Patent Application
20240190149
The present application is based on, and claims priority from JP Application Serial Number 2022-198761, filed Dec. 13, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a printing device and a printing method.
In an ink-jet printer, when ink thickens in a nozzle included in a printing head or air bubbles, dust, or the like enter the nozzle, clogging occurs in the nozzle, and such a nozzle becomes a so-called defective nozzle which cannot discharge ink dots normally. The defective nozzle is also referred to as an abnormal nozzle. The defective nozzle causes missing dots to be formed in a print result.
As a related technique, there is disclosed a recording device including a plurality of complementing units that form complementing dots for complementing dots to be formed by a defective nozzle, and a selection unit that selects any one complementing unit from the plurality of complementing units (see JP-A-2015-196340).
Of raster lines having length components in a main scanning direction of a printing head, one raster line formed using a plurality of nozzles including a defective nozzle is referred to as a defective raster line. In the defective raster line, dots assigned to the defective nozzle are missing from a print result. Missing of the dots may sometimes be substantially eliminated by making the missing dots inconspicuous using so-called neighborhood complementation of increasing an amount of ink discharged from another nozzle capable of discharging dots at positions near the missing dots.
However, when defective raster lines are continuously generated, missing of dots in a print result may not always be resolved appropriately by simply executing the neighborhood complementation. In view of such circumstances, there is a need for an improvement to prevent deterioration of print quality due to defective nozzles.
Provided is a printing device including: a printing head including a nozzle row in which a plurality of nozzles each configured to discharge a dot of liquid to a medium are arranged at a predetermined nozzle pitch in a sub-scanning direction, the printing head being configured to discharge the dot while moving in a main scanning direction intersecting the sub-scanning direction, a transport unit configured to perform relative movement between the medium and the printing head in the sub-scanning direction, a storage unit configured to store information about defective nozzles of the plurality of nozzles forming the nozzle row, and a control unit configured to control the printing head and the transport unit, wherein of raster lines having a length component in the main scanning direction, the raster line formed at the medium using two or more nozzles of the plurality of nozzles, the two or more nozzles including a first defective nozzle that is one of the defective nozzles and a first normal nozzle that is one of normal nozzles, the normal nozzles being included in the plurality of nozzles and not corresponding to the defective nozzles, is defined as a first raster line, the raster line formed at the medium using two or more nozzles of the plurality of nozzles, the two or more nozzles including a second defective nozzle that is one of the defective nozzles and a second normal nozzle that is one of the normal nozzles, is defined as a second raster line, and in a case in which the dot of the first raster line to be discharged by the first defective nozzle and the dot of the second raster line to be discharged by the second defective nozzle are determined to be adjacent to each other in the sub-scanning direction when the transport unit performs the movement by a predetermined first distance, the control unit performs first control of executing either control of changing a distance of the movement performed by the transport unit immediately before the first defective nozzle forms the first raster line by an integer multiple of the nozzle pitch from the first distance, or control of changing a distance of the movement performed by the transport unit immediately before the second defective nozzle forms the second raster line by an integer multiple of the nozzle pitch from the first distance.
Provided is a printing method including performing printing by controlling a printing head including a nozzle row in which a plurality of nozzles each configured to discharge a dot of liquid to a medium are arranged at a predetermined nozzle pitch in a sub-scanning direction, the printing head being configured to discharge the dot while moving in a main scanning direction intersecting the sub-scanning direction, and a transport unit configured to perform relative movement between the medium and the printing head in the sub-scanning direction, wherein of raster lines having a length component in the main scanning direction, the raster line formed at the medium using two or more nozzles of the plurality of nozzles, the two or more nozzles including a first defective nozzle that is one of defective nozzles of the plurality of nozzles forming the nozzle row and a first normal nozzle that is one of normal nozzles, the normal nozzles being included in the plurality of nozzles and not corresponding to the defective nozzles, is defined as a first raster line, the raster line formed at the medium using two or more nozzles of the plurality of nozzles, the two or more nozzles including a second defective nozzle that is one of the defective nozzles and a second normal nozzle that is one of the normal nozzles, is defined as a second raster line, and in the printing, in a case in which the dot of the first raster line to be discharged by the first defective nozzle and the dot of the second raster line to be discharged by the second defective nozzle are determined to be adjacent to each other in the sub-scanning direction when the transport unit performs the movement by a predetermined first distance, first control of executing either control of changing a distance of the movement performed by the transport unit immediately before the first defective nozzle forms the first raster line by an integer multiple of the nozzle pitch from the first distance, or control of changing a distance of the movement performed by the transport unit immediately before the second defective nozzle forms the second raster line by an integer multiple of the nozzle pitch from the first distance is performed.
Embodiments of the present disclosure will be described below with reference to the drawings. Also, each figure is merely illustrative for describing the present embodiment. Since each figure is illustrative, they may not show exact proportions or shapes, may not match each other, or may be partially omitted.
In the control unit 11, the processor, that is, the CPU 11a, executes arithmetic processing according to one or more programs 12 stored in the ROM 11b, other memories, or the like using the RAM 11c or the like serving as a work area, thereby controlling the printing device 10. Also, the processor is not limited to a single CPU, and a configuration in which the processing is performed by a hardware circuit such as a plurality of CPUs, an ASIC, or the like may be adopted, or a configuration in which a CPU and a hardware circuit cooperate to perform the processing may be adopted.
The display unit 13 is a unit that displays visual information and is constituted by, for example, a liquid crystal display, an organic EL display, or the like. The display unit 13 may have a configuration including a display and a drive circuit for driving the display. The operation receiving unit 14 is a unit that receives an operation performed by a user and is realized by, for example, a physical button, a touch panel, a mouse, a keyboard, or the like. Of course, the touch panel may be realized as one function of the display unit 13.
The display unit 13 and the operation receiving unit 14 may be part of the configuration of the printing device 10, or may be peripheral devices externally attached to the printing device 10. “Communication IF 15” is a general term for one or a plurality of IFs for coupling the printing device 10 to an external device in a wired or wireless manner in accordance with a predetermined communication protocol including known communication standards.
The storage unit 16 is configured of, for example, a storage device such as a hard disk drive, or a solid state drive. The storage unit 16 may be one memory included in the control unit 11. The storage unit 16 may be understood as part of the control unit 11. The storage unit 16 stores various types of information required for controlling the printing device 10.
The transport unit 17 is a unit that transports a medium in a predetermined “transport direction”, and includes rotating rollers and motors for rotating the rollers. Upstream and downstream in the transport direction are hereinafter simply referred to as upstream and downstream. The medium is typically paper, but in addition to paper, various materials that can be a target of printing with a liquid, such as fabrics and films, can be adopted as the medium. The transport direction is also referred to as a “sub-scanning direction”.
The carriage 18 is a mechanism that can reciprocate in a predetermined “main scanning direction” by receiving power from a carriage motor (not illustrated). The main scanning direction and the sub-scanning direction intersect each other. The intersection between the main scanning direction and the sub-scanning direction may be understood as being orthogonal or substantially orthogonal. The printing head 19 is mounted on the carriage 18. Accordingly, the printing head 19 reciprocates in the main scanning direction together with the carriage 18. Movement of the printing head 19 and movement of the carriage 18 are synonymous. The carriage 18 and the printing head 19 may be collectively understood as a printing head.
The printing head 19 has a plurality of nozzles 20 for discharging liquid dots. The dots are droplets. In the following description, the liquid is assumed to be ink, but the printing head 19 can also discharge liquids other than ink. The printing head 19 discharges ink based on print data for printing an image generated by the control unit 11. As is known, the control unit 11 controls application of drive signals to drive elements (not illustrated) included in each of the nozzles 20 in accordance with the print data to cause each of the nozzles 20 to discharge or not to discharge the dots, thereby printing the image on the medium. The printing head 19 can discharge each color ink such as cyan (C) ink, magenta (M) ink, yellow (Y) ink, and black (K) ink. Of course, the ink discharged by the printing head 19 is not limited to CMYK.
The printing head 19 includes nozzle rows 26 for each ink color in a configuration in which the printing head 19 receives supply of each color of ink from a liquid holding unit (not illustrated) referred to as ink cartridges, ink tanks, or the like and discharges them through the nozzles 20.
In the example of
A direction in which the plurality of nozzles 20 forming the nozzle rows 26 are arranged is referred to as a “nozzle arranging direction D3”. In the example of
An operation in which the printing head 19 discharges ink based on print data in accordance with movement of the carriage 18 in the main scanning direction D1 is referred to as “main scanning” or “pass”. In addition, an operation in which the transport unit 17 transports the medium 30 by a predetermined distance between passes is referred to as “paper feeding”. It can be said that the transport unit 17 performs relative movement between the medium 30 and the printing head 19 in the sub-scanning direction D2. By controlling the printing head 19, the carriage 18, and the transport unit 17 in this manner, the control unit 11 alternately repeats the pass and the paper feeding to print a two-dimensional image on the medium 30.
The configuration of the printing device 10 illustrated in
The defective nozzle detection unit 21 is a unit that detects “defective nozzles” from the plurality of nozzles 20 of the printing head 19. A defective nozzle is a nozzle 20 that is unable to discharge ink due to clogging or the like even though an ink discharging operation according to print data was performed. The inability to discharge ink includes, in addition to a state in which ink cannot be discharged at all, a case in which an amount of liquid discharged is too small, a case in which the discharged ink greatly bends and does not land on an intended location, and the like. A nozzle 20 that does not correspond to the defective nozzle is referred to as a “normal nozzle”.
Detection of a defective nozzle by the defective nozzle detection unit 21 may be performed using any method, including known methods, as long as it is possible to determine and detect whether each nozzle 20 is a defective nozzle. The defective nozzle detection unit 21 adopts, for example, a laser method in which a light emitter and the printing head 19 are aligned such that laser light emitted from the light emitter and an ink flight path of a nozzle 20 serving as an inspection target intersect each other, and when a light receiver cannot detect blocking of the laser light by the dots discharged from the nozzle 20, the inspection target is determined to be a defective nozzle. In addition, the defective nozzle detection unit 21 may detect a defective nozzle using a method disclosed in JP-A-2013-126776. Specifically, it is detected whether ink is normally discharged from each nozzle 20 by measuring a waveform of residual vibration of a partial configuration of the printing head 19 such as a so-called diaphragm that bends in accordance with deformation of a drive element (piezoelectric element) due to application of drive signals corresponding to print data.
The defective nozzle detection unit 21 generates “defective nozzle information” describing whether each nozzle 20 is a defective nozzle or not by performing defective nozzle detection processing. The defective nozzle information is stored in the storage unit 16. A timing at which the defective nozzle detection unit 21 executes the defective nozzle detection processing is not particularly limited. The defective nozzle detection unit 21 can overwrite the defective nozzle information in the storage unit 16 with the latest defective nozzle information at any time.
In step S100, the control unit 11 generates print data. The control unit 11 acquires image data representing an image serving as a printing target from a predetermined acquisition source such as the storage unit 16 or an external device in accordance with the user's operation. Then, various types of image processing such as resolution conversion processing, color conversion processing, and halftone processing are appropriately performed on the image data to generate the print data. The print data here is assumed to be data that defines discharge or non-discharge of dots for each pixel and for each CMYK ink color. Discharge of the dots is also referred to as dot-on, and non-discharge of the dots is also referred to as dot-off.
As is known, the printing head 19 is configured to discharge dots having a plurality of sizes from the nozzles 20. A size of a dot is, for example, a volume per dot droplet. For example, the nozzles 20 are configured to discharge dots of three different sizes referred to as large dots, medium dots, and small dots. Naturally, the size relationship is large dots>medium dots>small dots. Accordingly, dot-on information in the print data is information further indicating any one of large dot-on, medium dot-on, and small dot-on. Of course, the sizes of the dots that can be discharged from the nozzles 20 may not be limited to three types.
In step S110, the control unit 11 acquires the defective nozzle information stored in the storage unit 16. Also, the order of executing steps S100 and S110 may be reversed, or they may be executed simultaneously.
In step S120, the control unit 11 determines whether the dots to be discharged by the defective nozzles are adjacent to each other in the sub-scanning direction D2 based on the defective nozzle information acquired in step S110 and a preset “printing rule” and causes the processing to branch to step S130 or step S140 depending on the determination results. The dots to be discharged by the defective nozzles, that is, the dots to be formed by the defective nozzles based on the print data are missing from a print result. Accordingly, the dots to be discharged by the defective nozzles are also referred to as “missing dots” in the sense that the dots are missing as a result. If it is determined that the missing dots are not adjacent to each other in the sub-scanning direction D2, the control unit 11 proceeds from “No” in step S120 to step S130, executes “normal printing”, and ends the flowchart of
Steps S120, S130, and S140 will be described in detail below.
A pass number is a number assigned to each pass, and
The numbers written in the pixels are the nozzle numbers of the nozzles 20 used for printing the raster line to which the pixels belong. The nozzle numbers are numbers sequentially assigned one by one to each nozzle 20 forming the nozzle row 26 corresponding to one color of ink, and similarly to the raster numbers, a smaller number is assigned to a downstream nozzle 20. Since the description of the present embodiment is common to each ink of CMYK, the following description will be continued assuming printing of one color, for example, C ink. According to
In the example of
An amount of paper feeding immediately before the first pass is a large amount of feeding corresponding to 603 pixels due to so-called cueing, but an amount of paper feeding immediately before each pass after the second pass repeats 10 pixels and 11 pixels. For example, an amount of feeding in the paper feeding executed after the first pass ends and before the second starts is 10 pixels. For that reason, as compared to a position of the nozzle 20 with the nozzle number 32 in the first pass, a position of the nozzle 20 with the same nozzle number 32 in the second pass is shifted upstream by 10 pixels. Of course, during printing, the nozzle rows 26 do not move upstream between passes, but the medium 30 is fed downstream, and thus the illustrated correspondence relationship between each nozzle 20 and each raster line in the sub-scanning direction D2 is realized for each pass.
The pixel positions illustrated in
The nozzle 20 with the nozzle number 33 illustrated in gray in
On the other hand, in
As described above, when the two nozzles 20 with the nozzle numbers 25 and 33 are the defective nozzles, for example, the nozzle 20 with the nozzle number 25 can be understood as a “first defective nozzle”, and the nozzle 20 with the nozzle number 33 can be understood as a “second defective nozzle”. Also, a normal nozzle responsible for forming one raster line together with the first defective nozzle, for example, the nozzle 20 with the nozzle number 17 can be referred to as a “first normal nozzle”, and a normal nozzle responsible for forming one raster line together with the second defective nozzle, for example, the nozzle 20 with the nozzle number 20 can be referred to as a “second normal nozzle”. In addition, the defective raster line with the raster number #36 can be understood as an example of a “first raster line” formed at the medium 30 using two or more nozzles 20 including the first defective nozzle which is one of the defective nozzles and the first normal nozzle which is one of the normal nozzles, and the defective raster line with the raster number #37 can be understood as an example of a “second raster line” formed at the medium 30 using two or more nozzles 20 including the second defective nozzle which is one of the defective nozzles and the second normal nozzle which is one of the normal nozzles.
The normal printing in step S130 will be described later.
The normal printing is printing in accordance with the print data generated in step S100 and the above-described printing rule. Also, in the present embodiment, in both the normal printing in step S130 and the printing with the first control in step S140, the control unit 11 executes the neighborhood complementation depending on presence of the defective nozzle. Neighborhood complementation is processing of converting a size of a dot at a position adjacent to a missing dot into a larger size and discharging the dot. The conversion into a larger size is, for example, conversion from dot-off to small dot-on, conversion from small dot-on to medium dot-on, or conversion from medium dot-on to large dot-on. In addition, the conversion into a larger size may be processing of uniformly converting dots into the largest large dot even if a state before conversion is dot-off and regardless of the size of the dots.
In
The upper part of
In such a situation, the control unit 11 performs the neighborhood complementation. Specifically, the dots of each odd-numbered pixel in the normal raster line with the raster number #36 and the dots of each odd-numbered pixel in the normal raster line with the raster number #38 are adjacent to the missing dots, which are the dots of each odd-numbered pixel in the defective raster line with the raster number #37, in the sub-scanning direction D2. For that reason, as illustrated in the lower part of
Next, the printing with the first control in step S140 will be described.
When the transport unit 17 performs the paper feeding by the first distance in accordance with the printing rule, if the control unit 11 determines that a missing dot which is a dot of the first raster line to be discharged by the first defective nozzle and a missing dot which is a dot of the second raster line to be discharged by the second defective nozzle are adjacent to each other in the sub-scanning direction D2 (“Yes” in step S120), the control unit 11 executes the first control. The first control is processing of executing either control of changing a distance of movement, that is, paper feeding, performed by the transport unit 17 immediately before the first defective nozzle forms the first raster line from the first distance by an integer multiple of the nozzle pitch, or control of changing a distance of paper feeding performed by the transport unit 17 immediately before the second defective nozzle forms the second raster line from the first distance by an integer multiple of the nozzle pitch.
The upper part of
That is, when the paper feeding according to the amount of paper feeding, which is the first distance in accordance with the printing rule, is executed, the first raster line and the second raster line are adjacent to each other as illustrated in the upper part of
In order to solve such a problem, the control unit 11 differs the distance of paper feeding immediately before the first defective nozzle forms the first raster line from the first distance by an integer multiple of the nozzle pitch. Simply put, if a missing dot due to the first defective nozzle and a missing dot due to the second defective nozzle are adjacent to each other in the sub-scanning direction D2 when following the printing rule, the amount of paper feeding is partially changed so that these missing dots are not adjacent to each other.
That is, the amount of paper feeding immediately before the fourth pass, which is the amount of paper feeding immediately before the nozzle 20 with the nozzle number 25 serving as the first defective nozzle forms a raster line, is increased by the nozzle pitch. Thus, in each pass after the fourth pass, the nozzle numbers corresponding to the raster numbers are all shifted by 1 from the printing rule before change. For that reason, the raster line with the raster number #36, which becomes a defective raster line when following the printing rule before the change, is formed by two normal nozzles with the nozzle numbers 24 and 16 and becomes a normal raster line. In addition, in the fourth pass, the nozzle 20 with the nozzle number 25 is associated with the raster line with the raster number #40. For that reason, the raster line with the raster number #40, which becomes a normal raster line when following the printing rule before the change, is formed by the defective nozzle and the normal nozzle with the nozzle numbers 25 and 17 and thus becomes a defective raster line.
By partially changing the amount of paper feeding, the defective raster lines are no longer adjacent to each other in the sub-scanning direction D2, and a large missing dot area as illustrated in
After partially changing the printing rule as described above, the control unit 11 performs neighborhood complementation. Specifically, as illustrated in the lower part of
A difference of
In the embodiments and the first modified example described above, in the overlap printing in which one raster line is formed by two nozzles 20 regardless of whether the raster line is a normal raster line or a defective raster line, half of the pixels forming one raster line are assigned to each of the two nozzles 20, and a usage rate between the two nozzles 20 is 50% to 50%. A usage rate of a nozzle 20 is a rate of the number of pixels assigned as data and is not a ratio of the number of dots actually discharged to the medium 30. On the other hand, in a second modified example, when a raster line is formed at the medium 30 using two or more nozzles 20 including a defective nozzle and a normal nozzle, the control unit 11 is configured to execute “second control” of making a usage rate of the normal nozzle greater than that of the defective nozzle and causing the normal nozzle to discharge at least some of dots to be discharged by the defective nozzle.
That is, in the second control, a usage rate between the defective nozzle and the normal nozzle becomes unbalanced in formation of the defective raster line, and the usage rate between the defective nozzle and the normal nozzle is set to, for example, 0% to 100%, 20% to 80%, or 40% to 60%. Thus, if the usage rate is 50% to 50%, it is possible to cause the normal nozzle to discharge all or some of the dots that should have been discharged by the defective nozzle. Since the defective nozzle cannot actually discharge dots even if pixels are assigned, it is possible to reduce the number of missing dots in the defective raster line by executing the second control.
However, depending on capability of the printing head 19, it may not be possible to assign more than half of the pixels in one raster line to one nozzle 20 for printing. For example, it is assumed that a print resolution in the main scanning direction D1 set when the print data is generated is 1200 dpi, and the maximum print resolution that can be realized by one nozzle 20 in one pass is 600 dpi. In this case, since the print data is generated in accordance with the set 1200 dpi, more than half of the pixels in one raster line cannot be assigned to one nozzle 20. On the other hand, if the print resolution in the main-scanning direction D1 set when the print data is generated is equal to or less than 600 dpi, all pixels in one raster line can be assigned to one nozzle 20. Thus, when the set print resolution is equal to or less than a predetermined resolution, the control unit 11 executes the second control instead of the first control.
The print resolution is set through the user's operation of the operation receiving unit 14 or the like before the print data is generated in step S100, and print data having the resolutions corresponding to this setting is generated in step S100. That is, the user can set the print resolution through a user interface (hereinafter referred to as UI) provided by the display unit 13 and the operation receiving unit 14. Referring to the above-described specific example, if the print resolution is equal to or less than 600 dpi, the control unit 11 determines “Yes” in step S122 and proceeds to step S150. In step S150, the control unit 11 executes printing with the second control. Also, in step S150, the control unit 11 performs printing by controlling the transport unit 17, the carriage 18, and the printing head 19 in accordance with the print data and the printing rule. The printing rule mentioned here is the printing rule before the change. However, defective raster lines are exceptionally set as targets of the second control, and for example, all pixels forming the raster lines are assigned to normal nozzles.
As a result, in the defective raster line such as the first raster line or the second raster line, all the dots in the raster line including the dots that should have been assigned to the defective nozzle when following the printing rule are discharged by the normal nozzle, and no missing dots are generated. Alternatively, in the second control, for the defective raster line, the control unit 11 may assign, for example, 20% of the pixels forming the raster line to the defective nozzle and 80% of the pixels forming the raster line to the normal nozzle. Even in this case, in the defective raster line, some of the dots that should have been assigned to the defective nozzle when following the printing rule are discharged by the normal nozzle, and the number of generated missing dots is reduced.
Of course, the control unit 11 can execute the neighborhood complementation in step S150 as well. That is, if a missing dot is generated due to a defective nozzle in a certain raster line, printing may be executed after performing processing of converting a size of a dot at a position adjacent to the missing dot in the sub-scanning direction D2 into a larger size on the print data.
Also in a third modified example, similarly to the second modified example, the control unit 11 can execute the second control when a defective raster line is formed. However, in the third modified example, the set print resolution is not considered when the first control or the second control is selected. For example, even if the maximum print resolution that can be achieved by one nozzle 20 in one pass is 600 dpi at a normal moving speed of the carriage 18, the maximum print resolution that can be achieved by one nozzle 20 in one pass can be doubled to 1200 dpi if a moving speed of the carriage 18 is set to ½ of the normal moving speed.
For that reason, in the third modified example, it is assumed that the printing head 19 has the ability to print all pixels of a raster line with one nozzle 20 in one pass in correspondence with any of print resolutions which can be set by the user through the UI. In addition, the control unit 11 receives selection of either the first control or the second control, and executes either the first control or the second control in accordance with the received selection.
Through the UI, the user selects in advance which of the first control and the second control is to be executed as a countermeasure against the defective raster line. This selection result is recognized by the control unit 11. For that reason, the control unit 11 performs the determination of step S124 in accordance with the selection of the first control or the second control by the user.
As described above, according to the present embodiment, the printing device 10 includes the printing head 19 including the nozzle row 26 in which the plurality of nozzles 20 each configured to discharge a dot of liquid to the medium 30 are arranged at a predetermined nozzle pitch in the sub-scanning direction D2, the printing head 19 being configured to discharge the dot while moving in the main scanning direction D2 intersecting the sub-scanning direction D1, the transport unit 17 configured to perform relative movement between the medium 30 and the printing head 19 in the sub-scanning direction D2, the storage unit 16 configured to store the information about defective nozzles of the plurality of nozzles 20 forming the nozzle row 26, and the control unit 11 configured to control the printing head 19 and the transport unit 17. In addition, of raster lines having the length component in the main scanning direction D1, the raster line formed at the medium 30 using two or more nozzles 20 including the first defective nozzle that is one of the defective nozzles and the first normal nozzle that is one of normal nozzles, the normal nozzles being included in the plurality of nozzles 20 and not corresponding to the defective nozzles, is defined as the first raster line, the raster line formed at the medium 30 using two or more nozzles 20 including the second defective nozzle that is one of the defective nozzles and the second normal nozzle that is one of the normal nozzles is defined as the second raster line, and in a case in which the dot of the first raster line to be discharged by the first defective nozzle and the dot of the second raster line to be discharged by the second defective nozzle are determined to be adjacent to each other in the sub-scanning direction when the transport unit 17 performs the movement by the predetermined first distance, the control unit 11 performs the first control of executing either the control of changing the distance of the movement performed by the transport unit 17 immediately before the first defective nozzle forms the first raster line by an integer multiple of the nozzle pitch from the first distance, or the control of changing the distance of the movement performed by the transport unit 17 immediately before the second defective nozzle forms the second raster line by an integer multiple of the nozzle pitch from the first distance.
According to the above configuration, the printing device 10 executes the first control when the dot to be discharged by the first defective nozzle and the dot to be discharged by the second defective nozzle are determined to be adjacent to each other in the sub-scanning direction D2. Thus, it is possible to prevent the missing dots from being adjacent to each other in the sub-scanning direction D2. For this reason, the problem of the missing dots can be appropriately resolved by making them inconspicuous in the print result, and deterioration of the print quality due to the defective nozzles can be prevented. In addition, when the distance of the movement performed by the transport unit 17, that is, the amount of paper feeding, is changed from the first distance only immediately before the first defective nozzle forms the first raster line or the like, by changing the distance by an integer multiple of the nozzle pitch, it is possible to continue to appropriately form the raster lines without complicating the correspondence relationship between the raster lines and the nozzles in the subsequent printing.
Also, according to the present embodiment, in the first control, the control unit 11 changes the distance of the movement performed by the transport unit 17 by an integer multiple of the nozzle pitch and converts the size of the dot adjacent to the dot to be discharged by the first defective nozzle or the dot to be discharged by the second defective nozzle in the sub-scanning direction D2 into a larger size.
According to the above configuration, it is possible to make the missing of the dots inconspicuous in the print result using the neighborhood complementation.
Also, according to the present embodiment, in the first control, when a normal raster line is formed at the medium 30 adjacently to the raster line formed at the medium 30 using two or more nozzles 20 including the defective nozzle and the normal nozzle, the normal raster line being the raster line formed using two or more of the normal nozzles not including a defective nozzle, the control unit 11 may convert the size of the dot not targeted for conversion into the large size in the normal raster line, to a smaller size.
According to the above configuration, by reducing the size of the dot that does not correspond to the dot to be converted into the larger size for the neighborhood complementation, it is possible to inhibit an increase or decrease in the overall amount of liquid in the normal raster line, thereby inhibiting a variation in the image quality of the print result.
Also, according to the present embodiment, in the first control, the control unit 11 may increase the distance of the movement performed by the transport unit 17 immediately before the first defective nozzle forms the first raster line or the distance of the movement performed by the transport unit 17 immediately before the second defective nozzle forms the second raster line by an amount corresponding to the nozzle pitch from the first distance.
According to the above configuration, the meaning of the “integer multiple” is set to one times. That is, by making the difference between the amount of paper feeding and the first distance as small as possible, it is possible to inhibit transport errors and save time.
However, the above-mentioned “integer multiple” may be a numerical value larger than one times, such as two times or three times. The integer multiple does not include 0 times. In addition, as long as it is possible to prevent the missing dots that are the dots in the first raster line to be discharged by the first defective nozzle and the missing dots that are the dots in the second raster line to be discharged by the second defective nozzle from being adjacent to each other in the sub-scanning direction D2, the amount of paper feeding which is different from the first distance by an integer multiple of the nozzle pitch may be a distance shorter than the first distance.
Also, according to the present embodiment, in a case in which the raster line is formed at the medium 30 using two or more nozzles 20 including the defective nozzle and the normal nozzle, the control unit 11 may execute the second control of making the usage rate of the normal nozzle greater than that of the defective nozzle and causing the normal nozzle to discharge at least some of the dots to be discharged by the defective nozzle, and perform the second control instead of the first control when the set print resolution is equal to or less than a predetermined resolution.
According to the above configuration, by performing the second control instead of the first control when the defective raster line is formed, it is possible to reduce the number of missing dots and further improve the image quality without partially changing the amount of paper feeding as in the first control. In addition, since the condition that the set print resolution is equal to or less than the predetermined resolution is applied, there is no need to reduce the moving speed of the printing head 19 in order to increase the usage rate of the normal nozzle, and a decrease in printing throughput is not caused.
Also, according to the present embodiment, when the raster line is formed at the medium 30 using two or more nozzles 20 including the defective nozzle and the normal nozzle, the control unit 11 may perform the second control of making the usage rate of the normal nozzle greater than that of the defective nozzle and causing the normal nozzle to discharge at least some of the dots to be discharged by the defective nozzle, and receive the selection of either the first control or the second control and execute either the first control or the second control in accordance with the received selection.
According to the above configuration, it is possible to cause the user to select which of the first control and the second control is to be executed, and execute the first control or the second control in accordance with the selection.
In addition to the printing device 10, the present embodiment discloses the printing method and the program 12 for executing the printing method in cooperation with a processor.
For example, disclosed is the printing method including performing printing by controlling the printing head 19 including the nozzle row 26 in which the plurality of nozzles 20 each configured to discharge a dot of liquid to the medium 30 are arranged at the predetermined nozzle pitch in the sub-scanning direction D2, the printing head 19 being configured to discharge the dot while moving in the main scanning direction D1 intersecting the sub-scanning direction D2, and the transport unit 17 configured to perform relative movement between the medium 30 and the printing head 19 in the sub-scanning direction D2, wherein of raster lines having the length component in the main scanning direction D1, the raster line formed at the medium 30 using two or more nozzles 20 including the first defective nozzle that is one of defective nozzles of the plurality of nozzles 20 forming the nozzle row 26 and the first normal nozzle that is one of normal nozzles, the normal nozzles being included in the nozzles 20 and not corresponding to the defective nozzles, is defined as the first raster line, the raster line formed at the medium 30 using two or more nozzles 20 including the second defective nozzle that is one of the defective nozzles and the second normal nozzle that is one of the normal nozzles is defined as the second raster line, and in the printing, in a case in which the dot of the first raster line to be discharged by the first defective nozzle and the dot of the second raster line to be discharged by the second defective nozzle are determined to be adjacent to each other in the sub-scanning direction D2 when the transport unit 17 performs the movement by the predetermined first distance, the first control of executing either the control of changing the distance of the movement performed by the transport unit 17 immediately before the first defective nozzle forms the first raster line by an integer multiple of the nozzle pitch from the first distance, or the control of changing the distance of the movement performed by the transport unit 17 immediately before the second defective nozzle forms the second raster line by an integer multiple of the nozzle pitch from the first distance is performed.
Three or more nozzles 20 may be used to form one raster line. For example, a printing rule in which one raster line is formed by three different nozzles 20 is adopted. Then, if one of the three nozzles 20 for forming one raster line is a defective nozzle and the remaining two nozzles 20 are normal nozzles, the one raster line corresponds to a defective raster line. Further, there may be a plurality of the first normal nozzles for forming the first raster line corresponding to the defective raster line and a plurality of the second normal nozzles for forming the second raster line corresponding to the defective raster line.
The relative movement between the medium 30 and the printing head 19 in the sub-scanning direction D2 performed by the transport unit 17 may be upstream movement of the printing head 19 including the carriage 18 in the sub-scanning direction D2. That is, the transport unit 17 may be understood to include a mechanism for moving the printing head 19 including the carriage 18 upstream in the sub-scanning direction D2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-198761 | Dec 2022 | JP | national |
