JP2019084734A - Ink jet recording device - Google Patents

Abstract

To provide an ink jet recording device in which occurrence of a minute leak hole in a recording head can be detected.SOLUTION: An ink jet recording device has: a recording head 22 which has a nozzle face 22a provided with a nozzle 19 for discharging an ink; sealing means 52 which is brought into contact with the nozzle face, thereby tightly sealing the nozzle; filling means 52 which so makes a portion of the ink accommodated in the recording head, which may leak to the exterior of the recording head, as to be in an ink-filled state; negative pressure application means 35 which applies a negative pressure to the interior of the recording head; pressure detection means 34 which detects a pressure in the recording head; and notification means which performs notification to a user on the basis of change in the negative pressure applied to the recording head by the negative pressure application means in the state that the nozzle is tightly sealed by the sealing means, and the portion, which may leak, is filled with the ink by the filling means.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an inkjet recording apparatus.

  Conventionally, in an ink jet recording apparatus, it is regularly monitored whether there is a change with time with respect to changes in parts constituting the ink flow path in the apparatus, and if necessary from the monitoring result, the parts are replaced. There are some that display a warning such as prompting. As an example of this prior art, in the ink jet recording apparatus of Patent Document 1, for example, a filter for a foreign matter trap is provided in the ink flow path to prevent foreign matter flowing from the ink flow path from mixing into the recording head. It is done. In this conventional recording apparatus, the clogging of the filter is determined from the pressure level of the ink at the time of pressurization in the flow path measured using a pressure sensor provided at a position on the upstream side of the filter in the ink flow path. In case of clogging, a warning display prompting replacement of the filter is provided.

JP 2005-53075 A

  By the way, in the ink jet recording apparatus, the recording head may change with time. For example, when the adhesive strength of the sealant or adhesive used in the recording head is deteriorated due to the deterioration with time, part of the adhered portion may be peeled off to generate minute leak holes. In order to detect the occurrence of a minute leak hole at the bonding portion of such a recording head, the ink flow path is pressurized as in the conventional recording apparatus described above, and pressure is applied in the flow path using a pressure sensor It is conceivable to measure the pressure level of the ink.

  However, in the conventional recording apparatus, since the nozzles of the recording head are open to the atmosphere, when pressure is applied to the ink flow path, the ink not only leaks out from the minute leak holes, or from the nozzles before leaking. Ink will be discharged. That is, in the conventional recording apparatus, since the pressure level of the ink in the flow path is changed by the discharge from the nozzle, the change of the pressure level due to the ink leakage from the minute leak hole which should be detected is concealed. It was not possible to detect the occurrence of micro leak holes in the bonded area.

  Therefore, an object of the present invention is to provide an ink jet recording apparatus capable of detecting the occurrence of a minute leak hole in a recording head.

The inkjet recording apparatus according to the present invention is
A recording head having a nozzle surface provided with a nozzle for ejecting ink;
Sealing means for sealing the nozzle in contact with the nozzle surface;
A filling unit for filling a portion where ink leaked to the outside of the recording head may be caused to be filled with the ink,
Negative pressure application means for applying a negative pressure to the inside of the recording head;
Pressure detection means for detecting the pressure inside the recording head;
With the sealing means sealing the nozzle and the filling means filling the portion where the leak may occur, based on the change in negative pressure applied to the recording head by the negative pressure applying means. Notification means for notifying the user;
It is characterized by having.

  According to the present invention, it is possible to provide an ink jet recording apparatus capable of detecting the occurrence of minute leak holes in a recording head.

FIG. 1 is a schematic configuration diagram of an inkjet recording apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view of a cross section of a recording head in an ink jet recording apparatus. FIG. 2 is a block diagram of a capping mechanism provided in the inkjet recording apparatus. FIG. 2 is a view schematically showing the main configuration of an ink supply system and a recovery system in the inkjet recording apparatus. FIG. 2 is a block diagram showing the configuration of a control system of the inkjet recording apparatus. It is a figure for demonstrating the wiping operation | movement which an inkjet recording device performs. 6 is a flowchart (main routine) showing control for detecting the occurrence of a minute leak hole in the recording head. 7 is a flowchart (subroutine) showing control for detecting the occurrence of a minute leak hole in the recording head. FIG. 6 is a diagram showing a state of a leak check operation performed by the inkjet recording apparatus. It is the graph which showed the difference by the existence of the generating of the leak hole of the pressure change which a pressure sensor detects.

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

  FIG. 1 is a schematic view of an inkjet recording apparatus according to an embodiment of the present invention. A printer 10, which is an ink jet recording apparatus according to the present embodiment, is connected to a host PC (personal computer) 12 that transmits image information and the like for printing to the printer 10.

  In the printer 10, four print heads 22K, 22C, 22M and 22Y are arranged in order in the conveyance direction of the recording medium P (left direction indicated by arrow A in the figure). The four print heads 22K, 22C, 22M, and 22Y respectively eject ink of each color of black, cyan, magenta, and yellow. These four print heads 22 K, 22 C, 22 M, 22 Y are so-called line heads, and extend in the direction orthogonal to the conveyance direction of the recording medium P. Then, the length of each print head in the orthogonal direction is set to be slightly longer than the width of the recording medium in order to cover the width of the largest size recording medium usable for printing by the printer 10 ing. These four print heads 22K, 22C, 22M and 22Y are fixed so as not to move during formation of an image in the recording operation.

  Further, the printer 10 is provided with a recovery unit 40 for causing the four print heads 22 K, 22 C, 22 M, 22 Y to stably eject ink. In the printer 10, by performing the recovery operation using the recovery unit 40, the ink ejection state of each of the print heads 22K, 22C, 22M, and 22Y is recovered so as to be in the initial state. The recovery unit 40 includes a capping mechanism 50 having a blade or the like for removing ink from the ink discharge port forming surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the print heads 22K, 22C, 22M, and 22Y during the recovery operation. It is done. The capping mechanism 50 is provided independently for each of the print heads 22K, 22C, 22M, and 22Y, and the printer 10 according to the present embodiment is provided with four capping mechanisms 50 (that is, four colors).

  Here, the four print heads 22K, 22C, 22M and 22Y are moved to the standby position shown in FIG. 1 at the time of standby. At this time, the four capping mechanisms 50 of the recovery unit 40 are generally moved to the right position away from the print head to avoid interference with the print heads 22K, 22C, 22M, 22Y as shown in FIG. ing. The four print heads 22K, 22C, 22M and 22Y are moved to the recording position (image forming position) below the standby position shown in FIG. The ink is discharged at the positions close to each other to form an image. During the recovery operation, the four print heads 22K, 22C, 22M, and 22Y are moved upward as a whole, and the positions at which the capping mechanisms 50 face the ink ejection port formation surface of the corresponding print head. To each other (move to the left in FIG. 1). The details of the capping mechanism 50 will be described later.

  Further, the printer 10 is provided with a roll paper supply unit 14 for storing a recording medium (roll paper in the present embodiment) P, and the roll paper P supplied from the roll paper supply unit 14 is A transport mechanism 26 for transporting is provided. The recording medium is not limited to roll paper. The transport mechanism 26 comprises a transport belt 26a for loading and transporting the roll paper P, a transport motor 26b for rotating the transport belt 26a, and a roller 26c for applying tension to the transport belt 26a. When forming an image on the roll paper P, printing is performed based on the recording data (image information) after the recording start position of the roll paper P being conveyed reaches under the print head 22K for black. The black ink is selectively ejected from the head 22K. When forming a color image, the ink of each color is selectively selected in the order of the print head 22C for cyan, the print head 22M for magenta, and the print head 22Y for yellow based on the image information in the same procedure. Forms a color image on the roll paper P by

  In addition, the printer 10 is provided with main tanks 28K, 28C, 28M, and 28Y for storing the inks supplied to the print heads 22K, 22C, 22M, and 22Y. The main tanks 28 K, 28 C, 28 M, 28 Y are configured to be attachable to and detachable from the printer 10.

  FIG. 2 is a schematic view of a cross section of a recording head in the ink jet recording apparatus (printer 10) of the present embodiment. Since each print head has the same structure, hereinafter, the print heads 22K, 22C, 22M and 22Y will be generally referred to as the print head 22 and described. The recording head 22 includes a chip 20 having a nozzle portion 19 (corresponding to the nozzle of the present invention) for ejecting ink, a supply box 24 having a main supply liquid chamber 23 for storing ink in the recording head, and a base plate It consists of 27. Although FIG. 2 shows the cross section of the nozzle portion 19 for one nozzle, in fact, the recording head 22 has a plurality of nozzles (nozzle portions 19) in the longitudinal direction (width of the recording medium). Are provided to form a nozzle row.

  The chip 20 and the supply box 24 are aligned such that the ink supply ports communicate with each other through the bonding portion 25, and the bonding portion 25 is bonded by a sealant. On the other hand, the chip 20 and the base plate 27 are bonded with an adhesive. Further, the base plate 27 and the supply box 24 are assembled by screws (not shown). In the recording head 22, the bottom surface of the chip 20 on which the ink discharge ports of the nozzle portion 19 are formed (corresponding to the ink discharge port forming surfaces 22 Ks, 22 Cs, 22 Ms, and 22 Ys in FIG. 1) includes the supply box 24 and the base plate 27. It has a shape projecting downward from the bottom surface of. Hereinafter, the bottom surface of the chip 20 in the recording head 22 is referred to as a nozzle surface 22s. Further, in the recording head 22, when ink is supplied into the main supply liquid chamber 23 of the supply box 24, the interval from the portion of the ink liquid surface to the ink discharge port of the nozzle portion 19 in the chip 20 is normal ink It will be filled with

  FIG. 3 is a view showing the configuration of a capping mechanism 50 provided in the ink jet recording apparatus (printer 10) of the present embodiment. The capping mechanism 50 has a known cap 51 for preventing the ink from drying in the nozzle portion 19 of the recording head 22, a blade 52 for removing the ink from the nozzle surface 22s of the recording head 22, and the blade 52 Blade holding member 53 is provided. In the printer 10, the capping mechanism 50 is disposed such that the longitudinal direction of the cap 51 and the blade 52 is parallel to the nozzle array of the recording head 22. Here, the cap 51 and the blade 52 are configured such that the height of the blade 52 is higher than that of the cap 51 as shown in FIG. The following points are considered for these arrangements. When capping the nozzle row (mainly the nozzle surface 22s) of the recording head 22 using the cap 51, if the top of the blade 52 next to it interferes with the bottom of the supply box 24, capping does not occur well . Therefore, in the capping mechanism 50, an interval of the amount that does not cause interference during capping is provided between the cap 51 and the blade 52 and disposed. In this case, the entire blade 52 is positioned to the side of the supply box 24 at the time of capping.

  The length in the longitudinal direction (the nozzle row direction) of the blade 52 is longer than the entire length of the nozzle row so as to be able to wipe. A groove is formed in the nozzle row direction in the upper portion of the blade 52 to form a concave shape, and the depth of the groove is the distance from the bottom surface of the supply box 24 and base plate 27 of the recording head 22 to the nozzle surface 22s of the chip 20 It is shorter than that. Hereinafter, the groove at the top of the blade 52 is also referred to as a recess (corresponding to the sealing means and the filling means of the present invention). The blade 52 is manufactured using an elastic body such as rubber or elastomer.

  FIG. 4 is a view schematically showing the main configuration of the ink supply system and the recovery system in the ink jet recording apparatus (printer 10) of the present embodiment. Hereinafter, the main tanks 28K, 28C, 28M, and 28Y will be generally referred to as a main tank 28.

  The ink supply system of the printer 10 mainly includes the recording head 22, the main tank 28, the ink flow path 30, the refill valve 31, the air flow path 32, the supply valve 33, the buffer chamber 35, the pump 37 and the like. The ink flow path 30 connects the main tank 28 and the recording head 22. The refill valve 31 is an on-off valve that opens and closes the ink flow path 30. The air flow path 32 communicates with the ink flow path 30 via the inside of the recording head 22. The supply valve 33 is an on-off valve that opens and closes the air flow path 32. The buffer chamber 35 (corresponding to the negative pressure application means of the present invention) is a member for storing the pressure due to the change of the volume of the gas, and is connected to the air flow path 32. The pump 37 (corresponding to the negative pressure applying means and the pressurizing means of the present invention) is connected to the buffer chamber 35. Further, a pressure sensor 34 is provided in the air flow path 32. The pressure sensor 34 (corresponding to the pressure detection means of the present invention) can detect the level of pressure in the recording head 22 and in the buffer chamber 35. Further, the buffer chamber 35 is provided with a buffer valve 36 which is an on-off valve for communicating the inside of the buffer chamber 35 to the atmosphere when the valve is opened and returning the pressure to an initial state.

  In the printer 10, when the pump 37 is driven to suck air while the buffer valve 36 is closed and the supply valve 33 is opened, the inside of the air flow path 32 and the recording head 22 via the buffer chamber 35 Depressurized. Due to the pressure reduction, when the refill valve 31 is opened, the ink stored in the main tank 28 is suctioned through the ink flow path 30, and the ink is supplied to the recording head 22. A supply filter 18 is disposed in the recording head 22, and the ink supplied to the recording head 22 passes through the supply filter 18, flows into the main supply liquid chamber 23, and is stored there. In the ink supply system, the ink stored in the main supply liquid chamber 23 is configured not to flow out to the air flow path 32 side. The ink stored in the main supply liquid chamber 23 is eventually supplied into the nozzle unit 19 and discharged from the ink discharge port by the discharge operation of the recording head 22 or the like.

  The liquid level detection sensor 21 is attached to a part of the main supply liquid chamber 23, and the control of the ink supply is performed according to the detection result. That is, in the printer 10, when it is determined from the detection result that the liquid level of the main supply liquid chamber 23 is lower than a predetermined level, the pump 37 is driven to suck ink from the main tank 28. The suctioned ink is supplied to the recording head 22 and stored in the main supply liquid chamber 23. Then, in the printer 10, when it is determined from the detection result that the liquid level of the main supply liquid chamber 23 exceeds a certain level, the pump 37 is stopped to stop the supply of the ink to the recording head 22.

  Next, the recovery system of the printer 10 is mainly configured by the cap 51 of the capping mechanism 50, the recovery flow path 39, the pump 38, the waste liquid tank 29, and the like. The cap 51 is connected to the suction port of the pump 38 via the recovery flow passage 39. Although not shown in FIG. 4, actually, the caps corresponding to the print heads 22K, 22C, 22M and 22Y shown in FIG. 1 are respectively connected to the recovery flow path 39, and each cap is The suction port of the pump 38 is connected via the recovery flow path 39. Further, the discharge port of the pump 38 is connected to a waste liquid tank 29 for storing waste liquid (waste ink) generated by the cleaning operation.

  In the printer 10, a cleaning operation is required to discharge ink stably from the recording head 22. The cleaning operation is one of the recovery operations, which removes fine air bubbles and foreign substances (dust and the like) remaining in the nozzle portion 19 and the ink which is thickened by drying and fills the nozzle portion 19 with fresh ink. It is an operation. In the printer 10, during the cleaning operation, the capping mechanism 50 is moved to position the cap 51 at a position facing the nozzle surface 22s of the recording head 22. Thereafter, in the printer 10, the recording head 22 is lowered such that the nozzle portion 19 of the recording head 22 is sealed by the cap 51. As a result, the cap 51 abuts on the nozzle surface 22s to be in close contact (capping). Then, in the printer 10, by driving the pump 38 after this capping, the inside of the recovery flow path 39 and the cap 51 is decompressed, and residual air bubbles and foreign substances are sucked from the nozzle portion 19 of the recording head 22 together with a small amount of ink. . The sucked ink (waste ink), air bubbles and the like are discharged to the waste liquid tank 29.

  Further, when the power of the printer 10 is turned off (OFF), the refill valve 31 is opened, the supply valve 33 is closed, and the buffer valve 36 is controlled to be opened in the end operation, and the recording head is controlled. 22 is capped by cap 51. Thus, the drying of the ink at the nozzle portion 19 of the recording head 22 is prevented.

  FIG. 5 is a block diagram showing a configuration of a control system of the inkjet recording apparatus (printer 10) of the present embodiment.

  The CPU 100 is an arithmetic processing unit that generally controls the printer 10, and controls the overall operation performed by the printer 10 such as reception of recording data and commands, recording operation, handling of roll paper P, and the like. Recording data and commands transmitted by the host PC 12 are received by the CPU 100 via the interface controller 102. When these are received, after analyzing the command, the CPU 100 develops the image data of each color component of the recording data (image information) into a bit map in the image memory 106 and stores it. In performing the recording operation, the CPU 100 drives the capping motor 122 and the head up / down motor 118 via the output port 114 and the motor drive unit 116. By this driving, the CPU 100 moves the four capping mechanisms 50 to a position away from the print head as a whole, and moves each print head 22K, 22C, 22M, 22Y to a recording position (image forming position). Subsequently, the CPU 100 drives a roll motor (not shown) that delivers the roll paper P via the output port 114 and the motor drive unit 116, and a transport motor 26b that transports the roll paper P at a low speed. And roll paper P to the recording start position. At this time, the CPU 100 uses a tip detection sensor (not shown) for determining the timing (recording timing) to start discharging ink to the roll paper P conveyed at a constant speed. Detect the tip position. Thereafter, the CPU 100 sequentially reads out the image data of each color component stored from the image memory 106 in synchronization with the conveyance of the roll paper P. Then, the CPU 100 transfers the read image data of each color component to the print head control circuit 112, and starts the discharge of the ink by the print heads 22K, 22C, 22M, and 22Y. Thereby, in the printer 10, formation of an image on the roll paper P is performed.

  When the CPU 100 supplies ink to the print heads 22K, 22C, 22M, 22Y or performs cleaning operation, the CPU 100 drives the pump motor 124 via the output port 114 and the motor drive unit 116 to supply or suction ink, etc. Control the

  Further, when performing the wiping operation, the CPU 100 performs control as follows. The wiping operation is a recovery operation performed to remove ink from each of the ink discharge port forming surfaces 22Ks, 22Cs, 22Ms, and 22Ys (nozzle surface 22s) of the print heads 22K, 22C, 22M, and 22Y (recording heads 22). . The blade 52 of the capping mechanism 50 is used for the wiping operation. An image of this wiping operation is shown in FIG. When the CPU 100 starts the wiping operation, it drives the head up / down motor 118 via the output port 114 and the motor drive unit 116 to raise the recording head 22 to a position above the upper end of the blade 52 of the capping mechanism 50. . Thereafter, the CPU 100 drives the capping motor 122 via the output port 114 and the motor drive unit 116 to move the capping mechanism 50, and arranges the cap 51 at a position facing the nozzle surface 22 s of the recording head 22. The movement of the capping mechanism 50 by the capping motor 122 is performed in the direction orthogonal to the nozzle array of the recording head 22. Thereafter, the CPU 100 drives the head up / down motor 118 via the output port 114 and the motor drive unit 116 to lower the recording head 22 slightly. Here, the distance to be lowered is less than the depth of the groove formed in the upper portion of the blade 52, and is a distance within the range in which wiping by the blade 52 can be effectively performed. Then, the CPU 100 drives the capping motor 122 via the output port 114 and the motor drive unit 116, and moves the capping mechanism 50 (moves in the right direction indicated by the arrow B in the example of FIG. 6). By this movement, the nozzle surface 22s of the recording head 22 and the ink discharge port of the nozzle portion 19 formed thereon are wiped by the upper end portion of the blade 52, and the ink droplet and foreign matter adhering to the nozzle are removed.

  The program ROM 104 also stores processing programs corresponding to the above control operations and the like, and data (tables and the like) used in the programs. The CPU 100 executes control based on the processing program stored in the program ROM 104. At the time of execution of control, a work RAM 108 is used as a working memory.

  The CPU 100 can also execute the cleaning operation, the wiping operation, and the like in accordance with an instruction from the user via the operation panel 110.

  By the way, in the ink jet recording apparatus, for example, when the adhesive strength of the sealing agent or adhesive used in the recording head is deteriorated due to the deterioration with time, peeling occurs in a part of the adhered portion and a minute leak hole is generated. May. In the inkjet recording apparatus (printer 10) according to the present embodiment, when ink is supplied to the recording head 22, as shown in FIG. 2, the ink in the nozzle portion 19 in the chip 20 from the main supply liquid chamber 23 of the supply box 24. The space until the discharge port is normally filled with ink. In this case, since the bonding portion 25 between the supply box 24 and the chip 20 is constantly in contact with the ink, the bonding strength of the bonding portion 25 may gradually decrease with the passage of time. When the adhesive strength is reduced, peeling may eventually occur in a part of the adhesive portion 25 and a minute leak hole may be generated there.

  In order to detect the occurrence of a minute leak hole at a bonding point in such a recording head, the ink flow path is pressurized as in the conventional recording apparatus, and pressure is applied in the flow path using a pressure sensor. It is conceivable to measure the pressure level of the ink. However, in the ink jet recording apparatus, since the nozzles of the recording head are normally open to the atmosphere, when pressure is applied to the ink flow path, the ink not only leaks out from the leak hole, or before it leaks out. Ink will be discharged from the nozzle. As a result, the pressure level of the ink in the flow path is changed due to the discharge from the nozzle, and the change of the pressure level due to the ink leak from the minute leak hole to be originally detected is hidden. It becomes difficult to detect the occurrence of leak holes.

  In addition, in order to measure the change in pressure level due to the ink leakage from the leak hole that has occurred, it is necessary to break the meniscus formed on the inlet side of the leak hole by the ink in the recording head. It is necessary to apply the above pressure to the ink flow path. The smaller the leak hole, the stronger the meniscus of the ink formed on the inflow side, so that it is necessary to apply a larger pressure to the ink flow path in order to break the meniscus. When a large pressure is applied to the ink flow path, for example, if there is a leak from a connection of a tube, a leak from a crack in the tube itself or the like, the pressure level changes due to the leak. Therefore, it becomes more difficult to detect the occurrence of a minute leak hole in the recording head from the measurement result of the pressure level.

  Therefore, in the ink jet printing apparatus according to the present embodiment, the occurrence of the minute leak holes in the print head can be detected by the detection method described below. In addition, below, this detection method is demonstrated using FIGS. 7-10.

  7 and 8 are flowcharts showing control for detecting the occurrence of a minute leak hole in the recording head. These control programs are stored in advance in the program ROM 104 of the printer 10 and executed by the CPU 100 when the printer 10 is started. FIG. 7 is a main routine of a control program for detecting the occurrence of a minute leak hole in the recording head, and FIG. 8 is configured as a subroutine called from the main routine.

  When control is started, the CPU 100 reads out information on the mounting date and time recorded when the recording head 22 is mounted to the printer 10 from the non-volatile area of the work RAM 108 or the like in step S1. Then, based on the information of the mounting date and time, the elapsed period after the recording head 22 is mounted to the printer 10 is calculated, and it is determined whether the elapsed period exceeds a predetermined elapsed period. That is, it is determined whether or not a predetermined period has elapsed since the mounting of the recording head 22. Here, it is desirable that the predetermined elapsed period is a preset value, and it is desirable that it be a life period of the bonding portion 25 by the sealant used in the recording head 22, and that micro leak holes may start to occur. Set an elapsed period.

  As a result of the determination, when the calculated elapsed time does not exceed the predetermined elapsed time, the CPU 100 ends the control without performing the leak check as the minute leak hole is not generated (No side). On the other hand, when the calculated elapsed time exceeds the predetermined elapsed time, the CPU 100 proceeds to the process of step S2 (Yes side).

  In step S2, the CPU 100 determines whether there is a leak check history. The leak check history is information for determining an elapsed time from the execution of the previous leak check, and is recorded in a nonvolatile area or the like of the work RAM 108. When the recording head 22 is attached to the printer 10, information indicating "no history" is recorded as an initial value. Further, when the first process of the leak check of the subroutine (FIG. 8) is executed, the information of the date and time of the execution is recorded as the information of the previous leak check history.

  As a result of the determination, the CPU 100 does not have a leak check history, that is, if the leak check has not been performed yet, the CPU 100 proceeds to step S4 to perform a leak check process (Yes side). On the other hand, when there is a leak check history, the CPU 100 proceeds to step S3 in order to determine the elapsed time from the previous execution of the leak check (No side).

  In step S3, the CPU 100 calculates an elapsed time from the previous execution of the leak check, and determines whether the elapsed time exceeds a predetermined time. That is, it is determined whether a predetermined time has elapsed since the previous execution of the leak check. Here, the predetermined time is a value set in advance, and is a value indicating an interval at which the leak check should be performed.

  As a result of the determination, if the calculated elapsed time from the previous time does not exceed the predetermined time, the CPU 100 ends the control without performing the leak check, since the possibility of the occurrence of the minute leak hole is low. No side). On the other hand, when the elapsed time from the previous time exceeds the predetermined time, the CPU 100 proceeds to step S4 to perform a leak check because there is a possibility that a minute leak hole is generated (Yes side).

  In step S4, the CPU 100 calls the subroutine of FIG. 8 to perform a leak check process.

<Subroutine>
When the process of the subroutine is started, in step S41, the CPU 100 records information of the current date and time as a leak check history information in a nonvolatile area of the work RAM 108 or the like.

  Next, in step S42, in order to start the leak check, the CPU 100 first performs a pressing operation to press the inside of the recording head 22 to discharge the ink from the nozzles. Specifically, as shown in FIG. 9A showing the state of the leak check operation, the CPU 100 closes the refill valve 31, opens the supply valve 33, and closes the buffer valve 36. By driving the pump 37, the recording head 22 is pressurized. Then, when the pressure in the recording head 22 is increased by the pressurizing operation using the pump 37, the ink is gradually discharged from the nozzle portion 19 and adheres to the nozzle surface 22s. The pressing operation on the recording head 22 is performed after disposing the cap 51 of the capping mechanism 50 just below the nozzle surface 22s of the recording head 22 in consideration of the case where the ink on the nozzle surface 22s falls. Make it

  Next, in step S43, with the ink attached to the nozzle surface 22s, the CPU 100 presses the recess of the blade 52 of the capping mechanism 50 against the nozzle surface 22s to seal the nozzle portion 19. Specifically, as shown in FIG. 9B, the CPU 100 closes the supply valve 33 so as to maintain the pressure in the recording head 22 as it is, and drives the head up / down motor 118 to make the recording head Raise 22. Here, the pressure in the recording head 22 is maintained in a state in which the pressure is increased by pressurization. Next, the CPU 100 drives the capping motor 122 to move the capping mechanism 50 until the recess of the blade 52 is positioned just below the nozzle of the recording head 22. Then, when the recess of the blade 52 is positioned directly below the nozzle, the CPU 100 drives the head up / down motor 118 to lower the recording head 22 and presses the recess of the blade 52 against the nozzle surface 22s of the chip 20. Make them adhere closely. Thereby, the nozzle part 19 is sealed. At this time, a gap is formed between the tip 20 and the recess of the blade 52 by bringing the nozzle surface 22 s of the tip 20 into contact with the recess of the blade 52. Then, the ink discharged from the nozzle by the above-described pressurizing operation flows into the gap, and as a result, as shown in FIG. 9C, the periphery of the bonding portion 25 becomes filled with the discharged ink. The ink around it forms a meniscus I.

  Next, in step S44, the CPU 100 drives the pump 37 to accumulate the negative pressure P in the buffer chamber 35. Specifically, the CPU 100 opens the buffer valve 36 once to return the pressure in the buffer chamber 35 to the atmospheric pressure, and then closes the valve again. Thereafter, as shown in FIG. 9D, the pressure in the buffer chamber 35 is reduced to a preset pressure while driving the pump 37 to monitor the pressure sensor 34, and the negative pressure P is reduced to the buffer chamber 35. Accumulate. The timing at which the negative pressure P starts to be accumulated in the buffer chamber 35 may be simultaneous with the timing at which the nozzle portion 19 is sealed in step S43, but after pressurizing the inside of the recording head in step S42 You may make it start accumulating negative pressure. Thereby, the time required for the leak check can be shortened. When performing these operations, the supply valve 33 is closed first in any case.

  Next, in step S45, the CPU 100 monitors the pressure change ΔP for 10 seconds after applying the negative pressure P stored in the buffer chamber 35 to the recording head 22. Specifically, as shown in FIG. 9E, the CPU 100 applies the negative pressure P stored in the buffer chamber 35 to the recording head 22 by opening the supply valve 33, and the buffer chamber at this time. The pressure change ΔP in 35 is monitored by the pressure sensor 34 for 10 seconds. In this case, since the nozzle portion 19 is sealed as described above, the area from the pump 37 to the inside of the recording head 22 is a sealed system. Since the contact point between the nozzle surface 22s of the recording head 22 and the recess of the blade 52 is filled with ink, when a negative pressure P is applied to the recording head 22, the nozzle surface 22s and the recess are Adhesion is higher.

  Next, in step S46, the CPU 100 determines whether or not a minute leak hole is generated in the bonding portion 25 of the recording head 22 by determining whether or not the pressure change ΔP is equal to or greater than a predetermined value “0.5 kPa”. Do. The predetermined value of the pressure change ΔP is a value appropriately set according to the configuration of the flow path and the recording head.

  By the way, when the supply valve 33 is opened in step S45, the volume of air in the air flow path 32 from the supply valve 33 to the recording head 22 and the volume of air in the recording head 22 are buffered at the moment of opening the valve. The air is added to the air in the chamber 35 to increase its volume. When the leak hole is not generated, the nozzle portion 19 is sealed, and from the inside of the recording head 22 to the pump 37 is a closed system, the pressure in the buffer chamber 35 is as shown in FIG. Immediately after the valve opening, a pressure change corresponding to the increase of the volume occurs, but after that, it becomes constant. In the ink jet recording apparatus of the present embodiment, the pressure change corresponding to the fluctuation (increase) of the volume of air is set to less than “0.5 kPa”. Therefore, if the pressure change .DELTA.P in the buffer chamber 35 monitored by the pressure sensor 34 is ".DELTA.P <0.5 kPa", it is determined that no leak hole has occurred in the bonded portion 25 of the recording head 22.

  On the other hand, when a minute leak hole is generated in the recording head 22, a gap between the tip 20 and the recess of the blade 52 when the negative pressure P is applied to the recording head 22 by opening the supply valve 33. The meniscus I formed around the bonding portion 25 is broken by the ink accumulated in the above. Then, as shown by the thick solid line arrow in FIG. 9F, the ink which has formed the meniscus I is sucked into the main supply liquid chamber 23 of the recording head 22 through the minute leak holes of the bonding portion 25 due to the break. Be At this time, the ink is promoted into the leak holes by capillary force. In this case, as shown in FIG. 10B, the pressure in the buffer chamber 35 changes as the volume of air increases immediately after the supply valve 33 is opened, and the ink is subsequently sucked from the leak hole. It gradually increases (to the positive pressure side) as it is released. Finally, the pressure in the buffer chamber 35 becomes higher (to the positive pressure side) by the volume integral of the ink sucked into the main supply liquid chamber 23 of the recording head 22 from the leak hole. Therefore, the pressure change ΔP is larger than the pressure change due to the fluctuation (increase) of the volume of air which occurs when the leak hole is not generated. Therefore, if the pressure change .DELTA.P in the buffer chamber 35 monitored by the pressure sensor 34 is ".DELTA.P.gtoreq.0.5 kPa", it is determined that a leak hole is generated in the bonding portion 25 of the recording head 22. FIG.

  If the pressure change ΔP by monitoring is equal to or greater than a predetermined value “0.5 kPa”, the CPU 100 determines that a minute leak hole is generated, and proceeds to step S47 (Yes side). On the other hand, when the pressure change ΔP is less than the predetermined value “0.5 kPa”, the CPU 100 determines that the minute leak hole is not generated, and proceeds to step S48 (No side).

  In step S47, the CPU 100 sets the leak determination flag to "ON" indicating that a minute leak hole is generated, then ends the processing of this subroutine and returns to the main routine.

  In step S48, the CPU 100 sets the leak determination flag to "OFF", which indicates that a minute leak hole is not generated, and ends the processing of this subroutine and returns to the main routine.

<Continuation of main routine>
After returning to the main routine, in step S5, the CPU 100 refers to a leak determination flag indicating the result of the leak check in the subroutine in order to determine whether or not a minute leak hole is generated in the recording head 22. Then, when the leak determination flag is set to "ON", the CPU 100 proceeds to step S6 (Yes side), whereas when the leak determination flag is set to "OFF", the CPU 100 causes the recording head 22 to This control is ended (No side) because the minute leak holes are not generated.

  In step S6, the CPU 100 displays a warning or the like prompting the replacement of the recording head on the display unit or the like of the operation panel 110 since a minute leak hole is generated in the bonding portion 25 of the recording head 22, and then this control ends. Do. The warning or the like is not limited to the display on the display unit or the like, and may be notified by sound, for example. That is, the CPU 100 corresponds to the notification means of the present invention.

  As described above, in the ink jet printing apparatus according to the present embodiment, the nozzle portion 19 is sealed when performing a leak check to detect whether or not a minute leak hole is generated in the print head. To the inside of the recording head 22 is a closed system. Then, a negative pressure is applied to the recording head 22 in a state in which a portion of the recording head 22 where leakage may occur, such as the adhesive 25, is filled with the ink. At this time, the level of the negative pressure applied to the recording head 22 is equal to the level of the negative pressure P accumulated in the buffer chamber 35. Therefore, recording is performed by detecting the change in pressure relative to the pressure level of the negative pressure P from the time when the negative pressure is applied to the recording head until the lapse of 10 seconds of the predetermined time and determining the amount of change in the detected pressure. The presence or absence of the occurrence of a minute leak hole which may cause a leak in the head is detected. In this case, a warning such as prompting replacement of the print head can be issued before ink leakage from the leak hole occurs in the printing apparatus.

  Further, in the ink jet recording apparatus of the present embodiment, a negative pressure is applied to the recording head 22 in a closed system in a state in which a portion of the recording head 22 where leakage may occur is filled with ink. In this case, if a minute leak hole is generated in the portion filled with the ink, the meniscus formed in the portion of the minute leak hole by the ink is in a state where the strength is lowered. It can be broken by (underpressure). Therefore, in the ink jet recording apparatus of the present embodiment, the presence or absence of the occurrence of the minute leak holes can be detected with a smaller pressure than in the case where the ink is not filled with the ink.

  Further, in the ink jet recording apparatus according to the present embodiment, when a negative pressure is applied to the recording head 22 in a state in which a leakable part such as the adhesion part 25 of the recording head 22 in a closed system is filled with ink, Before the application of the negative pressure, the inside of the recording head 22 is pressurized. Then, since the negative pressure P is applied to the recording head 22 in a state where the internal pressure thereof is increased by pressurization, the recording head 22 has a smaller pressure (negative pressure P) than when the inside of the recording head is not pressurized. It becomes possible to detect the presence or absence of the occurrence of the minute leak holes by the application.

  Therefore, in the ink jet recording apparatus of the present embodiment, the generation of the minute leak holes in the recording head can be detected with a small pressure.

  In the above description, the nozzle 19 is sealed using the recessed portion of the blade 52, and the sealed portion by the recessed portion causes the ink to flow into the gap between the chip 20 and the recessed portion. Explained that the ink is filled with ink. That is, it has been described that the recess of the blade 52 performs sealing of the nozzle and filling of the portion where the leak may occur with the ink filled. However, the present invention is not limited to this, for example, the recess of the blade 52 is used as a sealing means to seal the nozzle, and the portion where leakage may occur is filled with ink using another means (filling means) other than the recess. May be performed.

Reference Signs List 19 nozzle unit 20 chip 21 liquid level detection sensor 22 recording head 22s nozzle surface 23 main supply liquid chamber 24 supply box 25 adhesion unit 27 base plate 28 main tank 29 waste tank 30 ink flow path 31 refill valve 32 air flow path 33 supply valve 34 Pressure sensor 35 Buffer chamber 36 Buffer valve 37 Pump 38 Pump 39 Recovery flow path 50 Capping mechanism 51 Cap 52 Blade

Claims (2)

A recording head having a nozzle surface provided with a nozzle for ejecting ink;
Sealing means for sealing the nozzle in contact with the nozzle surface;
A filling unit for filling a portion where ink leaked to the outside of the recording head may be caused to be filled with the ink,
Negative pressure application means for applying a negative pressure to the inside of the recording head;
Pressure detection means for detecting the pressure inside the recording head;
With the sealing means sealing the nozzle and the filling means filling the portion where the leak may occur, based on the change in negative pressure applied to the recording head by the negative pressure applying means. Notification means for notifying the user;
An inkjet recording apparatus comprising:   2. The ink jet recording apparatus according to claim 1, further comprising pressing means for pressing the inside of the recording head as the filling means.

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