JP2005205615A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover defective ejection corresponding to the cause thereof. <P>SOLUTION: This inkjet printer 1 comprises recording heads 7-10 each having ejection nozzles for ink, a suction unit 40 for sucking the ink from each of ejection nozzles, a sensor 32 for detecting presence or absence of an ejection nozzle with defective ejection, and a control device for controlling the operation of the suction unit 40 according to the detected result of the sensor 32. When the sensor 32 senses the ejection nozzle with defective ejection, the control device drives the suction unit 40. In the inkjet printer 1, the sensor 32 detects the presence or absence of the ejection nozzle with defective ejection after or before the suction unit 40 is operated. When it is judged that there is the ejection nozzle with defective ejection from the succeeding result sensed by the sensor 32, the control device drives the suction unit 40 again in a suction condition of the suction unit 40 different from that of the suction unit 40 which is operated before the succeeding sensing is carried out by the sensor 32, on the basis of the compared result between the preceeding sensed result and the succeeding sensed result by the sensor 32. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recovery process for ink ejection failure in a recording head of an ink jet printer.

  Various printers such as ink jet printers, laser printers, thermal transfer printers and the like have been developed as recording terminals connected to word processors, personal computers, and the like. In particular, inkjet printers have become mainstream printers because they have advantages such as quieter recording sound and easier and cheaper color recording than other types of printers. An ink jet printer is provided with a recording head having a large number of ejection holes for ejecting ink as fine droplets. The ink jet printer ejects ink from the ejection holes of the recording head to a recording medium based on image information. To record images.

  By the way, the ink jet printer ejects ink from each ejection hole of the recording head and records an image. Therefore, among the many ejection holes, in addition to the normal ejection holes that eject ink normally, ink is ejected. There will be ejection holes that are not ejected properly. There are two main causes of ejection failure. The first cause is that air bubbles are mixed in the channel communicating with the discharge hole. The second cause is that foreign matter such as thickened or solidified ink or paper dust is clogged in the channel communicating with the ejection hole.

As one method for recovering ink ejection failure, there is a method for forcibly sucking ink from each ejection hole of the recording head. An example of such a method is disclosed in Patent Document 1. In the method of Patent Document 1, the recording head is caused to perform idle ejection, and the temperature inside the recording head is measured at three points before the idle ejection, immediately after the idle ejection, and immediately after the predetermined time has elapsed since the idle ejection. Whether or not there is a discharge failure is determined from the temperature fluctuation value, and when it is determined that there is a discharge failure, ink is sucked from each discharge hole of the recording head to perform a recovery process for the discharge failure of the recording head.
JP-A-5-293968

However, in the method of Patent Document 1, regardless of the cause of the ejection failure (whether the ejection failure is caused by bubbles or clogging of foreign matter), the ink is always kept at a constant suction pressure. Therefore, the recovery process corresponding to the cause of the ejection failure has not been achieved, and there is a disadvantage associated with the recovery process. In other words, if the cause of ejection failure is the mixing of bubbles, the bubbles can be removed even with a relatively low suction pressure, but the ink is always sucked with a constant suction pressure that exceeds the suction pressure required for removing the bubbles. In this case, even ink (which can be used for image recording) unnecessary for removing bubbles is sucked unnecessarily, leading to waste of ink. On the other hand, when the cause of ejection failure is clogging of foreign matter, a relatively high suction pressure is required, but if ink is always sucked with a constant suction pressure lower than the suction pressure necessary for removing foreign matter, Foreign matter cannot be removed.
An object of the present invention is to recover ejection failure according to the cause of ejection failure.

In order to solve the above problem, the invention according to claim 1
A recording head having a plurality of ejection holes for ejecting ink;
A sensor for detecting the presence or absence of the ejection hole having a defective ejection;
A suction mechanism for sucking ink from each of the ejection holes;
A control device for controlling the operation of the suction mechanism based on the detection result of the sensor;
With
In the ink jet printer in which the control device operates the suction mechanism when the sensor detects the ejection hole that is defective in ejection,
The sensor is
Detecting the presence or absence of the ejection holes with poor ejection after the operation of the suction mechanism,
The control device includes:
When it is determined that the ejection hole having the ejection failure is present based on the detection result obtained later by the sensor, the previous detection result obtained by the sensor is compared with the later detection result. Based on the comparison result, the subsequent detection result obtained by the sensor is compared. The suction mechanism is operated again in a suction mode different from the suction mode of the suction mechanism operated before detection.

The invention described in claim 2
The inkjet printer according to claim 1, wherein
The control device includes:
Based on the comparison result, the suction mechanism is operated again at a suction pressure different from the suction pressure of the suction mechanism that was operated before subsequent detection by the sensor.

The invention according to claim 3
The inkjet printer according to claim 1 or 2,
The control device includes:
Based on the comparison result, it is determined whether or not the same discharge hole exists in the discharge hole having a defective discharge, and when it is determined that the same discharge hole does not exist, the sensor operates before subsequent detection by the sensor. The suction mechanism is operated again with a suction pressure lower than the suction pressure of the suction mechanism.

The invention according to claim 4
In the inkjet printer as described in any one of Claims 1-3,
The control device includes:
Based on the comparison result, it was determined whether or not the same discharge hole exists in the discharge hole of defective discharge, and when it was determined that the same discharge hole existed, the sensor was activated before subsequent detection by the sensor. The suction mechanism is operated again at a suction pressure higher than the suction pressure of the suction mechanism.

The invention described in claim 5
In the ink jet printer according to any one of claims 1 to 4,
First warning means for warning that the recording head is out of ink;
The control device includes:
Both the total number of the ejection holes determined to be ejection failure based on the previous detection result by the sensor and the total number of the ejection holes determined to be ejection failure based on the subsequent detection result by the sensor are equal to or greater than the specified number. If it is determined, the first warning means is activated.

The invention described in claim 6
In the ink jet printer according to any one of claims 1 to 5,
Second warning means for warning the recording head abnormality,
The control device includes:
The second warning means is actuated when it is determined that the number of actuations of the suction mechanism is equal to or greater than a prescribed number.

The invention described in claim 7
In the ink jet printer according to any one of claims 1 to 6,
A plurality of the recording heads;
A plurality of suction mechanisms corresponding to each of the plurality of recording heads;
With
The sensor is
Detecting the presence or absence of the ejection holes with defective ejection after the operation of each suction mechanism for each recording head,
The control device includes:
If it is determined that there are two or more recording heads out of the plurality of recording heads and the ejection holes that are defective in ejection are present based on the detection results obtained later by the sensor, It is characterized by operating the mechanism again.

  In the first aspect of the invention, since the control device compares the previous detection result by the sensor with the subsequent detection result, based on the comparison result, the discharge holes with the defective discharge are the same before and after the suction operation by the suction mechanism. It is possible to determine whether the discharge is different or not, and based on the determination result, it is possible to determine whether the cause of the ejection failure is air bubble contamination or clogging of foreign matter. That is, if the discharge holes with the same discharge failure are the same, it is possible to determine that mixing of bubbles is the cause of discharge failure, and if the discharge holes with the discharge failure are different, clogging of foreign matter is the cause of the discharge failure. And since the suction mechanism operates again in a suction mode different from the suction mechanism before detection by the sensor, the suction mode of the suction mechanism is changed according to the cause of ejection failure (whether it is due to air bubbles or clogging of foreign matter). By changing the suction mode of the suction mechanism based on the detection result of the sensor, it is possible to recover the discharge hole of the discharge failure according to the cause of the discharge failure.

  In the second aspect of the invention, since the suction mechanism operates again with a suction pressure different from the suction mechanism before detection by the sensor, the cause of ejection failure (whether it is due to air bubbles or foreign matter clogging) Accordingly, the suction pressure of the suction mechanism can be changed. Therefore, if the cause of the ejection failure is the mixing of bubbles, the amount of waste liquid of ink accompanying suction can be suppressed by lowering the suction pressure of the suction mechanism again, and if the cause of ejection failure is clogging of foreign matter, By increasing the suction pressure of the suction mechanism again, the certainty of removing foreign matters can be increased. As a result, it is possible to recover a discharge hole having a discharge failure according to the cause of the discharge failure.

  According to the third aspect of the invention, since the suction mechanism is operated again with a suction pressure lower than the suction pressure of the suction mechanism that was operated before the subsequent detection by the sensor, the amount of ink waste liquid accompanying suction can be suppressed.

  According to the fourth aspect of the present invention, the suction mechanism is operated again with a suction pressure higher than the suction pressure of the suction mechanism that was operated before the detection after the sensor, so that the certainty of removing the foreign matter can be improved.

  According to the fifth aspect of the present invention, the first warning means is activated when the total number of ejection holes with defective ejection is continuously greater than or equal to the prescribed number after the operation of the suction mechanism. The user can be notified.

  According to the sixth aspect of the invention, since the second warning means is activated when the number of times of operation of the suction mechanism is equal to or greater than the specified number, it is possible to notify the user of an abnormality of the recording head.

  According to the seventh aspect of the present invention, when two or more recording heads out of the plurality of recording heads have ejection holes that are defective in ejection, each suction mechanism operates again in a different suction mode for each suction mechanism. In each case, it is possible to recover the ejection hole of the ejection failure according to the cause of the ejection failure.

The best mode for carrying out the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a perspective view showing a schematic configuration of the ink jet printer 1.

  As shown in FIG. 1, the ink jet printer 1 has a flat platen 2 that supports a non-recording surface (a surface opposite to the recording surface) of a recording medium 99. 4 are arranged respectively. A transport motor 11 (see FIG. 3) serving as a drive source is connected to each of the transport rollers 3 and 4, and each transport roller 3 and 4 has a predetermined axis around the platen 2 as the transport motor is driven. The recording medium 99 is transported along the transport direction A by rotating in the respective directions.

  In FIG. 1, a guide member 5 extending in a direction B (hereinafter referred to as “scanning direction B”) orthogonal to the conveyance direction A is disposed above the platen 2. A carriage 6 is supported on the guide member 5. The carriage 6 can be scanned (reciprocated) in the scanning direction B while being guided by the guide member 5.

  On the carriage 6, four recording heads 7 to 10 for discharging process color inks of yellow (Y), magenta (M), cyan (C), and black (K) toward the recording surface of the recording medium 99, respectively. Is installed. The four recording heads 7 to 10 follow the reciprocating movement of the carriage 6 at the same time, and can be moved up and down by the operation of the carriage 6.

  A plurality of ink ejection holes (not shown) are formed on the lower surfaces 7a to 10a (surfaces facing the platen 2) of the recording heads 7 to 10, and the recording heads 7 to 10 receive ink from the ejection holes. It is designed to be ejected as drops. That is, the lower surfaces 7a to 10a of the recording heads 7 to 10 are ink ejection surfaces. In each of the recording heads 7 to 10, the ink ejection holes are arranged at equal intervals along one or more rows along the front-rear direction in FIG.

  In each of the recording heads 7 to 10, a flexible tube in which four ink tanks (not shown) for storing ink of each color of Y, M, C, and K for each color can follow the reciprocating movement of the carriage 6. (Not shown), and ink is supplied from each ink tank to each of the four recording heads 7 to 10 via a flexible tube for each color.

  In FIG. 1, a recovery unit 20 is disposed on the left side of the platen 2 to recover the ejection failure of the recording heads 7 to 10. The recovery unit 20 includes an empty ejection unit 30 for causing each recording head 7 to 10 to perform idle ejection, and a suction unit 40 for sucking ink from each recording head 7 to 10.

  The idle ejection unit 30 has an ink receiving portion 31 that receives ink that is idlely ejected from the recording heads 7 to 10. The ink receiving portion 31 is composed of a sponge-like absorber. In the vicinity of the ink receiving portion 31, an ejection detection sensor 32 that detects whether or not ink has been normally ejected from the ejection holes of the lower surfaces 7 a to 10 a of the recording heads 7 to 10 is disposed. The ejection detection sensor 32 includes a light emitting element 33 and a light receiving element 34 disposed before and after the ink receiving portion 31. The light emitting element 33 and the light receiving element 34 are arranged on the same straight line along the front-rear direction in FIG. 1, and the light emitted from the light emitting element 33 passes above the ink receiving portion 31 and is received by the light receiving element 34. It is like that.

  The suction unit 40 has a base member 41 that can slide in the front-rear direction in FIG. At the rear end of the base member 41, four blades 42 to 45 for removing ink and the like attached to the lower surfaces 7a to 10a of the recording heads 7 to 10 are disposed. The number of blades 42 to 45 is the same as the number of the recording heads 7 to 10, and one blade 42 to 45 corresponds to one recording head 7 to 10.

  In the central portion of the base member 41, four caps 46 to 49 that cover the lower surfaces 7a to 10a of the recording heads 7 to 10 are arranged. The number of caps 46 to 49 is the same as the number of recording heads 7 to 10, and one cap 46 to 49 corresponds to one recording head 7 to 10.

FIG. 2 is a drawing showing a schematic configuration of the suction unit 40, and more specifically, a drawing showing a suction mechanism 50 constituting a part of the suction unit 40.
The suction mechanism 50 is arranged for each of the four caps 46 to 49. Here, the configuration of the suction mechanism 50 will be described as corresponding to one cap 46. A waste ink tank 51 that stores waste ink is disposed below the base member 41. A tube 52 is disposed between the base member 41 and the waste ink tank 51. One end of the tube 52 communicates with the cap 46 via the base member 41, and the other end of the tube 52 communicates with the waste ink tank 51.

  A tube-type suction pump 53 that generates a suction pressure inside the cap 46 is disposed in the middle of the tube 52. The suction pump 53 has a motor 54. A plurality of rollers 56 are arranged at equal intervals on the shaft center portion 55 of the motor 54, and a plurality of protrusions 58 are arranged on the housing portion 57 of the motor 54. A rubber tube 52 is sandwiched between the shaft portion 55 of the motor 54 and each projection 58. When the suction pump 53 is activated (the motor 54 is activated and rotated), each roller 56 attaches the tube 52 to the tube. The suction pressure is generated inside the cap 46 through the grinding and tube 52.

  An electromagnetic valve 59 for releasing the suction pressure inside the cap 46 via the base member 41 is disposed below the cap 46. When the solenoid valve 59 is operated in a state where the suction pressure is generated in the cap 46, the suction pressure generated in the cap 46 is released and the inside of the cap 46 returns to the atmospheric pressure.

  Although only the suction mechanism 50 related to one cap 46 of the four caps 46 to 49 has been described here, as described above, such a suction mechanism 50 (waste ink tank 51, tube 52, suction pump 53). , A mechanism comprising a solenoid valve 59 and the like) corresponds to each of the four caps 46 to 49, and is arranged for each of the caps 46 to 49. Inside each cap 46 to 49, the suction pump 53 is provided. The suction pressure can be changed as appropriate according to the operation mode.

FIG. 3 is a block diagram showing a circuit configuration of the ink jet printer 1.
The control device 60 controls the operation of the inkjet printer 1 and includes a control unit 61 composed of a general-purpose CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and the like. Yes. The control unit 61 expands the processing program recorded in the ROM to the RAM and executes the processing program by the CPU.

  The control unit 61 is connected to the conveyance motor 11, the carriage 6, the recording heads 7 to 10, various members of the suction unit mechanism 40, and the control unit 61 includes the conveyance motor 11, the carriage 6, the recording heads 7 to 10, The operation of each component is controlled based on the status such as the operation status of various members of the suction unit 40. Moreover, the discharge detection sensor 32 is connected to the control part 61, and the control part 61 is based on the detection result of the discharge detection sensor 32, each suction pump 53 corresponding to each of caps 46-49, each electromagnetic valve 59, etc. Is to control.

  The ink jet printer 1 displays as first and second warning means for displaying out of ink in the recording heads 7 to 10 and abnormality of the recording heads 7 to 10 (damage of ejection holes and channels communicating therewith). A panel 12 is arranged, and the display panel 12 is also connected to the control unit 61.

Next, the operation and action of the inkjet printer 1 will be described.
When image data is input to the control unit 61 of the control device 60 and an image recording operation is started, the control unit 61 of the control device 60 transmits a control signal to the transport motor 11, the carriage 6, the recording heads 7 to 10, and the like. The operation of each component is controlled as follows. That is, the conveyance motor 11 is driven to cause each of the conveyance rollers 3 and 4 to repeatedly rotate and stop by a predetermined amount, thereby moving the recording medium 99 intermittently along the conveyance direction A.

  In this state, when the movement of the recording medium 99 is temporarily stopped, the carriage 6 is operated, and the recording heads 7 to 10 are moved from the left side to the right side in FIG. (Or from right to left). During the movement of the carriage 6, the ink is made into fine droplets from the ejection holes of the lower surfaces 7 a to 10 a of the recording heads 7 to 10 toward the image recording area (area for recording an image) on the recording surface of the recording medium 99. Discharge each.

  Thereafter, the above-described operation is repeatedly performed on each member of the ink jet printer 1 to sequentially record images on the image recording area of the recording surface of the recording medium 99 that has passed over the platen 2.

  Here, in addition to the above-described image recording operation, the control unit 61 of the control device 60 transmits a control signal to the carriage 6, the recording heads 7 to 10, various members of the recovery unit 20, and the like. 10 "recovery processing" of ejection failure is performed.

Hereinafter, the operation and action of the ink jet printer 1 during the recovery process of the recording heads 7 to 10 will be described with reference to FIG.
Since the control unit 61 performs the same recovery process for each of the four recording heads 7 to 10, the recovery process will be described in detail here, focusing on only one recording head 7.

FIG. 4 is a flowchart showing the recovery method of the ejection failure of the recording head 7 over time, and specifically shows the processing performed by the control unit 61 (CPU) of the control device 60 over time.
First, the CPU of the control unit 61 determines whether or not there is a defective ejection hole among all the ejection holes of the recording head 7 when the power is turned on, when a user operates, or when a predetermined number of images have been recorded. The discharge failure detection process is performed (step S1). Specifically, the carriage 6 is operated to position the recording head 7 directly above the ink receiving portion 31 of the idle ejection unit 30 (immediately above the trajectory of the light beam emitted from the light emitting element 33). When the recording head 7 is positioned at a predetermined position, ink is ejected from all the ejection holes of the recording head 7. In this case, the ink is sequentially ejected one by one from the one end to the other end of the plurality of ejection holes constituting the row, and the same operation is performed for each row.

  If the ink is normally ejected from the ejection hole, the light emitted from the light emitting element 32 is temporarily blocked by the ink and is received by the light receiving element 33. Therefore, the ejection detection sensor 32 has a normal ejection hole. Detects when ink is ejected. On the other hand, if ink is not ejected from the ejection hole, the light emitted from the light emitting element 32 is received by the light receiving element 33 as it is without being blocked. Therefore, the ejection detection sensor 32 detects that the ejection hole does not eject ink. To do.

  When the processing of step S1 is completed, it is determined whether or not there are a predetermined number or more of defective ejection holes that do not eject ink among all the ejection holes of the recording head 7 based on the detection result of the ejection detection sensor 32 (step S1). S2).

  In the process of step S2, if it is determined that the number of ejection holes with ejection failure is less than the specified number (step S2: NO), it is determined that the ejection failure recovery process other than the idle ejection is unnecessary, and the entire ejection of the recording head 7 is performed. Ink is again ejected from the holes again, and the recovery process is terminated. On the other hand, if it is determined that there are more than the prescribed number of defective ejection holes (step S2: YES), it is determined based on the detection result of the ejection detection sensor 32 that a recovery process for defective ejection is required in addition to idle ejection. Discharge failure information relating to defective discharge holes (information relating to the total number and arrangement positions of defective discharge holes; hereinafter referred to as “first discharge failure information”) is stored as data in the RAM or ROM (step S3).

  When the process of step S3 is completed, the recording head 7 is cleaned (step S4). Specifically, the carriage 6 is operated so that the recording head 7 is positioned immediately above the cap 46 of the base member 41, the recording head 7 is lowered from that position, and the cap 46 is brought into close contact with the lower surface 7 a of the recording head 7. . When the lower surface 7 a is in close contact with the cap 46, the suction pump 53 is operated to generate a suction pressure inside the cap 46, and ink is sucked from each ejection hole of the recording head 7.

When a predetermined time elapses in this state, the operation of the suction pump 53 is stopped and the pressure inside the cap 46 is returned to near atmospheric pressure. Thereafter, the electromagnetic valve 59 is opened and the suction pump 53 is operated again. The ink remaining in the cap 46 is sucked in a state in which the pressure inside is returned to atmospheric pressure.
In the process of step S4, the ink suction time from each ejection hole of the recording head 7 is set to 5 seconds, for example.

  When the ink inside the cap 46 is sucked for a predetermined time, the carriage 6 is operated to return the recording head 7 to its original height position. When the recording head 7 returns to the original height position, the base member 41 is operated and slid from the rear to the front. At this time, the upper part of the blade 42 moves while rubbing the lower surface 7a of the recording head 7 to remove the ink adhering to the lower surface 7a. With such a configuration, the cleaning process of the recording head 7 is completed.

  When the process in step S4 is completed, the ejection failure detection process similar to that in step S1 is performed (step S5), and then the ejection failure presence / absence determination process similar to that in step S2 is performed (step S6).

  If it is determined in step S6 that the number of ejection holes with ejection failure is less than the prescribed number (step S6: NO), it is determined that there is no need for ejection failure recovery processing other than idle ejection, and all ejections of the recording head 7 are performed. Ink is again ejected from the holes again, and the recovery process is terminated. On the other hand, if it is determined that there are more than a specified number of defective ejection holes (step S6: YES), it is determined based on the detection result of the ejection detection sensor 32 that a recovery process for defective ejection is necessary in addition to idle ejection. Discharge failure information relating to the defective discharge holes (hereinafter referred to as “second discharge failure information”) is stored as data in the RAM or ROM (step S7).

  It should be noted that the prescribed number to be determined in the processing of steps S2 and S6 may be, for example, 1/10 of the total number of ejection holes, or may be extremely 1 depending on the image quality of the recording operation. It can be set. That is, when the specified number is set to 1/10 of the total number of discharge holes, the first and second discharges are determined when it is determined that the number of discharge holes with defective discharge is 1/10 or more of the total number of discharge holes. When the defect information storage process is performed and the specified number is set to 1, the storage process of the first and second discharge defect information is performed when it is determined that there is even one discharge hole having a discharge defect. The smaller the prescribed number, the more accurately the ejection failure is detected and the image quality associated with the recording operation can be improved.

  When the process of step S7 is completed, the total number of ejection holes having ejection defects is determined in the idle ejection operation of ink based on the processes of steps S1 and S5 in consideration of the first ejection failure information and the second ejection failure information. Is continuously greater than or equal to a specified number (for example, 1/3 of the total number of ejection holes of the recording head 7) (step S8).

  In the process of step S8, when it is determined that the total number of ejection holes with defective ejection is continuously greater than or equal to the specified number (step S8: YES), a message to warn that the print head 7 is out of ink is displayed on the display panel 12. Display (step S9), and the recovery process ends. In the processes of steps S8 and S9, it is determined that there are more than a predetermined number of ejection holes with defective ejection continuously in the two empty ink ejection operations based on the processes of steps S1 and S5. It is determined that “out of ink” has occurred, and the fact is notified to the user as a warning.

  In the process of step S8, when it is determined that the total number of ejection holes with defective ejection has not continuously reached the specified number (step S8: NO), the number of processes of steps S4, S12, and S13 (cleaning of the recording head 7). It is determined whether or not the number of times has reached a specified number (two or more times) (step S10).

  In the process of step S10, when it is determined that the number of cleanings of the recording head 7 has reached the specified number (step S10: YES), the display panel 12 is displayed to warn of an abnormality of the recording head 7 (step S14). The recovery process ends. In the processing of steps S10 and S14, since it is determined that the number of cleanings due to the ejection failure of the recording head 7 has reached the specified number, the ejection failure of the ejection holes does not recover even if the recording head 7 is cleaned twice or more. That is, it is determined that “recording head 7 abnormality” has occurred, and a notification to that effect is given to the user.

  In the process of step S10, when it is determined that the number of cleanings of the recording head 7 has not reached the specified number (step S10: NO), the first ejection defect information and the second ejection defect information are referred to, and the step It is determined whether there is at least one ejection hole with the same arrangement position among the ejection holes determined to be ejection failure in the two empty ink ejection operations based on the processes of S2 and S6 (step S11). ).

  Here, it is assumed that the suction pump 53 is a pump having the pump characteristics of FIG. FIG. 5 shows the relationship between the elapsed time (seconds) from the start of suction in the suction pump 53 and the suction pressure (kPa) of the suction pump 53. As shown in FIG. 5, when the suction pump 53 is used, the ink suction pressure can be changed according to the length of the suction time. Referring to the pump characteristics shown in FIG. 5, the suction pressure reaches 30 kPa after 5 seconds from the start of suction. As described above, if the suction time is set to 5 seconds in the process of step S4, the ink in the process of step S4 The suction pressure is set to 30 kPa.

  In the process of step S11, when it is determined that there are no ejection holes having the same arrangement position (step S11: NO), the ink suction pressure is set equal to or lower than the suction pressure in the previous cleaning process. The same process as step S4, that is, the same process as step S4 for setting the ink suction time to 5 seconds or less than 5 seconds is performed (step S12).

  The reason why the ink suction pressure is the same as or lower than that in step S4 in the process of step S12 is considered that bubbles are simply mixed in the ejection holes, and the suction pressure corresponding to the suction time is set to the previous time. This is because it is considered that the discharge failure of the discharge hole can be recovered even if it is the same as or lower than that at the time of the cleaning process.

  On the other hand, when it is determined in step S11 that there is at least one ejection hole having the same arrangement position (step S11: YES), the same as step S4 in which the ink suction pressure is set higher than that in the previous cleaning process. Processing, that is, processing similar to step S4 in which the ink suction time is longer than 5 seconds is performed (step S13).

  The reason why the ink suction pressure is made higher than that of step S4 in the process of step S13 is considered that foreign matter is clogged in the same ejection hole, and the suction pressure corresponding to the suction time is not made higher than that in the previous cleaning process. This is because it is considered that the ejection failure (foreign material clogging) of the ejection holes cannot be recovered.

  In the process of step S13, for example, if the ink suction time is 15 seconds, the ink can be sucked with a suction pressure (60 kPa) that is twice the suction pressure (30 kPa) in the process of step S4.

  When the process of step S12 or step S13 is completed, the process from step S5 to step S12 or step S13 is repeated. In this case, when the processes in steps S8, S10, and S11 are performed again, the ejection failure information (second ejection failure information) stored in the previous step S7 and the ejection failure stored in the current step S7. Information (hereinafter referred to as “third ejection failure information”) is determined as a comparison target.

  Further, when the processes of steps S12 and S13 are performed again, the suction pressure in the processes of the previous steps S12 and S13 is determined as a comparison target.

  For example, it is assumed that the suction pump 53 is a pump having the pump characteristics shown in FIG. If the ink suction time is set to 15 seconds in the first step S13, the suction pressure reaches 60 kPa 15 seconds after the start of suction. However, in the second step S11, the ejection holes having the same arrangement position are used. If it is determined that the ink suction pressure does not exist, the same processing as Step S4 in which the ink suction pressure is made equal to or lower than the suction pressure in the previous cleaning process, that is, the ink suction time is set to 15 seconds or 15 seconds. The same processing as in step S4 is performed.

On the other hand, when it is determined in the second step S11 that there is at least one ejection hole with the same arrangement position, the same process as step S4 in which the ink suction pressure is higher than that in the previous cleaning process, that is, The same processing as step S4 in which the ink suction time is longer than 15 seconds is performed.
In the second step S13, for example, if the ink suction time is 50 seconds, the ink is drawn with a suction pressure (90 kPa) that is 1.5 times the suction pressure (60 kPa) in the first step S13. Can be aspirated.

  Then, regarding the subsequent processing of step S10, for example, when the specified number of cleanings is set to “3”, the number of cleanings of the recording head 7 is set at the time when the first processing of steps S12 and S13 is performed. In this case, the process of step S4 is not performed, but the process of step S12 is not performed, but the process of step S12, S13 is performed for the second time. At this time, the recording head 7 is cleaned three times. At this time, it is determined that an abnormality has occurred in the recording head 7, and the process of step S14 is performed.

  In the above, the details of the recovery process have been described focusing on only one recording head 7, but the CPU of the control unit 61 performs the same recovery process on each of the four recording heads 7 to 10 at the same time. Do it. In this case, when at least one of the four recording heads 7 to 10 has a defective ejection hole, the recovery process is performed only on the recording heads 7 to 10 having the ejection failure. The recovery process is not performed for the other recording heads 7 to 10. At this time, if two or more recording heads 7 to 10 out of the four recording heads 7 to 10 have a predetermined number or more of defective ejection holes, this corresponds to the recording heads 7 to 10 in which the ejection ports with the defective ejection exist. The suction time (suction pressure) of each suction pump 53 may be changed independently for each suction pump 53. Further, when the ink suction operation is simultaneously performed across the plurality of recording heads 7 to 10, the recording heads 7 to 10 are suctioned in accordance with the suction time of the recording head 7 to 10 having the highest suction pressure. When the ink suction of the recording heads 7 to 10 for which the suction operation has been performed is completed, the ink is removed by the blades 42 to 45.

  In the ink jet printer 1 described above, the arrangement positions are the same in the ejection holes of the ejection failure based on the two consecutive ejection failure information such as the first and second ejection failure information and the second and third ejection failure information. If there is no discharge hole, it is determined that the cause of the discharge failure is the mixing of bubbles, and the subsequent suction operation is performed at a suction pressure equal to or lower than the suction pressure of the previous suction operation. The amount of waste ink due to suction can be reduced. On the other hand, if there are discharge holes with the same arrangement position among the discharge holes with defective discharge, it is determined that the cause of the discharge failure is clogging of foreign matter. In addition, since the suction operation is performed at a suction pressure higher than the suction pressure of the previous suction operation, the certainty of removing the foreign matter can be improved. As a result, it is possible to recover a discharge hole having a discharge failure according to the cause of the discharge failure.

  Further, in the discharge failure detection process, not only the recovery of the discharge hole of the discharge failure but also two consecutive discharge failure information such as the first and second discharge failure information and the second and third discharge failure information. Ink of the recording heads 7 to 10 is displayed on the display panel 12 to determine whether the total number of ejection holes with defective ejection is continuously greater than or equal to the specified number and warn that the recording heads 7 to 10 are out of ink. The user can be notified of the break. Further, since it is determined whether the number of cleanings is equal to or more than the specified number and a message to warn of an abnormality of the recording heads 7 to 10 is displayed on the display panel 12, the abnormality of the recording heads 7 to 10 can be notified to the user. it can.

The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, in the above embodiment, the increase / decrease in the suction pressure is appropriately adjusted according to the suction time of the suction pump 53, but the suction pressure is corresponding to the grinding speed of each roller 56 of the suction pump 53 (rotational speed of the motor 54). The increase / decrease may be adjusted appropriately over a certain period of time.

  Further, a message is displayed on the display panel 12 to warn about the ink out of the recording heads 7 to 10 and the abnormality of the recording heads 7 to 10. However, the warning light and the warning buzzer are provided with the first and second warning means. The warning head may be turned on or blinked, or a warning buzzer may be sounded to warn of ink out of the recording heads 7 to 10 or abnormalities in the recording heads 7 to 10.

1 is a perspective view illustrating a schematic configuration of an inkjet printer. It is a front view which shows a partial schematic structure of a suction unit. It is a block diagram which shows the circuit structure of an inkjet printer. 5 is a flowchart showing a method for recovering ejection failure over time. It is a graph which shows the pump characteristic of a suction pump as an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 7-10 Recording head 12 Display panel (1st, 2nd warning means)
20 Cleaning mechanism 30 Empty discharge unit 32 Discharge detection sensor (sensor)
40 Suction Unit 50 Suction Mechanism 60 Control Device

Claims (7)

A recording head having a plurality of ejection holes for ejecting ink;
A sensor for detecting the presence or absence of the ejection hole having a defective ejection;
A suction mechanism for sucking ink from each of the ejection holes;
A control device for controlling the operation of the suction mechanism based on the detection result of the sensor;
With
In the ink jet printer in which the control device operates the suction mechanism when the sensor detects the ejection hole that is defective in ejection,
The sensor is
Detecting the presence or absence of the ejection holes with poor ejection after the operation of the suction mechanism,
The control device includes:
When it is determined that the ejection hole having the ejection failure is present based on the detection result obtained later by the sensor, the previous detection result obtained by the sensor is compared with the later detection result. Based on the comparison result, the subsequent detection result obtained by the sensor is compared. An ink jet printer, wherein the suction mechanism is operated again in a suction mode different from the suction mode of the suction mechanism operated before detection. The inkjet printer according to claim 1, wherein
The control device includes:
An ink jet printer, wherein, based on the comparison result, the suction mechanism is operated again with a suction pressure different from the suction pressure of the suction mechanism that was operated before subsequent detection by the sensor. The inkjet printer according to claim 1 or 2,
The control device includes:
Based on the comparison result, it is determined whether or not the same discharge hole exists in the discharge hole having a defective discharge, and when it is determined that the same discharge hole does not exist, the sensor operates before subsequent detection by the sensor. An ink jet printer, wherein the suction mechanism is operated again with a suction pressure lower than the suction pressure of the suction mechanism. In the inkjet printer as described in any one of Claims 1-3,
The control device includes:
Based on the comparison result, it was determined whether or not the same discharge hole exists in the discharge hole of defective discharge, and when it was determined that the same discharge hole existed, the sensor was activated before subsequent detection by the sensor. An ink jet printer, wherein the suction mechanism is operated again with a suction pressure higher than the suction pressure of the suction mechanism. In the ink jet printer according to any one of claims 1 to 4,
First warning means for warning that the recording head is out of ink;
The control device includes:
Both the total number of the ejection holes determined to be ejection failure based on the previous detection result by the sensor and the total number of the ejection holes determined to be ejection failure based on the subsequent detection result by the sensor are equal to or greater than the specified number. An ink jet printer, wherein the first warning means is actuated when it is determined. In the ink jet printer according to any one of claims 1 to 5,
Second warning means for warning the recording head abnormality,
The control device includes:
An ink jet printer characterized in that the second warning means is activated when it is determined that the number of actuations of the suction mechanism is equal to or greater than a prescribed number. In the ink jet printer according to any one of claims 1 to 6,
A plurality of the recording heads;
A plurality of suction mechanisms corresponding to each of the plurality of recording heads;
With
The sensor is
Detecting the presence or absence of the ejection holes with defective ejection after the operation of each suction mechanism for each recording head,
The control device includes:
If it is determined that there are two or more recording heads out of the plurality of recording heads and the ejection holes that are defective in ejection are present based on the detection results obtained later by the sensor, An ink jet printer, wherein the mechanism is operated again.

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