JP6323118B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an inkjet recording apparatus that maintains nozzles that are defective in ejection.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus including a recording unit having a plurality of nozzles that eject ink and a maintenance mechanism that removes foreign matter in the nozzles is known. For example, in Patent Document 1, check patterns of respective colors are recorded at different positions on a sheet, information indicating the degree of ejection failure is obtained from a user who views the sheet on which the check pattern is recorded, and based on the information. An ink jet recording apparatus for maintaining each nozzle is described.

Japanese Patent Laid-Open No. 11-78050

  However, in the method in which the user visually recognizes a single color check pattern as described in Patent Document 1, there is a possibility that erroneous recognition of the check pattern occurs. For example, it is difficult for the user to appropriately determine the degree of ejection failure based on a check pattern recorded with yellow ink on a white sheet. As a result, there is a possibility that maintenance of nozzles will not be performed even though ejection failure has occurred in many nozzles, or maintenance of nozzles will be performed even if ejection failure has not occurred in most nozzles. is there.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an ink jet recording apparatus capable of performing appropriate maintenance processing according to the degree of ink ejection failure.

  The inkjet recording apparatus according to the present embodiment discharges a first color ink different from black from a transport unit that transports a sheet in a transport direction, and the black and the first color from a second nozzle unit. By ejecting different second color inks, light is output toward a recording head for recording an image on the sheet conveyed by the conveying unit, and a passing area of the sheet conveyed by the conveying unit, and reflected light. An optical sensor that outputs a detection signal having a magnitude corresponding to the intensity of the recording head, a carriage that includes the recording head and the optical sensor, and that can move in a main scanning direction that intersects the transport direction, and a control unit. Prepare. And the said control part was faced to the said recording head in the conveyance process which makes the said conveyance part convey the sheet | seat in the said conveyance direction, and the pattern position on the said sheet | seat faces the said recording head, and the said conveyance process. A pattern recording process for recording a pattern image by causing each color ink to be ejected on the first nozzle portion and the second nozzle portion at the pattern position, and the detection signal corresponding to the intensity of reflected light at the pattern position. And a maintenance process for removing foreign matter in the first nozzle part and the second nozzle part in response to the detection signal obtained in the obtaining process being equal to or higher than a threshold level.

  According to the above configuration, since the pattern image is recorded by superimposing a plurality of colors of ink, the difference between the intensity of the reflected light on the sheet and the intensity of the reflected light on the pattern image becomes significant. Accordingly, necessary maintenance processing is executed according to the degree of ejection failure, and unnecessary maintenance processing is suppressed.

  According to the present invention, by recording a pattern image by overlapping a plurality of colors of ink, necessary maintenance processing is executed according to the degree of ejection failure, and unnecessary maintenance processing is suppressed.

FIG. 1 is an external perspective view of the multifunction machine 10. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a plan view of the carriage 23 and the guide rails 43 and 44. FIG. 4 is a diagram showing the nozzles 40 arranged on the nozzle surface of the recording head 39. FIG. 5 is a schematic diagram of the maintenance mechanism 70. FIG. 6 is a block diagram of the printer unit 11. FIG. 7 is a flowchart of nozzle check processing according to the present embodiment. FIG. 8 is a flowchart of the maintenance process. FIG. 9 shows an example of the paper 12 on which a pattern image is recorded. FIG. 9A shows an example in which there are few ejection failures, and FIG. 9B shows an example in which there are many ejection failures. FIG. 10 is a flowchart of nozzle check processing according to a modification. FIG. 11 shows another example of the paper 12 on which a pattern image is recorded.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention. Further, in the following description, the advance from the starting point of the arrow to the ending point is expressed as the direction, and the traffic on the line connecting the starting point and the ending point of the arrow is expressed as the direction. Further, the vertical direction 7 is defined with reference to the state where the multifunction machine 10 is installed (the state shown in FIG. 1), and the front / rear direction 8 is defined with the side where the opening 13 is provided as the front side (front). A left-right direction 9 is defined when the multifunction machine 10 is viewed from the front side (front side).

[Overall configuration of MFP 10]
As shown in FIG. 1, the multifunction machine 10 is formed in a substantially rectangular parallelepiped. The multifunction machine 10 includes a printer unit 11 that records an image on a sheet 12 (see FIG. 2) using an inkjet recording method at the bottom. The multifunction machine 10 has various functions such as a facsimile function and a print function. As shown in FIG. 2, the printer unit 11 includes a feeding unit 15, a feeding tray 20, a discharge tray 21, a transport roller unit 54, a recording unit 24, a discharge roller unit 55, and a platen 42. It has. The multifunction machine 10 is an example of an ink jet recording apparatus. The feeding unit 15, the conveyance roller unit 54, and the discharge roller unit 55 are examples of the conveyance unit.

[Feed tray 20, discharge tray 21]
The feeding tray 20 is inserted and removed in the front-rear direction 8 through an opening 13 (see FIG. 1) formed on the front surface of the printer unit 11. A plurality of sheets of paper 12 fed to the transport path 65 by the feeding unit 15 can be supported on the feeding tray 20. The discharge tray 21 is disposed on the upper side of the feeding tray 20. The discharge tray 21 supports the paper 12 discharged by the discharge roller unit 55 through the opening 13 formed on the front surface.

[Feeding unit 15]
As shown in FIG. 2, the feeding unit 15 includes a feeding roller 25, a feeding arm 26, and a shaft 27. The feeding roller 25 is rotatably supported on the leading end side of the feeding arm 26. The feed roller 25 rotates in a direction (hereinafter referred to as “forward rotation”) in which the paper 12 is transported in the first transport direction 16A (an example of the transport direction) by reverse rotation of the transport motor 102 (see FIG. 6). To do. The feeding arm 26 is rotatably supported on a shaft 27 supported by the frame of the printer unit 11. The feeding arm 26 is urged to rotate toward the feeding tray 20 by its own weight or an elastic force by a spring or the like.

[Conveyance path 65]
As shown in FIG. 2, the conveyance path 65 indicates a space formed by an outer guide member 18 and an inner guide member 19 that are partially opposed to each other at a predetermined interval inside the printer unit 11. The conveyance path 65 is a path extending from the rear end portion of the feeding tray 20 to the rear side of the printer unit 11. The conveyance path 65 is a path that makes a U-turn while extending upward from below on the rear side of the printer unit 11 and reaches the discharge tray 21 through the recording unit 24. In the transport path 65, the transport direction of the paper 12 from the feed tray 20 side to the discharge tray 21 side is defined as a first transport direction 16A, and the transport of the paper 12 from the discharge tray 21 side to the feed tray 20 side is defined. The transport direction is defined as the second transport direction 16B. That is, the first transport direction 16A and the second transport direction 16B are opposite to each other, as indicated by a dashed line arrow in FIG.

[Conveying roller unit 54]
As shown in FIG. 2, the transport roller unit 54 is disposed upstream of the recording unit 24 in the first transport direction 16A. The conveyance roller unit 54 includes a conveyance roller 60 and a pinch roller 61 that face each other. The conveyance roller 60 is driven by the conveyance motor 102. The pinch roller 61 is rotated along with the rotation of the conveyance roller 60. The paper 12 is sandwiched between a transport roller 60 and a pinch roller 61 that rotate forward by the forward rotation of the transport motor 102 and is transported in the first transport direction 16A, and a transport roller 60 and a pinch roller 61 that rotate backward by the reverse rotation of the transport motor 102. And conveyed in the second conveying direction 16B.

[Discharge roller section 55]
As shown in FIG. 2, the discharge roller unit 55 is disposed downstream of the recording unit 24 in the first transport direction 16 </ b> A. The discharge roller portion 55 includes a discharge roller 62 and a spur 63 that face each other. The discharge roller 62 is driven by the transport motor 102. The spur 63 is rotated along with the rotation of the discharge roller 62. The sheet 12 is sandwiched between the discharge roller 62 and the spur 63 that rotate forward by the forward rotation of the transport motor 102 and transported in the first transport direction 16A, and is sandwiched by the discharge roller 62 and the spur 63 that rotates backward by the reverse rotation of the transport motor 102 Then, it is transported in the second transport direction 16B.

[Registration sensor 120]
As shown in FIG. 2, the printer unit 11 includes a registration sensor 120 on the upstream side of the first conveyance direction 16 </ b> A from the conveyance roller unit 54. The registration sensor 120 is a sensor for detecting the presence of the sheet 12 at the installation position of the registration sensor 120. The registration sensor 120 outputs a low-level signal (refers to a signal whose signal level is less than the threshold) to the control unit 130 (see FIG. 6) described later in response to the presence of the sheet 12 at the installation position. To do. On the other hand, the registration sensor 120 outputs a high level signal (refers to a signal whose signal level is equal to or higher than a threshold) to the control unit 130 in response to the fact that the sheet 12 is not present at the installation position.

[Rotary encoder 121]
Further, as shown in FIG. 6, the printer unit 11 includes a known rotary encoder 121 that generates a pulse signal according to the rotation of the transport roller 60 (in other words, the rotational drive of the transport motor 102). The rotary encoder 121 includes an encoder disk and an optical sensor. The encoder disk rotates with the rotation of the transport roller 60. The optical sensor reads the rotating encoder disk to generate a pulse signal, and outputs the generated pulse signal to the control unit 130.

[Recording unit 24]
As shown in FIG. 2, the recording unit 24 is disposed between the conveyance roller unit 54 and the discharge roller unit 55 in the first conveyance direction 16 </ b> A. The recording unit 24 is disposed so as to face the platen 42 in the vertical direction 7. The recording unit 24 includes a carriage 23, a recording head 39, an encoder sensor 38A, and a media sensor 122 (an example of an optical sensor). Further, as shown in FIG. 3, an ink tube 32 and a flexible flat cable 33 are extended from the carriage 23. The ink tube 32 supplies ink from the ink cartridge to the recording head 39. The flexible flat cable 33 electrically connects the control board on which the control unit 130 is mounted and the recording head 39.

  As shown in FIG. 3, the carriage 23 is supported by guide rails 43 and 44 that extend in the left-right direction 9 at positions spaced in the front-rear direction 8. The carriage 23 is connected to a known belt mechanism provided on the guide rail 44. This belt mechanism is driven by a carriage motor 103 (see FIG. 6). That is, the carriage 23 connected to the belt mechanism that moves circumferentially by driving the carriage motor 103 can reciprocate in the main scanning direction along the left-right direction 9.

  The recording head 39 is mounted on the carriage 23 as shown in FIG. A plurality of nozzles 40 are formed on the lower surface of the recording head 39. The recording head 39 ejects ink from the nozzle 40 as fine ink droplets. In the process of moving the carriage 23, the recording head 39 ejects ink droplets onto the paper 12 supported by the platen 42. As a result, an image is recorded on the paper 12.

  The guide rail 44 is provided with a belt-like encoder strip 38 </ b> B extending in the left-right direction 9. The encoder sensor 38A is mounted on the carriage 23 at a position facing the encoder strip 38B. In the process of moving the carriage 23, the encoder sensor 38 </ b> A reads the encoder strip 38 </ b> B to generate a pulse signal, and outputs the generated pulse signal to the control unit 130. The encoder sensor 38A and the encoder strip 38B constitute the carriage sensor 38 shown in FIG.

  A plurality of nozzles 40 are arranged on the nozzle surface of the lower surface of the recording head 39 as shown in FIG. The nozzle surface has a B nozzle portion 41B having a plurality of nozzles 40 for discharging black ink, a C nozzle portion 41C having a plurality of nozzles 40 for discharging cyan ink, and a plurality of nozzles 40 for discharging magenta ink. An M nozzle portion 41M and a Y nozzle portion 41Y having a plurality of nozzles 40 for discharging yellow ink are formed. Each nozzle part 41B, 41C, 41M, 41Y is arranged adjacent to the left-right direction 9. Cyan, magenta, and yellow are examples of the first color or the second color, and the C nozzle part 41C, the M nozzle part 41M, and the Y nozzle part 41Y are examples of the first nozzle part or the second nozzle part.

  In the B nozzle portion 41 </ b> B according to the present embodiment, 420 nozzles 40 are arranged in a staggered manner along the front-rear direction 8. Hereinafter, the most downstream nozzle 40 in the first conveying direction 16A is the first nozzle, the second nozzle 40 from the downstream side in the first conveying direction 16A is the second nozzle,..., And the most upstream in the first conveying direction 16A. The nozzle 40 on the side is denoted as the 420th nozzle. The interval in the front-rear direction 8 of each nozzle 40 is, for example, 1/300 (inch). The first to sixth nozzles are spaced apart in the left-right direction 9. The same applies to the seventh nozzle to the twelfth nozzle, and the 415th nozzle to the 420th nozzle.

  Moreover, the 1st nozzle, 7th nozzle, ..., and 415 nozzle which are arrange | positioned on the straight line extended in the front-back direction 8 form a 1st nozzle row. Similarly, the second nozzle, the eighth nozzle,..., And the 416 nozzle arranged on a straight line extending in the front-rear direction 8 form a second nozzle row. That is, in the B nozzle portion 41 </ b> B according to the present embodiment, the first nozzle row to the sixth nozzle row each extending in the front-rear direction 8 are arranged in the left-right direction 9. Of the 70 nozzles 40 included in the j-th nozzle row, the k-th nozzle 40 from the downstream side in the first transport direction 16A is denoted as the (6 (k−1) + j) nozzle. However, 1 ≦ j ≦ 6 and 1 ≦ k ≦ 70. The same applies to the C nozzle portion 41C, the M nozzle portion 41M, and the Y nozzle portion 41Y. However, the number of nozzles 40 included in each nozzle part and the arrangement method thereof are not limited to the above example.

[Platen 42]
As shown in FIG. 2, the platen 42 is disposed between the transport roller unit 54 and the discharge roller unit 55 in the first transport direction 16A. The platen 42 is disposed so as to face the recording unit 24 in the vertical direction 7 and supports the paper 12 conveyed by the conveyance roller unit 54 from below. The light reflectance of the platen 42 according to this embodiment is set lower than that of the paper 12. For example, the upper surface of the platen 42 facing the recording unit 24 may be black.

[Media sensor 122]
As shown in FIG. 2, the media sensor 122 is mounted on the carriage 23 on the lower surface of the carriage 23 (the surface facing the platen 42). The media sensor 122 according to the present embodiment is mounted on the carriage 23 on the upstream side of the recording head 39 in the first transport direction 16A. Further, the media sensor 122 and the platen 42 face each other in the vertical direction 7.

  The media sensor 122 includes a light emitting unit composed of a light emitting diode or the like, and a light receiving unit composed of an optical sensor or the like. The light emitting unit irradiates the platen 42 with the amount of light instructed by the control unit 130. The light emitted from the light emitting unit is reflected by the platen 42 or the paper 12 supported by the platen 42, and the reflected light is received by the light receiving unit. The media sensor 122 outputs a detection signal corresponding to the amount of light received by the light receiving unit to the control unit 130. For example, the media sensor 122 outputs a detection signal having a higher level to the control unit 130 as the amount of received light is larger.

[Discharged ink tray 50]
As shown in FIG. 3, the multifunction machine 10 includes a waste ink tray 50 in a region that is off to the left in the left-right direction 9 from the passage region of the paper 12 that is transported by the transport roller unit 54 and the discharge roller unit 55. An ink absorbing member is accommodated in the internal space of the waste ink tray 50. The waste ink tray 50 has an opening 51 formed on the upper surface facing the lower surface of the recording head 39, and can receive ink droplets (an example of discharged matter) discharged from the recording head 39. The waste ink tray 50 is an example of a discharge receiving part. The area on the left side of the passage area is an example of an area that is out of the passage area toward one end in the main scanning direction.

[Maintenance mechanism 70]
The multifunction machine 10 further includes a maintenance mechanism 70 shown in FIGS. 3 and 5. The maintenance mechanism 70 is disposed at a position off the right side in the left-right direction 9 from the passage region of the paper 12. The maintenance mechanism 70 includes a cap 71, a pump 76, a port switching mechanism 90, tubes 91A, 91B, 91C, and a drainage tank 110. The maintenance mechanism 70 sucks and discharges ink and air in the nozzle 40 and foreign matters adhering to the nozzle surface (hereinafter collectively referred to as “ink etc.”) to the drainage tank 110. Execute. The region on the right side of the pass region is an example of a region that is out of the pass region to the other end side in the main scanning direction.

  The cap 71 is made of rubber. The cap 71 is provided to face the carriage 23 located on the right side of the passage area. The cap 71 is configured to be movable between a cap position that covers the nozzle surface and an uncap position that is separated from the nozzle surface. The cap 71 moves to the cap position when the carriage 23 reaches the facing position where the recording head 39 and the cap 71 face each other. Further, the cap 71 moves to the uncapping position when the carriage 23 is out of the facing position. The inside of the cap 71 is partitioned into a Bk cap and a Co cap. The Bk cap covers the B nozzle portion 41B and forms a sealed space with the B nozzle portion 41B. The Co cap covers the C nozzle portion 41C, the M nozzle portion 41M, and the Y nozzle portion 41Y, and forms a sealed space between the nozzle portions 41C, 41M, and 41M.

  The pump 76 is, for example, a rotary tube pump. The pump 76 forms a flow of fluid (such as ink or air) from the suction port 76A to the discharge port 76B shown in FIG. A port switching mechanism 90 is connected to the tip of the tube 91A extending from the suction port 76A. A cap 71 is connected to the distal end of the tube 91 </ b> B extended from the port switching mechanism 90. That is, the cap 71 and the suction port 76A communicate with each other through the tubes 91A and 91B and the port switching mechanism 90. On the other hand, the drainage tank 110 is attached to the tip of the tube 91C extended from the discharge port 76B.

  The port switching mechanism 90 switches the communication state between the cap 71 and the pump 76. For example, the port switching mechanism 90 can be switched between a first state in which the Bk cap and the pump 76 are in communication and a second state in which the Co cap and the pump 76 are in communication. The port switching mechanism 90 is switched from the first state to the second state or from the second state to the first state by, for example, normal rotation of the transport motor 102.

  When the pump 76 is driven with the port switching mechanism 90 in the first state, the sealed space between the B nozzle portion 41B and the Bk cap becomes negative pressure, and ink or the like is sucked from the nozzle 40 included in the B nozzle portion 41B. Is done. Further, when the pump 76 is driven with the port switching mechanism 90 in the second state, the sealed space between the C nozzle portion 41C, the M nozzle portion 41M, and the Y nozzle portion 41Y and the Co cap becomes negative pressure. Ink and the like are sucked from the nozzles 40 included in the nozzle portions 41C, 41M, and 41Y. Then, the ink discharged from each nozzle portion is discharged to the drainage tank 110 through each cap, tube 91B, port switching mechanism 90, tube 91A, pump 76, and tube 91C.

[Driving force transmission mechanism 104]
The driving force transmission mechanism 104 shown in FIG. 6 transmits the driving force of the conveyance motor 102 to the feeding roller 25, the conveyance roller 60, the discharge roller 62, and the maintenance mechanism 70. The driving force transmission mechanism 104 is configured by combining all or part of a gear, a pulley, an endless annular belt, a planetary gear mechanism (pendulum gear mechanism), a one-way clutch, and the like.

[Control unit 130]
As shown in FIG. 6, the control unit 130 includes a CPU 131, a ROM 132, a RAM 133, an EEPROM 134, and an ASIC 135, which are connected by an internal bus 137. The ROM 132 stores a program for the CPU 131 to control various operations. The RAM 133 is used as a storage area for temporarily recording data and signals used when the CPU 131 executes the program, or as a work area for data processing. The EEPROM 134 stores settings, flags, and the like that should be retained even after the power is turned off.

  A transport motor 102 and a carriage motor 103 are connected to the ASIC 135. The ASIC 135 generates a drive signal for rotating each motor, and controls each motor based on this drive signal. Each motor rotates normally or reversely according to a drive signal from the ASIC 135. For example, the control unit 130 controls the driving of the transport motor 102 to drive each roller. Further, the control unit 130 controls the drive of the carriage motor 103 to reciprocate the carriage 23. Further, the control unit 130 controls the recording head 39 to eject ink from the nozzles 40.

  In addition, a carriage sensor 38, a registration sensor 120, a rotary encoder 121, and a media sensor 122 are connected to the ASIC 135. The control unit 130 detects the position of the carriage 23 based on the pulse signal output from the carriage sensor 38. Further, the control unit 130 detects the position of the paper 12 based on the detection signal output from the registration sensor 120 and the pulse signal output from the rotary encoder 121. Further, the control unit 130 detects that the pattern image is recorded at the pattern position on the paper 12 based on the detection signal output from the media sensor 122.

[Nozzle check processing]
With reference to FIGS. 7 to 9, nozzle check processing by the multifunction machine 10 will be described. This nozzle check process is executed by the CPU 131 of the control unit 130. The following processes may be executed by the CPU 131 reading out and executing a program stored in the ROM 132, or may be realized by a hardware circuit mounted on the control unit 130. The image recording process will be described by paying attention to the rotation of the feeding roller 25, the transport roller 60, and the discharge roller 62, the movement of the carriage 23, and the operation of the maintenance mechanism 70. These operations are realized by driving the transport motor 102 and the carriage motor 103 as described above.

  The nozzle check process shown in FIG. 7 is started in response to, for example, obtaining a nozzle check instruction from the user through the operation unit provided in the multifunction machine 10. However, the start condition of the nozzle check process is not limited to this. For example, the nozzle check process may be started when a predetermined time (for example, one week) has passed since the ink was discharged immediately before the multifunction device 10 is turned on.

  First, the control unit 130 executes a feeding process (S11). In the feeding process, the sheet 12 supported by the feeding tray 20 is moved to a position where the leading end of the sheet 12 (referring to the “end on the downstream side of the first conveying direction 16 </ b> A”) reaches the conveying roller unit 54. It is a process of feeding. Specifically, the control unit 130 rotates the feeding roller 25 in the forward direction until the leading edge of the paper 12 reaches the conveyance roller unit 54. Note that the position of the leading edge of the paper 12 is specified by a combination of a change in the signal from the registration sensor 120 and a pulse signal from the rotary encoder 121. In this embodiment, it is assumed that white paper 12 is used.

  Next, the control part 130 performs a conveyance process (S12). The conveyance process is a process in which the pattern position of the sheet 12 on which the pattern image (see FIG. 9) is recorded next and the recording head 39 face each other in the vertical direction 7. Specifically, the control unit 130 causes the paper 12 to be conveyed in the first conveyance direction 16 </ b> A to at least one of the conveyance roller unit 54 and the discharge roller unit 55. Next, the control unit 130 executes a pattern recording process (S13). The pattern recording process is a process for recording a pattern image at a pattern position. Specifically, in the process of moving the carriage 23 in the left-right direction 9, the control unit 130 causes the C nozzle unit 41C, the M nozzle unit 41M, and the Y nozzle unit 41Y to eject ink toward each pattern position.

  Next, the control part 130 performs a reverse conveyance process (S14). The reverse conveyance process is a process in which the pattern position where the pattern recording process has been performed and the media sensor 122 face each other in the vertical direction 7. Specifically, the control unit 130 causes the paper 12 to be conveyed in the second conveyance direction 16 </ b> B to at least one of the conveyance roller unit 54 and the discharge roller unit 55. Next, the control unit 130 executes an acquisition process (S15). The acquisition process is a process of acquiring a detection signal from the media sensor 122 according to the intensity of reflected light at each pattern position. Specifically, the control unit 130 moves the carriage 23 in the left-right direction 9 while irradiating light from the light emitting unit of the media sensor 122, and outputs a detection signal output from the media sensor 122 at a position corresponding to the pattern position. get. And the control part 130 counts the number of high level signals which is the number of the detection signals more than a threshold level among several acquired detection signals.

  And the control part 130 repeatedly performs the process of step S12-S15 until the process with respect to all the pattern images is complete | finished (S16: No). That is, in this embodiment, each process is repeatedly executed in the order of the conveyance process, the pattern recording process, the reverse conveyance process, and the acquisition process. Thereby, a pattern image is recorded on the paper 12 using all the nozzles 40 included in each of the C nozzle part 41C, the M nozzle part 41M, and the Y nozzle part 41Y. With reference to FIG. 9, the process of step S12-S15 is demonstrated in detail. FIG. 9 shows the state of the paper 12 after the processes of steps S12 to S16 of FIG. 7 are repeated five times.

  As shown in FIG. 9, the pattern positions of the paper 12 are set in a matrix. More specifically, on the paper 12, a plurality of pattern forming regions including a plurality of pattern positions (six in the example of FIG. 9) and extending in the left-right direction 9 are set at positions separated in the front-rear direction 8. . Hereinafter, the pattern formation region on the most downstream side in the first conveyance direction 16A is referred to as a first pattern formation region, and the pattern formation region adjacent to the upstream side of the first pattern formation region in the first conveyance direction 16A is formed as the second pattern. This is expressed as a region.

  A plurality of pattern positions included in each pattern formation region are set at positions separated in the left-right direction 9. Hereinafter, among the pattern positions included in each pattern formation region, the pattern position located on the rightmost side of the paper 12 is referred to as a first pattern position, and the pattern position adjacent to the left side of the first pattern position is referred to as a second pattern position. The pattern position located on the leftmost side is denoted as the sixth pattern position.

  The control unit 130 causes different pattern formation regions in the front-rear direction 8 to face different nozzles 40 in the front-rear direction 8 in each of the plurality of transport processes. Based on the pulse signal output from the rotary encoder 121, the control unit 130 controls the transport amount in the transport process (the transport amount in the first transport direction 16A). For example, the number of pulse signals corresponding to the conveyance amount in each conveyance process may be stored in the EEPROM 134. That is, the conveyance amount in each conveyance process may be determined in advance.

  Next, in the pattern recording process, the control unit 130 differs in each of the C nozzle unit 41C, the M nozzle unit 41M, and the Y nozzle unit 41Y for each of a plurality of pattern positions included in the facing pattern formation region. Ink is ejected to the nozzle 40. The control unit 130 controls the timing at which each nozzle 40 ejects ink based on the pulse signal output from the carriage sensor 38. For example, the encoder value corresponding to each pattern position (the number of pulse signals corresponding to each position when the reference position is 0) may be stored in the EEPROM 134 or the like. That is, the timing for ejecting ink to each pattern position may be determined in advance.

  More specifically, in the conveyance process, the control unit 130 according to the present embodiment causes the nozzles 40 that discharge ink first in the next recording process to face each pattern position. In addition, the control unit 130 in the pattern recording process discharges ink to the nozzle 40 facing the pattern position in the process of moving the carriage 23 in one of the left and right directions 9 and the interval between the nozzles 40 in the front and rear direction 8. (In the example of FIG. 4, the fine conveyance process of conveying the paper 12 in the first conveyance direction 16A to the conveyance unit by a conveyance amount corresponding to 1/300 inch) is repeatedly executed.

  For example, in the first transfer process, the control unit 130 transfers the sixth nozzle, the twelfth nozzle,..., The 42nd nozzle (total of seven nozzles) of the nozzle portions 41C, 41M, and 41Y to the first transfer. It faces the downstream end of the first pattern formation region in the direction 16A. Next, in the first discharge process, the control unit 130 discharges ink toward the sixth pattern position to the sixth nozzle, the twelfth nozzle,..., The forty-second nozzle of each of the nozzle portions 41C, 41M, and 41Y. Let Next, in the first fine conveyance process, the control unit 130 sets the fifth nozzle, the eleventh nozzle,..., The 41st nozzle of each nozzle unit 41C, 41M, 41Y to the first in the first conveyance direction 16A. It faces the downstream end of the pattern formation region. Next, in the second ejection process, the control unit 130 causes the sixth nozzle, the twelfth nozzle,..., The forty-second nozzle to eject ink toward the sixth pattern position, and the fifth nozzle, Ink is discharged from the 11th nozzle,..., The 41st nozzle toward the fifth pattern position. Thereafter, in the eleventh ejection process, the ejection process and the fine transport process are repeatedly performed until the first nozzle, the seventh nozzle,..., The 37th nozzle eject ink toward the first pattern position.

  That is, in the pattern recording process described above, 11 ejection processes and 10 fine transport processes are executed. In the first to sixth ejection processes, ink is ejected from the sixth nozzle, the twelfth nozzle,..., The 42nd nozzle to the sixth pattern position in the first to sixth ejection processes. In the fifth discharge process, ink is discharged from the fifth nozzle, the eleventh nozzle,..., The 41st nozzle to the fifth pattern position, and in the sixth to eleventh discharge processes, the first nozzle, the seventh nozzle, ... ink is ejected from the 37th nozzle to the first pattern position. That is, a maximum of 126 (= 6 (number of ejection processes) × 3 (number of colors) × 7 (number of nozzles used in one ejection process)) drops of ink lands on each pattern position. .

  Similarly, in the N-th transport process, the control unit 130 (42 (N−1) +6) nozzles, (42 (N−1) +12) nozzles of the nozzle units 41C, 41M, and 41Y, .... (42 (N-1) +42) nozzles are made to face the downstream end of the Nth pattern formation region in the first transport direction 16A. The control unit 130 uses the (42 (N−1) +1) th nozzle to the (42 (N−1) +42) nozzle of each nozzle unit 41C, 41M, and 41Y in the Nth pattern recording process. A pattern image is recorded at each pattern position.

  That is, in each transport process, the control unit 130 according to the present embodiment includes a pattern formation region shifted from the pattern formation region in which the pattern image was formed immediately before to the upstream side in the first transport direction 16A, and the pattern image immediately before. The nozzle 40 shifted from the nozzle 40 used for formation to the upstream side in the first conveying direction 16A is made to face. Further, the control unit 130 according to the present embodiment uses each of the plurality of nozzle rows arranged in the left-right direction 9 for each of the plurality of pattern positions arranged in the left-right direction 9 in each pattern recording process. Form an image.

  A maximum of 126 drops of ink ejected from the three-color nozzles 40 land at each pattern position in the above example. In addition, 21 droplets (that is, three colors × 7 nozzles) ejected in one ejection process are landed on each pattern position, and the ink ejected in each of the plurality of ejection processes is first transported. Landing in the direction 16A. Each pattern image is set to an area larger than the diameter (for example, 3 mm) of the light beam output from the media sensor 122. The pattern image in the above example has a length along the front-rear direction 8 of about 3.5 mm (= (25.4 / 300) × 7 × 6). That is, the pattern image may be an image whose length along the left-right direction 9 is 3 mm or more. For example, a square with a side of 3.5 mm may be used, or a rectangle with a size of 3.5 mm × 3 mm (or more) may be used. In FIG. 9, the hatched pattern image indicates that most of 126 drops of ink have landed, and the broken line pattern image indicates that only a small number of 126 drops of ink have landed. However, the shape of the pattern image is not limited to the example of FIG. 9, and may be a rectangle, a triangle, a circle, or the like.

  Next, the control unit 130 causes the media sensor 122 to face different pattern formation areas in the front-rear direction 8 in each of the plurality of reverse conveyance processes (S14). In the present embodiment, the pattern formation area in which the pattern image is recorded immediately before is opposed to the media sensor 122. Based on the pulse signal output from the rotary encoder 121, the control unit 130 controls the reverse conveyance amount in the reverse conveyance process (the conveyance amount in the second conveyance direction 16B). For example, the number of pulse signals corresponding to the reverse conveyance amount in each reverse conveyance process may be stored in the EEPROM 134. That is, the reverse conveyance amount in each reverse conveyance process may be determined in advance.

  Next, in the acquisition process (S15), the control unit 130 emits light from the light emitting unit to each of a plurality of pattern positions included in the pattern formation region facing the media sensor 122, and is received by the light receiving unit. A detection signal corresponding to the reflected light is acquired. Then, the control unit 130 counts the number of high level signals among the plurality of acquired detection signals. Note that the control unit 130 may cause the light emitting unit to emit light only at a position facing the pattern position in the acquisition process. Alternatively, in the acquisition process, the control unit 130 may cause the light emitting unit to always emit light and acquire only the detection signal at the position facing the pattern position. The method for specifying the pattern position may be common to the pattern recording process. Further, the number of high level signals is cumulatively added in the repeatedly executed acquisition process.

  The detection signal acquired from the media sensor 122 becomes higher as the color of the reflecting surface is closer to white. That is, out of 126 drops of ink ejected at each pattern position, the signal level of the detection signal decreases as the number of actually landed inks increases, and the signal level of the detection signal decreases as the number of actually landed inks decreases. Becomes higher. For example, in the example of FIG. 9, it is assumed that the detection signal corresponding to the hatched pattern image is lower than the threshold level, and the detection signal corresponding to the broken pattern image is higher than the threshold level. That is, the number of high level signals counted in the example of FIG. 9A is 0 in the first pattern formation region and 1 in the second pattern formation region. Further, the number of high level signals counted in the example of FIG. 9B is 3 in the first pattern formation region and 4 in the second pattern formation region (that is, 7 in total).

  Next, in response to the counted number of high level signals being equal to or greater than the first threshold number (an example of the threshold number) (S17: Yes), the control unit 130 performs a maintenance process (S18). The maintenance process is a process for removing foreign substances in the nozzles 40 included in the C nozzle part 41C, the M nozzle part 41M, and the Y nozzle part 41Y. The maintenance process will be described in detail with reference to FIG.

  First, in response to the number of high level signals being less than the second threshold number (S21: Yes), the control unit 130 performs a flushing process (S22). The flushing process is a process in which the recording head 39 ejects ink together with foreign matter from the nozzle 40 toward the waste ink tray 50 (hereinafter referred to as “empty ejection”). Specifically, the control unit 130 moves the carriage 23 to a position where the recording head 39 and the opening 51 of the waste ink tray 50 face each other in the vertical direction 7 and causes the recording head 39 to eject ink and the like at that position. .

  On the other hand, the control unit 130 executes the purge process (S24, S25) in response to the number of high level signals being equal to or greater than the second threshold number (S21: No). The purge process is a process for causing the maintenance mechanism 70 to suck ink or the like from the C nozzle part 41C, the M nozzle part 41M, and the Y nozzle part 41Y. Specifically, the control unit 130 moves the carriage 23 to the facing position, switches the port switching mechanism 90 to the second state (a state where the Co cap and the pump 76 are communicated), and drives the pump 76.

  Note that the control unit 130 may vary the drive time of the pump 76 in the purge process according to the number of high level signals. Specifically, in response to the number of high level signals being greater than or equal to the second threshold number and less than the third threshold number (S21: No & S23: Yes), the control unit 130 causes the pump 76 to perform the first time in the purge process. Only drive (S24). On the other hand, when the number of high level signals is equal to or greater than the third threshold number (S23: No), the control unit 130 drives the pump 76 for a second time longer than the first time in the purge process (S25). That is, in the purge process according to the present embodiment, the driving time of the pump 76 is longer as the number of high level signals is larger, and the driving time of the pump 76 is shorter as the number of high level signals is smaller.

  Then, the control unit 130 discharges the paper 12 on which the pattern image is recorded from the discharge tray 21. Specifically, the control unit 130 controls the conveyance roller unit 54 and the discharge roller until the rear end of the sheet 12 (refers to the “upstream end of the first conveyance direction 16 </ b> A”) passes through the discharge roller unit 55. The paper 12 is transported to at least one of the sections 55 in the first transport direction 16A. Further, the control unit 130 discharges the paper 12 to the discharge tray 21 without executing the process of step S18 in response to the counted number of high level signals being less than the first threshold number (S17: No). .

  The control unit 130 records a plurality of pattern images on the paper 12 using each nozzle 40 included in the B nozzle unit 41B, and performs maintenance processing corresponding to the counted number of high level signals on the B nozzle unit 41B. May be executed. Since the processing in this case is common to the above processing except that the pattern image is recorded with only one color ink (that is, black ink), detailed description thereof is omitted.

[Effects of Embodiment]
According to the above embodiment, the pattern image is recorded by superimposing a plurality of colors (that is, cyan, magenta, and yellow), so that the paper 12 is compared with the case where the pattern image is recorded with one color ink. The difference between the intensity of the reflected light in the white area (that is, the area where the pattern image is not recorded) and the intensity of the reflected light in the pattern image becomes significant. Accordingly, necessary maintenance processing is executed according to the degree of ejection failure, and unnecessary maintenance processing is suppressed.

  In addition, according to the above-described embodiment, an example in which one pattern image is recorded with a maximum of 126 drops of ink has been described. However, the number of ink drops used for recording one pattern image is not limited to this, For example, it may be determined in consideration of the following circumstances. For example, since the area of the pattern image tends to be smaller as the number of ink droplets used in one pattern image is smaller, a part of the light emitted from the light emitting unit of the media sensor 122 is a white region around the pattern image. There is a possibility that the signal level of the detection signal becomes high. On the other hand, as the number of ink droplets used in one pattern image increases, the nozzle check process takes longer and the ink consumption increases.

  Further, more appropriate maintenance processing can be performed by changing the content of the maintenance processing according to the number of high level signals as in the above embodiment. For example, the case where the number of high level signals is greater than or equal to the first threshold number and less than the second threshold number is an example where the number of ejection defective nozzles 40 is not so large. In this case, the discharge failure can be sufficiently eliminated by the maintenance process having a shorter processing time than the purge process. On the other hand, the case where the number of high level signals is equal to or greater than the second threshold number is an example where the number of ejection defective nozzles 40 is considerably large. In this case, it is desirable to eliminate ejection defects by forcibly sucking ink or the like from the nozzle 40. Further, by changing the driving time of the pump 76 in the purge process according to the number of high level signals, it is possible to more reliably eliminate ejection defects and suppress unnecessary ink suction.

  However, the details of the maintenance process are not limited to the example of FIG. For example, the flushing process may be omitted, and the driving time of the pump 76 in the purge process may be changed according to the number of high level signals. Further, instead of the driving time of the pump 76, the driving speed (that is, the suction force) of the pump 76 is made faster (stronger) as the number of high level signals is larger, and slower (weaker) as the number of high level signals is smaller. Also good. Alternatively, the purge process may be omitted and only the empty discharge amount in the flushing process may be changed. For example, the amount of ink ejected in one flushing process may be increased as the number of high level signals is increased, and may be decreased as the number of high level signals is decreased.

  In the above embodiment, the number of high-level signals is compared with the first threshold number, the second threshold number greater than the first threshold number, and the third threshold number greater than the second threshold number. An example of determining the contents has been described. However, the threshold number is not limited to the above example, and at least one threshold is sufficient. Further, a function for outputting the driving time of the pump 76, the driving speed of the pump 76, or the idle discharge amount by inputting the number of high level signals may be used instead of the discrete threshold number.

  Further, according to the above-described embodiment, it is possible to obtain the ratio of defective ejection nozzles among all the nozzles 40 as the number of high level signals. Then, the maintenance process may be executed when the ratio of the ejection defective nozzles 40 is equal to or greater than a threshold (that is, the number of high level signals is equal to or greater than the threshold number). In step S15 in FIG. 7, the number of low level signals (that is, the ratio of the nozzles 40 that can normally eject ink), which is the number of detection signals whose signal level is less than the threshold level, is counted. Maintenance processing may be executed in response to the number of signals being less than the threshold number.

  Further, the parameter for determining that the maintenance recording process is executed is not limited to the number of high level signals or the number of low level signals. For example, the control unit 130 may acquire the average value of the detection signals in each pattern formation region in the acquisition process. That is, in the acquisition process, the control unit 130 moves the carriage 23 in the left-right direction 9 while irradiating light from the light emitting unit of the media sensor 122, and acquires an average value of a plurality of detection signals output from the media sensor 122. To do. And the control part 130 may perform a maintenance process according to the said average value being more than a threshold level. In this case, the plurality of pattern positions included in the pattern formation region may not be separated in the left-right direction 9.

  Further, the threshold level when counting the high level signal may be a fixed value or a value that varies depending on the color of the paper 12 and the platen 42. For example, the control unit 130 executes a first acquisition process for acquiring a first detection signal (so-called black level) corresponding to the intensity of reflected light from the platen 42 prior to the conveyance process. Next, prior to the pattern recording process, the control unit 130 executes a second acquisition process for acquiring a second detection signal (so-called white level) corresponding to the intensity of reflected light from the paper 12 conveyed in the conveyance process. And the control part 130 may perform the determination process which determines a threshold level based on the difference of a 1st detection signal and a 2nd detection signal prior to a maintenance process.

  According to the above configuration, an appropriate threshold level can be determined according to the colors of the platen 42 and the paper 12. In the above example, the average value of the first detection signal and the second detection signal may be the threshold level. Further, since the color of the platen 42 does not change so much, the threshold level may be determined by the black level stored in advance in the EEPROM 134 and the white level acquired in the second acquisition process.

[Modification 1]
In the above-described embodiment, an example in which each process is repeatedly executed in the order of the conveyance process, the pattern recording process, the reverse conveyance process, and the acquisition process has been described. Thereby, since the conveyance amount in one reverse conveyance process becomes small, a pattern position and the media sensor 122 can be faced more correctly. However, the execution order of steps S12 to S15 repeatedly executed in the nozzle check process is not limited to the example of FIG.

  For example, as illustrated in FIG. 10, the control unit 130 according to the first modification performs the conveyance process (S12) and the pattern recording process (S13) until all pattern images are recorded on the paper 12 (S31: No). Each process is repeatedly executed in order. Next, in response to all the pattern images recorded on the paper 12 (S31: Yes), the control unit 130 performs the reverse conveyance process until all the pattern images are read by the media sensor 122 (S32: No). Each process is repeatedly executed in the order of (S14) and the acquisition process (S15). By executing each process in the above order, the total transport amount in the plurality of transport processes is reduced, so that the processing time can be shortened. In addition, the same reference number is attached | subjected to the process which is common in FIG.

  In steps S14, S15, and S32 of FIG. 10, the control unit 130 causes the pattern formation region on the most downstream side in the second transport direction 16B to face the media sensor 122 in the first reverse transport process, and performs subsequent reverse transport. In the processing, the paper 12 may be gradually conveyed in the second conveyance direction 16B. Alternatively, the control unit 130 causes the most downstream pattern forming region in the first transport direction 16A to face the media sensor 122 in the first reverse transport process, and gradually moves the paper 12 in the first transport direction in the subsequent reverse transport process. You may convey to 16A. In other words, the reverse conveyance process is a process of causing the pattern formation area on which the pattern recording process has been performed to face the media sensor 122, and the conveyance direction of the paper 12 may not always be the reverse of the conveyance process (S12).

[Modification 2]
In the above embodiment, the example in which the pattern image is recorded by repeatedly executing the ejection process and the fine transport process in the pattern recording process has been described. However, the pattern image recording method is not limited to this. For example, the plurality of pattern positions included in each pattern formation region shown in FIG. Specifically, the first pattern position is located on the most downstream side in the first conveyance direction 16A, and the sixth pattern position is located on the most upstream side in the second conveyance direction 16B. Further, the shift amount of each pattern position in the front-rear direction 8 corresponds to the interval between the nozzles 40 in the front-rear direction 8.

  The control unit 130 according to Modification 2 causes the first to sixth nozzles of the nozzle units 41C, 41M, and 41Y to face the first pattern formation region shown in FIG. 11 in the first transport process. Then, in the first pattern recording process, the control unit 130 causes the first nozzles of the nozzle portions 41C, 41M, and 41Y to discharge the inks toward the first pattern position, and sets the nozzle portions 41C, 41M, and 41Y. Each ink is ejected toward the second pattern position by the second nozzle,..., Each ink is ejected toward the sixth pattern position by the sixth nozzle of each nozzle portion 41C, 41M, 41Y. That is, the pattern recording process according to the second modification is configured by a single ejection process. In addition, a maximum of 3 drops (one drop from each of the three color nozzles) of ink lands on each pattern position according to the second modification.

  Similarly, in the N-th transport process, the control unit 130 changes the (6 (N−1) +1) to (6 (N−1) +6) nozzles of the nozzles 41C, 41M, and 41Y to the It faces the N pattern formation region. Then, in the N-th pattern recording process, the control unit 130 causes the (6 (N−1) +1) nozzles of the nozzle units 41C, 41M, and 41Y to discharge each ink toward the first pattern position. The respective (6 (N−1) +2) nozzles of the nozzle portions 41C, 41M, and 41Y are caused to eject the respective inks toward the second pattern position, and so on. N-1) +6) Each ink is ejected from the nozzle toward the sixth pattern position.

  Further, in each acquisition process, the control unit 130 causes the light emitting unit of the media sensor 122 to irradiate light to a predetermined region including each pattern position (a region surrounded by a one-dot chain line circle in FIG. 11). A detection signal corresponding to the reflected light from the media sensor 122 is acquired. The signal level of the detection signal output from the media sensor 122 differs depending on the presence or absence (or shading) of the pattern image. The predetermined area may be a circular area corresponding to the diameter of the light beam output from the media sensor 122, for example. Further, it is assumed that adjacent pattern positions in the front-rear direction 8 and the left-right direction 9 are separated from each other by the diameter of the light beam output from the media sensor 122.

DESCRIPTION OF SYMBOLS 10 ... MFP 16A ... 1st conveyance direction 16B ... 2nd conveyance direction 23 ... Carriage 24 ... Recording part 39 ... Recording head 40 ... Nozzle 41B ... B nozzle Part 41C ... C nozzle part 41M ... M nozzle part 41Y ... Y nozzle part 42 ... platen 50 ... discharge ink tray 54 ... conveying roller part 55 ... discharge roller part 70. ..Maintenance mechanism 71 ... Cap 76 ... Pump 110 ... Drain tank 122 ... Media sensor 130 ... Control unit

Claims (12)

A transport unit that transports the sheet in the transport direction;
A first color ink different from black is discharged from the first nozzle part, and a black color and a second color ink different from the first color are discharged from the second nozzle part to the sheet conveyed by the conveyance part. A recording head for recording images;
An optical sensor that outputs light toward a passing region of a sheet conveyed by the conveying unit and outputs a detection signal having a magnitude corresponding to the intensity of reflected light;
A carriage mounted with the recording head and the optical sensor and movable in a main scanning direction intersecting the transport direction;
A platen that supports the sheet at a position facing the optical sensor;
A control unit, and
The control unit
A conveying process for causing the conveying unit to convey the sheet in the conveying direction so that the pattern position on the sheet faces the recording head; and
In the transport process, the ink of each color is superimposed on the first nozzle portion and the second nozzle portion at the pattern position facing the recording head, so that the light reflectance of the optical sensor is higher than that of the platen. A pattern recording process for recording a pattern image;
An acquisition process for acquiring the detection signal according to the intensity of reflected light at the pattern position;
A maintenance process for removing foreign matter in the first nozzle part and the second nozzle part in response to the detection signal acquired in the acquisition process being equal to or higher than a threshold level;
A process executed prior to the transport process, wherein a first acquisition process for acquiring a first detection signal according to the intensity of the reflected light on the platen;
A second acquisition process that is executed prior to the pattern recording process and acquires a second detection signal corresponding to the intensity of reflected light in the sheet conveyed in the conveyance process;
An inkjet recording apparatus that executes a determination process that is performed prior to the maintenance process and determines the threshold level based on a difference between the first detection signal and the second detection signal . The first nozzle part and the second nozzle part each have a plurality of nozzles,
The control unit
In the pattern recording process, the pattern image is recorded using a different nozzle of each of the first nozzle portion and the second nozzle portion at each of the plurality of pattern positions spaced apart from each other on the sheet,
In the acquisition process, a plurality of the detection signals corresponding to each of the plurality of pattern positions are acquired, and the number of the high level signals which is the number of the detection signals equal to or higher than the threshold level among the plurality of detection signals is counted. And
The inkjet recording apparatus according to claim 1, wherein the maintenance process is executed in response to the number of high level signals being equal to or greater than a threshold number.   The ink jet recording apparatus
  A discharge receiving part for receiving discharge discharged by the first nozzle part and the second nozzle part;
  A maintenance mechanism for sucking the first nozzle part and the second nozzle part,
  In the maintenance process, the control unit
  In response to the number of high-level signals being greater than or equal to the first threshold number and less than the second threshold number, ink together with foreign matter is placed on the first nozzle part and the second nozzle part at a position facing the discharge receiving part. Discharge
  3. The ink jet recording apparatus according to claim 2, wherein the maintenance mechanism causes the foreign matter to be sucked from the first nozzle portion and the second nozzle portion in response to the number of the high level signals being equal to or greater than the second threshold number.   A transport unit that transports the sheet in the transport direction;
  A first nozzle portion having a plurality of nozzles for discharging ink of a first color different from black, and a second nozzle portion having a plurality of nozzles for discharging ink of a second color different from black and the first color, A recording head for recording an image by discharging ink from the first nozzle portion and the second nozzle portion toward the sheet conveyed by the conveying portion;
  An optical sensor that outputs light toward a passing region of a sheet conveyed by the conveying unit and outputs a detection signal having a magnitude corresponding to the intensity of reflected light;
  A carriage that is mounted on the recording head and the optical sensor located upstream of the recording head in the transport direction, and that is movable in a main scanning direction intersecting the transport direction;
  A control unit, and
  The control unit
  A conveying process for causing the conveying unit to convey the sheet in the conveying direction so that the pattern position on the sheet faces the recording head; and
  Pattern recording processing for recording a pattern image by superimposing and discharging each color ink on the first nozzle portion and the second nozzle portion at the pattern position facing the recording head in the conveyance processing;
  An acquisition process for acquiring the detection signal according to the intensity of reflected light at the pattern position;
  A maintenance process for removing foreign matter in the first nozzle part and the second nozzle part in response to the detection signal acquired in the acquisition process being equal to or higher than a threshold level;
  In the pattern recording process, the pattern image is recorded using a different nozzle of each of the first nozzle portion and the second nozzle portion at each of the plurality of pattern positions spaced apart from each other on the sheet,
  In the acquisition process, a plurality of the detection signals corresponding to each of the plurality of pattern positions are acquired, and the number of the high level signals which is the number of the detection signals equal to or higher than the threshold level among the plurality of detection signals is counted. And
  In response to the number of high level signals being equal to or greater than the threshold number, the maintenance process is executed,
  Inkjet that performs reverse conveyance processing that causes the optical sensor to face the pattern position where the pattern recording processing is performed by conveying the sheet in the direction opposite to the conveyance direction to the conveyance unit. Recording device.   A transport unit that transports the sheet in the transport direction;
  A first nozzle portion having a plurality of nozzles for discharging ink of a first color different from black, and a second nozzle portion having a plurality of nozzles for discharging ink of a second color different from black and the first color, A recording head for recording an image by discharging ink from the first nozzle portion and the second nozzle portion toward the sheet conveyed by the conveying portion;
  An optical sensor that outputs light toward a passing region of a sheet conveyed by the conveying unit and outputs a detection signal having a magnitude corresponding to the intensity of reflected light;
  A carriage mounted with the recording head and the optical sensor and movable in a main scanning direction intersecting the transport direction;
  A discharge receiving part for receiving discharge discharged by the first nozzle part and the second nozzle part;
  A maintenance mechanism for sucking the first nozzle part and the second nozzle part;
  A control unit, and
  The control unit
  A conveying process for causing the conveying unit to convey the sheet in the conveying direction so that the pattern position on the sheet faces the recording head; and
  Pattern recording processing for recording a pattern image by superimposing and discharging each color ink on the first nozzle portion and the second nozzle portion at the pattern position facing the recording head in the conveyance processing;
  An acquisition process for acquiring the detection signal according to the intensity of reflected light at the pattern position;
  A maintenance process for removing foreign matter in the first nozzle part and the second nozzle part in response to the detection signal acquired in the acquisition process being equal to or higher than a threshold level;
  In the pattern recording process, the pattern image is recorded using a different nozzle of each of the first nozzle portion and the second nozzle portion at each of the plurality of pattern positions spaced apart from each other on the sheet,
  In the acquisition process, a plurality of the detection signals corresponding to each of the plurality of pattern positions are acquired, and the number of the high level signals which is the number of the detection signals equal to or higher than the threshold level among the plurality of detection signals is counted. And
  In response to the number of high level signals being equal to or greater than the threshold number, the maintenance process is executed,
  In the maintenance process, the first nozzle unit and the second nozzle at a position facing the discharge receiving unit when the number of high level signals is equal to or greater than the first threshold number and less than the second threshold number. Ink the ink together with foreign matter
  In the maintenance process, an ink jet recording apparatus that causes the maintenance mechanism to suck foreign matter from the first nozzle portion and the second nozzle portion in response to the number of high level signals being equal to or greater than the second threshold number.   In the maintenance process, the control unit
  In response to the number of the high level signals being greater than or equal to the second threshold number and less than the third threshold number, the suction time by the maintenance mechanism is set to the first time,
  6. The ink jet recording apparatus according to claim 3, wherein the suction time by the maintenance mechanism is a second time longer than the first time in response to the number of high level signals being equal to or greater than the third threshold number.   The inkjet recording apparatus includes a maintenance mechanism that sucks foreign matter from the first nozzle unit and the second nozzle unit in the maintenance process,
  The control unit
  In response to the number of high level signals being equal to or greater than the first threshold number and less than the second threshold number, the suction time by the maintenance mechanism is set to the first time,
  5. The ink jet recording apparatus according to claim 2, wherein when the high level signal number is equal to or greater than the second threshold number, the suction time by the maintenance mechanism is set to the second time. The optical sensor is mounted on the carriage on the upstream side in the transport direction from the recording head,
The control unit causes the acquisition unit to perform a reverse conveyance process for causing the optical sensor to face the pattern position where the pattern recording process is performed by causing the conveyance unit to convey the sheet in a direction opposite to the conveyance direction. The ink jet recording apparatus according to claim 2 , which is executed in advance. The control unit
Repetitively execute each process in the order of the transport process, the pattern recording process, the reverse transport process, and the acquisition process,
In each of the plurality of transport processes, the pattern positions different from each other in the transport direction are made to face the recording head,
In each of the plurality of reverse conveyance processes, the pattern position where the previous pattern recording process was performed is made to face the optical sensor,
The ink jet recording apparatus according to claim 4 or 8 , wherein the maintenance process is executed in response to the number of the high-level signals among the plurality of detection signals acquired in the plurality of acquisition processes being equal to or greater than a threshold number. The control unit
After repeatedly executing each process in the order of the transport process and the pattern recording process, repeatedly execute each process in the order of the reverse transport process and the acquisition process,
In each of the plurality of transport processes, the pattern position that is different in the transport direction faces the recording head,
In each of the plurality of reverse transport processes, the pattern position different in the transport direction is made to face the optical sensor,
The inkjet recording apparatus according to claim 4 or 8 , wherein the maintenance process is executed in response to the number of the high level signals among the plurality of detection signals acquired in the plurality of acquisition processes being equal to or greater than a threshold number. The control unit
In the acquisition process, an average value of the detection signals corresponding to the intensity of reflected light in a pattern formation region including the pattern position and extending in the main scanning direction is acquired;
The inkjet recording apparatus according to claim 1, wherein the maintenance process is executed in response to the average value acquired in the acquisition process being equal to or higher than the threshold level. The inkjet recording apparatus includes a platen that supports a sheet at a position facing the optical sensor, and has a light reflectance of the optical sensor lower than that of the pattern image.
The control unit
Performing a first acquisition process for acquiring a first detection signal corresponding to the intensity of reflected light on the platen prior to the transport process;
Prior to the pattern recording process, a second acquisition process for acquiring a second detection signal corresponding to the intensity of reflected light in the sheet conveyed in the conveyance process is performed.
The ink jet recording apparatus according to any one of the first detection signal and the second detection signal based on a difference between the determination process of determining the threshold levels of claims 4 to run before the maintenance processing 11.

Images