JP2008188838A - Inkjet recorder and discharge recovery control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an ink amount which is unnecessarily abandoned by carrying out a recovery processing according to a writing frequency while performing a recovery execution control with a timer management in an inkjet recorder. <P>SOLUTION: It is determined whether an elapsed time exceeds a threshold value (a203). It is determined that a maintenance is required when exceeding the threshold value time. Then, it is determined whether the mode established at that time is an ink consumption reducing mode (a204). At this time, if it is determined to be the ink consumption reducing mode, it is determined whether it is an abnormal condition from the difference of the head temperature before and after a preliminary discharge (i.e., T<SB>2</SB>-T<SB>1</SB>) (a205 to a208). In the case of the abnormal condition, a maintenance operation is performed (a209). Thus, the maintenance operation can be performed according to the writing frequency in a printer, and the ink amount which is unnecessarily abandoned can be reduced as compared with the case the maintenance operation is uniformly performed by the elapsed time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and an ejection recovery control method, and more particularly to a configuration for controlling execution of an ejection recovery operation of a recording head that ejects ink based on a time measured by a timer.

  2. Description of the Related Art In an ink jet recording type recording apparatus that forms an image on a recording medium by ejecting ink droplets, a recording head in which a plurality of fine ejection openings and liquid passages communicating therewith are used. In this ink jet recording apparatus, when there is a certain unused period, the moisture and volatile components of the ink near the ejection port evaporate, causing the ink to thicken and solidify. It is known that ink with increased viscosity cannot be ejected normally and a defect occurs in the image.

  In order to avoid such a deterioration in the discharge performance of the recording head, conventionally, when the non-use period is relatively short, ink is discharged to a discharge receptacle or the like provided in advance before the recording operation (hereinafter referred to as preliminary discharge). A relatively minor recovery process is performed to prevent defects. Further, as a recovery process that is heavier than the preliminary discharge, a recovery process is performed in which the thickened ink in the recording head is discharged from the discharge port, for example, by suction, and the recording head is filled with new ink.

  Among these more heavy recovery processes, in particular, the degree of further recovery in order to remove bubbles remaining in the ink supply path such as a tube that supplies ink from the ink tank to the recording head and in the recording head In some cases, processing with an increased number of times is performed. The execution timing of the recovery process is executed when the elapsed time from the previous recovery process is managed by a timer as described in Patent Document 1, for example, and this time exceeds a reference time (hereinafter, referred to as “recovery process”). Also called timer recovery). In the case of the heavier recovery process described above, the reference time is a relatively long time such as one month. This is because the bubbles in the recording head and the supply path tend to increase in volume and number over time, and it becomes a relatively long time that the ejection volume is hindered by the increased volume of bubbles. It is.

JP 2001-001558 A

  However, depending on the user or the like, the frequency with which the recording apparatus is used varies for a relatively long time. As a result, the amount of bubbles staying in the recording head or the ink supply path may be different. That is, the bubble generation is largely caused by the recording operation. For this reason, the higher the recording frequency is, the more bubbles are generated, and accordingly, ejection defects are likely to occur due to the increase of bubbles with the passage of time.

  In the above-described timer recovery, a certain amount of ink is discarded every time the reference time elapses. On the other hand, reducing such discarded ink is desirable from the viewpoint of running cost. For example, for a user who performs recording only rarely, timer recovery is performed each time recording is performed, and the amount of discarded ink may be an amount that cannot be ignored compared to the amount of ink consumed in recording.

  As another point of view, the amount of recovery processing necessary to maintain good ejection characteristics varies from recording head to recording head. In addition, the degree of ink thickening in the recording head varies depending on the environmental conditions. For this reason, some recording heads or apparatuses do not necessarily require recovery executed based on a predetermined time in timer recovery. That is, in some cases, the recovery operation may be performed more than necessary.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus capable of performing recovery processing according to recording frequency while adopting control by the same time as timer recovery, and reducing the amount of ink discarded unnecessarily. It is to provide a discharge recovery control method.

  Therefore, in the present invention, an ink jet recording apparatus that performs recording by using a recording head that ejects ink and ejecting ink onto a recording medium, the recovery means performing the ejection recovery operation of the recording head, and the recovery by the recovery means Timer means for measuring the elapsed time since the operation was performed, determination means for determining whether the elapsed time measured by the timer means has exceeded a threshold time interval, and determining the recording frequency in the ink jet recording apparatus When the recording frequency determining means and the determining means determine that the elapsed time has exceeded the threshold time interval and the recording frequency determined by the recording frequency determining means is less than or equal to a predetermined frequency, recording is performed by the recovery means. And a recovery execution control means for performing a recovery operation of the head.

  Further, there is provided a recording head ejection recovery control method in an inkjet recording apparatus that performs recording by ejecting ink onto a recording medium using a recording head that ejects ink, and a recovery unit that performs an ejection recovery operation of the recording head; A timer unit for measuring an elapsed time after the recovery operation by the recovery unit is performed, a determination step for determining whether the elapsed time measured by the timer unit exceeds a threshold time interval, A recording frequency determining step for determining a recording frequency in the ink jet recording apparatus, and the determining step determines that the elapsed time has exceeded the threshold time interval, and the recording frequency determined by the recording frequency determining step is a predetermined frequency or less. A recovery execution control step of causing the recovery means to perform a recovery operation of the recording head when the recovery means is determined.

  According to the above configuration, the recovery operation is performed when the elapsed time after the recovery operation is performed exceeds a certain threshold time interval and the recording frequency is determined to be equal to or lower than the predetermined frequency. As a result, it is possible to perform a recovery process according to the recording frequency while adopting the same time control as the timer recovery, and it is possible to reduce the amount of ink that is unnecessarily discarded.

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

  FIG. 1 is a diagram schematically showing an ink jet printer according to an embodiment of the ink jet recording apparatus of the present invention. FIG. 2 is a schematic diagram mainly showing an ink supply system between the recording head and the ink tank. As shown in these drawings, the ink tank 1 is prepared according to the number of ink colors to be used. In the example shown in FIG. 1, for example, six types of inks of cyan, magenta, yellow, black, and two matte blacks are used. Six ink tanks 1 are mounted corresponding to the six colors of ink. In FIG. 1, a total of six ink tanks 1 are arranged at both ends of the printer in half. Needless to say, the arrangement is not limited to the case of being arranged on both sides as in this example, and may be arranged on one side. A sub tank 2 is attached to the ink tank 1. Thus, the ink 10 can be favorably supplied to the recording head 5 via the supply tube 3 while maintaining a balance between the pressure in the ink tank 1 and the atmospheric pressure.

  The recording head 5 is mounted on a carriage (not shown) and moves above the platen 4, and the recording operation is performed by discharging ink from the recording head 5 to the recording medium on the platen 4 during the movement. In the example shown in FIG. 1, two recording heads 5 are shown, but each of the four color ink ejection portions and the two color ink ejection portions are integrally configured. Needless to say, a recording head may be configured for each ink color ejection unit.

  At the time of non-recording, the recording head 5 prevents the evaporation of ink moisture by covering the ejection port surface with the cap 6. The cap 6 is connected to the tube pump 8 via a tube. In addition, a tube provided with a valve 7 is also connected to the inside of the cap 6. By switching the valve, the capping operation with respect to the recording head is brought into a state where the inside of the cap communicates with the atmosphere as necessary. The supply tube 3 is also provided with a valve 9 for switching the ink supply.

  In the above configuration, an ejection recovery operation (hereinafter also referred to as a maintenance operation) for maintaining good ejection characteristics of the recording head will be described. In the present embodiment, preliminary ejection for ejecting ink from the recording head 5 into the cap 6 is performed at a predetermined timing. In addition, the pump 6 is driven in a state where the discharge port surface of the recording head 5 is covered with the cap 6, and suction recovery is performed in which the inside of the cap is set to a negative pressure and ink is sucked and discharged from the recording head. Further, wiping for wiping the discharge port surface with a blade (not shown) is also performed. In specific maintenance control, any of these alone or in combination is performed at each timing. The maintenance that will be described later with reference to FIG. 5 is performed when a relatively long time has elapsed. First, suction recovery is performed, and then preliminary discharge and wiping are sequentially performed. The suction recovery is a relatively heavy recovery process to such an extent that bubbles existing in the supply tube 3 and the ink reservoir of the recording head can be removed.

  The printer according to the present embodiment shown in FIGS. 1 and 2 includes a control configuration (not shown) having a CPU, a RAM, a ROM, and the like, and will be described later with reference to FIGS. 4 and 5. The data processing and various controls in the printer of this embodiment are executed.

  FIG. 3 is a diagram schematically showing the configuration of the recording head 5. Ink 10 is stored in the ink reservoir 11 inside the recording head 5. A heater 13 is provided corresponding to each of a plurality of ejection openings constituting each ejection section of the recording head 5. A voltage is applied to the heater to generate thermal energy and cause film boiling in the ink 10. Then, ink is ejected from the corresponding ejection port 12 by the pressure of the ejection bubbles due to the film boiling.

  A temperature sensor 14 is provided inside the recording head 5. In this embodiment, as will be described later with reference to FIG. 5, the temperature before and after the preliminary ejection is measured, and the presence of bubbles in the recording head is detected based on whether or not the temperature difference exceeds a threshold value. That is, the heat generated during ink ejection is released to the ink 10 in the ink reservoir 11 in addition to the ejected ink. However, if the amount of ink accumulated in the ink reservoir 11 decreases, the heat generated from the heater 13 cannot be sufficiently released. As a result, the temperature of the entire recording head 5 rises. Therefore, the temperature before and after the preliminary discharge is measured using the temperature sensor 14, and the presence of bubbles in the recording head is detected based on the difference in temperature, and therefore the presence of bubbles in the supply tube 3 is detected with high probability. can do.

  In one embodiment of the present invention, the above-described maintenance operation for removing bubbles existing in the recording head or the ink supply path is set to the frequency of the recording operation performed during the elapsed time measured by the timer. To be executed accordingly. Then, a “normal mode” and a “consumption reduction mode” are set as recovery operation modes corresponding to the recording frequency. Among these, the “consumption reduction mode” indicates a mode in which the frequency of the recording operation is low. In this mode, the maintenance operation is not performed uniformly, but it is detected whether or not bubbles remain in the recording head or the ink supply path, and whether or not the maintenance operation can be performed is determined accordingly. To do.

  FIG. 4 is a flowchart showing processing for setting the normal mode and the consumption reduction mode. This mode setting process is activated when the printer of this embodiment receives a recording job from the host device (a101). Next, the recording job information before X days which becomes unnecessary for the determination of the recording frequency described below is deleted from the memory (a102). This X day is the maximum number of days used when calculating the recording frequency. Next, the reception time and the number of recorded sheets of the received recording job are stored for the next frequency calculation (a103).

  Next, it is determined whether the mode already set at the time of the setting is the normal mode or the ink consumption reduction mode (a104). In the present embodiment, the mode setting reference is made different according to the mode set at that time. Specifically, when the current mode is the normal mode, it is determined whether or not the number of recordings for the past X days is A or less (a105). If the number is not A or less, the normal mode is set (a106), and if the number is A or less, the ink consumption reduction mode is set (a108). On the other hand, if the current mode is the ink consumption reduction mode, it is determined whether or not the number of recordings on the following Y day is B or less (a107). In the case of B sheets or less, the ink consumption reduction mode is set (a108). In other cases, the normal mode is set (a106).

  Here, the number of days of X and Y and the number of sheets of A and B are arbitrary, but appropriate values can be obtained by experiments and the like in consideration of the characteristics of the recording head. In the case where a certain range is given according to the experimental result, X> Y is set, and A and B are set to a small value in order to improve the throughput of the entire maintenance operation. Thereby, it becomes easy to set the normal mode. Conversely, when it is desired to shift to the ink consumption reduction mode as much as possible, X <Y and A and B are set to large values. In this case, since X <Y, the recording job before the Y day is deleted in the process of step a102. Depending on the result of the experiment, X and Y, and A and B may be the same value.

  FIG. 5 is a flowchart showing a discharge recovery control process for determining whether or not to perform a maintenance operation using the mode set in the process shown in FIG. This process is executed subsequent to the process shown in FIG. 4, and specifically, is executed as a series of processes when transferring print data based on the received print job to the printer engine.

  When the recording data is transferred (a201), first, the elapsed time from the previous maintenance operation to the present is calculated (a202), and it is determined whether the maintenance operation is necessary based on this elapsed time (a203). Specifically, it is determined whether or not the elapsed time exceeds a reference threshold time interval. When the threshold time is exceeded, it is determined that maintenance is necessary. If the maintenance operation is not necessary, the recording operation is started immediately (a210).

  When the maintenance operation is necessary, it is determined whether or not the mode set at that time is the ink consumption reduction mode (a204). That is, the recording frequency is determined. When it is determined that the normal mode is selected, a maintenance operation (a209) is performed, and then a recording operation (a210) is started. On the other hand, when the ink consumption reduction mode is determined, that is, when it is determined that the recording frequency is equal to or lower than the predetermined frequency described with reference to FIG. 4, first, the temperature of the recording head is measured and stored as T1 (a205). Next, a predetermined amount of preliminary discharge is executed (a206), and the result of measuring the print head temperature again is set as T2 (a207). (A208). That is, the ejection state of the recording head is detected.

  As an abnormal temperature determination method, not only the determination method using the temperatures T1 and T2 before and after the preliminary discharge shown in FIG. 6 but also the temperature is measured at regular intervals while executing the preliminary discharge shown in FIG. There is a way. In this case, the preliminary discharge time is divided into a plurality of times, and the temperature is measured before and after each of the divided preliminary discharge intervals. For example, when there is a temperature rise equal to or higher than the threshold value at any of the preliminary ejection intervals, it is determined that the recording head is abnormal due to the retention of bubbles. According to this, it is possible to detect the abnormal state of the recording head with higher accuracy. Of course, the method for detecting the ejection failure of the recording head is not limited to the embodiment described above. Any method may be used as long as it is a well-known method for detecting a discharge failure due to air bubbles particularly in the recording head.

  If it is determined in step a208 that the difference between the head temperatures before and after the preliminary ejection is equal to or less than the threshold value, it is determined that the maintenance operation is unnecessary, and the recording operation is performed (a210). On the other hand, if the head temperature difference before and after the preliminary ejection is equal to or greater than the threshold value, the maintenance operation is executed and the maintenance timer is reset (a209). Thereafter, a recording operation is performed (a210).

  As described above, according to the recovery execution control of the present embodiment, when the frequency at which the printer is used varies and the amount of bubbles staying in the recording head or the ink supply path is different, Maintenance operations can be performed according to the frequency of use. As a result, it is possible to suppress unnecessary maintenance from being performed and to reduce the amount of ink that is unnecessarily discarded as compared with the case where the maintenance operation is uniformly performed by timer management.

It is a figure which shows typically the ink jet printer which concerns on one Example of the ink jet recording device of this invention. FIG. 2 is a schematic diagram showing an ink supply system mainly between a recording head and an ink tank shown in FIG. 1. FIG. 3 is a schematic diagram illustrating an internal configuration of the recording head illustrated in FIGS. 1 and 2. It is a flowchart which shows the process which sets the normal mode and consumption reduction mode concerning embodiment of this invention. FIG. 5 is a flowchart illustrating a process for determining whether or not to perform a maintenance operation using the mode set in the process illustrated in FIG. 4. It is a figure explaining an example of the temperature measurement before and behind preliminary discharge concerning the embodiment of the present invention. It is a figure explaining other examples of temperature measurement before and behind preliminary discharge concerning an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ink tank 2 Sub tank 3 Ink supply tube 5 Recording head 6 Cap 8 Pump 10 Ink 11 Ink storage 12 Discharge port 13 Heater 14 Temperature sensor

Claims (8)

An inkjet recording apparatus that performs recording by ejecting ink onto a recording medium using a recording head that ejects ink,
Recovery means for performing the ejection recovery operation of the recording head;
Timer means for measuring an elapsed time since the recovery operation by the recovery means is performed;
Determining means for determining whether the elapsed time measured by the timer means exceeds a threshold time interval;
A recording frequency determining means for determining a recording frequency in the ink jet recording apparatus;
Based on the fact that the determining means determines that the elapsed time has exceeded the threshold time interval, and the recording frequency determined by the recording frequency determining means is less than or equal to a predetermined frequency, the recovery means recovers the recording head. Recovery execution control means for performing
An ink jet recording apparatus comprising:   The apparatus further comprises discharge state detection means for detecting the discharge state of the recording head, wherein the determination means determines that the elapsed time has exceeded the threshold time interval, and the recording frequency determination means determines When determining that the recording frequency is equal to or less than a predetermined frequency, the recovery execution control unit determines that the discharge state detection unit detects that the discharge state of the recording head is defective. The inkjet recording apparatus according to claim 1, wherein the recovery operation of the recording head is performed by a recovery unit.   It further comprises mode setting means for setting a plurality of modes according to the recording frequency, and the recording frequency determining means performs the determination according to the mode set by the mode setting means, and the mode has a recording frequency equal to or lower than a predetermined frequency. 3. The ink jet recording apparatus according to claim 1, wherein the recording frequency is determined to be equal to or less than a predetermined frequency when the mode corresponds to the above.   4. The ink jet recording apparatus according to claim 3, wherein the mode set by the mode setting means is a consumption reduction mode in which the recording frequency is equal to or lower than a predetermined frequency, and a normal mode in which the recording frequency is higher than the predetermined frequency. .   The mode setting means varies the predetermined frequency depending on whether the mode already set at the time of the setting is the consumption reduction mode or the normal mode, and sets the consumption reduction mode when the recording frequency is less than the predetermined frequency. The inkjet recording apparatus according to claim 4, wherein the inkjet recording apparatus is set. A recording head ejection recovery control method in an inkjet recording apparatus that performs recording by ejecting ink onto a recording medium using a recording head that ejects ink,
A step of preparing a recovery means for performing an ejection recovery operation of the recording head, and a timer means for measuring an elapsed time after the recovery operation by the recovery means is performed;
A determination step of determining whether the elapsed time measured by the timer means exceeds a threshold time interval;
A recording frequency determining step for determining a recording frequency in the inkjet recording apparatus;
Based on the fact that the determining step determines that the elapsed time has exceeded the threshold time interval and that the recording frequency determined by the recording frequency determining step is not more than a predetermined frequency, the recovery means recovers the recording head. A recovery execution control process for performing
A discharge recovery control method characterized by comprising:   A discharge state detecting step of detecting a discharge state of the recording head, wherein the discharge state detecting step determines that the elapsed time exceeds the threshold time interval, and the recording frequency determining step includes Based on the determination that the recording frequency to be determined is less than or equal to the predetermined frequency, the discharge state of the recording head is determined, and the recovery execution control step detects that the discharge state of the recording head is defective in the discharge state detection step The discharge recovery control method according to claim 6, wherein the recovery means causes the recovery operation of the recording head to be performed.   It further has a mode setting step for setting a plurality of modes according to the recording frequency, and the recording frequency determining step performs the determination according to the mode set by the mode setting step, and the mode has a predetermined recording frequency. 8. The discharge recovery control method according to claim 6, wherein the recording frequency is determined to be equal to or lower than a predetermined frequency when the mode corresponds to the following.

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