JP2011178053A - Liquid ejector - Google Patents

Abstract

A discharge port is prevented from being blocked by aggregates or precipitates.
A precoat head that discharges precoat droplets that agglomerate or deposit ink pigment components and four inkjet heads that discharge ink droplets are sequentially arranged along the paper transport direction. Immediately after the paper jam detection unit detects a paper jam in which the paper is jammed between the conveyance belt that conveys the paper and the ejection surface (S102), the purge control unit detects ink from the ejection port of the inkjet head that faces the paper. Is forcibly discharged (S105). When the head elevating control unit moves the inkjet head 1 to the maintenance position (S107), the purge control unit stops forced ink discharge (S108).
[Selection] Figure 7

Description

  The present invention relates to a liquid ejection apparatus that applies a second liquid that aggregates or deposits components in a first liquid to a recording medium before ejecting a first droplet from an ejection port.

  In an inkjet printer that ejects only ink droplets from the ejection port, if the paper is jammed between the transport surface and the ejection surface where the ejection port of the inkjet head opens (jam), the ejection port is removed after the jammed paper is removed It is known to restore the printable state by discharging ink from the ink and wiping the ejection surface (see, for example, Patent Document 1).

JP 2006-69163 A

  In order to reduce the bleeding of dots formed on the paper by discharging the ink onto the paper or improve the color development of the dots, the pigment in the ink prior to the ink droplets at the location where the dots are formed In an ink jet printer that applies a pretreatment liquid that aggregates or precipitates components, when a jam occurs, the pretreatment liquid applied to the paper may adhere to the ejection surface of the ink jet head. At this time, before the jammed paper is removed, the ink in the ejection port reacts with the pretreatment liquid adhering to the ejection surface, and the pigment component in the ink in the ejection port aggregates or precipitates, and the aggregate Alternatively, the discharge port is blocked by the deposit. In this case, it becomes difficult to recover the blockage of the discharge port.

  An object of the present invention is to provide a liquid discharge apparatus capable of preventing the discharge port from being blocked by aggregates or precipitates.

  The liquid ejection apparatus according to the present invention includes a conveyance mechanism that conveys a recording medium, a liquid ejection head in which an ejection port for ejecting a first liquid that forms an image on the recording medium, and the conveyance direction of the recording medium. A second liquid application unit that is disposed upstream of the liquid ejection head and that imparts to the recording medium a second liquid that reacts with the first liquid to aggregate or deposit components in the first liquid; and the ejection port; And a detection unit that detects clogging of the recording medium at the opposite position, a discharge unit that discharges the first liquid from the discharge port, and a control unit that controls the discharge unit. The control means controls the discharge means so that the first liquid is discharged from the discharge port immediately after the detection means detects the clogging of the recording medium.

  According to the present invention, even if the recording medium coated with the second liquid comes into contact with the ejection port and the first liquid and the second liquid are mixed at the ejection port due to the recording medium being jammed, the recording medium is clogged. Immediately after is detected, the second liquid is discharged from the discharge port together with the first liquid. Thus, since the first and second liquids mixed from the discharge port are discharged before the components in the first liquid are aggregated or deposited, the discharge port is blocked by the aggregate or precipitate. Can be prevented.

  In the present invention, the discharge means includes a pump that discharges the first liquid from the discharge port by forcibly supplying the first liquid to a liquid flow path connected to the discharge port. It is preferable. According to this, the first liquid can be efficiently discharged from the discharge port.

  The present invention further includes a moving mechanism that moves at least one of the transport mechanism and the liquid discharge head so that the distance between the transport surface of the transport mechanism and the discharge port changes. The control means immediately after the detection means detects the clogging of the recording medium until the moving mechanism sets the distance between the transport surface and the discharge port to a predetermined value or more from the discharge port. It is preferable to control the discharging means so that the liquid continues to be discharged. According to this, since the first liquid is continuously discharged from the discharge port until the preparation for removing the jammed recording medium is completed, the discharge port can be further prevented from being blocked.

  Furthermore, in the present invention, as the amount of the second liquid applied to the recording medium by the second liquid applying means increases until the control means detects the clogging of the recording medium. Thus, it is preferable to control the discharge means so that the amount of the first liquid discharged from the discharge port increases. According to this, when the amount of the second liquid applied to the recording medium is increased, the discharge port may be tightly blocked, and the first liquid necessary for preventing the discharge port from being blocked is discharged. The discharge amount can be prevented from being blocked by appropriately adjusting the amount. In addition, it is possible to prevent the first liquid from being discharged unnecessarily as compared with the case where a large discharge amount of the first liquid is set from the beginning.

  In addition, the present invention further includes a wiping mechanism having a wiper for wiping the discharge port, and a cleaning mechanism for cleaning the conveying surface of the conveying mechanism, and after the clogging of the recording medium is released, It is preferable that wiping of the discharge port by the wiping mechanism and cleaning of the transport surface by the cleaning mechanism are performed simultaneously. According to this, it is possible to quickly return to a normal state.

  Further, in the present invention, an image sensor that reads an image recorded on a recording medium, and recording is performed by discharging droplets of the first liquid from all the ejection openings after the clogging of the recording medium is released. Test pattern control means for controlling the liquid ejection head so that a test pattern is recorded on the medium, and from the reading result of the image sensor when the test pattern control means causes the test pattern to be recorded on the recording medium, It is preferable that the apparatus further includes a determination unit that determines whether or not a droplet is discharged from the discharge port. According to this, it is possible to reliably detect whether or not the discharge port is closed.

  Further, in the present invention, there are provided a plurality of the liquid discharge heads arranged in the transport direction, and the detection means is the presence or absence of a recording medium respectively disposed on the downstream side of the liquid discharge head in the transport direction And a plurality of recording medium sensors for detecting the liquid ejection heads facing the jammed recording medium from the detection results of the plurality of recording medium sensors, and the control means Controlling the discharge means so that the first liquid is discharged from the discharge port of the liquid discharge head specified by the detection means immediately after the detection means detects the clogging of the recording medium. preferable. According to this, it is possible to easily identify the liquid discharge head facing the jammed recording medium, and it is possible to suppress the wasteful discharge of the first liquid.

  At this time, as the distance from the second liquid applying unit and the detection unit specified by the detection unit to the liquid discharge head specified by the detection unit is shortened, the control unit applies the liquid discharge head specified by the detection unit to the liquid discharge head specified by the detection unit. More preferably, the discharge means is controlled so that the amount of the first liquid discharged from the discharge port increases. When the second liquid applied to the paper dries, the second liquid is less likely to adhere to the liquid discharge head when a jam occurs. According to this, as the undried rate of the second liquid in the second liquid increases. Thus, since the discharge amount of the first liquid increases, it is possible to efficiently prevent the discharge port from being blocked by aggregates or precipitates.

  In the present invention, the detection means includes two recording medium sensors that detect the presence or absence of a recording medium respectively disposed upstream of the second liquid applying means and downstream of the liquid ejection head with respect to the transport direction. And the control means includes the discharge means so that the first liquid is discharged from the discharge ports of all the liquid discharge heads immediately after the detection means detects clogging of the recording medium. It is preferable to control. According to this, the clogging of the recording medium can be efficiently detected by the two recording medium sensors. In addition, the number of recording medium sensors can be reduced and the cost can be reduced.

  According to the present invention, even if the recording medium coated with the second liquid comes into contact with the ejection port and the first liquid and the second liquid are mixed at the ejection port due to the recording medium being jammed, the recording medium is clogged. Immediately after is detected, the second liquid is discharged from the discharge port together with the first liquid. Thus, since the first and second liquids mixed from the discharge port are discharged before the components in the first liquid are aggregated or deposited, the discharge port is blocked by the aggregate or precipitate. Can be prevented.

1 is a schematic side view of an inkjet printer according to an embodiment of the present invention. It is a top view which concerns on the head main body of the inkjet head shown in FIG. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG. It is a functional block diagram of the control apparatus shown in FIG. It is a figure for demonstrating operation | movement of the wiper control part shown in FIG. It is a figure for demonstrating the test pattern printed by the test pattern printing part shown in FIG. 3 is a flowchart showing a printing operation of the ink jet printer shown in FIG. 1.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the inkjet printer 101 includes a transport unit 20 that transports the paper P from the right to the left in FIG. 1, and black (K) and cyan (cyan) on the paper P transported by the transport unit 20. C) Four inkjet heads 1 for ejecting magenta (M) and yellow (Y) ink droplets, respectively, and a precoat head 2 for ejecting droplets of a precoat liquid (Pre) for aggregating or depositing the pigment component of each ink. A pump 32 (see FIG. 4) corresponding to the four inkjet heads 1 and the precoat head 2, six paper sensors 31a to 31f, a line sensor 30, a head lifting mechanism 33 (see FIG. 4), and a wiper unit. 36 (see FIGS. 4 and 5), a cleaner unit 37, and a control device for controlling the entire inkjet printer 101 And a 6. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction. In addition, a precoat liquid for aggregating pigment pigments is used for pigment ink, and a precoat liquid for depositing dye pigments is used for dye ink.

  The transport unit 20 includes two belt rollers 6 and 7 and an endless transport belt 8 wound around the rollers 6 and 7. The belt roller 7 is a driving roller, and rotates counterclockwise in FIG. 1 when a driving force is applied from a conveyance motor (not shown). The belt roller 6 is a driven roller and rotates as the conveyor belt 8 travels due to the rotation of the belt roller 7. A weakly adhesive silicon layer is formed on the outer peripheral surface of the conveyor belt 8 and holds the loaded paper P. The paper P placed on the outer peripheral surface of the transport belt 8 is transported to the left in FIG. A peeling plate 13 is disposed on the downstream side in the transport direction of the four inkjet heads 1. The paper P transported in the transport direction sequentially passes under the precoat head 2 and the four inkjet heads 1 and then is peeled off from the transport surface of the transport belt 8 by the peeling plate 13 and is also shown in the drawing of the transport belt 8. The paper is discharged to a paper discharge tray 14 arranged on the left side. The platen 10 is disposed to face the four inkjet heads 1 and the precoat head 2 and supports the upper loop of the conveyor belt 8 from the inside. Thereby, a predetermined gap suitable for image formation is formed between the outer peripheral surface of the conveyor belt 8 and the ejection surfaces of the four inkjet heads 1 and the precoat head 2.

  The four inkjet heads 1 and the precoat head 2 have the same structure, each extend along the main scanning direction, and are arranged in parallel to each other in the sub scanning direction. The precoat head 2 is disposed on the upstream side in the transport direction of the four inkjet heads 1. The lower surface of each inkjet head 1 and precoat head 2 is an ejection surface in which a plurality of ejection ports 108 (see FIG. 3) are arranged. That is, the ink jet printer 101 is a line type color ink jet printer in which a plurality of ejection openings 108 for ejecting ink droplets in the main scanning direction are arranged.

  The outer peripheral surface of the upper loop of the conveyor belt 8 and each discharge surface are parallel to each other while facing each other. When the paper P conveyed by the conveyance belt 8 passes just below the precoat head 2, the precoat liquid is applied from the precoat head 2 so that the precoat liquid is applied to the area where the image is formed on the upper surface of the paper P. A droplet is ejected. Thereafter, when the paper P passes just below the four inkjet heads 1, ink droplets of each color are sequentially ejected from each inkjet head 1 to a region where the precoat liquid is applied on the upper surface of the paper P. Thereby, a desired color image is formed on the paper P. At this time, when the ink droplets land on the precoat liquid applied on the paper P, the precoat liquid aggregates or deposits the pigment component of the ink droplets, so that ink bleeding on the paper P is prevented and an image formed on the paper P is formed. The color developability is improved.

  Next, the inkjet head 1 and the precoat head 2 will be described in detail with reference to FIGS. Note that the precoat head 2 has the same structure as the ink jet head 1, and therefore the description thereof is omitted. In FIG. 3, for convenience of explanation, the pressure chamber 110, the aperture 112, and the discharge port 108 that are to be drawn with broken lines below the actuator unit 21 are drawn with solid lines.

  As shown in FIG. 2, the inkjet head 1 is a laminated body in which four actuator units 21 are fixed to the upper surface 9 a of the flow path unit 9. As shown in FIGS. 2 and 3, the flow path unit 9 has an ink flow path including a pressure chamber 110 and the like formed therein. The actuator unit 21 includes a plurality of actuators corresponding to the pressure chambers 110, and has a function of selectively giving ejection energy to the ink in the pressure chambers 110.

  The flow path unit 9 is a laminated body in which a plurality of metal plates made of stainless steel are aligned with each other. A large number of individual ink flow paths are formed in the flow path unit 9 from the manifold flow path 105 to the sub-manifold flow path 105a, and from the outlet of the sub-manifold flow path 105a to the discharge port 108 through the pressure chamber 110.

  A total of ten ink supply ports 105 b to which ink from a reservoir unit (not shown) is supplied are opened on the upper surface 9 a of the flow path unit 9. A discharge surface is formed on the lower surface of the flow path unit 9, and a large number of discharge ports 108 are arranged in a matrix. The ejection ports 108 are arranged at an interval of 600 dpi, which is the resolution in the main scanning direction with respect to the main scanning direction.

  The ink flow in the flow path unit 9 will be described. As shown in FIGS. 3 to 4, the ink supplied from the reservoir unit into the flow path unit 9 via the ink supply port 105b is distributed from the manifold flow path 105 to the sub-manifold flow path 105a. The ink in the sub-manifold channel 105 a flows into each individual ink channel and reaches the ejection port 108 via the pressure chamber 110.

  The pump 32 forces the ink to the ink supply port 105b of the flow path unit 9 via the reservoir unit so that the ink in the ejection port 108 is discharged to the outside in the corresponding inkjet head 1 or precoat head 2. Supply. Although one pump 32 is shown in FIG. 4, the inkjet printer 101 has five pumps 32 corresponding to the inkjet head 1 and the precoat head 2.

  Returning to FIG. 1, the six paper sensors 31 a to 31 f are reflective sensors for detecting the presence or absence of the paper P on the transport surface of the transport belt 8, and both sides of the precoat head 2 in the transport direction and four On the downstream side in the transport direction of the inkjet head 1, they are arranged so as to face the transport surface of the transport belt 8. Specifically, the paper sensor 31a, precoat head 2, paper sensor 31b, ink jet head 1 (K), paper sensor 31c, ink jet head 1 (C), paper sensor 31d, ink jet head 1 ( M), the paper sensor 31e, the inkjet head 1 (Y), and the paper sensor 31f are arranged in this order. Thereby, it is possible to identify which of the four inkjet heads 1 is facing the paper P from the detection results of the six paper sensors 31a to 31f.

  The line sensor 30 is disposed so as to face the outer peripheral surface of the transport belt 8 on the downstream side in the transport direction of the four inkjet heads 1. The line sensor 30 has a plurality of optical elements arranged in the main scanning direction, and can read an image printed on the paper P by ink droplets ejected from the four inkjet heads 1.

  Four inkjet heads 1 and precoat heads 2, six paper sensors 31 a to 31 f, and a line sensor 30 are fixed to the frame 35. The head elevating mechanism 33 elevates and lowers the four inkjet heads 1 and the precoat head 2 together with the frame 35 in the vertical direction in FIG.

  The wiper unit 36 includes a wiper 36a (see FIG. 5) that is a plate member made of an elastic material such as rubber for wiping each discharge surface in a maintenance operation described later. The wiper unit 36 wipes each ejection surface by moving the wiper 36a along the main scanning direction while being in contact with the ejection surfaces of the inkjet head 1 and the precoat head 2.

  The cleaner unit 37 cleans the outer peripheral surface of the conveyor belt 8 in a maintenance operation described later. The cleaner unit 37 is disposed on the lower left side of the transport belt 8 in FIG. 1 and includes a cleaning liquid application member 37a and a blade 37b. The cleaning liquid application member 37 a has a porous body that holds the cleaning liquid supplied from a cleaning liquid tank (not shown) while extending so as to face the entire width direction of the transport belt 8. The blade 37b is disposed immediately downstream of the cleaning liquid application member 37a with respect to the rotation direction of the conveyance belt 8, and is a plate made of an elastic material such as rubber that extends so as to face the entire width direction of the conveyance belt 8. It is a member.

  The cleaning liquid applying member 37a and the blade 37b are moved by a moving mechanism (not shown), a contact position where the porous body of the cleaning liquid applying member 37a and the tip of the blade 37b contact the outer peripheral surface of the transport belt 8, and a porous position of the cleaning liquid applying member 37a. The body and the tip of the blade 37b can be selectively taken away from the outer peripheral surface of the conveyor belt 8. In a maintenance operation described later, the cleaner unit 37 moves the cleaning liquid application member 37a and the blade 37b to the contact positions. At this time, the conveyor belt 8 rotates counterclockwise, so that the cleaning liquid application member 37a applies the cleaning liquid to the outer peripheral surface of the transport belt 8, and the blade 37b scrapes dirt adhered to the outer peripheral surface of the transport belt 8 together with the cleaning liquid. take. The cleaning liquid scraped off by the blade 37b flows into a waste liquid tank (not shown).

  Next, the control device 16 will be described with reference to FIG. The control device 16 includes a CPU (Central Processing Unit), a program executed by the CPU, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) that stores data used for these programs in a rewritable manner. It includes RAM (Random Access Memory) for temporary storage. Each functional unit constituting the control device 16 is constructed by cooperation of these hardware and software in the EEPROM. As shown in FIG. 4, the control device 16 controls the entire inkjet printer 101, and includes a conveyance control unit 50, an image data storage unit 41, a head control unit 42, a paper jam detection unit 43, and a purge. A control unit 44, a head lifting control unit 45, a wiper control unit 46, a cleaner control unit 47, a test pattern printing unit 48, and an ejection abnormality detection unit 49 are included.

  The transport controller 50 controls the transport motor of the transport unit 20 so that the paper P is transported along the transport direction. The image data storage unit 41 stores image data relating to an image printed on the paper P.

  The head control unit 34 drives the actuator unit 21 of the precoat head 2 based on the image data stored in the image data storage unit 41, thereby discharging precoat droplets from the discharge port 108 at a desired timing. By driving the actuator unit 21 of each inkjet head 1, a desired volume of ink droplets is ejected from the ejection port 108 at a desired timing.

  The paper jam detection unit 43 detects that the conveyed paper P is jammed at a position facing the ejection surface of each inkjet head 1 and precoat head 2 as a paper jam. (Note that the paper jam detector 43 and the paper sensors 31a to 31e are included in the detection means.) Specifically, the paper jam detector 43 detects the paper P on which the paper sensors 31a to 31e are conveyed. The paper sensors 31b to 31f adjacent to the downstream side in the transport direction of the paper sensors 31a to 31e that have detected the paper P do not detect the paper P within a predetermined time determined from the transport speed of the paper P. Then, a paper jam is detected and a display device (not shown) displays that a paper jam has been detected.

  Further, when detecting a paper jam, the paper jam detection unit 43 specifies the inkjet head 1 that is facing the jammed paper from the detection results of the paper sensors 31a to 31f. For example, the paper jam detection unit 43 detects the paper P by the paper sensors 31b to 31d, and the ink jet head 1 that faces the jammed paper P if the paper sensors 31a, 31e, and 31f do not detect the paper P. Are identified as three inkjet heads 1 (K), inkjet head 1 (C), and inkjet head 1 (M).

  The head raising / lowering control unit 45 includes a printing position when the four inkjet heads 1 and the precoat head 2 perform printing on the paper P (see FIGS. 1 and 5C), and the inkjet head 1 and the precoat head 2. Of the frame 35 by the head elevating mechanism 33 so as to selectively take a maintenance position (see FIG. 5A and FIG. 5B) where the discharge surface and the transport surface of the transport belt 8 are separated by a predetermined distance. Controls the lifting operation. The maintenance position is located above the printing position (in the direction away from the conveyor belt 8).

  Here, when the above-mentioned paper jam occurs, the user performs the removal operation of the jammed paper P. The head lifting control unit 45 moves the four inkjet heads 1 and the precoat head 2 from the printing position to the maintenance position in response to a removal work start command from the user who performs the removal work. As a result, the distance between the ejection surfaces of the four inkjet heads 1 and the precoat head 2 and the conveyance surface of the conveyance belt 8 increases, and the user can easily remove the jammed paper P. After removing the jammed paper P, the user inputs a print restart command to an operation panel (not shown). As will be described later, a maintenance process related to the inkjet head 1 and the precoat head 2 is executed in response to a print restart command from the user.

  The purge control unit 44 drives the five pumps 32 so as to perform a purge operation in which the ink in the ejection port 108 related to the inkjet head 1 or the precoat liquid in the ejection port 108 related to the precoat head 2 is discharged. To do. When the above-mentioned paper jam occurs, the printing surface of the jammed paper P may come into contact with the ejection surface of the inkjet head 1.

  The purge control unit 44 stops the rotation of the conveyance belt 8 via the conveyance control unit 50 immediately after the paper jam detection unit 43 detects the paper jam, and at the same time, the purge control unit 44 applies the ink jet head 1 specified by the paper jam detection unit 43 to the inkjet head 1. The driving of the pump 32 is started so that the ink is discharged from the ejection port 108. As a result, the ink in the ejection port 108 relating to the inkjet head 1 is discharged to the outside together with the precoat liquid to which the ink has adhered. The discharged ink and precoat liquid flow down on the conveyor belt 8. When the head lifting control unit 45 receives a removal work start command from a user who performs the removal work and moves the four inkjet heads 1 and the precoat head 2 from the printing position to the maintenance position, the purge control unit 44 causes the pump 32 to Stop driving.

  At this time, the purge control unit 44 detects the precoat liquid applied to the jammed paper P as the distance in the transport direction from the precoat head 2 of the inkjet head 1 specified by the paper jam detection unit 43 decreases. As the amount increases, the drive rotation speed of the pump 32 corresponding to each inkjet head is controlled so that the amount of ink discharged from the ejection port 108 of the inkjet head 1 increases. Note that the amount of the precoat liquid applied to the paper P is calculated from the image data.

  Further, the purge control unit 44 drives each pump 32 so that a predetermined amount of ink and precoat liquid are discharged from each ejection port 108 of the inkjet head 1 and the precoat head 2 in a maintenance process described later.

  In the maintenance operation, the wiper control unit 46 controls the wiper unit 36 so that the ejection surfaces of the inkjet head 1 and the precoat head 2 are wiped by the wiper 36a.

  The maintenance operation is started by a print resuming instruction from the user after the jammed paper P is removed by removing the jammed paper P. When the maintenance operation is started, the purge control unit 44 discharges a predetermined amount of ink from each ejection port 108 of the inkjet head 1 as shown in FIG. At the same time, a predetermined amount of precoat liquid is discharged from each discharge port 108 of the precoat head 2. Then, as shown in FIG. 5B, the wiper control unit 46 controls the wiper unit 36 so that the wiper 36a moves along the main scanning direction while being in contact with the respective discharge surfaces. Wipe away. When the wiping of each ejection surface is completed, as shown in FIG. 5C, the head lifting control unit 45 moves the four inkjet heads 1 and the precoat head 2 from the maintenance position to the printing position, thereby completing the maintenance operation. To do.

  In the maintenance operation, the cleaner control unit 47 starts the wiping of the discharge surface by the wiper unit 36, and simultaneously rotates the conveyance belt 8 counterclockwise via the conveyance control unit 50, and the cleaning liquid application member 37a and the blade 37b is moved to the contact position. As a result, the ink and precoat liquid discharged to the outer peripheral surface of the conveyor belt 8 are scraped off by the blade 37b together with the cleaning liquid applied to the cleaning liquid application member 37a.

  The test pattern printing unit 48 prints a test pattern 90 as shown in FIG. 6 on the paper P for each inkjet head 1 through the head control unit 42 and the conveyance control unit 50 after the maintenance operation is completed. The test pattern printing unit 48 simultaneously discharges ink droplets from the three ejection ports 108 selected in order from one side in the main scanning direction via the head control unit 42, and sets the other ejection port 108 to start selection. The test pattern 90 is formed by repeating the process three times while moving the sample one by one. Thereby, in the test pattern 90, three straight line groups are formed in which a plurality of straight lines extending in the transport direction corresponding to the ejection ports 108 are arranged in the main scanning direction. These three straight line groups are arranged in the transport direction. As described above, the straight lines adjacent to each other in the main scanning direction are formed at different positions in the transport direction, thereby preventing the straight lines from contacting each other.

  The ejection abnormality detection unit 49 causes the line sensor 30 to read the test pattern 90 printed on the paper P, and detects the position of each straight line of the test pattern 90 in the main scanning direction from the read result. The ejection abnormality detection unit 49 detects, from the detection result, the ejection port 108 that has caused an ejection abnormality such as a displacement of the landing position of the ink droplet or a non-ejection of the ink droplet. When the ejection abnormality detection unit 49 detects the ejection port 108 in which the ejection abnormality has occurred, the ejection abnormality detection unit 49 displays that fact on a display device (not shown).

  Next, the printing operation of the inkjet printer 101 will be described. As shown in FIG. 7, when the inkjet printer 101 receives a print command from a host computer, printing according to the received print command is started (S101). Specifically, the precoat head 2 starts precoating so that the transport unit 20 starts transporting the paper P and the image related to the image data stored in the image data storage unit 41 is printed on the transported paper P. Each inkjet head 1 discharges ink droplets while discharging droplets.

  When printing is started, the paper jam detection unit 43 has detected whether or not the paper jam caused by the jammed paper P being jammed at a position facing the ejection surface of each inkjet head 1 and precoat head 2 is detected. Is determined (S102). If the paper jam detection unit 43 does not detect the paper jam (S102: NO), the determination as to whether the paper jam has been detected is repeated until the printing related to the print command is completed (S103: NO). If printing is completed (S103: YES), the printing operation is terminated.

  On the other hand, if the paper jam detection unit 43 detects a paper jam (S102: YES), the paper jam detection unit 43 detects the ink jet head 1 facing the jammed paper from the detection results of the paper sensors 31a to 31f. At the same time (S104), the fact that a paper jam has been detected is displayed on a display device (not shown). Further, immediately after the paper jam detection unit 43 detects a paper jam, the purge control unit 44 starts discharging ink from the ejection port 108 related to the inkjet head 1 specified by the paper jam detection unit 43 (S105). Here, immediately after the paper jam is detected, the ink-jet head 1 and the pre-coat head 2 move from the printing position at the latest until the dye component of the ink is completely aggregated or deposited by the pre-coat liquid adhering to the ejection port 108. Until you start. The head lifting control unit 45 waits until a removal work start command is received from the user (S106). If the removal work start command is received (S106: YES), the four inkjet heads 1 and the precoat head 2 are maintained from the printing position. Move to position (S107). When the four inkjet heads 1 and the precoat head 2 have moved to the maintenance position, the purge control unit 44 stops discharging ink from the ejection ports 108 (S108).

  After that, after the paper P related to the paper jam is removed, the control device 16 stands by until a print resumption command is received from the user (S109). If the print resumption command is received (S109: YES), the discharge of the inkjet head 1 is performed. A maintenance operation including wiping of the ejection surface by the wiper 36a after forcibly discharging the ink from the outlet 108 and cleaning of the outer peripheral surface of the transport belt 8 by the cleaner unit 37 performed at the same time is executed (S110).

  When the maintenance operation is completed, the test pattern printing unit 48 prints the test pattern 90 on the paper P, and the ejection abnormality detection unit 49 causes the line sensor 30 to read the test pattern 90 printed on the paper P and analyze it (S111). ), It is determined whether or not there is a discharge port 108 causing discharge abnormality (S112). If the discharge abnormality detection unit 49 determines that there is no discharge port 108 that has caused the discharge abnormality (S112: NO), the control device 16 again performs printing according to the print command on the new paper P. Start (S101). If the discharge abnormality detection unit 49 determines that there is a discharge port 108 that has caused a discharge abnormality (S112: NO), the discharge abnormality detection unit 49 displays that fact on a display device (not shown) (S113). This completes the printing operation.

  As described above, according to the ink jet printer 101 of the present embodiment, the paper P coated with the precoat liquid comes into contact with the discharge port 108 of the ink jet head 1 when the paper P is clogged, and the ink and the precoat liquid are discharged at the discharge port 108. Are mixed, the ink is discharged from the ejection port 108 immediately after the paper jam is detected. In this way, since the mixed ink and the precoat liquid are discharged before the pigment component of the ink aggregates or precipitates at the ejection port 108, the ejection port 108 is caused by the aggregate or deposit of the pigment component of the ink. Occlusion can be prevented.

  Further, the pump 32 forcibly supplies ink to the ink supply port 105b of the flow path unit 9 via the reservoir unit in the corresponding inkjet head 1, thereby discharging the ink in the ejection port 108 to the outside. Ink can be efficiently discharged from the ejection port 108.

  Further, the purge control unit 44 controls the pump 32 so that the ink is discharged from the ejection port 108 of the inkjet head 1 specified by the paper jam detection unit 43 immediately after the paper jam detection unit 43 detects the paper jam. Driving is started, and when the four inkjet heads 1 and the precoat head 2 are moved from the printing position to the maintenance position, the driving of the pump 32 is stopped. As described above, since the ink is continuously discharged from the discharge port 108 until the preparation for removing the jammed paper P is completed, the discharge port 108 is further prevented from being blocked by aggregates or deposits of the pigment component of the ink. can do.

  At this time, the paper jam detection unit 43 is based on the detection results of the six paper sensors 31a to 31f arranged on both sides of the precoat head 2 in the transport direction and on the downstream side of the four inkjet heads 1 in the transport direction. Thus, in order to identify the inkjet head 1 facing the paper P, it is possible to easily identify the ejection port 108 from which the ink is to be ejected, and the ink can be ejected by ejecting ink only from the characteristic ejection port 108. It is possible to suppress wasteful discharge.

  Further, the purge control unit 44 increases the amount of ink discharged from the ejection port 108 related to the inkjet head 1 as the amount of the precoat liquid applied to the jammed paper P increases. In other words, since the drive rotation speed of the pump 32 is controlled so that the amount of discharged ink decreases as the amount of the precoat liquid decreases, it is possible to suppress the wasteful discharge of ink. Can do.

  Further, the purge control unit 44 detects ink discharged from the ejection port 108 of the inkjet head 1 as the distance in the transport direction of the inkjet head 1 specified by the paper jam detection unit 43 from the precoat head 2 becomes shorter. The drive rotational speed of the pump 32 is controlled so that the amount increases. As a result, the amount of ink discharged increases as the undried rate in the precoat liquid adhering to the ejection port 108 increases, so that the ejection port 108 is blocked by the aggregate or precipitate of the pigment component of the ink. It can be prevented efficiently.

  In addition, in the maintenance operation, the wiping of the discharge surface by the wiper 36a after the ink is forcibly discharged from the discharge port 108 of the inkjet head 1 and the cleaning of the outer peripheral surface of the transport belt 8 by the cleaner unit 37 are simultaneously performed. The inkjet printer 101 can be quickly returned to a printable state.

  Further, after the maintenance operation is completed, the test pattern printing unit 48 causes the test pattern 90 to be printed on the paper P, and the ejection abnormality detection unit 49 causes the line sensor 30 to read the test pattern 90 printed on the paper P for analysis. In order to determine whether or not there is an ejection port 108 that has caused an ejection failure such as a displacement of the landing position of the ink droplet or a non-ejection of the ink droplet, is the ejection port 108 related to the inkjet head 1 closed? Whether or not can be reliably detected.

  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. In the above-described embodiment, the pump 32 forcibly supplies ink to the ink supply port 105 b of the flow path unit 9 via the reservoir unit in the corresponding inkjet head 1 or precoat head 2. However, it may be configured such that the ink in the ejection port 108 is discharged by driving the actuator unit 21 of the inkjet head 1. The discharge method in this case indicates that ink droplets are discharged from all the discharge ports 108 of the ink jet head 1 by driving the actuator unit 21, and the ink droplets are discharged a plurality of times until a predetermined discharge amount is reached. It is desirable to do.

  In the above-described embodiment, the pump 32 is driven immediately after the paper jam detection unit 43 detects paper jam until the four inkjet heads 1 and the precoat head 2 are moved from the printing position to the maintenance position. In this configuration, the discharge of the ink from the ejection port 108 is continued. However, until a predetermined time elapses after the paper jam detection unit 43 detects the paper jam, or the paper jam detection unit 43 detects the paper jam. The configuration may be such that ink is continuously discharged from the ejection port 108 immediately after detection until the user receives a discharge stop command. Further, in the above-described embodiment, the head lifting control unit 45 is configured to move the four inkjet heads 1 and the precoat head 2 from the printing position to the maintenance position in response to a removal work start command from the user who performs the removal work. However, it may be moved to the maintenance position without receiving a removal work start command from the user. In this case, the jammed paper P and the four inkjet heads 1 and the precoat head 2 can be separated quickly, so that the pretreatment liquid applied to the paper can be prevented from continuing to adhere to the ejection surface of the inkjet head.

  Further, in the above-described embodiment, the paper jam detection unit 43 includes six paper sensors 31a to 31a disposed on both sides of the precoat head 2 in the transport direction and on the downstream side of the four inkjet heads 1 in the transport direction. Based on the detection result of 31f, the configuration is such that the inkjet head 1 that should discharge ink from the ejection port facing the paper P is specified, but the upstream side in the transport direction of the precoat head 2 or the four inkjet heads 1, In addition, a configuration in which a total of two paper sensors are arranged one by one on the downstream side in the transport direction of the four inkjet heads 1 may be employed. At this time, the paper jam detection unit detects a paper jam if the downstream paper sensor does not detect the paper P after a predetermined time after the upstream paper sensor detects the paper, and immediately after detecting the paper jam. It is preferable to start discharging ink from the ejection ports 108 associated with all the inkjet heads 1. According to this, since the paper jam can be detected efficiently by the two paper sensors, the number of paper sensors can be reduced and the cost can be reduced.

  In addition, in the above-described embodiment, the paper jam detection unit 43 is applied to the jammed paper P as the distance in the transport direction from the precoat head 2 of the inkjet head 1 specified is shortened. As the amount of the precoat liquid increases, the amount of ink discharged from the ejection port 108 of the inkjet head 1 increases, but the distance of the inkjet head 1 from the precoat head 2 in the transport direction and clogging. The amount of ink discharged from the ejection port 108 may not be changed by at least one of the amounts of the precoat liquid applied to the sheet P.

  Further, in the above-described embodiment, in the maintenance operation, the wiper 36a wipes the discharge surface after the ink is discharged from the discharge port 108 of the inkjet head 1, and the cleaner unit 37 cleans the outer peripheral surface of the transport belt 8. However, a configuration in which these are performed at different timings may be used.

  In addition, in the above-described embodiment, after the maintenance operation is completed, the test pattern 90 is printed on the paper P, and the discharge port 108 causing the discharge abnormality from the result of reading the test pattern 90 by the line sensor 30. However, there may be a configuration in which it is not determined whether or not there is the ejection port 108 that causes the printing and ejection abnormality of the test pattern 90.

  In the above-described embodiment, the precoat liquid is applied to the paper P by discharging the precoat liquid droplets from the discharge port 108 of the precoat head 2. However, the precoat liquid is applied to the paper P in another structure. May be. For example, the precoat liquid may be applied to the paper P by bringing a roller that holds the precoat liquid on the outer peripheral surface into contact with the paper P.

  Furthermore, in the above-described embodiment, the head lifting mechanism 33 is configured to lift and lower the four inkjet heads 1 and the precoat head 2 together with the frame 35, but the head lifting mechanism is configured to lift only the inkjet head 1. Or the structure which raises / lowers the conveyance unit 20 may be sufficient. In the latter case, the inkjet head 1 may be fixed, or may be movable up and down.

  In addition, in the above-described embodiment, immediately after the paper jam detection unit 43 detects the paper jam, the ink from the ejection port 108 related to the inkjet head 1 specified by the paper jam detection unit 43 is discharged, and another ink jet Although the configuration is such that ink is not discharged from the ejection port 108 related to the head 1, the configuration may be such that ink droplets are ejected by driving the actuator unit 21 from the ejection port 108 related to another inkjet head 1. According to this, it is possible to suppress the viscosity of the ink in the ejection ports 108 related to the other inkjet heads 1 from being increased.

  Further, in the above-described embodiment, in the purge operation, the ink is forcibly discharged from the ejection port 108 in units of the inkjet head, but a part of the inkjet head can be obtained by making the flow paths in the inkjet head independent from each other. The ink may be discharged from only the discharge ports facing the paper P among the discharge ports related to the inkjet head 1. For example, a configuration in which the width of the paper P to be conveyed and the position of the paper P in the main scanning direction is detected, the ejection port facing the paper P is identified based on the detection result, and ink is discharged from the identified ejection port It may be. According to this, it is possible to further suppress the wasteful discharge of ink.

  In the above-described embodiment, the four inkjet heads 1 are configured to eject ink droplets of different colors, but two, three, or five or more inkjet heads 1 are configured to eject ink droplets of different colors. There may be a configuration in which one inkjet head ejects ink droplets and precoat droplets of a plurality of colors.

  The present invention is also applicable to a liquid ejecting apparatus that ejects liquid other than ink. Further, the present invention is not limited to a printer, and can be applied to a facsimile, a copier, and the like.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Precoat head 8 Conveyor belt 16 Control apparatus 30 Line sensor 31a-31f Paper sensor 32 Pump 33 Head raising / lowering mechanism 34 Head control part 36 Wiper unit 36a Wiper 37 Cleaner unit 37a Cleaning liquid application member 37b Blade 42 Head control part 43 Paper Clogging detection unit 44 Purge control unit 45 Head lift control unit 46 Wiper control unit 47 Cleaner control unit 48 Test pattern printing unit 49 Discharge abnormality detection unit 50 Conveyance control unit 101 Inkjet printer 108 Discharge port

Claims (9)

A transport mechanism for transporting the recording medium;
A liquid discharge head in which discharge ports for discharging a first liquid for forming an image on a recording medium are formed;
A second liquid application that is disposed upstream of the liquid ejection head in the recording medium conveyance direction and applies a second liquid that reacts with the first liquid and aggregates or precipitates components in the first liquid to the recording medium. Means,
Detecting means for detecting clogging of a recording medium at a position facing the ejection port;
Discharging means for discharging the first liquid from the discharge port;
Control means for controlling the discharge means,
The liquid ejection apparatus, wherein the control unit controls the ejection unit so that the first liquid is ejected from the ejection port immediately after the detection unit detects the clogging of the recording medium.   The discharge means includes a pump that discharges the first liquid from the discharge port by forcibly supplying the first liquid to a liquid flow path connected to the discharge port. The liquid ejection device according to claim 1. A moving mechanism that moves at least one of the transport mechanism and the liquid discharge head so that the distance between the transport surface of the transport mechanism and the discharge port changes;
The control means starts from the discharge port immediately after the detection unit detects clogging of the recording medium until the moving mechanism sets the distance between the transport surface and the discharge port to a predetermined value or more. The liquid discharging apparatus according to claim 1, wherein the discharging unit is controlled so as to continue to be discharged.   The control means discharges from the discharge port as the amount of the second liquid applied to the recording medium by the second liquid applying means increases until the detection means detects clogging of the recording medium. The liquid discharging apparatus according to claim 1, wherein the discharging unit is controlled so that the amount of the first liquid to be increased is increased. A wipe mechanism having a wiper for wiping the discharge port;
A cleaning mechanism for cleaning the transport surface of the transport mechanism,
The wiping of the discharge port by the wiping mechanism and the cleaning of the transport surface by the cleaning mechanism are performed simultaneously after the clogging of the recording medium is released. The liquid ejection device according to item. An image sensor for reading an image recorded on a recording medium;
Test pattern control for controlling the liquid ejection head so that a test pattern is recorded on the recording medium by ejecting droplets of the first liquid from all the ejection openings after the clogging of the recording medium is released Means,
Judgment means for judging whether or not liquid droplets have been ejected from each ejection port from the reading result of the image sensor when the test pattern control unit has recorded the test pattern on a recording medium. The liquid discharge apparatus according to claim 1, wherein the liquid discharge apparatus is a liquid discharge apparatus. A plurality of the liquid discharge heads arranged in the transport direction;
The detecting means is disposed on the downstream side of the liquid ejection head in the transport direction, and has a plurality of recording medium sensors for detecting the presence or absence of a recording medium;
The detection means identifies the liquid ejection head facing the jammed recording medium from the detection results of the plurality of recording medium sensors,
The control means controls the discharge means so that the first liquid is discharged from the discharge port of the liquid discharge head specified by the detection means immediately after the detection means detects the clogging of the recording medium. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.   The control unit is configured to reduce the discharge rate of the liquid discharge head specified by the detection unit as the distance from the second liquid application unit to the liquid discharge head specified by the detection unit in the transport direction decreases. The liquid discharge apparatus according to claim 7, wherein the discharge unit is controlled so that the amount of the first liquid discharged from the outlet increases. The detection means has two recording medium sensors that detect the presence or absence of a recording medium respectively arranged on the upstream side of the second liquid applying means and the downstream side of the liquid ejection head in the transport direction;
The control means controls the discharge means so that the first liquid is discharged from the discharge ports of all the liquid discharge heads immediately after the detection means detects the clogging of the recording medium. The liquid ejecting apparatus according to claim 1.

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