JP2016210020A - Liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device that can determine whether or not exhaust operation is normally executed.SOLUTION: A control portion of a printer portion performs: exhaust processing by which exhaust operation and liquid purge are sequentially executed; test pattern recording processing by which a predetermined test pattern is recorded on a sheet after the exhaust processing; and exhaust determination processing by which whether or not exhaust operation is normally executed by an exhaust mechanism is determined based on information relating to the test pattern on the sheet recorded by the test pattern recording processing. The liquid purge is set so that when air bubble equal to a predetermined threshold or more is stored in an air-bubble storage part after the exhaust operation, air bubble which flows from the ari-bubble storage part into a liquid discharge head is stored in a pressure chamber, and when air bubble less than the predetermined threshold is stored in the air-bubble storage part after the exhaust operation, the air bubble which flows from the air-bubble storage part into the liquid discharge head is not stored in the pressure chamber and liquid is discharged from a plurality of discharge ports.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a liquid ejection apparatus.

  In Patent Document 1, a suction purge for forcibly sucking and discharging thickened ink and bubbles from the nozzles of the recording head and an exhausting operation for sucking and discharging bubbles from the ink flow path upstream of the nozzles can be performed. Inkjet printers are described. This ink jet printer includes a nozzle cap that covers the nozzle in close contact with the recording head as a configuration for suction purge. In addition, as a configuration for exhaust operation, a buffer tank having a bubble storage chamber communicating with the recording head, a discharge path extending from the bubble storage chamber, an on-off valve for opening and closing the discharge path, and a discharge path And an exhaust cap that covers the exhaust port. The nozzle cap and the exhaust cap are connected to the suction pump via the switching unit.

  In this ink jet printer, the suction pump is operated in a state in which the nozzle is covered with the nozzle cap, thereby sucking and discharging thickened ink or ink containing bubbles from the nozzle into the nozzle cap. On the other hand, by operating the suction pump with the exhaust cap covering the exhaust port of the discharge path and the open / close valve opening the discharge path, the bubble storage chamber in the buffer tank passes through the discharge path. To discharge air bubbles to the exhaust cap. By performing this exhausting operation, it is possible to reduce the number of suction purges and the suction time for discharging bubbles, and to suppress the ink consumption.

JP-A-2005-246828

  In the ink jet printer described in Patent Document 1, the exhaust operation is performed after a certain amount of bubbles accumulate in the bubble storage chamber. For this reason, it is often the case that the exhaust operation is executed once every several months, for example. Thus, when the execution interval of the exhaust operation becomes long, for example, the ink or the like entering the discharge path is dried and thickened or solidified. When the thickened or solidified ink adheres to the on-off valve, it may not be normally opened even if the operation of opening the on-off valve is executed. Even if the exhaust operation is executed in a state where such a problem occurs, the exhaust operation may not be executed normally in practice. If the evacuation operation is continued without knowing that the evacuation operation is not normally performed, the bubbles in the bubble storage chamber increase. When printing is performed by ejecting ink from a nozzle in a state where bubbles above the threshold are stored in the bubble storage chamber, the bubbles in the bubble storage chamber may remain in the pressure chamber even when the ink is drawn during printing. . When bubbles remain in the pressure chamber in this way, ink is not ejected from the nozzle associated with the pressure chamber, and the recording head becomes defective in ejection.

  For example, it is possible to determine whether the exhaust operation can be performed based on mechanically detecting whether or not the on-off valve is open. However, when the discharge path itself is clogged with thickened or solidified ink, the exhaust operation may not actually be executed normally even if the on-off valve is opened. Therefore, it cannot be determined whether the exhaust operation has been normally executed based on mechanical detection of whether the on-off valve is open.

  Accordingly, an object of the present invention is to provide a liquid ejection device capable of determining whether or not an exhaust operation has been normally performed.

  The liquid ejection device of the present invention includes a plurality of ejection ports for ejecting liquid, a plurality of pressure chambers connected to each of the plurality of ejection ports, and a pressure for ejecting liquid from the ejection port. A liquid discharge head having a pressure applying unit for applying the liquid to the liquid in the pressure chamber; a transport mechanism for transporting the recording medium; a flow path for supplying liquid to the liquid discharge head; From the bubble reservoir through the communication passage so that the amount of bubbles in the bubble reservoir is less than a threshold value. An exhaust mechanism for performing an exhaust operation for discharging bubbles, a liquid purge mechanism for discharging liquid from the plurality of discharge ports, the liquid discharge head, the transport mechanism, the exhaust mechanism, and the liquid purge mechanism Control And a because of the control unit. The control unit is configured to cause the bubble to flow into the liquid discharge head from the bubble storage unit when the bubble operation unit stores an amount of bubbles equal to or greater than the threshold value after the exhaust operation. The bubble stays in the chamber, and after the exhaust operation, when the amount of bubbles less than the threshold is stored in the bubble storage unit, the bubbles flowing into the liquid ejection head from the bubble storage unit do not stay in the pressure chamber. Liquid purge for discharging liquid from a plurality of ejection ports, and test pattern recording for recording on the recording medium a test pattern for determining whether or not the exhaust operation by the exhaust mechanism has been normally executed after the liquid purge And the exhaust movement by the exhaust mechanism based on the information on the test pattern of the recording medium recorded in the test and the test pattern recording process. It is to perform a determining exhaust determination process whether or not it has been successful.

  According to the liquid ejection device of the present invention, when the exhaust operation is not normally performed for some reason, such as when a part of the communication path is clogged, the amount of bubbles in the bubble storage unit is equal to or greater than the threshold value. There is. When the liquid purge is executed in this state, the bubbles in the bubble storage section remain in the pressure chamber. In this state, it becomes difficult for the liquid to be discharged from the discharge port, and a normal test pattern is not recorded on the recording medium. For this reason, it is possible to determine whether or not the exhaust operation has been normally performed based on the information regarding the test pattern recorded on the recording medium after the liquid purge.

1 is a perspective view of a multifunction machine. It is a schematic side view which shows the internal structure of the printer part shown in FIG. FIG. 2 is a schematic plan view of a printer unit illustrated in FIG. 1. FIG. 3 is a schematic cross-sectional view regarding a vertical plane orthogonal to the left-right direction of the recording head. It is a top view of a head body. (A) is the B section enlarged view of FIG. 5, (b) is CC sectional view taken on the line of FIG. 6 (a). FIG. 5 is a schematic cross-sectional view regarding a vertical plane orthogonal to the left-right direction of the exhaust unit and the exhaust purge mechanism of the maintenance unit when the recording head is in the maintenance position. (A) is a situation diagram showing a state in which the suction cap and the exhaust cap are separated from the recording head and a state in which the opening / closing member is disposed at the valve closing position, and (b) is a state in which the suction cap and the exhaust cap abut against the recording head It is the situation figure which shows the state which has performed and the opening-and-closing member has been arrange | positioned in the valve opening position. It is a bottom view of a carriage and a recording head. FIG. 10 is a partial cross-sectional view of the photosensor shown in FIG. 9. It is a block diagram of a control part. It is a flowchart which shows the procedure of a maintenance operation | movement. FIG. 5A shows a pattern of a test pattern recorded on a sheet, FIG. 5A is a diagram showing a normal pattern, and FIG. 5B is a diagram showing a first upstream omission in which ink is not ejected from an ejection port upstream in the ink flow direction. It is a figure which shows a pattern, (c) is a figure which shows the 2nd pattern of the downstream omission where the ink is not discharged from the discharge outlet downstream of an ink flow direction. It is a flowchart which shows the procedure of the maintenance operation | movement in the 1st modification of one Embodiment of this invention. It is a time chart of a part of maintenance operation in the 2nd modification of one embodiment of the present invention.

  Hereinafter, a multi-function apparatus 1 that employs a printer unit according to an embodiment of the present invention will be described. The multi-function device 1 is installed and used in the state shown in FIG. In the present embodiment, three directions indicated by arrows in FIG. 1 are a vertical direction A1, a front-rear direction A2, and a left-right direction A3. The three directions shown in FIG. 1 are the same in other drawings.

<Overview of MFP 1>
As shown in FIG. 1, the multi-function device 1 is formed in a generally thin rectangular parallelepiped, and has a display unit, operation buttons, and the like on the upper surface thereof. A printer unit 10, which is an example of a liquid ejection device of the present invention, is provided at the lower part of the multifunction device 1. The multifunction device 1 has various functions such as a scanner function and a print function.

  The printer unit 10 has a housing 11. An opening 12 is formed in the approximate center of the front wall 11 a of the housing 11. A paper feed tray 15 and a paper discharge tray 16 are provided in two upper and lower stages. The paper feed tray 15 is configured to be insertable / removable from the opening 12 in the front-rear direction A2, that is, to be detachable from the housing 11. A paper P having a desired size is placed on the paper feed tray 15. The multifunction device 1 can be connected to an external device such as a personal computer (hereinafter referred to as a PC), and performs a recording operation based on a recording command from the PC. Various functions are also executed by operating the operation buttons by the user.

<Internal structure of printer unit 10>
Next, the internal structure of the printer unit 10 will be described. 2 and 3, the printer unit 10 includes a feeding unit 20, a conveying roller pair 35, a recording unit 40, a holder 17, a paper discharge roller pair 36, and an ASF (Auto Sheet Feed) motor. 20M (refer FIG. 11), LF (Line Feed) motor 35M (refer FIG. 11), the optical sensor 58, the maintenance part 60, and the control part 5 (refer FIG. 11). The feeding unit 20 feeds the paper P placed on the paper feed tray 15 to the transport path 25. The conveyance roller pair 35 conveys the paper P fed by the feeding unit 20 to the recording unit 40. The recording unit 40 has, for example, an inkjet recording system configuration, and records an image on the paper P conveyed by the conveyance roller pair 35. The paper discharge roller pair 36 discharges the paper P recorded by the recording unit 40 to the paper discharge tray 16.

  As shown in FIG. 3, the holder 17 is provided on the front right side in the housing 11. Four ink cartridges 18 a to 18 d are detachably mounted on the holder 17. Four ink cartridges 18a to 18d store inks of four colors, yellow, cyan, magenta, and black, respectively. The holder 17 is provided with four cartridge detection sensors 59a to 59d (see FIG. 11) for detecting whether or not the four ink cartridges 18a to 18d are mounted. The cartridge detection sensors 59a to 59d are, for example, optical sensors having a light emitting element and a light receiving element, and light from the light emitting element is blocked by the ink cartridges 18a to 18d attached to the holder 17. A device that detects the wearing state can be employed. Alternatively, when the ink cartridges 18a to 18d are mounted in the holder 17, the contact provided on the holder 17 side and the contact provided on the ink cartridge 18a to 18d side come into contact with each other, and both the contacts are conducted. The ink cartridges 18a to 18d may be detected by the contact type.

<Feeding unit 20>
As shown in FIG. 2, the feeding unit 20 is provided on the upper side of the paper feed tray 15. The feeding unit 20 includes a sheet feeding roller 21 and an arm 22. The paper feed roller 21 is pivotally supported at the tip of the arm 22. The arm 22 is rotatably supported by the support shaft 22 a and is biased by a spring or the like so as to be rotated downward so that the paper feed roller 21 contacts the paper feed tray 15. The arm 22 is configured to be retractable upward when the paper feed tray 15 is inserted and removed. The paper feed roller 21 is rotated by the power of the ASF motor 20M transmitted through a transmission mechanism (not shown), and the paper P stacked in the paper feed tray 15 is fed to the transport path 25.

<Paper Tray 15>
As shown in FIG. 2, the paper feed tray 15 has a slanted wall portion 15a. The inclined wall portion 15 a guides the paper P to the transport path 25 when the paper P placed on the paper feed tray 15 is fed by the paper feed roller 21.

<Conveyance path 25>
As shown in FIG. 2, the conveyance path 25 is formed by an outer guide member 25a and an inner guide member 25b that face each other at a predetermined interval. The conveyance path 25 is configured to bend upward from the rear end portion of the paper feed tray 15 and to the front side of the printer unit 10. The paper P fed from the paper feed tray 15 is guided to make a U-turn from the lower side to the upper side by the transport path 25 and reaches the recording unit 40.

<Conveying roller pair 35 and paper discharge roller pair 36>
The conveyance roller pair 35 includes a conveyance roller 35a disposed on the lower side and a pinch roller 35b disposed on the upper side. The pinch roller 35b is rotated along with the rotation of the conveying roller 35a. The transport roller 35a and the pinch roller 35b cooperate to sandwich the paper P from the vertical direction A1, and transport the paper P to the recording unit 40.

  The paper discharge roller pair 36 includes a paper discharge roller 36a disposed on the lower side and a spur roller 36b disposed on the upper side. The spur roller 36b rotates with the rotation of the paper discharge roller 36a. The paper discharge roller 36a and the spur roller 36b cooperate to sandwich the paper P from the vertical direction A1 and convey the paper P to the paper discharge tray 16.

  When the LF motor 35M is driven, the driving roller pair 35 and the paper discharge roller pair 36 are transmitted to the transport roller 35a and the paper discharge roller 36a by a transmission mechanism (not shown). Both rollers 36a rotate clockwise in FIG. At this time, the transport roller 35a and the paper discharge roller 36a are intermittently driven with a predetermined line feed width. The rotations of the transport roller 35a and the paper discharge roller 36a are synchronized, and the rotation of the transport roller 35a and the paper discharge roller 36a is controlled by detection by a rotary encoder 37 (see FIG. 11) provided on the transport roller 35a. The In this way, the paper P sandwiched between the transport roller pair 35 is intermittently transported on a platen 6 (described later) with a predetermined line feed width. The recording head 41 is scanned for each line feed, and image recording is performed from the front end side of the paper P. Thereafter, the front end side of the paper P on which image recording has been performed is held between the pair of paper discharge rollers 36. Accordingly, the paper P is intermittently transported with a predetermined line feed width with the front end side sandwiched between the paper discharge roller pair 36 and the rear end side sandwiched between the transport roller pair 35. Image recording is performed. When the paper P is further transported, the rear end of the paper P passes through the transport roller pair 35 and the nipping by these is released. Accordingly, the paper P is sandwiched between the paper discharge roller pair 36 and is intermittently conveyed with a predetermined line feed width, and image recording is similarly performed by the recording head 41. After image recording is performed on a predetermined area of the paper P, the paper discharge roller 36a is continuously driven to rotate. As a result, the paper P held by the paper discharge roller pair 36 is discharged to the paper discharge tray 16. As described above, the feeding unit 20, the transport roller pair 35, and the paper discharge roller pair 36 constitute a transport mechanism of the present invention that transports the paper P.

<Recording unit 40>
As shown in FIGS. 2 and 3, the recording unit 40 includes a recording head 41, a head moving mechanism 50, and a platen 6. The head moving mechanism 50 includes a carriage 51. The carriage 51 reciprocates in the scanning direction (the left-right direction A3 and the direction orthogonal to the conveyance direction of the paper P). The recording head 41 is supported by the carriage 51.

  The recording head 41 includes a head main body 42 (liquid ejection head), four sub tanks 43a to 43d, and four exhaust units 45a to 45d. The lower surface of the head main body 42 is an ejection surface 41 b formed with a plurality of ejection ports 41 a that eject ink onto the paper P conveyed below the recording head 41.

  The four sub tanks 43a to 43d are arranged side by side along the scanning direction. Moreover, the tube joint 44 is integrally provided in these four sub tanks 43a-43d. The four sub tanks 43a to 43d and the four ink cartridges 18a to 18d are connected to each other through four flexible tubes (not shown) connected to the tube joint 44. The four sub tanks 43 a to 43 d supply ink of each color to the head main body 42. The four exhaust units 45a to 45d are arranged side by side in the front-rear direction A2 on the right side of the sub tank 43d. These exhaust units 45 a to 45 d are in communication with the four sub tanks 43 a to 43 d, respectively, and are for discharging bubbles staying in the sub tank 43.

  Below the recording head 41, a platen 6 that supports the paper P conveyed by the conveyance roller pair 35 is disposed. The platen 6 is disposed in a portion where the paper P passes in the reciprocating range of the carriage 51. Since the width of the platen 6 is sufficiently larger than the maximum width of the transportable paper P, the paper P transported through the transport path 25 always passes over the platen 6. The area on the platen 6 is an image recording area G1. The color of the upper surface of the platen 6 carrying the paper P is preferably a color having a reflectance that is different from the white color of the general paper P, and particularly preferably black.

  As shown in FIG. 3, the head moving mechanism 50 includes a pair of guide rails 52 and a belt transmission mechanism 53. The pair of guide rails 52 are spaced apart in the front-rear direction A2 and extend parallel to each other in the left-right direction A3. The carriage 51 is disposed so as to straddle the pair of guide rails 52, and is reciprocated along the left-right direction A3 on the pair of guide rails 52.

  The belt transmission mechanism 53 includes two pulleys 54 and 55, an endless timing belt 56, and a CR motor 50M. The two pulleys 54 and 55 are spaced apart from each other in the left-right direction A <b> 3, and a timing belt 56 is stretched over the pulleys 54 and 55. The pulley 54 is connected to the drive shaft of the CR motor 50M. When the CR motor 50M is driven, the timing belt 56 travels and the recording head 41 moves in the scanning direction together with the carriage 51.

  The recording head 41 ejects ink of each color from the ejection port 41a under the control of the control unit 5 based on the recording command. That is, the carriage 51 reciprocates in the left-right direction A3, whereby the recording head 41 is scanned with respect to the paper P, and the ink of each color is ejected from the ejection port 41a, thereby being conveyed on the platen 6. An image is recorded on the paper P. In the printer unit 10, a linear encoder (not shown) having a large number of light transmitting parts (slits) arranged at intervals in the scanning direction is provided. On the other hand, the carriage 51 is provided with a transmission type position detection sensor (not shown) having a light emitting element and a light receiving element. The printer unit 10 can recognize the current position in the scanning direction of the carriage 51 from the count value of the light transmitting portion of the linear encoder detected by the position detection sensor while the carriage 51 is moving. The reciprocation, that is, the rotational drive of the CR motor 50M is controlled.

<Maintenance unit 60>
The maintenance unit 60 forcibly discharges ink from the discharge ports 41a of the recording head 41 to recover the discharge performance. The maintenance unit 60 is on the right side of the image recording region G1 in the moving range of the carriage 51 in the scanning direction. The maintenance area G2 is disposed at the maintenance position. Details of the maintenance unit 60 will be described later.

  Next, the sub tank 43 will be described. Since the structures of the four sub tanks 43a to 43d that respectively store the four color inks are basically the same, one of the sub tanks 43 will be described below.

  As shown in FIG. 4, the sub tank 43 has a flow path 46 having one end connected to the tube joint 44. As shown in FIG. 4, the flow path 46 includes a damper chamber 46a and a bubble storage chamber 46b. The damper chamber 46a is connected to the tube joint 44 and extends in the front-rear direction A2. The upper portion of the damper chamber 46a is covered with a flexible film 47. Thereby, the pressure fluctuation generated in the ink in the flow path 46 is absorbed by the damper chamber 46a. As a result, pressure fluctuations are not easily transmitted to the ink in the head flow path 123 in the head main body 42, and ink ejection can be stabilized.

  The bubble storage chamber (bubble storage portion) 46b extends in the vertical direction A1, has an upper end connected to the damper chamber 46a and a lower end connected to the supply port 125 of the head main body 42. The ink in the sub tank 43 flows from the damper chamber 46a to the supply port 125 through the bubble storage chamber 46b. Due to such an ink flow, the air bubbles that have entered the flow path 46 from the outside are gathered and stored in the upper part of the air bubble storage chamber 46b. In the bubble storage chamber 46b, a partition wall 46c constituting two flow paths 46b1 and 46b2 is formed in the front-rear direction A2. The partition wall 46c has a vertical portion 46c1 extending in the up-down direction A1, and an inclined portion 46c2 inclined forward from the lower end of the vertical portion 46c1. A communication hole 46c3 is formed at the lower end of the slope 46c2. The communication hole 46c3 is a portion where the flow path resistance is the largest in the flow path 46b2, and is larger than the flow path resistance of the flow path 46b1.

  Next, the head body 42 will be described. As shown in FIGS. 5 and 6, the head body 42 includes a flow path unit 121 and an actuator unit 122. As shown in FIG. 6B, the flow path unit 121 has a structure in which five plates 131 to 135 are stacked. The lowermost plate 135 among the five plates 131 to 135 is a nozzle plate 135 in which a plurality of nozzles 135a constituting the discharge port 41a are formed. On the other hand, holes such as a manifold 136 and a pressure chamber 137 communicating with the plurality of nozzles 135a are formed in the remaining four plates 131 to 134 on the upper side.

  As shown in FIG. 5, the plurality of discharge ports 41a are arranged such that four rows of discharge port arrays 124 arranged along the front-rear direction A2 are formed in the left-right direction A3. In the present embodiment, black ink is ejected from the ejection ports 41a belonging to the rightmost ejection port array 124d in FIG. 5, and from the ejection ports 41a belonging to the other three ejection port arrays 124a, 124b, and 124c, Color ink (yellow, cyan, magenta) is ejected. More specifically, yellow, cyan, and magenta inks are ejected in order from the leftmost ejection port array 124 in FIG.

  Next, a flow path structure that is formed on the upper four plates 131 to 134 of the flow path unit 121 and communicates with the plurality of nozzles 135a will be described. First, as shown in FIG. 5, four supply ports 125 arranged in the left-right direction A <b> 3 are formed at the rear end portion (upstream end portion in the transport direction) of the upper surface of the flow path unit 121. The four supply ports 125 are supplied with ink of four colors from the sub tanks 43a to 43d. The four supply ports 125 are a yellow supply port 125a, a cyan supply port 125b, a magenta supply port 125c, and a black supply port 125d. Each supply port 125 is covered with a filter (not shown) so that bubbles in the bubble storage chamber 46 b and foreign matters in the ink in the flow channel 46 are difficult to enter the head flow channel 123.

  In addition, four manifolds 136 that extend in the front-rear direction A <b> 2 are formed inside the flow path unit 121. The four manifolds 136 are respectively connected to the four supply ports 125 at their rear end portions. In each manifold 136, ink flows from the rear to the front. That is, ink flows in the transport direction.

  Further, the flow path unit 121 has a plurality of pressure chambers 137 respectively corresponding to the plurality of nozzles 135a. The plurality of pressure chambers 137 are formed in the plate 131 positioned in the uppermost layer of the flow path unit 121, and are arranged in a plane corresponding to the plurality of nozzles 135a. As shown in FIG. 5, the pressure chambers 137 are arranged so that four pressure chamber rows arranged along the front-rear direction A2 are formed in the left-right direction A3, corresponding to the four discharge port rows 124, respectively. ing. As described above, as indicated by arrows in FIG. 6B, a plurality of individual flow paths 126 branched from the respective manifolds 136 and reaching the nozzles 135 a through the pressure chambers 137 are formed in the flow path unit 121. . These four manifolds 136 and a plurality of individual flow paths 126 constitute a head flow path 123 formed in the flow path unit 121.

  As shown in FIGS. 5 and 6, the actuator unit 122 includes a diaphragm 141, piezoelectric layers 142 and 143, a plurality of individual electrodes 144, and a common electrode 145. The vibration plate 141 is joined to the upper surface of the flow path unit 121 in a state of covering the plurality of pressure chambers 137. The two piezoelectric layers 142 and 143 are stacked on the upper surface of the vibration plate 141. The plurality of individual electrodes 144 are arranged on the upper surface of the upper piezoelectric layer 143 so as to face the plurality of pressure chambers 137, respectively. The common electrode 145 is disposed across the plurality of pressure chambers 137 between the two piezoelectric layers 142 and 143.

  When a drive signal is supplied from the driver IC 138 to the individual electrode 144 in response to a signal from the control unit 5, a piezoelectric strain is generated in a portion facing the pressure chamber 137 of the upper piezoelectric layer 143, so that the diaphragm It deform | transforms so that 141 may bend. At this time, as the volume of the pressure chamber 137 changes, pressure is applied to the ink in the individual flow path 126 and ink is ejected from the nozzle 135a (ejection port 41a).

  Next, the exhaust units 45a to 45d will be described. The exhaust units 45a to 45d are provided on the right side of the sub tank 43 as shown in FIG. As shown in FIG. 7, the four exhaust units 45 a to 45 d are respectively provided for the four sub tanks 43 a to 43 d that store four colors of ink (yellow, cyan, magenta, black).

  Since the structure of the four exhaust units 45a to 45d respectively corresponding to the four sub tanks 43a to 43d is basically the same, one of the exhaust units (hereinafter referred to as reference numeral 45) will be described below. The exhaust unit 45 includes a case 151 fixed to the side surface of the sub tank 43, an exhaust passage 152 extending in the vertical direction A <b> 1 within the case 151, and an opening / closing valve 153 that opens and closes the exhaust passage 152. The exhaust channel 152 is connected via a connection channel 48 (see FIG. 4) whose upper end communicates with the upper end of the bubble storage chamber 46b. The exhaust passage 152 extends to an exhaust port 152 a formed at the lower end of the case 151. The exhaust passage 152 and the connection passage 48 constitute the communication passage 161 of the present invention.

  The on-off valve 153 includes a valve member 154 that is disposed in the exhaust passage 152 so as to be movable in the vertical direction A1 and can close the exhaust passage 152, and a coil spring 155 that biases the valve member 154 downward. Have.

  The valve member 154 has a bottomed cylindrical valve body 156 that can move in the vertical direction A <b> 1 in the exhaust flow path 152, and a valve rod 157 that extends downward from the bottom of the valve body 156. The outer diameter of the valve body 156 is smaller than the inner diameter of the exhaust flow path 152, and ink can flow between the valve body 156 and the inner wall surface of the exhaust flow path 152. An annular sealing material 158 is attached to the lower surface of the valve body 156, and the valve body 156 contacts the valve seat surface 159 provided at a step portion in the middle of the exhaust passage 152 via the sealing material 158. The exhaust channel 152 is configured to be closed by contact.

  The coil spring 155 is disposed in a compressed state between the upper end portion of the case 151 and the valve body 156 of the valve member 154, and the valve member 154 is urged downward by the coil spring 155. When the valve body 156 is driven upward against the biasing force of the coil spring 155 by the exhaust mechanism 67a described later, the valve body 156 is separated from the valve seat surface 159 and the exhaust flow path 152 is opened.

  Next, the maintenance unit 60 will be described. As shown in FIGS. 3, 7, and 8, the maintenance unit 60 includes a suction cap 61 that can be in close contact with the ejection surface 41 b of the recording head 41, an exhaust cap 63 that can be in close contact with the lower surfaces of the four exhaust units 45, The suction pump 66 connected to both the suction cap 61 and the exhaust cap 63, the four open / close members 68a to 68d for opening and closing the open / close valves 153 in the four exhaust units 45, and the open / close members 68a to 68d are moved. And a moving mechanism 68e (see FIG. 11).

  The suction cap 61 is formed of a flexible material such as rubber or synthetic resin, and is divided into two so as to constitute two concave portions 61a and 61b. As shown in FIG. 8, when the recording head 41 (carriage 51) has moved to the maintenance position, the suction cap 61 faces the ejection surface 41b. In this state, by being driven upward by a drive mechanism (not shown) including a suction cap drive motor 61M (see FIG. 11), the suction cap 61 is placed on the discharge surface 41b as shown in FIG. 8B. It adheres and covers the plurality of discharge ports 41a. At this time, a sealed space K1 in which the discharge port 41a for discharging the three color inks on the discharge surface 41b is formed and the discharge port 41a for discharging the black ink on the discharge surface 41b are formed. Two sealed spaces of the sealed space K2 whose region is covered by the recess 61b are formed.

  Similarly to the suction cap 61, the exhaust cap 63 is also formed of a flexible material such as rubber or synthetic resin. As shown in FIG. 3, the exhaust cap 63 is disposed on the right side of the suction cap 61, and when the recording head 41 has moved to the maintenance position, as shown in FIGS. 7 and 8A. The exhaust cap 63 faces the lower surfaces of the four exhaust units 45. In this state, the exhaust cap 63 is driven upward by a drive mechanism (not shown) including an exhaust cap drive motor 63M (see FIG. 11), so that the exhaust cap 63 is exhausted as shown in FIG. 8B. The exhaust ports 152a of the four exhaust units 45 are covered at a time.

  The four open / close members 68a to 68d (the reference numeral 68 may be used in the following for matters common to all open / close members) are respectively rod-like members extending in the vertical direction, as shown in FIG. These are arranged side by side at intervals in the front-rear direction A2. Further, the opening / closing member 68 penetrates the bottom wall of the exhaust cap 63 while maintaining airtightness, and is configured to be movable up and down relative to the exhaust cap 63. When the recording head 41 has moved to the maintenance position, the opening / closing member 68 is positioned directly below the exhaust port 152a on the lower surface of the corresponding exhaust unit 45, as shown in FIG.

  As shown in FIG. 7, among the four open / close members 68a to 68d, the open / close member 68d corresponding to the black ink exhaust unit 45d is independently movable in the vertical direction. On the other hand, the three open / close members 68a to 68c respectively corresponding to the exhaust units 45a to 45c of the three color inks (yellow, cyan and magenta) are connected to each other at their lower ends, and the three open / close members 68a to 68c are connected. 68c is integrally movable in the vertical direction. Further, the color ink opening / closing members 68a to 68c and the black ink opening / closing member 68d connected to each other are independently of each other by a moving mechanism 68e including two valve drive motors 68M1 and 68M2 (see FIG. 11). Driven up and down. That is, the opening / closing members 68a to 68c are driven by driving the valve drive motor 68M1 of the moving mechanism 68e, and the opening / closing member 68d is moved between the valve opening position and the valve closing position by driving the valve driving motor 68M2 of the movement mechanism 68e. Move between. As shown in FIG. 8A, the valve closing position is a position where the opening / closing members 68 a to 68 d are separated from the opening / closing valve 153 to close the opening / closing valve 153. As shown in FIG. 8B, the valve opening position is a position where the opening / closing members 68 a to 68 d abut against the opening / closing valve 153 to open the opening / closing valve 153.

  When the exhaust cap 63 covers the exhaust port 152a on the lower surface of the exhaust unit 45 and the open / close members 68a to 68d move upward relative to the exhaust cap 63, the upper ends of the open / close members 68a to 68d are exhausted. It is inserted into the exhaust passage 152 from the port 152a, and the valve rod 157 in the exhaust passage 152 is pressed upward. Then, the valve body 156 moves upward integrally with the valve stem 157 and is separated from the valve seat surface 159, and the exhaust passage 152 is opened (valve opening).

  The suction pump 66 is connected to the suction cap 61 and the exhaust cap 63 by a tube via a switching mechanism 69. The switching mechanism 69 includes a first communication state in which the suction pump 66 and the recess 61a of the suction cap 61 are communicated, a second communication state in which the suction pump 66 and the recess 61b of the suction cap 61 are in communication, and the suction pump 66 and the exhaust gas. The third communication state in which the cap 63 communicates can be selectively set.

  When the suction pump 61 performs the suction operation when the suction cap 61 is in close contact with the discharge surface 41b and covers the discharge port 41a and the switching mechanism 69 is in the first communication state, the inside of the sealed space K1 The air is sucked to reduce the pressure, and the color ink is discharged into the recess 61a from the discharge port 41a for discharging the color ink (first liquid purge). When the suction cap 61 is in close contact with the discharge surface 41b to cover the discharge port 41a and the suction mechanism of the suction pump 66 is performed when the switching mechanism 69 is in the second communication state, the inside of the sealed space K2 The air is sucked to reduce the pressure, and the black ink is discharged into the recess 61b from the discharge port 41a for discharging the black ink (first liquid purge). Accordingly, it is possible to discharge the thickened ink in the ejection port 41a and the bubbles in the recording head 41 (mainly bubbles in the head main body 42) from the ejection port 41a together with the ink.

  Further, when the first liquid purge is executed when the amount of bubbles in the bubble storage chamber 46b is less than the threshold value, the bubbles in the bubble storage chamber 46b do not reach the pressure chamber 137, and ink is discharged from the plurality of ejection ports 41a. The ink discharge amount, suction force, and the like are set so that the ink is discharged. Thereby, when the exhaust operation in the exhaust process described later is normally executed, the amount of bubbles in the bubble storage chamber 46b becomes less than the threshold value, and the bubbles reach the pressure chamber 137 even when the first liquid purge is executed. No (that is, bubbles do not remain in the pressure chamber 137). For this reason, a normal test pattern is easily recorded on the paper P.

  On the other hand, when the first liquid purge is executed when the amount of bubbles in the bubble storage chamber 46b is equal to or greater than the threshold value, the bubbles in the bubble storage chamber 46b remain in the pressure chamber 137 and ink is discharged from the plurality of ejection ports 41a. As described above, the ink discharge amount, suction force, and the like are set. In this embodiment, the ink discharge amount for each color is equal to or less than the volume for each color of the head flow path 123, and the pressure chamber 137 from the supply port 125 (the pressure chamber closest to the supply port 125 along the head flow path 123). 137) is set to be equal to or larger than the partial volume for each color of the head flow path 123. Thereby, the amount of ink discharged by the first liquid purge can be made equal to or less than the volume of the head flow path 123 for each color. Note that the amount of bubbles until the bubbles stored in the bubble storage chamber 46b reach the boundary indicated by the two-dot chain line in FIG. 4 is the bubble threshold of the bubble storage chamber 46b.

  Further, in the present embodiment, the suction pump 66 can perform a suction operation with a higher suction speed than when the first liquid purge is performed (hereinafter referred to as high speed suction). In the second liquid purge by this high-speed suction, the pressure in the sealed space K1 or the sealed space K2 is rapidly increased to, for example, −60 kPa so that the flow velocity of the ink flowing through the flow path 46 and the head flow path 123 is faster than that of the first liquid purge. The purpose of this is to discharge the bubbles remaining in the upper part of the bubble storage chamber 46b through the head flow path 123 together with the ink from the discharge port 41a.

  On the other hand, the exhaust cap 63 is in close contact with the lower surface of the exhaust unit 45 to cover the exhaust port 152a, the switching mechanism 69 is in the third communication state, and the exhaust passage 152 is opened by the opening / closing member 68. In this state, when the suction operation of the suction pump 66 is performed, the air in the sealed space formed by the exhaust cap 63 and the lower surface of the exhaust unit 45 is sucked and the pressure is reduced. At this time, the bubbles staying in the upper part of the bubble storage chamber 46b of the sub tank 43 are discharged through the connection channel 48 and the exhaust channel 152 (exhaust operation). In this exhaust operation, although the air bubbles staying in the air bubble storage chamber 46b are mainly discharged, the ink in the sub tank 43 is also discharged. However, the amount of ink discharged by the exhaust operation is significantly smaller than the amount of ink discharged by the second liquid purge that is discharged in order to discharge bubbles by the same amount as the amount of bubble discharged by the exhaust operation.

  In the present embodiment, the suction pump 66, the suction cap 61, the switching mechanism 69, the tube connecting the suction pump 66 and the suction cap 61, and the like constitute the liquid purge mechanism 67b for performing the liquid purge. , An exhaust cap 63, a switching mechanism 69, a tube connecting the suction pump 66 and the exhaust cap 63, a drive mechanism including an exhaust cap drive motor 63M, a moving mechanism 68e including open / close members 68a to 68d and valve drive motors 68M1 and 68M2, etc. Thus, an exhaust mechanism 67a for performing an exhaust operation is configured. The suction pump 66 and the switching mechanism 69 serve as both the liquid purge mechanism 67b and the exhaust mechanism 67a.

  Next, the optical sensor 58 will be described. As shown in FIG. 9, the optical sensor 58 is mounted on the carriage 51 together with the recording head 41. As shown in FIGS. 9 and 10, the optical sensor 58 includes a light emitting unit 58a and a light receiving unit 58b. As shown in FIG. 10, the optical sensor 58 is configured such that the light emitting unit 58a emits light toward the platen 6 and the light receiving unit 58b receives the reflected light of the light.

  The color of the upper surface of the platen 6 is black, which has a reflectance different from that of the paper P. When the paper P does not exist, the light receiving unit 58b receives the reflected light from the platen 6 having a low reflectance. Detection is low. On the other hand, when the paper P is present, the light receiving unit 58b receives the reflected light from the paper P having a high reflectance, so that the detection value of the optical sensor 58 is a high value. Therefore, the presence or absence of the paper P can be detected from the difference in the amount of reflected light received by the optical sensor 58.

  Further, when the light receiving unit 58b receives reflected light from the recording area where the image of the paper P is recorded, the detection value of the optical sensor 58 receives reflected light from the non-recording area where the image of the paper P is not recorded. It becomes smaller than the case where the part 58b receives light. In this way, the optical sensor 58 reads reflected light of a test pattern described later recorded on the paper P, and generates and outputs a detection value (read data) that is information relating to the test pattern. Therefore, the test pattern information can be acquired by the optical sensor 58, and it is possible to determine whether or not a discharge failure has occurred in the recording head 41.

  As shown in FIG. 3, such an optical sensor 58 is mounted on the carriage 51 on the upstream side in the transport direction of the recording head 41, and is configured to reciprocate in the scanning direction by the carriage 51. As a result, it is possible to detect the position information of the left end and the right end of the paper P, to acquire the width information of the transported paper P, and to acquire the information of the test pattern recorded on the paper P. it can.

  Next, the control unit 5 will be described. As shown in FIG. 11, the control unit 5 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an ASIC (Application Specific Integrated Circuit) 104, and the like. In cooperation, the operations of the recording head 41, the ASF motor 20M, the LF motor 35M, the CR motor 50M, the suction cap drive motor 61M, the exhaust cap drive motor 63M, the valve drive motors 68M1 and 68M2, the suction pump 66, and the like are controlled. For example, the control unit 5 controls the recording head 41, the ASF motor 20M, the LF motor 35M, the CR motor 50M, and the like based on a recording command transmitted from an external device such as a PC, and records an image or the like on the paper P. Let In addition, the control unit 5 controls the CR motor 50M, the suction cap drive motor 61M, the exhaust cap drive motor 63M, the valve drive motors 68M1 and 68M2, the suction pump 66, and the like, and a liquid purge that discharges ink from the ejection port 41b. Perform maintenance operations. Note that the control unit 5 of the present embodiment has one CPU and one ASIC, but the control unit 5 includes only one CPU and performs processing necessary for the one CPU at a time. Alternatively, a plurality of CPUs may be included, and the plurality of CPUs may share the necessary processing. Further, the control unit 5 may include only one ASIC and perform processing necessary for the one ASIC in a lump, or may include a plurality of ASICs and share the processing necessary for the plurality of ASICs. May be performed. The control unit 5 is connected to an optical sensor 58, four cartridge detection sensors 59a to 59d, a rotary encoder 37, and the like.

  Next, the maintenance operation of the printer unit 10 will be described below with reference to FIGS. The control unit 5 determines whether or not a predetermined time has elapsed (S1). The predetermined time referred to here is an elapsed time after a mounting signal indicating that the ink cartridges 18a to 18d are mounted on the holder 17 is output from the corresponding cartridge detection sensors 59a to 59d to the control unit 5 (previous bubble growth). This is a period derived by finding the condition through an experiment, for example, one month), and is reset every time the predetermined time elapses and timed again. For color inks (magenta, cyan, yellow), three colors are simultaneously executed in both the exhaust operation and the first and second liquid purges, so that the elapsed time related to any one of the color inks reaches a predetermined time. Three elapsed times are reset and timed again. When a predetermined time elapses, bubbles that have entered when the ink cartridge 18 is installed, bubbles that have entered the tube that connects the ink cartridge 18 and the sub tank 43 from the outside, etc. stay in the bubble storage chamber 46b as a certain amount. There are things to do. If the bubbles are left without being discharged, the amount of bubbles in the bubble storage chamber 46b becomes equal to or greater than the threshold value. When the amount of bubbles in the bubble storage chamber 46b is equal to or greater than the threshold value, the bubbles in the bubble storage chamber 46b may flow and stay in the pressure chamber 137 even when ink is drawn from the discharge port 41a during printing. If air bubbles remain in the pressure chamber 137 in this way, an ink ejection defect in which ink cannot be ejected from the ejection port 41a occurs. For this reason, in this embodiment, every time a predetermined time for each of black and color inks (magenta, cyan, yellow) elapses, a maintenance operation is performed to discharge bubbles from the bubble storage chamber 46b of the sub tank 43 related to black and color inks. A certain exhaust mode is selected. The operation in the exhaust mode for discharging bubbles will be described below.

  In the present embodiment, an exhaust mode related to black ink that is executed every time a predetermined time has elapsed after the ink cartridge 18d that stores black ink is mounted on the holder 17 will be described. Since the ink cartridges 18a to 18c are mounted in the holder 17 and executed in the same manner even in the exhaust mode related to color ink that is executed each time a predetermined time elapses, detailed description thereof will be omitted. Further, when the operator transmits an exhaust command for executing an exhaust operation from a PC or the like and the control unit 5 receives the exhaust command, the processes after S1 are similarly executed. In this case, the exhaust mode related to at least one of the designated black and color inks is selected.

  When the predetermined time has not elapsed (S1: NO), the control unit 5 repeats the process of S1. On the other hand, when a predetermined time has elapsed (S1: YES), it is determined whether or not a flag is set (S2). The following description assumes that the recording head 41 (carriage 51) is disposed in the image recording area G1.

  Next, when the flag is set (S2: YES), the control unit 5 proceeds to S11 described later. When the flag is not set (S2: NO), the control unit 5 sets n = 1 (S3). Here, n is a value for counting the number of times that the pattern is determined to be the second pattern in the first pattern determination process described later.

  Next, the control part 5 performs an exhaust process (S4). The exhaust process is a process of performing the first liquid purge after performing the exhaust operation. That is, the control unit 5 first controls the CR motor 50M to place the recording head 41 at the maintenance position. Thereafter, the control unit 5 controls the exhaust cap drive motor 63M, the valve drive motor 68M2, the switching mechanism 69, and the suction pump 66, covers the four exhaust ports 152a with the exhaust cap 63, and connects the switching mechanism 69 to the third communication. The suction pump 66 performs the suction operation in a state in which the exhaust passage 152 of the exhaust unit 45d is opened by the opening / closing member 68. In this way, the bubbles in the bubble storage chamber 46b of the sub tank 43d are discharged. Then, after stopping the driving of the suction pump 66, the control unit 5 controls the exhaust cap drive motor 63M and the valve drive motor 68M2, closes the exhaust passage 152 of the exhaust unit 45d, and connects the exhaust cap 63 to the exhaust unit 45. Separate from. Next, the control unit 5 controls the suction cap drive motor 61M, the switching mechanism 69, and the suction pump 66 to cover the discharge port 41a with the suction cap 61, and sets the switching mechanism 69 to the second communication state. Perform the suction operation. Thereby, the inside of the sealed space K2 is decompressed to, for example, −50 kPa, and the black ink is discharged from the discharge port 41a to the recess 61b (first liquid purge). By the first liquid purge performed here, the bubbles present in the flow path unit 121 and the thickened ink near the discharge port 41a are discharged, and the discharge failure is recovered.

  Further, when the first liquid purge is executed when the amount of bubbles in the bubble storage chamber 46b is less than the threshold, the bubbles in the bubble storage chamber 46b do not reach the pressure chamber 137 (that is, no ink ejection failure occurs). However, when executed when the amount of bubbles in the bubble storage chamber 46b is equal to or greater than the threshold, the bubbles in the bubble storage chamber 46b remain in the pressure chamber 137. That is, the ink discharge failure is caused.

  Next, the control unit 5 controls the recording head 41, the ASF motor 20M, the LF motor 35M, and the CR motor 50M to determine whether or not a predetermined test pattern (exhaust operation is normally performed) on the paper P. Test pattern) is recorded (S5: first test pattern recording process). In the present embodiment, with the paper P and the recording head 41 facing each other, a plurality of black ink is ejected from all the ejection ports 41a while moving the recording head 41 in one of the left and right directions A3. Are continuously ejected. Thus, a test pattern having a predetermined width consisting of a plurality of dots shorter than the paper width in the left-right direction A3 is recorded on the paper P, with the length in the front-rear direction A2 being substantially the same as the length of the nozzle row.

  Next, the control unit 5 controls the LF motor 35M and the CR motor 50M to move the paper P rearward (carrying) until the test pattern recorded on the paper P is located behind the optical sensor 58 (upstream in the carrying direction). After transporting in the direction opposite to the direction), the carriage 51 is scanned while intermittently transporting forward (in the transport direction) with a smaller line feed width than when the test pattern is recorded, and the test pattern is read by the optical sensor 58 (S6). ).

  When the test pattern recorded on the paper P is recorded as shown in FIG. 13A, it is a normal pattern in which substantially the same amount of ink is ejected from all the ejection ports 41a. In this case, the detection value related to the test pattern from the optical sensor 58 is substantially the same value from the rear end to the front end of the test pattern in the front-rear direction A2.

  When the test pattern is recorded as shown in FIG. 13B, the first pattern has a smaller ink discharge amount as the discharge port 41 a located upstream of the ink supplied from the supply port 125. In this case, the detection value related to the test pattern from the optical sensor 58 is output such that the detection value is higher toward the rear end of the test pattern in the front-rear direction A2. When the exhaust operation is not normally performed, the bubbles in the bubble storage chamber 46b flow into the head channel 123 from the supply port 125 by the first liquid purge, and one or more pressures in the upstream portion of the head channel 123 in the ink flow direction. It enters the chamber 137 and stays there. For this reason, ink is not ejected as much as the ejection port 41a located behind (upstream in the ink flow direction) among the plurality of ejection ports 41a arranged along the front-rear direction A2. As a result, the test pattern becomes the first pattern. That is, when the test pattern is the first pattern, there is a very high possibility that the exhaust operation is not normally performed.

  When the test pattern is recorded as shown in FIG. 13C, the second pattern has a smaller ink ejection amount toward the ejection port 41 a located downstream of the ink supplied from the supply port 125. In this case, the detection value related to the test pattern from the optical sensor 58 is output such that the detection value is higher at the front end of the test pattern in the front-rear direction A2. The first pattern and the second pattern are defective patterns that are generated when ink is not ejected from the ejection port 41a. The second pattern may include a pattern other than the first pattern, for example, a pattern in which ink discharge omission occurs in the entire region of the test pattern. The reason why the first pattern is generated is that the evacuation operation is not normally executed, but the reason why the second pattern is generated is that the evacuation operation was not executed normally, so that the first liquid purge entered the head flow path 123. Although there are bubbles, there are many ejection failures due to drying of the ink near the ejection port 41a. In the case of the ejection failure due to the ink drying, it may be recovered by executing the first liquid purge again.

  Next, the control unit 5 determines whether or not the test pattern is normal based on the detection value output from the optical sensor 58 (S7: exhaust determination processing). That is, when it is determined from the detected value that the test pattern is normal (S7: YES), it is determined that the exhaust operation is being executed normally, and the control unit 5 ends the flow. On the other hand, when it is determined from the detected value that the test pattern is not normal (S7: NO), it is determined that the exhaust operation is not normally executed, and the control unit 5 determines that the test pattern is the first pattern from the detected value. (S8: first pattern determination process). When the test pattern is the first pattern (S8: YES), it is determined that the exhaust operation is not normally executed, and the process proceeds to S11. When the test pattern is the second pattern (S8: NO), the process proceeds to S9. .

  In S9, the control unit 5 determines whether n is 2, and when n is not 2 (S9: NO), 1 is added to n (S10). Then, the process returns to S4. On the other hand, when n is 2 (S9: YES), the determination number that the test pattern is the second pattern is the second time, and the control unit 5 proceeds to S11. At this time, the test pattern is the second pattern even though the exhaust process is executed twice. That is, it is indicated that the discharge port 41a could not be recovered by the exhaust operation and the first liquid purge performed again. For this reason, it is determined that the exhaust operation is not normally performed, and the process proceeds to S11.

  In the exhaust operation, the ink in the sub tank 43 is also discharged although the bubbles in the bubble storage chamber 46b are mainly discharged from the exhaust port 152a of the exhaust unit 45. For this reason, the ink adhering to the valve body 156 is dried and thickened or solidified, so that the seal member 158 may be stuck to the valve seat surface 159 and the like together with the valve body 156. As a result, even if the opening / closing member 68 moves upward and comes into contact with the valve body 156, the valve body 156 does not move and the exhaust flow path 152 remains closed. Even if the valve body 156 is moved by the opening / closing member 68, if the thickened or solidified ink is clogged between the valve body 156 and the inner wall of the case 151, the inside of the exhaust cap 63 may be decompressed by the suction pump 66. In addition, neither air bubbles nor ink is discharged from the exhaust port 152a. That is, the exhaust operation may not be executed normally even though the operation for executing the exhaust operation is being performed.

  Next, the control part 5 performs a liquid purge process in S11. The liquid purge process is a continuous liquid purge process in which the first liquid purge is performed after the second liquid purge is performed. That is, the control unit 5 controls the suction cap drive motor 61M and the switching mechanism 69, covers the discharge port 41a with the suction cap 61, and sets the switching mechanism 69 in the second communication state. Thereafter, the control unit 5 controls the suction pump 66 to perform high-speed suction first. At this time, the negative pressure in the close contact space K2 becomes larger than the pressure due to the water head difference between the two flow paths 46b1 and 46b2 by the partition wall 46c of the sub tank 43. For this reason, the ink and bubbles in the flow path 46b2 flow over the upper end of the partition wall 46c and flow into the flow path 46b1 having a small flow resistance, and the ink and bubbles in the flow path 46b1 flow into the supply port 125. The ink in the damper chamber 46a flows to the flow path 46b2. In this way, the ink flows together with the bubbles in the bubble storage chamber 46b to the head channel 123 via the supply port 125, and the bubbles and the ink that have flowed into the head channel 123 are discharged from the discharge port 41a into the suction cap 61 (recess 61b). (Second liquid purge). After the second liquid purge is performed, the control unit 5 controls the suction pump 66 to execute the first liquid purge. Note that the negative pressure in the close contact space K2 in the first liquid purge is smaller than the pressure due to the water head difference between the two flow paths 46b1 and 46b2 due to the partition wall 46c of the sub tank 43. For this reason, the ink mainly flows from the flow path 46b2 to the supply port 125. In this way, the ink is discharged from the ejection port 41 a together with the bubbles remaining in the head flow path 123. By such a liquid purge process, the bubbles in the bubble storage chamber 46b are discharged through the discharge port 41a.

  When the first liquid purge is executed when the amount of bubbles in the bubble storage chamber 46b after the second liquid purge is less than the threshold, the bubbles in the bubble storage chamber 46b do not reach the pressure chamber 137 (that is, the ink However, when the amount of bubbles in the bubble storage chamber 46b is greater than or equal to the threshold value, the bubbles in the bubble storage chamber 46b remain in the pressure chamber 137. That is, the ink discharge failure is caused.

  Next, the control part 5 performs the process of S12-S14 similar to S5-S7. That is, in S12, a test pattern (a test pattern for determining whether or not the second liquid purge is normally executed) is recorded on the paper P (second test pattern recording process). The test pattern recorded here is the same as the test pattern recorded in S5. Thereafter, the recorded test pattern is read by the optical sensor 58 in S13. In S14, it is determined whether the test pattern is normal based on the detection value output from the optical sensor 58 (liquid purge determination process).

  In S14, when it is determined that the test pattern is not normal (S14: NO), the control unit 5 determines that the second liquid purge is not normally performed, and the test pattern is the first pattern from the detected value. (S15: second pattern determination process). When the test pattern is the first pattern, the exhaust operation is normally executed, but it is considered that the amount of air bubbles discharged from the sub tank 43 is insufficient, and the process returns to S4. Thereafter, S4 to S7 are performed, and if it is determined in S7 that the test pattern is normal, the flow ends. On the other hand, when the test pattern is the second pattern, it is considered that the amount of ink discharged by the second liquid purge is insufficient, so the process returns to S11 and the liquid purge process is executed again.

  When it is determined in S14 that the test pattern is normal (S14: YES), the control unit 5 determines that the second liquid purge is normally executed and determines that the exhaust operation cannot be normally executed. Then, the flag is set (S16). Thereby, when the exhaust mode is selected after the next time (when a predetermined time has elapsed in S1), the process of S11 is executed after the process of S2. That is, in the subsequent exhaust mode, the liquid purge process of S11 is executed instead of the exhaust process of S4, the second test pattern recording process of S12 is executed instead of the first test pattern recording process of S5, and the process of S7 Instead of the exhaust determination process, the liquid purge determination process of S14 is executed. In this way, it is possible to prevent the exhaust operation that cannot be normally performed from being performed again in the subsequent exhaust modes.

  Thus, the maintenance operation related to the exhaust mode is completed.

  As described above, according to the printer unit 10 according to the present embodiment, if the exhaust operation in the exhaust process is not normally performed for some reason, such as clogging of the exhaust flow path 152 or malfunction of the valve body 156, The amount of bubbles in the storage chamber 46b may be greater than or equal to a threshold value. For example, some printers are equipped with a clock for managing the execution interval of the exhaust operation, and when an outlet is removed, the clock is driven by a built-in battery and measures time. However, if the built-in battery runs out and the timepiece cannot measure the time, the exhaust operation is not performed at a predetermined interval, and the ink or the like that has entered the exhaust path (exhaust flow path 152) dries and thickens or solidifies. When this thickened or solidified ink adheres to the on-off valve (valve element 156), it may not be normally opened even if the operation of opening the on-off valve is executed. Further, the thickened or solidified ink may block the discharge path itself. Even if the exhaust operation is performed in a state where such a problem occurs, the exhaust operation is not normally performed as described above, and the amount of bubbles in the bubble storage chamber 46b becomes equal to or greater than the threshold value. When the first liquid purge is executed in this state, the bubbles in the bubble storage chamber 46 b remain in the pressure chamber 137. In this state, it becomes difficult for ink to be ejected from the ejection port 41a, and a normal test pattern is not recorded on the paper P. Therefore, it is possible to determine whether or not the exhaust operation has been normally executed in S7 based on the detection value (information) related to the test pattern in S6 after the exhaust process in S4.

  If it is determined in S7 that the test pattern is normal, it is determined that the exhaust operation has been executed normally. In this case, since the flag is not set, the exhaust process is continuously executed even in the next exhaust mode.

  If it is determined by S7 and S8 that the exhaust operation is not normally executed, S11 is executed. That is, by performing the second liquid purge instead of the exhaust operation, the bubbles in the sub tank 43 can be discharged via the head main body 42. In addition, it is possible to determine whether or not the second liquid purge is normally executed by executing S14 after the processing of S11.

  Even if it is determined in S7 that the exhaust operation is not normally executed, if it is determined in S8 that the test pattern is the second pattern, the process returns to S4 again and the exhaust process is executed. When the number of determinations that the pattern is the second pattern is the second time in S8, the liquid purge process of S11 is executed. If it is determined in S8 that the pattern is the first pattern, the liquid purging process in S11 is executed. As a result, even if the first exhaust operation is not normally performed, if it is determined in S7 after the second pattern is determined in S8 that the exhaust operation is normally performed, the next exhaust operation is performed. Exhaust operation is executed in the mode. For this reason, possibility that exhaust operation will be performed in exhaust mode can be raised.

  If it is determined in S14 that the second liquid purge is not normally executed, it is determined in S15 whether the test pattern is the first pattern or the second pattern. If it is determined that the pattern is the first pattern, the processes of S4 to S7 are executed again. If it is determined that the pattern is the second pattern, the processes of S11 to S14 are executed again. As described above, when the liquid purge process is not normally executed, an appropriate process can be performed depending on whether the recorded test pattern is the first pattern or the second pattern.

  The control unit 5 determines the test pattern in S <b> 7 based on the detection value from the optical sensor 58. For this reason, the determination accuracy of S7 (exhaust determination processing) is improved.

  Next, a first modification of the maintenance operation of the printer unit 10 will be described below with reference to FIG. Also in this modification, the exhaust mode related to the black ink will be described, but the description relating to the color ink need only be executed in the same manner, and thus detailed description thereof will be omitted. In the above-described embodiment, even if the test pattern is the first pattern in S8 (first pattern determination process), if the test pattern is the first pattern in S15 (second pattern determination process), the exhaust process is performed again. In the present modification, a flag is set when the test pattern is the first pattern in the first pattern determination process.

  In more detail, as shown in FIG. 14, the control part 5 performs the process of F1-F7 similar to the above-mentioned S1, S2, S4-S8. In F7, the control unit 5 determines whether or not the test pattern is the first pattern based on the detection value output from the optical sensor 58 (first pattern determination process). When the test pattern is the first pattern (F7: YES), it is determined that the exhaust operation is not normally executed, and the process proceeds to F8. When the test pattern is the second pattern (F7: NO), the process returns to F3. The exhaust process is executed again.

  In F8, the control unit 5 sets a flag. And the control part 5 performs the process of F9-F12 similar to above-mentioned S11-S14. In F12, when it is determined that the test pattern is not normal (F12: NO), the control unit 5 returns to F9 and performs the liquid purge process (continuous liquid purge process) again. On the other hand, when it is determined that the test pattern is normal (F12: YES), the control unit 5 ends the flow.

  According to this modification, when it is determined in F7 that the pattern is the first pattern, a flag is set, and when the exhaust mode is selected after the next time (when a predetermined time has passed in F1), after the processing of F2 , F9 is executed. That is, in the subsequent exhaust mode, the F9 liquid purge process is executed instead of the F3 exhaust process, the F10 second test pattern recording process is executed instead of the F4 first test pattern recording process, and the F6 process Instead of the exhaust determination process, the F12 liquid purge determination process is executed. In this way, it is possible to prevent the exhaust operation that cannot be normally performed from being performed again in the subsequent exhaust modes.

  If it is determined in F7 that the pattern is the second pattern, the process returns to F3 again, and the exhaust process is executed. As a result, even if the first exhaust operation is not normally executed, if it is determined that the exhaust operation is normally executed in F6 after being determined as the second pattern in F7, the next exhaust operation is performed. Exhaust operation is executed in the mode. For this reason, possibility that exhaust operation will be performed in the next exhaust mode can be raised. In addition, the same effect can be acquired about the part similar to the above-mentioned embodiment.

  In the above-described embodiment and the first modification, one type of exhaust processing for executing the exhaust operation and the first liquid purge is performed, but the suction pressure (energy) for discharging the ink is the first liquid purge. Alternatively, another exhaust process may be executed in which the third liquid purge (exhaust liquid purge) set to be smaller than the first liquid purge is executed instead of the first liquid purge. In the third liquid purge in the second modification, the ink discharge amount and suction are performed so that the inside of the sealed space can be depressurized to, for example, -30 kPa, and the bubbles in the head channel 123 can be discharged from the discharge port 41a. Force is set. Further, when the third liquid purge is executed when the amount of bubbles in the bubble storage chamber 46b is less than the threshold value, the bubbles in the bubble storage chamber 46b do not flow into the head flow path 123 and are discharged from the plurality of discharge ports 41a. The ink discharge amount and suction force are set so that the ink is discharged. This makes it difficult for the bubbles in the bubble storage chamber 46 b to flow into the head channel 123 when another exhaust process is performed.

  In this modification, the exhaust process and another exhaust process are alternately performed. That is, the exhaust process is executed when the exhaust mode is selected, and another exhaust process is executed when the exhaust mode is selected next. In this case, the test pattern recording process and the exhaust determination process are not executed after the execution of another exhaust process (third liquid purge) until the exhaust process (first liquid purge) is executed. That is, as shown in FIG. 15, when the exhaust process is executed, the test pattern recording process and the exhaust determination process are executed in order. Thereafter, even if another exhaust process is executed, the test pattern recording process and the exhaust determination process are not executed until the next exhaust process is executed. As a result, the maintenance operation such as the test pattern recording process and the exhaust determination process is not performed after another exhaust process, so that the time required for the maintenance can be shortened. The exhaust process and the separate exhaust process may not be executed alternately. For example, the exhaust process may be performed after another exhaust process is performed twice or more, and may be determined as appropriate.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in the above-described embodiment and each modification, the exhaust mode is selected when a predetermined time has elapsed in S1 and F1, but for example, the processing of S5 (F4), S6 (F5), and S7 (F6) is performed. When the test pattern is not normal, the exhaust mode may be selected.

  In addition, when the first liquid purge in the above-described embodiment and each modification is performed when the amount of bubbles in the bubble storage chamber 46b is less than the threshold value, the bubbles in the bubble storage chamber 46b must remain in the pressure chamber 137. For example, the ink discharge amount or suction force may be set so that the bubbles in the bubble storage chamber 46b flow into the head flow path 123 or are discharged from the plurality of discharge ports 41a. Further, the amount of ink discharged by the first liquid purge may exceed the volume of the head flow path 123 for each color.

  In the above-described embodiment and each modification, the control unit 5 determines whether the test pattern is normal and whether it is the first or second pattern based on the detection value output from the optical sensor 58. Although it was determined, it may be determined based on a signal from the operator. That is, when the user looks at the test pattern recorded on the paper P, the control unit 5 selectively selects a signal indicating whether the test pattern is normal and a signal indicating the first or second pattern. May be sent to. The control unit 5 may make the determination as described above based on information on these test patterns.

  Moreover, in the above-mentioned embodiment and each modification, the process after S7 and F6 does not need to be. In short, it suffices if it is possible to determine whether or not the exhaust operation has been normally executed based on the information related to the test pattern. As a result, it is possible to detect that the exhaust operation in the exhaust processing is not normally performed for some reason, such as clogging of the exhaust flow path 152 or malfunction of the valve body 156.

  Further, the mechanism for discharging the bubbles in the sub tank 43 (bubble storage chamber 46b) is not particularly limited to the discharge mechanism 67a. That is, a suction pump may be directly connected to the communication path 161. In this case, the suction pump serves as a discharge mechanism, and the on-off valve 153 or the like may not be provided. Even in such a configuration, the communication path 161 may be blocked by the thickened or solidified ink. However, as described above, whether or not the exhaust operation has been normally performed may be determined based on the information regarding the test pattern. As a result, it is possible to detect that the exhaust operation in the exhaust process is not normally performed for some reason such as clogging of the communication path 161.

  In the above description, an example in which the present invention is applied to a printer unit that performs recording by discharging ink from nozzles has been described, but the present invention is not limited thereto. The present invention can also be applied to a liquid ejecting apparatus other than a printer unit that ejects liquid other than ink from an ejection port. Further, the present invention can be applied to both a line type and a serial type.

5 Control unit 10 Printer unit (liquid ejection device)
41a Discharge port 42 Head body (liquid discharge head)
46 channel 46b bubble storage chamber (bubble storage part)
58 Optical sensor (reading unit)
67a Exhaust mechanism 67b Liquid purge mechanism 123 Head flow path 125 Supply port 161 Communication path

Claims (13)

A plurality of discharge ports for discharging liquid, a plurality of pressure chambers connected to each of the plurality of discharge ports, and a pressure for discharging liquid from the discharge ports are applied to the liquid in the pressure chamber A liquid ejection head having a pressure applying means of
A transport mechanism for transporting the recording medium;
A flow path for supplying liquid to the liquid discharge head;
A bubble reservoir for storing bubbles in the flow path;
A communication path communicating with the bubble storage unit;
An exhaust mechanism for performing an exhaust operation for discharging the bubbles from the bubble reservoir through the communication path so that the amount of bubbles in the bubble reservoir is less than a threshold;
A liquid purge mechanism for discharging liquid from the plurality of ejection ports;
A control unit for controlling the liquid discharge head, the transport mechanism, the exhaust mechanism, and the liquid purge mechanism;
The controller is
The exhaust operation;
When the amount of bubbles equal to or greater than the threshold value is stored in the bubble storage portion after the exhaust operation, the bubbles flowing into the liquid discharge head from the bubble storage portion remain in the pressure chamber, and are less than the threshold value after the exhaust operation. A liquid purge for discharging liquid from the plurality of discharge ports so that bubbles flowing into the liquid discharge head from the bubble storage portion do not stay in the pressure chamber when an amount of bubbles are stored in the bubble storage portion; ,
A test pattern recording process for recording on the recording medium a test pattern for determining whether or not the exhaust operation by the exhaust mechanism has been normally executed after the liquid purge;
And an exhaust determination process for determining whether or not the exhaust operation by the exhaust mechanism has been normally executed based on information on the test pattern of the recording medium recorded in the test pattern recording process. Liquid ejecting device. The controller is
The liquid ejection apparatus according to claim 1, further comprising an exhaust execution determination process for determining whether or not to execute an exhaust mode that is a mode for executing the exhaust operation and the liquid purge thereafter. .   When the liquid purging is performed when the amount of bubbles less than the threshold is stored in the bubble storage unit after the exhaust operation, the bubbles in the bubble storage unit do not reach the pressure chamber and the The liquid discharge apparatus according to claim 1, wherein the liquid discharge apparatus is set to discharge liquid from a plurality of discharge ports. The liquid discharge head includes a supply port connected to the flow path and supplied with liquid, and a head flow path connected to each of the supply port, the plurality of pressure chambers, and the plurality of discharge openings. ,
In the liquid purge, the amount of liquid discharged from the plurality of ejection ports is equal to or smaller than the volume of the head flow channel and is equal to or larger than the volume of the head flow channel portion extending from the supply port to the plurality of pressure chambers. The liquid ejection device according to claim 1, wherein the liquid ejection device is set as described above. The controller is
An exhaust liquid purge that is set so that energy for discharging the liquid is smaller than the liquid purge is executed after the exhaust operation,
5. The test pattern recording process and the exhaust determination process are not executed during a period from the execution of the exhaust liquid purge to the next execution of the liquid purge. The liquid ejection device according to item.   When it is determined in the exhaust determination process that the exhaust operation has been normally executed, the control unit performs the exhaust operation, the liquid purge, the test pattern recording process, and the exhaust determination process even in the next exhaust mode. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is executed in order. In the exhaust determination process, the control unit determines that the exhaust operation is not normally performed, and if the predetermined condition is satisfied, after the exhaust determination process,
A flow rate higher than the flow rate of the liquid in the flow path generated by the first liquid purge, which is the liquid purge, is generated in the flow path, and the bubbles in the bubble storage unit are allowed to flow through the liquid discharge heads. A second liquid purge discharged from the discharge port, and a continuous liquid purge process for sequentially executing the first liquid purge;
Separately from the test pattern recording process after the continuous liquid purge process, a test pattern for determining whether or not the second liquid purge by the liquid purge mechanism has been normally executed is recorded on a recording medium. Test pattern recording process,
A liquid purge determination process for determining whether or not the second liquid purge by the liquid purge mechanism has been normally executed based on information on the test pattern of the recording medium recorded in the other test pattern recording process. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is executed. The liquid discharge head includes a supply port connected to the flow path and supplied with liquid, and a head flow path connected to each of the supply port, the plurality of pressure chambers, and the plurality of discharge openings. ,
When the control unit determines that the exhaust operation is not normally performed in the exhaust determination process, the recorded test pattern is upstream of the liquid supplied from the supply port based on the information. A pattern determination process for determining which of the first pattern and the second pattern different from the first pattern indicate that the discharge port has a smaller amount of liquid discharge,
When the control unit determines that the test pattern is the second pattern, the control unit again executes the exhaust operation, the liquid purge, the test pattern recording process, and the exhaust determination process.
The predetermined condition is that the pattern determination process determines that the test pattern is the first pattern and the determination that the test pattern is the second pattern is repeated two or more predetermined times. The liquid ejection apparatus according to claim 7, wherein the liquid ejection apparatus is any one of the following. The controller is
In the liquid purge determination process, when it is determined that the second liquid purge by the liquid purge mechanism has been normally executed, the continuous liquid purge process is performed instead of the exhaust operation and the liquid purge in the subsequent exhaust mode. 9. The liquid purge determination process is executed instead of the exhaust determination process, and the test pattern recording process is executed instead of the test pattern recording process. Liquid discharge device. When the control unit determines that the second liquid purge by the liquid purge mechanism is not normally executed in the liquid purge determination process, the recorded test pattern is the first pattern based on the information. And a pattern determination process that is different from the pattern determination process for determining which of the second patterns is performed,
The control unit performs the exhaust operation, the liquid purge, the test pattern recording process, and the exhaust determination process when it is determined in the another pattern determination process that the recorded test pattern is the first pattern. When it is determined that the recorded test pattern is the second pattern, the continuous liquid purge process, the another test pattern recording process, and the liquid purge determination process are executed again. The liquid ejection device according to claim 8. The liquid discharge head includes a supply port connected to the flow path and supplied with liquid, and a head flow path connected to each of the supply port, the plurality of pressure chambers, and the plurality of discharge openings. ,
When the control unit determines that the exhaust operation is not normally performed in the exhaust determination process, the recorded test pattern is upstream of the liquid supplied from the supply port based on the information. A pattern determination process for determining which of the first pattern and the second pattern different from the first pattern indicate that the discharge port has a smaller amount of liquid discharge,
When it is determined that the test pattern recorded in the pattern determination process is the first pattern, the flow velocity of the liquid in the flow path generated by the first liquid purge that is the liquid purge in the next and subsequent exhaust modes. A second liquid purge and a first liquid purge that cause a higher flow rate in the flow path to discharge the bubbles in the bubble storage portion from the plurality of discharge ports via the liquid discharge head in order. A continuous liquid purge process is performed instead of the exhaust operation and the liquid purge, and after the continuous liquid purge process, the second liquid purge by the liquid purge mechanism is normal, separate from the test pattern recording process. Another test pattern recording process for recording a test pattern for determining whether or not the test pattern has been executed on the recording medium Whether or not the second liquid purge by the liquid purge mechanism has been normally executed based on the information on the test pattern of the recording medium recorded in the other test pattern recording process. 7. The liquid ejection apparatus according to claim 2, wherein a liquid purge determination process for determining whether or not the exhaust gas determination process is executed instead of the exhaust determination process.   When the control unit determines that the test pattern recorded in the pattern determination process is the second pattern, the control unit performs the exhaust operation, the liquid purge, the test pattern recording process, and the exhaust determination process again. The liquid ejecting apparatus according to claim 11, wherein the liquid ejecting apparatus is executed. A reading unit that reads the test pattern recorded on the recording medium and generates read data;
The liquid ejection apparatus according to claim 1, wherein the information is the read data generated by the reading unit.