JP6525605B2 - Ink jet recording device - Google Patents

Description

  The present invention relates to an inkjet recording apparatus.

  Techniques relating to inkjet recording devices have been proposed. For example, Patent Document 1 discloses an image recording apparatus. The image recording apparatus includes a control unit, a first nozzle array, and a second nozzle array. The first nozzle row and the second nozzle row constitute a line head. The first nozzle row and the second nozzle row are rows of ink discharge nozzles that discharge ink onto a recording medium to form an image. In the first nozzle row and the second nozzle row, the discharge nozzles are provided so as to overlap each other. It is assumed that the conveyance direction of the recording medium is meandering or obliquely, and a conveyance vector inclined to the lower left direction is generated. The transport vector is obtained by finely dividing the landed dot transport trace line in the transport direction, and using the least squares method for each section. In the image recording apparatus, the relative positional deviation amount of the second nozzle row with respect to the first nozzle row is calculated from the distance between the first nozzle row and the second nozzle row and the direction of the transport vector. In the image recording apparatus, the ink density correction amount at the adjustment discharge nozzle is obtained based on the relationship between the relative positional deviation amount and the density correction amount. The adjustment discharge nozzles are provided in the first nozzle row or in both the first nozzle row and the second nozzle row. In the image recording apparatus, discharge control of the adjustment discharge nozzle is performed based on the determined density correction amount.

  Patent Document 2 discloses an inkjet recording apparatus. The inkjet recording apparatus includes a belt conveyance device including two meandering sensors. In the belt conveyance device, two meandering sensors are provided on the upper side on the upstream side in the conveyance direction, respectively, on the right side and the left side. The meandering sensor detects both side edges of the endless belt. In the ink jet recording apparatus, the meandering of the endless belt is detected by the output from the meandering sensor.

JP 2007-175870 A JP 2014-84208 A

  An inkjet recording apparatus provided with a line type first inkjet head and a second inkjet head is used for recording an image on a recording medium. This inkjet recording apparatus can record high definition images at high speed. The inkjet recording apparatus includes a transport unit including an endless belt. The transport unit transports the recording medium placed on the outer circumferential surface of the endless belt in a first direction. At this time, the endless belt rotates in the direction corresponding to the first direction. The recording medium passes through the line-type first inkjet head and the second inkjet head while being transported. In the line-type first inkjet head, a plurality of first nozzles for ejecting ink are arranged at a first interval in a second direction orthogonal to the first direction. In the line-type second inkjet head, a plurality of second nozzles for ejecting ink are arranged at a first interval in a second direction. The second inkjet head is provided on the downstream side of the first direction separated from the first inkjet head by a second distance. At this time, the second inkjet head is provided with the second nozzles overlapping in the second direction with respect to the first nozzle of the first inkjet head. In the inkjet recording apparatus, the first inkjet head and the second inkjet head are positioned in the above-described state on the premise that the recording medium is correctly transported in the first direction by the transport unit.

  In the transport section, the endless belt may meander or skew. When the endless belt meanders or is skewed, the actual transport trajectory of the recording medium deviates from the linear theoretical trajectory along the first direction. In the ink jet recording apparatus, the discharge of the ink in the second nozzle of the second ink jet head can be controlled according to the amount of deviation. The inventor examined a configuration capable of acquiring the meandering amount or the skewing amount of the endless belt without performing complicated analysis when controlling the discharge of the ink from the second nozzle.

  An object of the present invention is to provide an ink jet recording apparatus capable of smoothly acquiring the amount of meandering or the amount of skew of an endless belt of a conveyance unit which conveys a recording medium.

One aspect of the present invention includes an endless belt, wherein the endless belt is rotated in a direction corresponding to a first direction for conveying a recording medium, and the recording medium placed on the outer peripheral surface of the endless belt is A conveyance unit conveying in a first direction and a plurality of first nozzles ejecting ink onto the recording medium conveyed by the conveyance unit are orthogonal to the first direction and coincide with the width direction of the endless belt A line-type first inkjet head arranged at first intervals in two directions, and a plurality of second nozzles for discharging ink onto the recording medium transported by the transport unit are the first direction in the second direction. An arrangement is made at intervals, and the second nozzles are provided downstream of the first inkjet head by a second interval in the first direction in a state where the second nozzles are overlapped in the second direction with respect to the first nozzle. Et al A second line-type second inkjet head, and a first detection of detecting a position of one end of the endless belt moving in the first direction at the first position in the first direction in the second direction; And a second position downstream of the first position by a third interval in the first direction, the position of one end of the endless belt moving in the first direction in the second direction is detected. When the endless belt is moved in the first direction by the third interval from the second detector, the position detected by the first detector, and the position detected by the second detector According to a displacement amount of the second direction obtained by the first control portion, a first control portion acquiring the displacement amount of the second direction of the position of one end of the endless belt in the second direction; Control the discharge of the ink from the second nozzle And a second control unit, wherein the in the first ink jet head, the arrangement of the plurality of the second direction of the first nozzle, is a plurality of rows in the fourth interval in said first direction, said second inkjet In the head, the arrangement of the plurality of second nozzles in the second direction is the arrangement of the plurality of first nozzles in the first ink jet head in the second direction at the fourth interval in the first direction. The first nozzle row by the first nozzle and the first nozzle row and the first nozzle row and the second ink jet head have the same sequence with respect to the upstream side of the first direction. The center-to-center distances of the second nozzle with the second nozzle row in the first direction are all set equal, and the second interval is the center-to-center distance, and the second detector In the direction The position of one end in the second direction of the endless belt moving in the first direction is detected at a second position downstream of the first position by the third interval equal to the second interval. , And an ink jet recording apparatus.

According to this, the endless belt moved by the third distance in the first direction by providing the first detector and the second detector at one side in the second direction with the first distance separated by the third distance. The second displacement amount of the position of the one end of the second direction can be obtained. The amount of displacement corresponds to the amount of meandering or skewing of the endless belt. The discharge of the ink from the second nozzle can be controlled according to the displacement amount. In the first inkjet head and the second inkjet head, the center of the first nozzle row by the first nozzle and the second nozzle row by the second nozzle in the first direction are the same in order based on the upstream side in the first direction By setting all the inter-distances equally, it is possible to obtain a displacement amount corresponding to the third interval that matches the second interval which is the center-to-center distance.

  In the inkjet recording apparatus, the second control unit may set discharge and non-discharge of the ink to the second nozzle in the control of the discharge of the ink from the second nozzle. According to this, the ink is discharged from the second nozzle set to discharge, and the ink is not discharged from the second nozzle set to non-discharge.

  In the inkjet recording apparatus, the second control unit may set an ejection size of the ink to the second nozzle in the control of the ejection of the ink from the second nozzle. According to this, the discharge size of the ink can be set according to the second nozzle. For example, for a predetermined second nozzle, a discharge size smaller than that of the other second nozzles can be set. According to the ink ejected from the second nozzle in which the small ejection size is set, the ink dots can be made small.

  In the inkjet recording apparatus, the second inkjet head adjusts a plurality of adjustments which is a part of the plurality of second nozzles with respect to a plurality of third nozzles which is a part of the plurality of first nozzles. The nozzles are provided downstream of the first inkjet head by the second interval in the first direction in a state in which the nozzles overlap in the second direction, and the second control unit is configured to receive the ink from the second nozzle. As the control of the ejection of the ink, the ejection of the ink from the adjustment nozzle may be controlled according to the displacement amount in the second direction acquired by the first control unit. According to this, the control of the discharge of the ink according to the displacement amount in the second direction can be performed for the adjustment nozzle.

In the inkjet recording apparatus, the first detector is an order of the plurality of first nozzle rows in which the plurality of first nozzles are arranged in the second direction, based on the upstream side in the first direction. End of the endless belt moving in the first direction at the first position in the first direction, which coincides with the position in the first direction of the predetermined first nozzle row, that issues detects the position of the parts, it may be.

  In the inkjet recording apparatus, the first control unit repeatedly acquires a first acquisition unit that repeatedly acquires the position detected by the first detector and a second acquisition unit that repeatedly acquires the position detected by the second detector. An acquisition unit, a first storage area for storing a position detected by the first detector, acquired by the first acquisition unit, and a second storage unit acquired by the second acquisition unit; A second storage area for storing the determined position, a timing at which the position detected by the first detector is acquired by the first acquisition unit, and a position acquired by the second detector is the second acquisition By the first detector, wherein the timing acquired by the recording unit differs by a time corresponding to the value obtained by dividing the third interval by the conveyance speed of the recording medium in the conveyance unit The first detector identified by the identifying unit and an identifying unit that identifies the position taken out and the position detected by the second detector from the first storage area and the second storage area, respectively And a third acquisition unit configured to acquire a displacement amount in the second direction from the position detected by the second detection unit and the position detected by the second detector. According to this, the displacement amount corresponding to the third interval can be acquired.

  According to the present invention, it is possible to obtain an ink jet recording apparatus capable of smoothly acquiring the amount of meandering or the amount of skew of the endless belt of the conveyance unit which conveys the recording medium.

FIG. 1 is a perspective view showing a schematic configuration of an inkjet recording apparatus. It is the figure which looked at the 1st recording part and the 2nd recording part from the side where the nozzle was formed. The outline of the physical relationship of the nozzle in the 1st ink jet head, and the nozzle in the 2nd ink jet head is shown. 5 is a flowchart of a first part of the discharge correction process. 7 is a flowchart of a second part of the discharge correction process. It is a flowchart of subroutine processing. It is a flow chart of subroutine processing of a modification.

  Embodiments for carrying out the present invention will be described using the drawings. The present invention is not limited to the configurations described below, and various configurations can be adopted in the same technical idea. For example, part of the configuration described below may be omitted or replaced with another configuration or the like. Other configurations may be included.

<Ink jet recording apparatus>
The inkjet recording apparatus 10 will be described with reference to FIGS. 1 and 2. In the inkjet recording apparatus 10, the recording medium 15 is conveyed, and an image is recorded on the recording surface 16 of the recording medium 15. In the inkjet recording apparatus 10, an image is recorded for various recording media 15. Examples of the recording medium 15 include a fabric or a building material. In the embodiment, the case where the recording medium 15 is a long cloth will be described as an example.

  As shown in FIG. 1, the inkjet recording apparatus 10 includes a transport unit 20, a first recording unit 30, a second recording unit 40, a first detector 61, a second detector 62, and a control device 70. Prepare. The transport unit 20 transports the recording medium 15 along the longitudinal direction of the recording medium 15. The recording medium 15 conveyed by the conveyance unit 20 passes through the first recording unit 30 and the second recording unit 40. In the embodiment, the direction in which the recording medium 15 is conveyed by the conveyance unit 20 is referred to as a “first direction”. The direction orthogonal to the first direction is referred to as "second direction".

  The transport unit 20 is a belt conveyor. As shown in FIG. 1, the transport unit 20 includes a pair of transport rollers 21 and 22, an endless belt 23, and a motor 24. The transport roller 21 is provided downstream of the second recording unit 40 in the first direction. The transport roller 22 is provided upstream of the first recording unit 30 in the first direction. The endless belt 23 is an annular belt. In the embodiment, the endless belt 23 is a belt of uniform width. The second direction coincides with the width direction of the endless belt 23. The endless belt 23 is stretched over the transport rollers 21 and 22 under tension. In a state in which the endless belt 23 is stretched over the transport rollers 21 and 22, the outer peripheral surface of the endless belt 23 is in a horizontal state between the transport rollers 21 and 22. The motor 24 is coupled to the transport roller 21. The motor 24 rotates the transport roller 21 in the direction corresponding to the first direction. The endless belt 23 rotates in a direction corresponding to the first direction as the transport roller 21 rotates. The transport roller 22 follows the rotation of the endless belt 23 and rotates in a direction corresponding to the first direction. In FIG. 1, an arc-shaped arrow shown inside the conveyance roller 21 indicates the rotation direction of the conveyance roller 21.

  The first recording unit 30 and the second recording unit 40 are provided side by side at a predetermined interval in the first direction at a position above the transport unit 20 in the vertical direction. The first recording unit 30 and the second recording unit 40 record an image on the recording medium 15. The pattern attached to the portion of the recording medium 15 illustrated between the first recording unit 30 and the second recording unit 40 in FIG. 1 corresponds to the image recorded on the recording medium 15 by the first recording unit 30. The pattern attached to the portion of the recording medium 15 illustrated on the downstream side of the second recording unit 40 in the first direction corresponds to the image recorded on the recording medium 15 by the first recording unit 30 and the second recording unit 40 .

  The first recording unit 30 includes a first inkjet head 31 and a first carriage 32. The first inkjet head 31 is a line-type inkjet head. The first inkjet head 31 is formed by a plurality of head units 50, as shown in FIG. The plurality of head units 50 forming the first inkjet head 31 are the same head unit. In the first inkjet head 31, the plurality of head units 50 are provided side by side in a state of being separated by a dimension L in the second direction. In the embodiment, the first inkjet head 31 is formed by arranging the three head units 50 in a state of being separated by the dimension L in the second direction. However, in the first inkjet head 31, the number of head units 50 may be two or four or more.

  The first inkjet head 31 is mounted on the first carriage 32 in a state of being positioned at a predetermined position. That is, the plurality of head units 50 that form the first inkjet head 31 are provided in a state of being positioned at predetermined positions of the first carriage 32 in the positional relationship described above.

  The second recording unit 40 includes a second inkjet head 41 and a second carriage 42. The second inkjet head 41 is a line-type inkjet head. The second inkjet head 41 is formed by a plurality of head units 50, as shown in FIG. The plurality of head units 50 forming the second inkjet head 41 are the same head unit. The head unit 50 forming the second inkjet head 41 is the same as the head unit 50 forming the first inkjet head 31.

  In the second inkjet head 41, the plurality of head units 50 are provided side by side in a state of being separated by a dimension L in the second direction. That is, the dimension between the head units 50 adjacent in the second direction is set to the same dimension L as the first inkjet head 31. In the embodiment, the second inkjet head 41 is formed by arranging two head units 50, which is one less than the three head units 50 in the first inkjet head 31, spaced apart by a dimension L in the second direction. There is. However, in the second inkjet head 41, the number of head units 50 may be one or three or more.

  The second inkjet head 41 is mounted on the second carriage 42 in a state of being positioned at a predetermined position. That is, the plurality of head units 50 forming the second inkjet head 41 are provided in the state of being respectively positioned at predetermined positions of the second carriage 42 in the positional relationship described above.

  The head unit 50 is formed with a plurality of nozzles 51 for discharging ink. The plurality of nozzles 51 are arranged at predetermined intervals in the second direction. In the embodiment, the distance between the nozzles 51 adjacent in the second direction is referred to as “first distance W1”. The first distance W1 is the distance between the centers of the nozzles 51 adjacent in the second direction (see FIG. 2). Inks of the same color are ejected from the nozzles 51 of the plurality of head units 50 forming the first inkjet head 31 and the second inkjet head 41, respectively.

  With the first inkjet head 31 mounted on the first carriage 32 and the second inkjet head 41 mounted on the second carriage 42, the positional relationship between the first inkjet head 31 and the second inkjet head 41 in the first direction is , Is set as follows. That is, the second inkjet head 41 is provided downstream of the first inkjet head 31 by the second interval W2 in the first direction. The second distance W2 is the center-to-center distance between the nozzles 51 of the first inkjet head 31 and the second inkjet head 41 (see FIG. 2).

  An ink tank for storing ink is connected to the head unit 50 forming the first inkjet head 31 and the second inkjet head 41 via a supply flow path. The ink flows out of the ink tank, flows through the above-described supply flow path, and is supplied to the head unit 50 forming the first inkjet head 31 and the second inkjet head 41.

  One or one ink tank is provided for each of the first inkjet head 31 and the second inkjet head 41. When one ink tank is used for the first ink jet head 31 and the second ink jet head 41, the supply flow path is branched to each side of the first ink jet head 31 and the second ink jet head 41 on the way May be included. The number of ink tanks is appropriately determined in consideration of various conditions. The feeding of the ink from the ink tank to the first inkjet head 31 and the second inkjet head 41 is performed in the same manner as in a known inkjet recording apparatus. For example, the delivery of ink is performed by pressurizing the inside of the ink tank. In addition to this, the liquid supply of the ink is performed by providing a pump in the middle of the supply flow path. In each drawing in the embodiment, illustration of the ink tank and the supply flow path is omitted. In each drawing in the embodiment, the illustration of the configuration for feeding the ink is also omitted.

  The first detector 61 is a displacement sensor that detects the position of one end of the endless belt 23 moving in the first direction at the first position P1 in the first direction. The first detector 61 outputs a detection value D1. The detection value D1 is position information corresponding to the position of one end of the endless belt 23 in the second direction at the first position P1. The second detector 62 is a displacement sensor that detects the position of one end of the endless belt 23 moving in the first direction at the second position P2 in the first direction. The second detector 62 outputs a detection value D2. The detection value D2 is position information corresponding to the position of one end of the endless belt 23 in the second direction at the second position P2. As the first detector 61 and the second detector 62, for example, a known contact-type displacement sensor can be adopted. In this case, the first detector 61 and the second detector 62 contact one end of the endless belt 23 in the second direction at each position described above. However, the first detector 61 and the second detector 62 may be known noncontact type displacement sensors.

  In the embodiment, the first detector 61 and the second detector 62 are provided on the first side of the endless belt 23 in the second direction. Therefore, one end of the endless belt 23 in the second direction detected by the first detector 61 and the second detector 62 is the end of the first side in the second direction. The first position P <b> 1 is a position corresponding to the first inkjet head 31 in the first recording unit 30 provided on the upstream side in the first direction of the first recording unit 30 and the second recording unit 40. Furthermore, the first position P1 corresponds to a position in the first direction in which the plurality of nozzles 51 of the first inkjet head 31 are arranged in the second direction (see FIG. 2). The second position P2 is a position downstream of the first position P1 by a third interval W3 in the first direction. The third interval W3 is set to the same dimension as the second interval W2. Therefore, the second position P2 corresponds to the position in the first direction in which the plurality of nozzles 51 of the second inkjet head 41 are arranged in the second direction in the second recording unit 40 provided on the downstream side in the first direction Position (see FIG. 2).

  As shown in FIG. 1, the control device 70 includes a CPU 71, a storage unit 72, a RAM 73, a connection interface 74, a head drive unit 75, and a mask circuit 76. In the embodiment, the connection interface 74 is described as “connection I / F 74”. The CPU 71 executes arithmetic processing and controls various processes executed by the inkjet recording apparatus 10. The storage unit 72 is, for example, a non-volatile memory and / or a hard disk. The storage unit 72 stores programs of various processes executed by the inkjet recording apparatus 10. For example, the storage unit 72 stores a program for the ejection correction process shown in FIGS. 3 and 4 and a program for the subroutine process shown in FIG. When the subroutine processing shown in FIG. 6 is adopted as the subroutine processing, the storage unit 72 stores a program of the subroutine processing. In addition to this, for example, the storage unit 72 stores a program of processing related to recording of an image. The RAM 73 is a work area when the CPU 71 executes a program stored in the storage unit 72. The RAM 73 stores predetermined data while the process is being performed. In the inkjet recording apparatus 10, the CPU 71 executes each program stored in the storage unit 72 using the RAM 73 to realize various functions and configure various control units.

  The connection I / F 74 is an interface for connecting a predetermined external device to the control device 70. For example, the first detector 61 and the second detector 62 are connected to the connection I / F 74 via a signal cable. The illustration of the signal cable is omitted in FIG. The CPU 71 acquires the detection value D1 from the first detector 61 and the detection value D2 from the second detector 62 via the connection I / F 74 (see S11 and S13 in FIG. 3 described later).

  The head drive unit 75 outputs a drive voltage of a predetermined voltage value at a predetermined cycle. The drive voltage output from the head drive unit 75 is applied to the piezo element. Piezo elements are provided corresponding to the nozzles 51 of the first inkjet head 31 and the second inkjet head 41. The piezo element is a drive element that generates energy to eject ink from the nozzle 51. As a drive element which generates the energy mentioned above besides a piezo element, a heater is mentioned, for example. In the embodiment, a piezo element will be described as an example. In each drawing in the embodiment, illustration of the piezo element is omitted.

  The mask circuit 76 executes thinning processing of print data generated from image data corresponding to an image to be printed. In the inkjet recording apparatus 10, four (four gradations) mask data for four types of thinning-out processing are set corresponding to subroutine processing shown in FIG. 5 described later. The first mask data among the four mask data is 4-bit mask data in which the ink ejection is not performed by one dot every four dots. When the first mask data is expressed in binary, for example, it becomes "1101". Here, “1” corresponds to the discharge, and “0” corresponds to the non-discharge. The second mask data of the four mask data is 4-bit mask data in which the ink ejection is not performed by 2 dots every 4 dots. When the second mask data is expressed in binary, for example, it becomes “0101”. The third mask data among the four mask data is 4-bit mask data in which the ink ejection is not performed by 3 dots for every 4 dots. When the third mask data is expressed in binary, for example, it becomes “0100”. The fourth mask data of the four mask data is 4-bit mask data in which the ejection of ink is regarded as non-ejection with all four dots. When the fourth mask data is expressed in binary, it is "0000".

  Recording of an image by the inkjet recording apparatus 10 is started when the control device 70 receives an instruction to start recording the image and the CPU 71 acquires the start instruction. The transport unit 20 transports the recording medium 15 in the first direction. In the first recording unit 30, the ink is ejected from the nozzles 51 of the first inkjet head 31 toward the recording medium 15 at a predetermined timing. The ink ejected from each nozzle 51 of the first inkjet head 31 lands on the recording surface 16 of the recording medium 15. In the second recording unit 40, the ink is discharged from the nozzles 51 of the second inkjet head 41 toward the recording medium 15 at a predetermined timing. The ink ejected from each nozzle 51 of the second inkjet head 41 lands on the recording surface 16 of the recording medium 15. An image is recorded on the recording surface 16 of the recording medium 15 by the landed ink. For example, after the recording of the image is completed, the conveyance unit 20 stops at a predetermined timing. With the stop of the conveyance unit 20, the conveyance of the recording medium 15 in the first direction ends.

<Positional relationship of nozzles based on second direction>
The positional relationship between the first inkjet head 31 and the nozzles 51 of the second inkjet head 41 based on the second direction will be described with reference to FIG.

  First, of the two head units 50 forming the second inkjet head 41, the head unit 50 provided on the first side in the second direction is one of the three head units 50 forming the first inkjet head 31. The head unit 50 provided on the first side in the second direction is in the following state. That is, in the head unit 50 in the second inkjet head 41, the plurality of nozzles 51 provided in the area on the first side in the second direction of the head unit 50 is the head unit 50 in the first inkjet head 31. The plurality of nozzles 51 provided in the region on the second side in the second direction is overlapped in the second direction. Furthermore, among the three head units 50 forming the first ink jet head 31, the head unit 50 in the second ink jet head 41 described above is the following with respect to the head unit 50 provided at the center in the second direction. State. That is, in the head unit 50 in the second inkjet head 41, the plurality of nozzles 51 provided in the area on the second side in the second direction of the head unit 50 is the head unit 50 in the first inkjet head 31. The plurality of nozzles 51 provided in the area on the first side in the second direction is overlapped in the second direction. In the embodiment, the number of overlapping nozzles 51 is six.

  Next, among the two head units 50 forming the second inkjet head 41, the head units 50 provided on the second side in the second direction are the three head units 50 forming the first inkjet head 31. Among the head units 50 provided at the center in the second direction, the following state is obtained. That is, in the head unit 50 in the second inkjet head 41, the plurality of nozzles 51 provided in the area on the first side in the second direction of the head unit 50 is the head unit 50 in the first inkjet head 31. The plurality of nozzles 51 provided in the region on the second side in the second direction is overlapped in the second direction. Furthermore, among the three head units 50 forming the first inkjet head 31, the above-described head unit 50 in the second inkjet head 41 is next to the head unit 50 provided on the second side in the second direction. It is in a state like That is, in the head unit 50 in the second inkjet head 41, the plurality of nozzles 51 provided in the area on the second side in the second direction of the head unit 50 is the head unit 50 in the first inkjet head 31. The plurality of nozzles 51 provided in the area on the first side in the second direction is overlapped in the second direction. In the embodiment, the number of overlapping nozzles 51 is six, as described above.

<Discharge correction processing>
The discharge correction process will be described with reference to FIGS. 3 and 4. The ejection correction process is a process for the six nozzles 51 overlapping in the second direction with respect to the predetermined nozzles 51 of the first inkjet head 31 in the second inkjet head 41 as described above. The ejection correction processing is processing for appropriately setting the ejection and non-ejection of the ink for each of the six nozzles 51 in the second inkjet head 41. The discharge correction processing will be described on the premise of the following matters.

  That is, in this description, when the endless belt 23 moves in the first direction between the first position P1 and the second position P2, the endless belt 23 moves obliquely from the first side to the second side in the second direction. In this example, the endless belt 23 moves linearly along the first direction. In this description, among the two head units 50 forming the second inkjet head 41, the second head unit 50B provided on the first side in the second direction is targeted (see FIG. 2). The nozzles 51 in the second head unit 50B to be described are referred to as "second nozzles 51B" (see FIG. 2). The plurality of second nozzles 51 </ b> B is a part of the plurality of nozzles 51 of the second inkjet head 41. Furthermore, the six nozzles 51 provided in the first side area in the second direction among some of the plurality of second nozzles 51B are subjected to the discharge correction process. The six second nozzles 51B, which are targets of the discharge correction process, are respectively "adjustment nozzle E", "adjustment nozzle F", "adjustment nozzle G", "adjustment nozzle H", "adjustment nozzle I" and "adjustment" It is called "nozzle J" (see FIG. 2).

  The adjustment nozzles E, F, G, H, I, J are directed from the first side to the second side in the second direction, the adjustment nozzle E, the adjustment nozzle F, the adjustment nozzle G, the adjustment nozzle H, the adjustment nozzle I and The adjustment nozzles J are arranged in the order. That is, the adjustment nozzle E is the second nozzle 51B provided at the first side end in the second direction. The adjustment nozzles F, G, H, I, J are all the second nozzles 51B separated from the adjustment nozzle E on the second side in the second direction. The adjustment nozzle F is a second nozzle 51B directly adjacent to the adjustment nozzle E on the second side in the second direction of the adjustment nozzle E. The adjustment nozzle G is a second nozzle 51B directly adjacent to the adjustment nozzle F on the second side in the second direction of the adjustment nozzle F. The adjustment nozzle H is a second nozzle 51B directly adjacent to the adjustment nozzle G on the second side in the second direction of the adjustment nozzle G. The adjustment nozzle I is a second nozzle 51B directly adjacent to the adjustment nozzle H on the second side in the second direction of the adjustment nozzle H. The adjustment nozzle J is a second nozzle 51B directly adjacent to the adjustment nozzle I on the second side in the second direction of the adjustment nozzle I. The adjustment nozzle F is disposed between the adjustment nozzle E and the adjustment nozzle G. The adjustment nozzle G is disposed between the adjustment nozzle F and the adjustment nozzle H. The adjustment nozzle H is disposed between the adjustment nozzle G and the adjustment nozzle I. The adjustment nozzle I is disposed between the adjustment nozzle H and the adjustment nozzle J. The adjustment nozzle J is disposed most distant from the adjustment nozzle E in the second direction among the five second nozzles 51B that are targets of the discharge correction process except the adjustment nozzle E.

  The adjustment nozzles E, F, G, H, I, J are in the second direction with respect to six third nozzles of the plurality of first nozzles 51A in the first head unit 50A of the first inkjet head 31. Duplicate (see Figure 2). The first head unit 50A is a head unit 50 provided on the first side of the first inkjet head 31 in the second direction. The plurality of first nozzles 51 </ b> A are a part of the plurality of nozzles 51 of the first inkjet head 31 and the nozzles 51 formed in the first head unit 50 </ b> A. The six third nozzles are a part of the plurality of first nozzles 51A, and the six first nozzles 51A provided in the region on the second side in the second direction. In FIG. 2, a broken line frame R is a description frame that clearly shows six third nozzles.

  The CPU 71 starts the discharge correction process in synchronization with the start of the recording of the image by the first recording unit 30 and the second recording unit 40. The CPU 71 that has started the ejection correction process starts acquiring the detection value D1 output from the first detector 61 (S11), and starts acquiring the detection value D2 output from the second detector 62 (S13). ). The CPU 71 repeatedly acquires the detection value D1 and the detection value D2 at regular intervals. The first detector 61 repeatedly outputs the detection value D1 at regular intervals. The second detector 62 repeatedly outputs the detection value D2 at regular intervals. The detection values D1 repeatedly acquired at constant intervals are stored in the RAM 73 in the order according to the acquisition order. The detection values D2 repeatedly acquired at constant intervals are stored in the RAM 73 in the order according to the acquisition order. For example, the detection value D1 is stored in the first storage area of the RAM 73 in the order according to the acquisition order, and the detection value D2 is stored in the second storage area of the RAM 73 in the order according to the acquisition order. Subsequently, the CPU 71 acquires the displacement amount D3 (S15). The displacement amount D3 is a displacement amount in the second direction of the endless belt 23 which has moved in the first direction by the third distance W3. Specifically, the displacement amount D3 is determined on the first side in the second direction of the endless belt 23 when the endless belt 23 moves from the first position P1 to the second position P2 in the first direction by the third distance W3. It is an amount of deviation in the second direction of the position of the end. The displacement amount D3 corresponds to the amount (the amount of meandering or the amount of skewing) of the endless belt 23 meandering or skewing in the second direction. The CPU 71 acquires, for example, the difference between the position indicated by the detection value D1 and the position indicated by the detection value D2 as the displacement amount D3.

  Regarding the detection values D1 and D2 used for acquiring the displacement amount D3, the detection value D1 to be processed is a detection value acquired a predetermined time before the timing when the detection value D2 to be processed is acquired. In other words, regarding the detection values D1 and D2 used to acquire the displacement amount D3, the detection value D2 to be processed is a detection value acquired a predetermined time after the timing when the detection value D1 to be processed is acquired. is there. Here, the above-mentioned predetermined time is a time required for the recording medium 15 to be transported by the third interval W3. That is, the predetermined time corresponds to a value obtained by dividing the third interval W3 by the transport speed of the recording medium 15 in the transport unit 20. As described above, the detection values D1 and D2 are repeatedly acquired at constant intervals. Therefore, when acquiring the displacement amount D3 in S15, the CPU 71, for example, specifies the latest detection value D2 as the processing target, and responds to the detection value D2 to be the processing target according to the predetermined time and the predetermined interval described above. The detected value D1 is identified. However, while specifying the predetermined detection value D1 stored in the RAM 73 as the processing target, the CPU 71 specifies the detection value D2 corresponding to the detection value D1 to be processed according to the predetermined time and the predetermined interval described above. You may do so. The displacement amount D3 acquired in S15 is stored in the RAM 73. In the embodiment based on the above-described example, the displacement amount D3 when the endless belt 23 moves obliquely from the first side to the second side in the second direction is a positive value.

  Next, the CPU 71 determines whether the displacement amount D3 is “0” (S17). The displacement amount D3 “0” indicates that the endless belt 23 linearly moves in the first direction. In this case, the recording medium 15 is conveyed linearly along the first direction. If the displacement amount D3 is “0” (S17: Yes), the CPU 71 sets the adjustment nozzles E, F, G as non-ejection, and sets the adjustment nozzles H, I, J as ejection (S19). Along with this, a drive voltage is applied to the piezoelectric element corresponding to the adjustment nozzle H, the piezoelectric element corresponding to the adjustment nozzle I, and the piezoelectric element corresponding to the adjustment nozzle J. A drive voltage is not applied to each of the piezoelectric elements corresponding to each of the adjustment nozzles E, F, and G. Ink is ejected from the adjustment nozzles H, I, J, respectively. Ink is not ejected from the adjustment nozzles E, F, and G.

  If the displacement amount D3 is not “0” (S17: No), the CPU 71 determines whether the displacement amount D3 is smaller than the first interval W1 (S21). The first interval W1 is registered, for example, in a program of discharge correction processing. The CPU 71 reads the first interval W1 from the program of the discharge correction processing, and stores the first interval W1 in the RAM 73. If the displacement amount D3 is smaller than the first interval W1 (S21: Yes), the CPU 71 sets the adjustment nozzles E, F, G as non-ejection, and sets the adjustment nozzles I, J as ejection (S23). Along with this, a drive voltage is applied to the piezoelectric element corresponding to the adjustment nozzle I and the piezoelectric element corresponding to the adjustment nozzle J. A drive voltage is not applied to each of the piezoelectric elements corresponding to each of the adjustment nozzles E, F, and G. Ink is ejected from the adjustment nozzles I and J. Ink is not ejected from the adjustment nozzles E, F, and G. Subsequently, the CPU 71 executes subroutine processing (S25). The subroutine processing in S25 is executed for the adjusting nozzle H. With regard to control of ink ejection, the adjustment nozzle H is set to a state according to the result of the subroutine processing of S25. The subroutine processing will be described later.

  If the displacement amount D3 is equal to or greater than the first interval W1 (S21: No), the CPU 71 shifts the process to S27 of FIG. In S27, the CPU 71 determines whether the displacement amount D3 is smaller than twice the first interval W1 (S27). If the displacement amount D3 is smaller than twice the first interval W1 (S27: Yes), the CPU 71 sets the adjustment nozzles E, F, G, H as non-ejection and sets the adjustment nozzle J as ejection (S29) . Along with this, a drive voltage is applied to the piezo element corresponding to the adjustment nozzle J. A drive voltage is not applied to each piezo element corresponding to each of the adjustment nozzles E, F, G, H. Ink is ejected from the adjustment nozzle J. Ink is not ejected from the adjustment nozzles E, F, G, and H. Subsequently, the CPU 71 executes subroutine processing (S31). The subroutine processing in S31 is executed for the adjustment nozzle I. With regard to control of ink ejection, the adjustment nozzle I is set to a state according to the result of the subroutine processing of S31. The subroutine processing will be described later.

  If the displacement amount D3 is twice or more of the first interval W1 (S27: No), the CPU 71 determines whether the displacement amount D3 is smaller than three times the first interval W1 (S33). If the displacement amount D3 is smaller than three times the first interval W1 (S33: Yes), the CPU 71 sets the adjustment nozzles E, F, G, H, I as non-ejection (S35). Along with this, no drive voltage is applied to each of the piezo elements corresponding to the adjustment nozzles E, F, G, H, and I, respectively. Ink is not ejected from the adjustment nozzles E, F, G, H, and I. Subsequently, the CPU 71 executes subroutine processing (S37). The subroutine processing in S37 is executed for the adjusting nozzle J. With regard to control of ink ejection, the adjustment nozzle J is set in a state according to the result of the subroutine processing of S37. The subroutine processing will be described later.

  If the displacement amount D3 is three or more times the first interval W1 (S33: No), the CPU 71 sets the adjustment nozzles E, F, G, H, I, and J as ejection failure (S39). Along with this, no drive voltage is applied to the respective piezo elements corresponding to the respective adjustment nozzles E, F, G, H, I, J. Ink is not ejected from the adjustment nozzles E, F, G, H, I, J. After executing S19 or S25 of FIG. 3 or S31, S37 or S39 of FIG. 4, the CPU 71 returns the process to S11 of FIG. 3. Thereafter, the CPU 71 repeatedly executes the processing of S11 and subsequent steps. The ejection correction process ends with the end of the recording of the image.

<Subroutine process>
The subroutine processing executed in S25 of FIG. 3 or S31 or S37 of FIG. 4 will be described with reference to FIG. This explanation also assumes the same matters as the explanation of the ejection correction processing described above based on FIG. 3 and FIG. In the subroutine processing executed in S25 of FIG. 3, as described above, the adjustment nozzle H is to be processed. In the subroutine processing executed in S31 of FIG. 4, as described above, the adjustment nozzle I is to be processed. In the subroutine processing executed in S37 of FIG. 4, as described above, the adjustment nozzle J is to be processed. The correction value to be described later is set to a value that matches the displacement amount D3 acquired in S15 of FIG. 3 (see S25 of FIG. 3 or S31 or S37 of FIG. 4). In the description of the subroutine processing, a predetermined adjustment nozzle to be processed among the adjustment nozzles H, I, and J is referred to as “adjustment nozzle to be processed”.

  The CPU 71 that has started the subroutine processing determines whether the correction value is equal to or less than 1⁄4 of the first interval W1 (S41). If the correction value is equal to or less than 1⁄4 of the first interval W1 (S41: Yes), the CPU 71 applies the first mask data to the adjustment nozzle to be processed (S43). The first mask data is, for example, data of “1101” as described above. In this case, when the logical product of the first mask data “1101” and the print data generated from the image data corresponding to the image to be printed is “1”, the adjustment nozzle to be processed is set to discharge. When the above-mentioned logical product is “0”, the adjustment nozzle to be processed is set to the non-ejection. It is assumed that the first mask data is “1101” and the print data for 4 dots is “1111”. In the adjustment nozzle to be processed, the first and second dots are set to discharge, the third dot is set to non-discharge, and the fourth dot is set to discharge. When the ejection is set, a drive voltage is applied to the piezoelectric element corresponding to the adjustment nozzle to be processed. When the ejection failure is set, the drive voltage is not applied to the piezoelectric element corresponding to the adjustment nozzle to be processed.

  If the correction value is larger than 1⁄4 of the first interval W1 (S41: No), the CPU 71 determines whether the correction value is 2⁄4 or less of the first interval W1 (S45). If the correction value is 2/4 or less of the first interval W1 (S45: Yes), the CPU 71 applies the second mask data to the adjustment nozzle to be processed (S47). The second mask data is, for example, data of “0101” as described above. In this case, when the logical product of the second mask data “0101” and the print data generated from the image data corresponding to the print target image is “1”, the adjustment nozzle to be processed is set to discharge. When the above-mentioned logical product is “0”, the adjustment nozzle to be processed is set to the non-ejection. It is assumed that the second mask data is "0101" and the recording data for four dots is "1111". In the adjustment nozzle to be processed, the first dot is set to non-ejection, the second dot is set to ejection, the third dot is set to non-ejection, and the fourth dot is set to ejection. When the ejection is set, a drive voltage is applied to the piezoelectric element corresponding to the adjustment nozzle to be processed. When the ejection failure is set, the drive voltage is not applied to the piezoelectric element corresponding to the adjustment nozzle to be processed.

  If the correction value is larger than 2/4 of the first interval W1 (S45: No), the CPU 71 determines whether the correction value is 3/4 or less of the first interval W1 (S49). When the correction value is equal to or less than 3/4 of the first interval W1 (S49: Yes), the CPU 71 applies the third mask data to the adjustment nozzle to be processed (S51). The third mask data is, for example, data of “0100” as described above. In this case, when the logical product of the third mask data “0100” and the print data generated from the image data corresponding to the image to be printed is “1”, the adjustment nozzle to be processed is set to discharge. When the above-mentioned logical product is “0”, the adjustment nozzle to be processed is set to the non-ejection. It is assumed that the third mask data is "0100" and the recording data for 4 dots is "1111". In the adjustment nozzle to be processed, the first dot is set to be non-ejection, the second dot is set to ejection, and the third and fourth dots are set to be non-ejection. When the ejection is set, a drive voltage is applied to the piezoelectric element corresponding to the adjustment nozzle to be processed. When the ejection failure is set, the drive voltage is not applied to the piezoelectric element corresponding to the adjustment nozzle to be processed.

  If the correction value is larger than 3/4 of the first interval W1 (S49: No), the CPU 71 applies the fourth mask data to the adjustment nozzle to be processed (S53). The fourth mask data is, for example, data of "0000" as described above. In this case, the logical product of the fourth mask data “0000” and the print data generated from the image data corresponding to the image to be printed is “0” in all four dots. That is, the adjustment nozzle to be processed is set to be non-ejection continuously for four dots. Therefore, the drive voltage is not applied to the piezoelectric element corresponding to the adjustment nozzle to be processed four dots continuously. After executing S43, S47, S51, or S53, the CPU 71 ends the subroutine processing, and returns the processing to the discharge correction processing. In the adjustment nozzle to be processed, the ink is ejected at the timing when the drive voltage is applied, and when the drive voltage is not applied, the ink is not ejected.

<Effect of the embodiment>
According to the embodiment, the following effects can be obtained.

  (1) In the inkjet recording apparatus 10, the predetermined six nozzles 51 of the second inkjet head 41 are provided to overlap the predetermined six nozzles 51 of the first inkjet head 31 in the second direction. (See Figure 2). The predetermined six nozzles 51 in the second inkjet head 41 are, for example, adjustment nozzles E, F, G, H, I, J shown in FIG. In this case, predetermined six nozzles 51 in the first inkjet head 31 are six third nozzles surrounded by a frame R shown in FIG. In the inkjet recording apparatus 10, the first detector 61 is provided at the first position P1 in the first direction, and the second detector 62 is provided at the second position P2 in the first direction (see FIGS. 1 and 2). The second position P2 is a position downstream of the first position P1 by a third interval W3 in the first direction. The first detector 61 detects the position of the end on the first side of the second direction of the endless belt 23 moving in the first direction (see FIG. 1). The second detector 62 detects the position of the end of the first side of the endless belt 23 moving in the first direction in the second direction (see FIG. 1).

  Therefore, the displacement amount D3 can be obtained from the detection value D1 from the first detector 61 and the detection value D2 from the second detector 62 in the discharge correction process shown in FIGS. 3 and 4 (FIG. 3). See S15). The displacement amount D3 corresponds to the meandering amount or skewing amount of the endless belt 23. In the discharge correction process and the subroutine process shown in FIG. 5, discharge or non-discharge can be set for each of the adjustment nozzles E, F, G, H, I, J (S19, S23 in FIG. 3, FIG. S29, S35, S39 of 4 and S43, S47, S51, S53 of FIG. 5). In each of the adjustment nozzles E, F, G, H, I, and J, the ink is ejected or the ink is not ejected according to the setting. In the first recording unit 30 and the second recording unit 40, the recording was performed on the recording surface 16 of the recording medium 15 in an area where the nozzles 51 of the first inkjet head 31 and the second inkjet head 41 overlap in the second direction. It is possible to suppress the occurrence of color spots on an image.

  (2) In the inkjet recording apparatus 10, the distance between the first inkjet head 31 and the second inkjet head 41 is set to the second interval W2 in the first direction (see FIG. 2). In the inkjet recording apparatus 10, the first position P1 in the first direction in which the first detector 61 is provided coincides with the position in the first direction in which the plurality of nozzles 51 of the first ink jet head 31 are arranged in the second direction. Is set to the desired position (see FIG. 2). The third interval W3 is set to the same dimension as the second interval W2 (see FIG. 2). The second position P2 in the first direction in which the second detector 62 is provided is set to a position corresponding to the position in the first direction in which the plurality of nozzles 51 of the second inkjet head 41 are arranged in the second direction (See Figure 2). Therefore, the displacement amount D3 can be set to a value corresponding to the positional relationship between the nozzles 51 of the first inkjet head 31 and the second inkjet head 41 based on the first direction. That is, the displacement amount D3 corresponding to the positional relationship described above can be acquired in S15 (see FIG. 3) of the ejection correction process shown in FIGS. 3 and 4.

<Modification>
Embodiments can also be as follows. Several configurations of the modifications shown below can be combined appropriately and adopted. In the following, different points from the above will be described, and the description of the same points will be appropriately omitted.

  (1) In the above, in the first inkjet head 31 and the second inkjet head 41, the ink ejected from the plurality of nozzles 51 has the same color. In the first inkjet head 31 and the second inkjet head 41, the inks ejected from the plurality of nozzles 51 may have different colors.

  (2) In the above, in each of the first inkjet head 31 and the second inkjet head 41, the array of the plurality of nozzles 51 in the second direction is one row. In the first inkjet head and the second inkjet head, the plurality of nozzles may be arranged in a plurality of rows. In this case, the second distance is the distance between the centers of the nozzles forming the corresponding rows in the first inkjet head and the second inkjet head. For example, the arrangement of the nozzles in the first inkjet head and the second inkjet head is assumed to be two rows each. In this case, the second distance is the distance between the centers of the nozzles arranged upstream of the first inkjet head in the first direction and the nozzles arranged upstream of the first ink jet head in the first direction. The distance between the centers of the nozzles arranged downstream of the first ink jet head in the first direction and the nozzles arranged downstream of the first ink jet head in the first direction is arranged upstream of the first direction It is made equal to the center-to-center distance of each nozzle.

  When arranging a plurality of nozzles in a plurality of rows, even in the region where the nozzles overlap based on the second direction, the nozzles of the first inkjet head and the second inkjet head have the same positional relationship in the first direction. It is set as a target.

  (3) In the above, the first detector 61 and the second detector 62 are provided on the first side in the second direction with respect to the endless belt 23 (see FIG. 1). The first detector 61 and the second detector 62 respectively detect the position of the first end of the endless belt 23 in the second direction. The first detector 61 and the second detector 62 may be provided on the second side in the second direction with respect to the endless belt 23. In this case, the first detector 61 and the second detector 62 respectively detect the position of the second end of the endless belt 23 in the second direction.

  The first position P1 in the first direction in which the first detector 61 is provided corresponds to the position in the first direction in which the plurality of nozzles 51 of the first inkjet head 31 are arranged in the second direction (see FIG. 2). The first position may be a position different from this. For example, a position in the first direction not based on the first inkjet head 31 may be used. The first position where the first detector 61 is provided is appropriately set in consideration of various conditions. The third interval W3 is set to the same dimension as the second interval W2. The third interval may be set to a dimension shorter than the second interval W2. The third interval between the first detector 61 and the second detector 62 is appropriately set in the range of “0 <third interval ≦ second interval W2” in consideration of various conditions.

  (4) In the above, S21 (see FIG. 3) of the discharge correction process shown in FIGS. 3 and 4 is determined according to whether the displacement amount D3 is smaller than the first interval W1. S21 may be determined based on whether the displacement amount D3 is equal to or greater than the first interval W1. If this determination is negative, the CPU 71 shifts the process to S23 and sequentially executes S23 and S25. On the other hand, when this determination is affirmed, the CPU 71 shifts the processing to S27 of FIG. In S27, it is determined in the same manner as described above whether the displacement amount D3 is smaller than twice the first interval W1. However, also in S27, the transition destination when the determination is negative is S29, and the determination destination when the determination is positive may be S33. Also in S33, the transition destination when the determination is negative is S35, and the transition destination when the determination is positive may be S39. The execution order of S23 and S25 in FIG. 3 may be reversed from the above. The execution order of S29 and S31 in FIG. 4 may be reversed from the above. The execution order of S35 and S37 in FIG. 4 may be reversed from the above.

  (5) In the above, S41 of the subroutine processing shown in FIG. 5 is determined according to whether the correction value is equal to or less than 1⁄4 of the first interval W1. S41 may be determined according to whether the correction value is larger than 1⁄4 of the first interval W1. If the determination is negative, the CPU 71 shifts the processing to S43 and executes S43. On the other hand, when this determination is affirmed, the CPU 71 shifts the processing to S45. In S45, it is determined whether the correction value is equal to or less than 2/4 of the first interval W1 in the same manner as described above. However, also in S45, the transition destination when the determination is negative is S47, and the determination destination when the determination is positive may be S49. The same applies to S49.

  (6) In the above, in the subroutine processing shown in FIG. 5, with respect to the adjustment nozzles H, I, J to be processed, the first mask data, the second mask data, the third mask data, and the fourth mask data One of them is applied (see S43, S47, S51, and S53 in FIG. 5). That is, in the subroutine processing shown in FIG. 5, the adjustment nozzles H, I, J to be processed are set to ejection or non-ejection regarding control of ejection of ink. The subroutine process executed in S25 (see FIG. 3), S31 or S37 (see FIG. 4) of the ejection correction process shown in FIGS. 3 and 4 may be a process as shown in FIG.

  In the subroutine processing shown in FIG. 6, a discharge size smaller than the reference discharge size is appropriately set for any of the adjustment nozzles H, I, J to be processed. The reference discharge size is a reference of the discharge size, and is, for example, the discharge size of the ink discharged from the adjustment nozzles H, I, and J set to discharge in S19 (see FIG. 3) of the discharge correction process. The ejection size is defined, for example, by the volume of one drop of ink, or the area of ink dots by one drop of ink that has landed on the recording surface 16 of the recording medium 15. The subroutine processing shown in FIG. 6 will be described below. Also in this description, among the adjustment nozzles H, I, and J, a predetermined adjustment nozzle to be processed is referred to as “adjustment nozzle to be processed”, as described above.

  The CPU 71 having started the subroutine processing determines whether the correction value is equal to or less than 1⁄4 of the first interval W1 (S61). If the correction value is equal to or less than 1⁄4 of the first interval W1 (S61: Yes), the CPU 71 sets a first discharge size for the adjustment nozzle to be processed (S63). The first discharge size is, for example, 3/4 the size of the reference discharge size (first discharge size = 3/4 × reference discharge size). When the ejection size is set to the first ejection size, a drive voltage having a voltage value and / or application time corresponding to the first ejection size is applied to the piezoelectric element corresponding to the adjustment nozzle to be processed. An amount of ink corresponding to the first ejection size is ejected from the adjustment nozzle to be processed.

  If the correction value is larger than 1⁄4 of the first interval W1 (S61: No), the CPU 71 determines whether the correction value is 2⁄4 or less of the first interval W1 (S65). If the correction value is 2/4 or less of the first interval W1 (S65: Yes), the CPU 71 sets a second discharge size for the adjustment nozzle to be processed (S67). The second discharge size is, for example, 2/4 the size of the reference discharge size (second discharge size = 2/4 × reference discharge size). When the ejection size is set to the second ejection size, a drive voltage having a voltage value and / or application time corresponding to the second ejection size is applied to the piezo element corresponding to the adjustment nozzle to be processed. An amount of ink corresponding to the second ejection size is ejected from the adjustment nozzle to be processed.

  If the correction value is larger than 2/4 of the first interval W1 (S65: No), the CPU 71 determines whether the correction value is 3/4 or less of the first interval W1 (S69). When the correction value is equal to or less than 3/4 of the first interval W1 (S69: Yes), the CPU 71 sets a third discharge size for the adjustment nozzle to be processed (S71). The third discharge size is, for example, a size of 1⁄4 of the reference discharge size (third discharge size = 1⁄4 × reference discharge size). When the ejection size is set to the third ejection size, a drive voltage having a voltage value and / or application time corresponding to the third ejection size is applied to the piezo element corresponding to the adjustment nozzle to be processed. An amount of ink corresponding to the third ejection size is ejected from the adjustment nozzle to be processed.

  If the correction value is larger than 3/4 of the first interval W1 (S69: No), the CPU 71 sets the fourth discharge size for the adjustment nozzle to be processed (S73). The fourth ejection size is, for example, "0". In other words, in S73, the CPU 71 sets the adjustment nozzle to be processed to non-ejection. Ink is not ejected from the adjustment nozzle to be processed. After executing S63, S67, S71 or S73, the CPU 71 ends the subroutine processing, and returns the processing to the ejection correction processing shown in FIG. 3 and FIG.

  With regard to the drive voltage corresponding to the first discharge size, the second discharge size or the third discharge size, the relationship between the voltage value of the drive voltage and / or the application time and the discharge size is as follows. That is, when the application time is constant, the discharge size can be reduced by decreasing the voltage value. When the voltage value is constant, the discharge size can be reduced by shortening the application time. The drive voltage of the reference discharge size is used as a reference. In this case, the discharge size of the ink can be made smaller than the reference discharge size by reducing the voltage value or shortening the application time. When the voltage value is reduced and the application time is shortened, the ink discharge size can be further reduced. By reducing the ejection size of the ink, it is possible to make small ink dots. The recording surface of the recording medium 15 in an area where the nozzles 51 of the first inkjet head 31 and the second inkjet head 41 overlap in the second direction in the first recording unit 30 and the second recording unit 40 by small ink dots. It is possible to suppress the occurrence of color spots in the image recorded in 16.

  The first discharge size is 3⁄4 of the reference discharge size, the second discharge size is 2⁄4 of the reference discharge size, and the third discharge size is 1⁄4 of the reference discharge size. The fourth discharge size is set to “0” (non-discharge). For each of the first discharge size, the second discharge size, and the third discharge size, the ratio to the reference discharge size is appropriately set in consideration of various conditions. The discharge size of the fourth discharge size is appropriately set in consideration of various conditions. The fourth size may be a discharge size larger than "0". However, in the first discharge size, the second discharge size, the third discharge size, and the fourth discharge size, the relationship of “first discharge size> second discharge size> third discharge size> fourth discharge size” is satisfied. .

  Although the description has been omitted above, S61 corresponds to S41 of FIG. 5, S65 corresponds to S45 of FIG. 5, and S69 corresponds to S49 of FIG. Therefore, S61, S65, and S69 may be determined in accordance with the determination conditions as described above in relation to S41, S45, and S49 in FIG. In the ejection correction process, the adjustment nozzles E, F, and G set to be non-ejection in S19 or S23 of FIG. 3 and the adjustment nozzles E, F, G, and H set to non-ejection in S29 of FIG. The adjustment nozzles E, F, G, H, I set to be non-ejection in S35 of 4 and the adjustment nozzles E, F, G, H, I, J set to be non-ejection in S39 of FIG. Under conditions such as, it may be set to discharge. That is, in the adjustment nozzle set to non-ejection described above, an ejection size smaller than the ejection size (reference ejection size) of the adjustment nozzle set to ejection in each process described above is appropriately set as the ejection size. For example, a discharge size satisfying “0 <discharge size <third discharge size (see S71 in FIG. 6)” is set as the discharge size.

  When the subroutine processing shown in FIG. 6 is employed, in the inkjet recording apparatus 10, the first mask data, the second mask data, the third mask data, and the fourth mask data described above may be omitted. In this case, the mask circuit 76 corresponding to the first mask data, the second mask data, the third mask data, and the fourth mask data may be omitted.

DESCRIPTION OF SYMBOLS 10 inkjet recording device, 15 recording medium, 16 recording surface, 20 conveyance part 21, 22 conveyance roller, 23 endless belt, 24 motor, 30 1st recording part 31 1st inkjet head, 32 1st carriage, 40 2nd recording part 41 second ink jet head, 42 second carriage, 50 head unit 50A first head unit, 50B second head unit, 51 nozzle 51A first nozzle, 51B second nozzle, 61 first detector 62 second detector, 70 Control device, 71 CPU, 72 storage unit 73 RAM, 74 connection interface (connection I / F), 75 head drive unit 76 mask circuit, E, F, G, H, I, J adjustment nozzle, L dimension P1 first position , P2 second position, W1 first interval, W2 second interval W3 third interval

Claims (6)

Conveying the recording medium placed on the outer peripheral surface of the endless belt in the first direction by rotating the endless belt in a direction corresponding to the first direction of conveying the recording medium, including an endless belt Department,
A plurality of first nozzles for ejecting ink onto the recording medium transported by the transport unit are arranged at a first interval in a second direction orthogonal to the first direction and coincident with the width direction of the endless belt. Line type first inkjet head,
A plurality of second nozzles for ejecting ink onto the recording medium transported by the transport unit are arranged at the first interval in the second direction, and the second nozzles are arranged with respect to the first nozzle, A line type second inkjet head provided downstream of the first inkjet head by a second distance in the first direction in a state of overlapping in the second direction;
A first detector that detects a position of one end of the endless belt moving in the first direction at the first position in the first direction;
A second detection that detects the position of one end of the endless belt in the second direction, which moves in the first direction, at a second position downstream of the first position by a third interval in the first direction. And the
The second of the endless belt when the endless belt moves in the first direction by the third interval from the position detected by the first detector and the position detected by the second detector A first control unit configured to obtain the second direction displacement amount of the position of the one end of the direction;
A second control unit configured to control the discharge of the ink from the second nozzle according to the displacement amount in the second direction acquired by the first control unit ;
In the first inkjet head, the arrangement of the plurality of first nozzles in the second direction is a plurality of lines at a fourth interval in the first direction,
In the second inkjet head, the arrangement of the plurality of second nozzles in the second direction is the second direction of the plurality of first nozzles in the first inkjet head at the fourth interval in the first direction. There are as many columns as the array in the direction,
The first ink jet head and the second ink jet head have the same order based on the upstream side in the first direction, the first nozzle row by the first nozzle and the second nozzle row by the second nozzle And the center-to-center distances in the first direction are all set equal, and the second interval is the center-to-center distance,
The second detector is configured to move in the first direction at a second position downstream of the first position in the first direction by a third interval equal to the second interval. An inkjet recording apparatus that detects the position of one end of the direction .   The inkjet recording apparatus according to claim 1, wherein the second control unit sets ejection and non-ejection of the ink to the second nozzle in the control of the ejection of the ink from the second nozzle.   The inkjet recording apparatus according to claim 1, wherein the second control unit sets an ejection size of the ink to the second nozzle in the control of the ejection of the ink from the second nozzle. The second inkjet head includes a plurality of third nozzles that are a part of the plurality of first nozzles, a plurality of adjustment nozzles that are a part of the plurality of second nozzles, It is provided downstream of the first ink jet head by the second interval in the first direction, in a state of being overlapped in two directions,
The second control unit controls the discharge of the ink from the adjustment nozzle according to the displacement amount in the second direction acquired by the first control unit as the control of the discharge of the ink from the second nozzle. The inkjet recording device according to any one of claims 1 to 3. The first detector has a predetermined order based on the upstream side of the first direction among the plurality of first nozzle rows in which the plurality of first nozzles are arranged in the second direction. In the first position in the first direction, which corresponds to the position in the first direction of the first nozzle row, the position of one end of the endless belt in the second direction, which moves in the first direction, is detected out that, ink jet recording apparatus according to any one of claims 1 to 4. The first control unit is
A first acquisition unit that repeatedly acquires the position detected by the first detector;
A second acquisition unit that repeatedly acquires the position detected by the second detector;
A first storage area for storing the position detected by the first detector, acquired by the first acquisition unit;
A second storage area for storing the position detected by the second detector, acquired by the second acquisition unit;
The timing at which the position detected by the first detector is acquired by the first acquisition unit, and the timing at which the position detected by the second detector is acquired by the second acquisition unit are the third The position detected by the first detector and the position detected by the second detector differ by a time corresponding to a value obtained by dividing the interval by the transport speed of the recording medium in the transport unit. An identifying unit that identifies each of the storage area and the second storage area;
And a third acquisition unit configured to acquire a displacement amount in the second direction from the position detected by the first detector and the position detected by the second detector, which are specified by the specifying unit. The ink jet recording apparatus according to any one of claims 1 to 5 .

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