ejection failure nozzle and the difference between the reference position and the landing position is not equal to or greater than the reference interval ("NO" in step S155), the process of the control unit 50 proceeds to step S158. .

If it is determined that the nozzle is defective in ejection or the difference between its own reference position and the landing position is equal to or greater than the reference interval ("YES" in step S155), the control unit 50 causes the first alternative nozzle to eject. A first set value (usually "0" in the case of a defective ejection nozzle), which is a set value related to the droplet amount, and a set value related to the droplet amount due to the defective ejection nozzle of the target pixel to be complemented. It is determined whether or not the sum of the set transfer setting value is equal to or greater than "2" (that is, the medium-sized liquid droplets of three stages of ejection) (step S156). If it is determined to be "2" or more ("YES" in step S156), the processing of the control unit 50 proceeds to step S158. If it is determined that the number is not "2" or more ("NO" in step S156), the first alternative nozzle and the second alternative nozzle are exchanged (step S157). Then, the processing of the control unit 50 proceeds to step S158.

When the processing of any one of steps S155 to S157 shifts to the processing of step S158, the control unit 50 adds the transfer set value to the first set value (step S158; setting step). The control unit 50 determines whether or not the first set value exceeds the maximum set value corresponding to the discharge amount preset for each nozzle (step S159). If it is determined that it has not exceeded ("NO" in step S159), the process of the control unit 50 proceeds to step S175 (A). If it is determined that it exceeds ("YES" in step S159), the control unit 50 sets the set value of the first alternative nozzle to the maximum set value (step S160).

The control unit 50 controls whether the sum of the first set value and the transfer set value exceeds the maximum set value and the set value related to the amount of liquid droplets to be ejected by the second alternative nozzle exceeds the maximum set value. It is discriminated whether or not there is (step S161). If it is determined that it has not exceeded ("NO" in step S161), the control unit 50 determines whether or not the second alternative nozzle is an ejection failure nozzle (step S162). If it is determined that the nozzle is not an ejection failure nozzle ("NO" in step S162), the process of the control unit 50 proceeds to step S165. If it is determined that the nozzle is defective in ejection ("YES" in step S162), the control unit 50 determines whether or not the sum of the second set value and the excess amount is "2" or more. (step S163). If it is determined to be "2" or more ("YES" in step S163), the processing of the control unit 50 proceeds to step S165. If it is determined that it is not "2" or more ("NO" in step S163), the control unit 50 switches the second alternative nozzle and the third alternative nozzle (step S164). Then, the processing of the control unit 50 proceeds to step S165.

When the processing of steps S162 to S164 is shifted to the processing of step S165, the control unit 50 adds the above-described excess amount to the second set value (step S165). Then, the processing of the control unit 50 proceeds to step S175 (A).

If it is determined in the determination process of step S161 that the sum of the second set value and the excess amount is greater than the maximum set value ("YES" in step S161), the control unit 50 sets the second set value to the maximum value. The set value is determined (step S166). Then, the processing of the control unit 50 proceeds to step S167 (B).

Moving to the flow of FIG. 9, in the process of step S167, the control unit 50 determines whether or not the ejection failure of the ejection failure nozzle related to the target pixel is an abnormality in the landing position (ejection direction) (step S167). ). If it is determined that the landing position is abnormal ("YES" in step S167), the control unit 50 sets the amount by which the second set value exceeds the maximum set value as the set value for the ejection failure nozzle ( step S168). Then, the processing of the control unit 50 proceeds to step S175.

If it is determined that the landing position is not abnormal (there is another abnormality) ("NO" in step S167), the control unit 50 causes the set third alternative nozzle to move to the next line in the transport direction. It is determined whether or not there is (step S169). If it is determined to be the next line ("YES" in step S169), the maximum sum of the second set value originally set for the second alternative nozzle and the excess amount exceeded for the first alternative nozzle The amount in excess of the set value is carried over to the ejection failure nozzles in the next row (step S170). Then, the processing of the control unit 50 proceeds to step S175.

If it is determined that the third alternative nozzle is not in the next row (is in the same row) ("NO" in step S169), the control unit 50 determines whether the third alternative nozzle is a defective ejection nozzle. (step S171). If it is determined that the nozzle is not an ejection failure nozzle ("NO" in step S171), the process of the control unit 50 proceeds to step S174. If it is determined that the nozzle is defective in ejection ("YES" in step S171), the control unit 50 sets the excess amount of the set value exceeding the maximum set value in the second alternative nozzle and the amount originally set in the third alternative nozzle. It is determined whether or not the sum with the set value (third set value) related to the set ejection amount is equal to or greater than "2" (step S172). If it is determined to be "2" or more ("YES" in step S172), the processing of the control unit 50 proceeds to step S174. If it is determined that it is not "2" or more (it is "1") ("YES" in step S172), the control unit 50 switches the third alternative nozzle and the fourth alternative nozzle (step S173). . Then, the processing of the control unit 50 proceeds to step S174.

When the process of steps S171 to S173 is shifted to the process of step S174, the control unit 50 adds the amount by which the set value of the second alternative nozzle exceeds the maximum set value to the third set value. (Step S174). Then, the processing of the control unit 50 proceeds to step S175.

When the processing of steps S153, S159, S165, S168, S170, and S174 is shifted to the processing of step S175, the control unit 50 determines whether setting of all pixels in each row of halftone image data has been completed. (Step S175). If it is determined that setting of all pixels in the row has not been completed ("NO" in step S175), the control unit 50 shifts the target pixel to the next pixel in the same row (step S176). Then, the processing of the control unit 50 returns to step S153 (C).

If it is determined that the setting of all the pixels in the row has been completed ("YES" in step S175), the control section 50 outputs the driving data related to the ink ejection setting of the set row data to the head driving section 25. (Step S177). Note that the control of the image recording operation according to the output pixel data may be separately controlled according to the transport state of the recording medium and the synchronization signal based on the signal of the encoder 43 .

The control unit 50 determines whether setting of pixel data for all rows in the halftone image data has been completed (step S178). If it is determined that the setting has not been completed ("NO" in step S178), the control unit 50 shifts the pixel to be set to the first pixel of the next row (step S179). Then, the processing of the control unit 50 returns to step S153 (C). If it is determined that the setting of pixel data for all rows has been completed ("YES" in step S178), the control unit 50 ends the image data adjustment process.
Note that the set image data may not be output line by line, but may be collectively output to the head driving section 25 after the setting (adjustment) of all lines is completed.

FIG. 10 is a flow chart showing the control procedure of the alternative nozzle identification process called in the image data adjustment process.

When the alternative nozzle specifying process is called, the control unit 50 acquires from the ejection position information 63 information on ink landing positions from the nozzles N corresponding to a predetermined number (for example, three) of pixels on the left and right of the target pixel (step S201). ). The control unit 50 calculates (specifies) the distance of each impact position from the reference position. The control unit 50 ranks (sorts) the calculated distances in ascending order (step S202). In this case, nozzles other than the fourth nozzles are not required in ascending order, so the control unit 50 may order only the fourth nozzles.

The control unit 50 stores and stores the sorted and ordered information on each alternative nozzle in association with information on whether or not the alternative nozzle is an ejection failure nozzle (step S203). Then, the control unit 50 ends the alternative nozzle identification process and returns the process to the image data adjustment process.

[Modification]
FIG. 11 is a diagram for explaining the arrangement of nozzles in the print head 211 of the modification.

As shown in FIG. 11A, in each recording head 211, the openings of the nozzles N are two-dimensionally arranged, specifically, two rows extending in the width direction are set at different positions in the transport direction. It is The respective openings are positioned at equal intervals so as to alternate in order of position in the width direction between these two rows. When such a recording head 211 is mounted with a minute rotational angle deviation (mounting error) in a plane including the width direction and the transport direction due to the limit of mounting accuracy, a Further, the amount of positional deviation in the width direction according to the rotation angle differs between the nozzle openings of the two nozzle rows. Therefore, the interval D11 in the width direction between the nozzles N11 and N12 is different from the interval D12 in the width direction between the nozzles N12 and N13. That is, even if ink is ejected from each nozzle N in an accurate direction, a systematic deviation amount occurs in which the interval between the ink landing positions alternately changes in size.

In this case, even if a slight positional deviation smaller than the average nozzle interval occurs overall, it does not greatly affect the image quality, but depending on the ejection failure and its complement, When density unevenness occurs, it is visually conspicuous especially when the image around the density unevenness portion has a uniform density.

When a nozzle N of the recording head 211 has an ink ejection failure, if the ink ejection direction from the other nozzles N is exactly perpendicular to the nozzle opening surface, the line to which the ejection failure nozzle belongs and the inclination Depending on the orientation, it is mechanically determined which of the left and right nozzles N should perform the alternative discharge. Here, since the interval D11 is smaller than the interval D12, the nozzle N12 is set as an ejection failure nozzle, and if there is no deviation in the ink ejection direction of the nozzles N11 and N13, the alternative nozzle is the nozzle N11. If there is a deviation in the direction in which ink is ejected from each nozzle N, it can be simply determined based on the sum of the effect of the deviation in the rotation angle and the effect of the deviation in the direction of ejection, that is, the final ink landing position. good.

As described above, the inkjet recording apparatus 100 of this embodiment includes the recording operation section 20 having a plurality of nozzles N that eject ink, and the control section 50 that controls the operation of the recording operation section 20 . The control unit 50 selects the second nozzle whose landing position is closest to the reference position related to the landing of the ink by the first nozzle causing the ink ejection failure to compensate for the ejection failure of the first nozzle. Defined as
In this way, instead of simply allocating complementary nozzles uniformly to adjacent nozzles (where the distance between nozzles is the closest), a minute deviation of the landing position according to the actual ink ejection direction from each nozzle N can be achieved. Since priority is given to nozzles at landing positions closest to the reference position, it is possible to suppress the occurrence of white streaks and black streaks more than conventionally. Therefore, the quality of recorded images can be maintained more reliably.

The inkjet recording apparatus 100 also includes a storage unit 60 that stores ejection position information 63 relating to the landing positions of the ink ejected from the nozzles N, and the control unit 50 stores the landing positions and the reference positions based on the ejection position information. Determine the distance of By checking and storing the information on the actual landing position in advance in this manner, when a nozzle with ejection failure newly occurs, it is possible to quickly and easily replace ink ejection with an optimal nozzle.

In addition, the recording operation unit 20 is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles N, and the control unit 50 controls the first ink droplet amount related to the ink droplet amount to be ejected from the first nozzles. The set value is added to a second set value related to the amount of droplets of ink to be ejected from the second nozzle, and the amount of ink droplets corresponding to the added second set value is ejected from the second nozzle. let it happen
That is, it is possible to appropriately replace the ejection amount of the ink ejection failure nozzle with other nozzles.

Further, when the second set value becomes larger than the predetermined maximum set value due to the addition, the control unit 50 causes the difference between the second set value and the maximum set value to be ejected from another nozzle different from the second nozzle. is assigned to a set value related to the amount of ink droplets to be ejected from the other nozzle.
Since there is an upper limit to the amount of ink that can be ejected from each nozzle N, if it is not possible to compensate with one nozzle, it may be compensated with another nozzle. When the amount of ink increases, white streaks are less likely to occur and black streaks are less noticeable.

Specifically, the control unit 50 converts the above difference to a third set value related to the amount of droplets of ink to be ejected by the third nozzle that lands the ink at the position second closest to the reference position. , and the second set value is set as the maximum set value. Naturally, complementing the nozzle N at the landing position closer to the ejection failure nozzle will result in an image that is more faithful to the image data. Complementing the remainder with N ensures that the image quality remains adequate.

Further, when the third set value becomes larger than the predetermined maximum set value as a result of the addition and the ejection failure of the original ejection failure nozzle (first nozzle) is due to the landing position failure, the control unit 50 The difference between the 3 set value and the maximum set value is caused to be discharged from the first nozzle, and the 3rd set value is set as the maximum set value. In this way, if the complementary discharge amount cannot be covered by the nozzles closest to the first and second landing positions (normally, the nozzles on both sides), it is assumed that the density is sufficiently high, so there will be some positional deviation. Even if there is, the image does not deteriorate. Therefore, when a defective ejection nozzle has a defective landing position, it is possible to maintain the overall ejection amount by causing the defective ejection nozzle to eject the insufficient amount of ink, thereby maintaining the image quality.

In addition, the control unit 50 identifies the second nozzles including the defective nozzles that are causing ejection failures related to the ink landing positions. In other words, if the ink landing position is determined, even a defective ejection nozzle can be caused to eject ink instead of another defective ejection nozzle having a reference position close to the landing position. As a result, it is possible to effectively use the nozzles that are normally out of use, and to record an image with an image quality that is closer to proper than in the past.

In addition, the control unit 50 identifies other nozzles including defective nozzles that are causing ejection failures related to ink landing positions. In the same manner as described above, nozzles having ejection failures related to landing positions may also be set for the third and subsequent nozzles.

Further, the control unit 50 determines whether or not to include the defective nozzle in the specified value depending on whether or not the set value related to the amount of ink droplets ejected by the nozzle N specified as the alternative nozzle is equal to or greater than a predetermined first reference value. Decide whether or not In the case of a defective landing position, when the amount of ink droplets to be ejected is small, the landing position tends to be blurred. may be limited to Thereby, image quality can be maintained more stably.

Further, the control unit 50 determines that the set value related to the amount of ink droplets to be ejected by the specified nozzle is less than a predetermined second reference value (here, equal to the first reference value) and the reference position of the specified nozzle itself. If the deviation from the landing position is equal to or greater than a predetermined reference interval, the nozzle is not used as the second nozzle. That is, even with a nozzle that is considered to be normally ejecting, if the flight distance of the ink becomes longer due to a deviation within the reference distance, the impact position of the small droplet may slightly fluctuate. In the case of ejecting small droplets from the second nozzle, which is likely to be affected by positional misalignment, the stability of the image quality can be maintained by not using the second nozzle as an alternative nozzle.

Moreover, the recording operation part 20 performs recording operation with respect to the fabric. The above technique can more effectively maintain the image quality of a material, such as cloth, in which ink droplets are unlikely to permeate and unevenness to occur on the surface.

In addition, the control unit 50 causes the recording operation unit 20 to eject ink from each of the nozzles N to record a test pattern in which the ink is landed on the recording medium in a predetermined arrangement, and based on the ink landing positions in the test pattern, to generate the ejection position information 63 .
Since the ejection position information 63 is generated based on the actual landing position in this manner, the alternative nozzle can be determined with high accuracy.

In addition, the control unit 50 causes the test pattern to be printed by ejecting the second smallest droplet amount or more among the plurality of stages.
As described above, when the droplet volume is small and the flight distance increases, the ink landing position tends to be blurred. can be done.

The inkjet recording apparatus 100 also includes an imaging unit 42 that reads the surface of the recording medium, and the control unit 50 causes the imaging unit 42 to read the test pattern and specifies the landing position. Since this enables in-line processing, it is possible to quickly reflect the test image and obtain the amount of positional deviation that changes with time as data closer to real time. In addition, since an imaging unit for confirming a recorded image may be used together, the imaging unit can be used more effectively.

The control unit 50 causes the recording operation unit 20 to eject ink onto the recording medium while the recording medium is moved in a predetermined transport direction by the transport unit 10, thereby producing a test pattern. 1, lines in which the ink ejected from each nozzle N extends in the transport direction are arranged so as to be identifiable.
In other words, the test pattern normally used for identifying defective ejection nozzles can be used as it is for identifying the landing position, so that the increase in processing time and effort is minimized.

Further, the control unit 50 calculates the landing position according to the distance between the recording medium and the nozzle N opening. This interval may vary depending on the type of recording medium. Since the landing position of the ink ejected with a certain inclination shifts according to this change, by adjusting the landing position according to the interval, it is possible to flexibly select an appropriate alternative nozzle.

The inkjet recording apparatus 100 also includes an input reception unit (the operation reception unit 82 and the communication unit 70) that receives input of settings related to the type of recording medium, and the control unit 50 sets the interval based on the type. That is, since an appropriate distance is determined in advance for each type of print medium, selection of an appropriate alternative nozzle can be adjusted without taking time and effort only by setting the print medium.

Further, the printing operation unit 20 has a printing head 211 in which a plurality of nozzles N are arranged two-dimensionally, and the landing position includes a systematic amount of deviation according to the installation error of the printing head 211 . In other words, the selection of the alternative nozzles described above is effective not only for defective ejection caused by each of the nozzles N, but also for misalignment caused by mechanical accuracy.

Further, in the complementary setting method of the ejection failure nozzle of the present embodiment, the second nozzle whose landing position is closest to the reference position related to the landing of the ink by the first nozzle causing the ejection failure of the ink is selected as the second nozzle. It includes a setting step of determining an alternative nozzle that complements the ejection failure of one nozzle.
As a result, it becomes possible to record a complementary image with less unevenness, and the occurrence of white streaks and black streaks can be suppressed more than before. Therefore, the quality of recorded images can be maintained more reliably.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible.
For example, in the above embodiment, the case where the amount of ink ejection can be adjusted in three stages has been described as an example, but the ink jet recording apparatus may be one in which only the presence or absence of ink ejection can be set. In this case, the maximum set value is "1".

Further, in the above-described embodiment, an ejection failure nozzle (defective nozzle) due to a deviation in the landing position may be used as an alternative nozzle. May be used without Alternatively, the defective nozzle may not be set as the second nozzle, but may be set as the third and subsequent nozzles.

Also, for normal nozzles, the size of the droplet amount may not be considered. Also, when the normal nozzle is set as the third nozzle, the size of the droplet amount may be taken into consideration.

Further, in the above-described embodiment, the displacement of the landing position occurs in the width direction, but the displacement of the landing position may occur in the transport direction. If the impact position deviation in the transport direction cannot be corrected by finely adjusting the ink ejection timing, the distance between the reference position and the impact position may be considered in consideration of this position deviation. It is also possible not to consider the positional deviation in the direction. In this case, the nozzles that are misaligned in the transport direction are simply handled in the same way as the defective ejection nozzles that are causing ejection failures.

Also, the ink need not be limited to color ink. Even in the case of forming a protective film, it is possible to reduce the unevenness of the film thickness. Also, the recording medium is not limited to fabric, and may be paper, film, or the like.

Also, the pattern of the test image is not limited to the one shown above. Alternatively, each part may be divided and recorded according to the margin of the recording medium.

Further, regardless of whether the inkjet recording apparatus 100 is equipped with the imaging unit 42 or not, the reading of the test image may be performed outside. Further, the operation of specifying the ink landing position based on the reading result may also be performed outside. In these cases, the control unit 50 may acquire the test image or the reading result from the outside.

Further, in the above embodiment, the distance between the print medium and the nozzle openings is set according to the type of print medium, but an appropriate distance may be set directly. Also, if the distance cannot be changed, the landing position may be fixed.

Further, in the above embodiments, the inkjet recording apparatus 100 having a line head was described as an example, but a scanning inkjet recording apparatus may be used.
In addition, specific details such as the configuration, control contents, and procedures shown in the above embodiments can be changed as appropriate without departing from the scope of the present invention.

10 transport unit 20 recording operation unit 21 head unit 211 recording head 22 carriage 25 head driving unit 251 recording control unit 252 electromechanical conversion element 26 recording element 30 ink supply unit 40 detection unit 42 imaging unit 43 encoder 50 control unit 60 storage unit 61 program 62 ejection failure nozzle list 63 ejection position information 64 job data 70 communication unit 81 display unit 82 operation reception unit 90 bus 100 inkjet recording apparatus N nozzle

Claims (24)

a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
The control unit compensates for the ejection failure of the first nozzle with a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure. A first set value related to the amount of ink droplets to be ejected from the first nozzle is added to a second set value related to the amount of ink droplets to be ejected from the second nozzle. No. 2 nozzles are caused to eject ink in an amount corresponding to the added second set value.
An inkjet recording apparatus characterized by: a storage unit that stores ejection information related to the landing position of the ink ejected from the nozzle;
2. The inkjet recording apparatus according to claim 1, wherein the control unit specifies a distance between the landing position and the reference position based on the ejection information. When the second set value becomes larger than a predetermined maximum set value as a result of the addition, the control unit calculates the difference between the second set value and the maximum set value for another nozzle different from the second nozzle. 3. The ink jet recording apparatus according to claim 1, wherein a setting value relating to the amount of droplets of ink to be ejected to the other nozzle is assigned to the other nozzle. The control unit adds the difference to a third set value relating to the amount of droplets of ink to be ejected by a third nozzle that lands ink at a position second closest to the reference position. 4. The ink jet recording apparatus according to claim 3 , wherein the set value is the maximum set value. When the third set value becomes larger than the predetermined maximum set value as a result of the addition and the ejection failure of the first nozzle is a landing position failure, the control unit sets the third set value and 5. An ink jet recording apparatus according to claim 4 , wherein a difference from said maximum set value is ejected from said first nozzle, and said third set value is set as said maximum set value. The inkjet recording according to any one of claims 1 to 5 , wherein the control unit specifies the second nozzles including defective nozzles that cause ejection failures related to ink landing positions. Device. The inkjet recording apparatus according to any one of claims 3 to 5, wherein the control unit specifies the other nozzles including defective nozzles that cause ejection failures related to ink landing positions. . The control unit determines whether or not to cause the specified nozzle to perform the supplementation according to whether or not a set value related to the amount of ink droplets ejected by the specified nozzle is equal to or greater than a predetermined first reference value. 8. The ink jet recording apparatus according to claim 6 , wherein: a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit
determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle;
identifying the second nozzles including defective nozzles that are causing ejection failures related to ink landing positions;
Depending on whether or not the set value related to the amount of ink droplets to be ejected by the identified nozzle is equal to or greater than a predetermined first reference value, it is determined whether or not to cause the nozzle to perform the complement.
An inkjet recording apparatus characterized by: The controller determines that a set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value, and a deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval. 10. The inkjet recording apparatus according to claim 1, wherein the nozzle is not used as the second nozzle when . a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit
determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle;
When the set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value and the deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval, Do not use the nozzle as the second nozzle
An inkjet recording apparatus characterized by: The inkjet recording apparatus according to any one of claims 1 to 11 , wherein the recording operation section performs a recording operation on a cloth. a storage unit that stores ejection information related to the landing position of the ink ejected from the nozzle;
The control unit causes the recording operation unit to eject ink from each of the nozzles to land on a recording medium in a predetermined arrangement to print a predetermined test pattern, and based on the landing positions of the ink in the test pattern. The inkjet recording apparatus according to any one of claims 1 to 12 , wherein the ejection information is generated by The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
14. The inkjet recording apparatus according to claim 13 , wherein the control unit records the test pattern by ejecting droplets of the second smallest amount or more among the plurality of stages. Equipped with a reading unit that reads the surface of the recording medium,
15. The inkjet recording apparatus according to claim 13 , wherein the control section specifies the landing position by causing the reading section to read the test pattern. A transport unit for transporting a recording medium is provided,
The control unit causes the recording operation unit to eject ink onto the recording medium while moving the recording medium in a predetermined conveying direction by the conveying unit;
16. The inkjet recording method according to any one of claims 13 to 15 , wherein the test pattern is a line in which ink ejected from each nozzle extends in the transport direction so that each line can be identified. Device. The inkjet recording apparatus according to any one of claims 1 to 16 , wherein the control section calculates the landing position according to the distance between the recording medium and the opening of the nozzle. a recording operation unit having a plurality of nozzles for ejecting ink;
a control unit that controls the operation of the recording operation unit;
with
The control unit compensates for the ejection failure of the first nozzle with a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure. defined as a nozzle,
calculating the landing position according to the distance between the recording medium and the opening of the nozzle;
An inkjet recording apparatus characterized by: An input reception unit that receives input of settings related to the type of the recording medium,
19. The inkjet recording apparatus according to claim 17 , wherein the controller sets the interval based on the type. The recording operation unit has a recording head in which a plurality of nozzles are arranged two-dimensionally,
20. The inkjet recording apparatus according to any one of claims 1 to 19 , wherein the landing position includes a systematic amount of deviation corresponding to an installation error of the recording head. A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
The recording operation unit is capable of ejecting a plurality of levels of droplet amounts of ink from each of the nozzles,
In the setting step,
A first set value related to the amount of ink droplets to be ejected from the first nozzle is added to a second set value related to the amount of ink droplets to be ejected from the second nozzle. It is determined to eject ink in a droplet amount corresponding to the second set value to which the addition is made.
A complementary setting method for an ejection failure nozzle, characterized by: A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step,
identifying the second nozzles including defective nozzles that are causing ejection failures related to ink landing positions;
Depending on whether or not the set value related to the amount of ink droplets to be ejected by the identified nozzle is equal to or greater than a predetermined first reference value, it is determined whether or not to cause the nozzle to perform the complement.
A complementary setting method for an ejection failure nozzle, characterized by: A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle having a landing position closest to a reference position related to ink landing by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step,
When the set value related to the amount of ink droplets ejected by the identified nozzle is less than a second predetermined reference value and the deviation between the reference position of the identified nozzle itself and the landing position is greater than or equal to a predetermined reference interval, Do not use the nozzle as the second nozzle
A complementary setting method for an ejection failure nozzle, characterized by: A complementary setting method for defective ejection nozzles in a recording operation unit having a plurality of nozzles for ejecting ink,
A setting step of determining a second nozzle whose landing position is closest to a reference position related to the landing of ink by the first nozzle causing the ink ejection failure as a nozzle that complements the ejection failure of the first nozzle. including
In the setting step, the landing position is calculated according to the distance between the recording medium and the opening of the nozzle.
A complementary setting method for an ejection failure nozzle, characterized by:

Images