JP2008143137A - Inkjet recording device and restoring method of inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately feed electric energy to an ink heating portion in an inkjet recording device, stabilize ink discharge by properly removing burnt deposit sticking to the surface of the heating portion, and elongate the service life of the heating portion, and reduce waste consumption of ink. <P>SOLUTION: In the inkjet recording device, restoring action for removing the burnt deposit 206 deposited on the surface 205 of the heating portion 102 of a recording means is carried out. In this case, a restoring means applying the electric energy for restoration to the heating portion 102 changes the electric energy for restoration applied to the heating portion 102 according to the property of the ink to be discharged from the recording means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and a method for recovering the ink jet recording apparatus.

  2. Description of the Related Art Inkjet recording systems that perform recording by ejecting a recording liquid (hereinafter referred to as ink) are known that use thermal energy as ink ejection energy. In this type of ink jet recording system, a recording head that discharges ink generally uses an electrothermal conversion body (discharge heater) that converts an electrical signal into heat energy corresponding to each of a plurality of ink discharge ports. It has been. The electrothermal transducer provided in the recording head generates bubbles in the ink by heating the ink according to the supplied electric energy according to the heat energy, and pressure fluctuations in the ink caused by the generation of the bubbles Thus, ink is ejected from the ink ejection port.

  In the method using the electrothermal transducer, the discharge ports for discharging the recording ink can be arranged at high density, so that high resolution can be obtained in the recorded image, the recording head can be miniaturized, etc. Has the advantage of

  However, in a recording head using this method, a substance is deposited by heating the ink on the contact surface with the ink of the discharge heater of the recording head at the beginning of recording or when used for a long time. Most of the deposited material is caused by the kogation of ink, and is hereinafter referred to as kogation. As a result, the foaming of ink becomes unstable, causing defective ejection in which ink is not ejected, and phenomena such as the amount of ink ejected and the ink landing position becoming unstable, which deteriorate the recording quality. It was a factor inviting.

  As techniques for removing the kogation generated in the discharge heater of the recording head and recovering the performance of the recording head, there are techniques disclosed in Patent Documents 1 and 2. In this technique, a so-called aging recovery operation is performed in which a kogation is removed by applying a drive pulse of a predetermined voltage to a recording head and performing an ink ejection operation.

  Specifically, a method of performing an aging recovery operation according to the number of ejection dot counts or the number of electrical signal counts, or aging for performing ink ejection by increasing the applied energy of an electrical signal compared to a recording operation on a normal recording medium. A recovery method is disclosed. Further, Patent Document 3 discloses a method in which a recording element having a higher printing ratio in each scan performs a larger amount of kogation removing means, and Patent Document 4 further removes kogation on the heater using an electrolyte for cleaning the head. How to do is shown.

JP 08-39825 A JP2004-314440 JP2005-131907 Patent No. 3412971

  In the kogation removal method proposed in Patent Documents 1 to 4, the start / end of aging is determined based on the number of ejections (number of recording dots) in the recording operation, the number of electrical signals supplied to the heater, and the like. The number of drive pulses in one aging operation is set.

  However, the amount of accumulated kogation varies depending on the ink characteristics, and also varies depending on the characteristics of the electrothermal conversion element and the conditions of the electric signal (drive pulse signal) supplied during the recording operation, that is, the voltage and pulse width. Therefore, the number of ejections (the number of recording dots) and the number of electrical signals cannot be appropriate indexes for controlling the timing and time for performing aging. For this reason, there is a possibility that kogation is not sufficiently removed by the aging recovery operation in the technology disclosed in each of the above patent documents in which aging is controlled based on the number of ejections (number of recording dots) and the number of electrical signals. . Therefore, in order to surely remove kogation by aging, usually, electric energy larger than energy originally required is supplied to the heater. For this reason, depending on the adhesion amount of kogation, the supplied energy becomes excessive, resulting in a problem that the durability of the heater portion is reduced, the life is shortened, and the waste of ink is increased.

  The present invention makes it possible to supply electric energy to the ink heating unit without excess and deficiency, to appropriately remove the kog attached to the surface of the heating unit to stabilize ink ejection, and to improve the life of the heating unit and An object is to reduce waste of ink.

  In order to achieve the above object, the present invention has the following configuration.

That is, according to the first aspect of the present invention, recording is performed using a recording unit that heats and discharges ink including at least a pigment and a pigment dispersant by a heating unit that generates thermal energy according to applied electric energy. In the ink jet recording apparatus to perform, in order to perform a recovery operation to remove the kog deposited on the surface of the heating unit by heating the ink, the recovery unit is configured to apply recovery electrical energy to the heating unit, The recovery means changes the electrical energy for recovery applied to the heating section in accordance with the characteristics of the ink to be ejected from the recording means. Inkjet recording using a recording means for ejecting ink containing at least a pigment and a pigment dispersant by applying electric energy to the part In the recovery method of the recording apparatus, in order to perform a recovery operation of removing the kog attached to the surface of the heating unit by heating ink, a recovery step of applying recovery electrical energy to the heating unit is provided. In the recovery step, the electrical energy for recovery to be applied to the heating unit is determined according to the characteristics of the ink ejected from the recording means.

  According to the present invention, since an appropriate recovery condition of the recording unit is set, it is possible to reliably remove the kogation deposited on the heating unit while suppressing excessive consumption of energy and ink, and the life of the heating unit Can be extended. In addition, since the recovery conditions are optimally set, it is possible to appropriately set the start time, end time, and recovery time of the recovery operation, and it is possible to shorten the recovery operation time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below.

  FIG. 1 is a diagram showing one ejection port and its peripheral structure of a recording head (recording means) used in an ink jet recording apparatus according to the present invention, and (a) is a partially enlarged view seen from the ejection surface side. (B) is the BB sectional view taken on the line in (a).

  In FIG. 1, a heating unit (hereinafter also referred to as a heater unit) 102 that heats ink is formed on a substrate 101. On the substrate 101, a nozzle plate 106 in which an ink flow path 103, a foaming chamber 104, and a discharge port 105 formed by a semiconductor manufacturing process are formed. The ink flow path 103 communicates with the ejection port 105 through the foaming chamber 104. Further, the discharge port 105 is formed at a position facing the heater unit 102. A portion including the ink discharge port 105, the foam chamber 104, the ink flow path 103, and the heater unit 102 is referred to as a nozzle in the following description. In the ink jet recording head, a plurality of nozzles having the above-described configuration are arranged with a predetermined density.

  In the above configuration, ink supplied from an ink tank (not shown) is filled into the foaming chamber 104 through the flow path 103. In this state, when electricity corresponding to the recording signal is supplied to the heater unit 102, bubbles are instantaneously generated in the ink filled in the foaming chamber 104 by the heat energy converted by the heater unit 102. Ink droplets are ejected from the ejection port 105 communicating with the foaming chamber 104 using the pressure change caused by the bubble growth, and recorded on the recording medium.

FIG. 2 shows an example of a cross-sectional configuration of the heating unit (heater unit) 102 shown in FIG.
In the figure, reference numeral 202 denotes a heating resistor, and as its material, for example, Ta (tantalum), Ta compound (tantalum compound), W (tungsten), W compound (tungsten compound) or the like is used. Reference numeral 203 denotes an electrode for supplying power to the heating resistor 202. Reference numeral 204 denotes a protective layer for protecting the heating resistor 202 and the electrode 203 from chemical corrosion such as ink, and is usually formed of SiO2 or SiN which is electrically insulating. The outermost layer 205 has conductivity and is usually formed of Ta, Cr (chromium), or the like. Reference numeral 101 denotes a substrate for supporting the heating resistor 202. For this substrate 101, Si (silicon) whose surface in contact with the heating resistor 202 is thermally oxidized is preferably used.

  In the heater unit 102 configured in this manner, as described above, when an initial recording start or a recording operation for a long time is performed, the kog 206 is heated on the surface of the heater unit 102, that is, the outermost surface layer. Accumulate on 205.

Next, the ink used for recording will be described.
In many cases, an ink jet recording apparatus uses an aqueous dye ink having excellent color developability. However, in recent years, it has been proposed and practiced to use pigments instead of dyes as a method for improving the water resistance and light resistance of recorded images. In such a pigment ink, a dispersant resin (pigment dispersant) is contained in the ink in order to disperse the pigment in the solvent. As the dispersant resin, a general water-soluble resin is generally used.

Specifically, for example, styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acid, etc.
Acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, vinyl acetate, vinyl pyrrolidone, acrylamide, and derivatives thereof,
A block copolymer, a random copolymer, a graft copolymer, or a salt thereof comprising at least two monomers selected from the above (at least one of which is a hydrophilic monomer). It is done.

Here, the change in the ejection speed in the recording head will be described for two types of inks using dispersant resins having different thermal decomposition temperatures.
FIG. 3 is a diagram showing the relationship between the ejection speed and the cumulative number of recording dots for two types of ink. In the figure, the dispersant resin contained in ink A has a higher thermal decomposition temperature than the dispersant resin contained in ink B.

  The recording head immediately after manufacture is unfamiliar with the heater unit 102 and the ink, and the kogation starts to accumulate, so the discharge speed decreases (area indicated by a in FIG. 3). Thereafter, when the number of recording dots increases, the initially accumulated kogation peels off and the ejection speed stabilizes, but when used for a long time, kogation accumulates again, and the ejection speed begins to gradually decrease (in FIG. 3, b).

  As shown in the figure, the discharge speed of the ink A is larger than that of the ink B, and the speed (recovery speed) at which the kogation is removed from the heater unit 102 by the recovery operation described later is also slow. This is considered due to the thermal decomposition temperature of the dispersant resin contained in the ink. That is, the ink containing the dispersant resin having a higher thermal decomposition temperature has a larger amount of kogation accumulated in the heater portion, and the accumulated kogation is more difficult to decompose.

  Conventionally, an aging recovery operation and a cleaning operation have been started according to the cumulative number of recording dots (the number of ejection pulses) empirically so as to perform image recording in the region where the ejection speed is normal as shown in FIG. In some cases, when the user recognizes image deterioration, the recovery operation is executed by arbitrarily determining the timing. In this case as well, the number of drive pulses used in the recovery operation is the cumulative recording dot number (the number of ejection pulses). ).

  In this specification, the aging recovery operation is a method of removing kogation by applying a drive pulse signal having a predetermined voltage to the print head and performing an ink discharge operation. Specifically, a drive pulse signal is applied to the heater unit corresponding to the target discharge port in the same manner as in the normal recording operation, but the voltage or pulse width of the drive pulse is different from that in the recording operation. It has become. For example, a pulse having a voltage value larger than a normally applied voltage value at the time of recording or the like is applied. Ink ejection in this operation is generally performed toward a dedicated ejection receptacle or cap. In this specification, the recovery operation in which a voltage is applied to the heater unit for purposes other than the purpose of removing kogation is referred to as a cleaning operation in order to distinguish it from the above-described aging recovery operation.

  As described above, the reduction in the discharge speed and the degree of recovery differ depending on the thermal decomposition temperature of the dispersant resin contained in the ink. Therefore, in the present invention, the recovery operation is changed according to the thermal decomposition temperature of the dispersant resin. Let That is, in a recording head that discharges ink containing a dispersant resin having a high thermal decomposition temperature, pulsed electric energy (electric signal) applied by a drive pulse signal is increased. Further, the energy applied to each drive pulse is reduced for a recording head that ejects ink having a low thermal decomposition temperature. As a result, it is possible to apply appropriate electrical energy without excess or deficiency to the discharge heater 102, and an appropriate recovery operation can be performed.

  Note that the electrical energy applied by the drive pulse signal in one recovery operation described above (applied energy in each recovery operation) is determined by, for example, the voltage value, the pulse width, the number of pulses, and the like. That is, increasing each applied energy means increasing the voltage value, increasing the pulse width, or increasing the number of pulses used for one aging recovery operation. All of these change the heat energy generated by the discharge heater in a direction to further increase.

  Subsequently, in the dispersant resin contained in the ink, the relationship between the ejection speed and the cumulative number of recording dots was examined for two types of inks having different contents. As a result, it was found that the higher the content of the dispersant resin, the greater the decrease in discharge speed and the slower the recovery of the discharge heater (removal of kogation). Therefore, as in the case of the thermal decomposition temperature described above, in the recording head that ejects ink having a high content of the dispersant resin, the electric energy applied by the drive pulse signal during one recovery operation is increased. Conversely, in a recording head that drives ink with a low dispersant content, the energy applied to the drive pulse signal is reduced. As a result, an appropriate recovery operation can be performed.

  Next, the relationship between the discharge speed and the amount of carbon contained in the kogation (hereinafter referred to as C amount) will be described. Here, a case is considered where the outermost layer 205 and the heating resistor 202 of the heater unit 102 shown in FIG. 2 are composed of a component containing Ta.

  First, elemental analysis of the heater unit 102 with different discharge speeds was performed, and the amount of C contained in the koge was confirmed. SEM-EDS (scanning electron microscope-energy dispersive X-ray spectroscopy) was used as an elemental analysis method, and surface analysis was performed at an applied voltage of 15 kV.

  FIG. 4 shows the relationship between the discharge speed and the amount of C in the burnt portion based on the result of the surface analysis. The amount of C in the burnt portion on the horizontal axis is represented by the ratio (C / Ta) of the number of atoms of C (carbon) to the number of Ta atoms in the heater portion where the burnt is deposited. FIG. 4 shows that the discharge speed decreases as C / Ta increases. This relationship is the same even if the ink type and other ejection conditions are changed.

  As described above, in order to perform recording at a normal portion of the discharge speed, a management value (upper limit threshold and lower limit threshold) is determined based on the C amount on the surface (outermost layer) of the heater unit 102, and the C amount is determined as the upper limit threshold. If the discharge is performed within the range of the lower threshold, appropriate management and control can be performed.

  That is, when the amount of C increases and reaches the upper threshold value, the removal of kogation is started by a recovery operation such as a cleaning operation or an aging operation. Then, it is desirable to finish the kogation removal operation when the C amount sufficiently falls below the upper threshold value (when the C amount reaches the lower threshold value), and then perform a normal recording discharge operation. As a method for monitoring the amount of C, measurement of the sheet resistance value on the surface of the heater section described below is suitable.

  FIG. 5 shows the relationship between the sheet resistance value on the surface of the heater part and the C amount (C / Ta, ratio of the number of atoms) of the burnt part. As the amount of C increases, the sheet resistance value increases. By detecting the sheet resistance value of the surface (outermost layer 205) of the heater unit 102 from the relationship of FIG. 5 and the relationship between the discharge speed and the C amount shown in FIG. 4, the start and end of cleaning and aging are detected. Is possible. In this case, it is preferable that the sheet resistance value measurement is performed during a recording pause in which the heater temperature is low.

  Moreover, as a sheet resistance measuring method, the influence of the contact resistance of a terminal can be reduced by using the four terminal method as shown in FIG. In this method, a constant current is passed between the two outer terminals and the potential difference generated between the two inner terminals is measured to obtain the resistance value of the object to be measured. Resistance value can be measured. If this four-terminal method cannot be used due to some restrictions such as the apparatus and method, the sheet resistance may of course be measured by other measurement methods.

  As a method for monitoring the amount of C, in addition to the method of measuring the resistance value of the surface of the heater unit 102, a method of measuring the reflectance or unevenness of the surface of the heater unit 102 using a laser beam may be used. Is possible. In order to monitor the amount of C, a monitoring nozzle may be set separately from the nozzle used for the recording operation, or a normal recording operation nozzle may be used for the monitoring. Further, although one nozzle may be monitored, it is also possible to perform the above different measurement methods for a plurality of different nozzles. In this case, the C amount can be measured more reliably.

As described above, according to the ink jet recording apparatus of the embodiment of the present invention, an appropriate recovery operation is performed for each of a plurality of recording heads that eject inks having different thermal decomposition temperatures or content rates of the dispersant resin. Can do. In other words, depending on the type of ink to be ejected, it is possible to apply energy for recovery operation without excess or deficiency, and it is possible to reliably remove kogation while suppressing wasteful consumption of energy and ink. become.
In addition, by measuring the amount of C, it is possible to determine the optimal start time and end time of the recovery operation, and it is possible to perform aging at an appropriate time. Effects such as life extension can be obtained.

  In addition, since the aging recovery operation is performed by monitoring the actual state of the head and heater instead of the experience value, it is not affected by the history so far, and it effectively works for sudden head troubles.

Hereinafter, the present invention will be described more specifically based on examples of the present invention.
(First embodiment)
FIG. 7 is a perspective view schematically showing a schematic configuration of an ink jet printer that can perform recording by ejecting ink onto a recording medium such as recording paper, using the recording head provided with the ink ejecting section described in FIG. It is.

  As shown in FIG. 7, in the first embodiment, a plurality of types of recording heads 701, 702, and 703 corresponding to yellow (Y), magenta (M), cyan (C), and black (B) inks. 704 are used. Further, ink tanks 705, 706, 707, and 708 for individually storing the inks of the respective colors are used for supplying ink to each of these recording heads. These recording heads and ink tanks are configured to be detachable from the carriage, so that the recording heads and ink tanks can be used interchangeably. Further, when the corresponding recording head and ink tank are mounted on the carriage, they constitute a mutual ink supply path.

  In the present embodiment, the four recording heads corresponding to the four colors of Y, M, C, and B are configured as an aggregate (unit) of the recording heads. It is distinguished as a discharge port array. In addition, the number of ejection ports of each of the four recording heads is 1280. This discharge port is the same as that shown in FIG. 1, and in this embodiment, TaN is used for the heating resistor 202 and Ta is used for the outermost layer 205 in the electrothermal conversion element portion (heater portion) shown in FIG.

  The carriage is slidably engaged with the guide rail 709 and is connected to a rubber belt 710 stretched in parallel with the guide rail 709. As a result, the carriage can move in both directions of the arrows in the figure as the rubber belt 710 rotates. Specifically, a rubber belt 710 is stretched around pulleys 711 and 712 disposed near both ends of the apparatus, and one pulley 711 is fixed to the carriage motor 713. Then, the carriage moves in either direction of the arrow according to the rotational drive of the motor 713.

  By this movement of the carriage, the recording head can scan (scan) the recording medium 714 in any direction of an arrow, and ink can be discharged during this time to perform recording. At this time, the position and speed of the recording head in the scanning direction can be known by detecting an encoder 715 provided along the carriage moving direction with a position sensor (not shown) on the carriage. The signal from the position sensor is also used for carriage position control, print head ejection control, and the like.

  Each time the recording head is scanned, the recording medium 714 is conveyed (paper fed) by a predetermined amount in a direction substantially perpendicular to the scanning direction. This transport operation is performed by a transport roller 716 that is rotationally driven by a paper feed motor (not shown) and a pinch roller for pressing a sheet against the transport roller 716. As the recording medium 714, recording paper represented by a cut sheet form, continuous paper, or the like can be used.

  In the recording area by the scanning of the recording head, the conveying roller 716 rotates with high accuracy so as to maintain a predetermined feed amount (generally, an amount corresponding to the recording width in one scanning of the recording head 1). Thus, the movement amount of the recording medium 714 is controlled. During the recording, the recording medium 714 is also conveyed by an auxiliary conveying roller (not shown) such as a spur and a roller so as to hold the recording head against a platen (not shown) so that the recording medium does not lift up. The

  Next, the schematic configuration of the control system of the ink jet recording apparatus used in the above embodiment will be described with reference to the block diagram of FIG.

  In FIG. 8, reference numeral 1700 denotes an interface which receives a recording signal including a command and image data sent from a host apparatus 1000 having an appropriate form such as a computer, a digital camera, or a scanner. Further, status information of the recording device is transmitted to the host device 1000 as necessary. Reference numeral 1701 denotes an MPU, which controls each unit in the ink jet recording apparatus according to a control program stored in the ROM 1702 and required data. The data includes, for example, the management values (upper limit threshold value, the driving pulse voltage, the pulse width, the number of pulses, etc.) for determining the recording head driving conditions and the start timing of the aging recovery operation. Lower threshold). In addition, conditions for conveying the recording medium, carriage speed, and the like can also be included.

  Reference numeral 1703 denotes a DRAM for storing various data (such as the recording signal and recording data supplied to the head). The DRAM 1703 can be provided with a flag area or the like used in the control process described later. Reference numeral 1704 denotes a gate array (GA) that controls supply of recording data to the head 1. The gate array 1704 also controls data transfer among the interface 1700, MPU 1701, and DRAM 1703. Reference numeral 1725 denotes a dot counter that counts the number of ink ejections (number of dots) for each printing operation. Reference numeral 1726 denotes a nonvolatile memory such as an EEPROM for storing necessary data even when the recording apparatus is powered off.

  A conveyance motor 1709 is used as a drive source for conveying the recording paper P. A recovery system motor 1711 is used as a drive source for the capping operation of the cap 513 and the operation of suction recovery means such as a pump for performing recovery of suction. It should be noted that these motors 1709 and 1711 can be used together by appropriately configuring the transmission mechanism. Reference numeral 1705 denotes a head driver that drives the head 1, and 1706, 1707, and 1708 denote motor drivers that drive the transport motor 1709, the carriage motor 504, and the recovery system motor 1711, respectively. Reference numeral 1703 denotes a C amount monitoring unit that monitors the amount of C deposited on a predetermined heater unit 102 of the recording head. As the C amount monitor unit 1703, a resistance value measuring unit that detects the sheet resistance value of the surface layer of the heater unit 102 by the above-described four-terminal method, and a reflectance or unevenness of the heater unit 102 by using the above-described laser beam. The laser projector / receiver 1731 is provided. The operation of the C amount monitor unit 1730 is controlled by the MPU, and the monitored result is sent to the MPU 1701 via the gate array 1704. The MPU 1701 controls the execution of the aging recovery operation based on the received result and preset upper and lower thresholds.

  In the above-described ink jet recording apparatus, it has been found that the discharge speed of the recording head decreases at the initial discharge stage as shown in FIG. In order to prevent this initial drop in the discharge speed, the aging recovery operation is usually performed before shipment, but the aging recovery operation distinguished for each ink characteristic has not been performed.

On the other hand, in the first embodiment, different aging recovery operations are performed for each ink characteristic in the initial stage of ejection.
FIG. 9 is a diagram showing the relationship between the ejection speed of each ink and the cumulative number of recording dots in the initial stage of ejection in the first embodiment. The thermal decomposition temperature of the dispersant resin contained in each ink is B ink (black ink)> Y ink (yellow ink)> M ink (magenta ink)> C ink (cyan ink) in descending order. Yes. As shown in FIG. 9, it can be confirmed that the number of drive pulse signals necessary for the aging recovery operation for recovering the ejection speed in the recording head for ejecting B ink is 3 × 10 ⁵ . Conventionally, the aging recovery operation is performed based on this value. The conditions of the drive pulse signal are a voltage value of 24.0 V and a pulse width of 5.0 μs.

Further, it can be seen from FIG. 9 that the number of drive pulse signals required for the recording head that discharges Y ink is 1 × 10 ⁵ , and that the aging recovery operation is not required for the recording head that discharges M and C inks.
Based on the above results, in the initial stage of the recording operation, the number of drive pulse signals related to the aging recovery operation was determined according to the thermal decomposition temperature of the dispersant resin contained in the ink. As a result, it was possible to confirm an appropriate recovery state (burnt removal state) without using excessive energy or ink.

(Second embodiment)
Next, a second embodiment of the present invention will be described. The ink jet recording apparatus used in the second embodiment also has the configuration shown in FIGS.
In the second embodiment, the recovery operation of the recording head accompanying the ink discharge with different content of the dispersant resin will be described based on the relationship between the discharge speed of each ink and the cumulative number of recording dots in the initial discharge stage. The second embodiment differs from the first embodiment in that the Y ink is changed to the gray ink (Gy ink) among the four colors of ink. Normally, such an ink configuration is not seen, but in order to investigate the behavior of inks having different dispersant resin contents, the ink configuration was changed to such an ink configuration.

FIG. 10 shows the relationship between the ejection speeds of B ink and Gy ink and the cumulative number of recording dots in the initial stage of ejection in the second embodiment. Note that the content of the dispersant resin contained in each of the B ink and the Gy ink is B ink> Gy ink in order from the highest. As shown in FIG. 10, with B ink, the number of drive pulses necessary for recovery of the ejection speed is 3 × 10 ⁵ as in the first embodiment, and with Gy ink, the number of drive pulses required for recovery is 1.5 × 10 ^5. Met. Note that the M and C inks do not require a recovery operation (not shown) as in the first embodiment.

  Based on the above results, it is possible to determine the drive pulse signal related to the aging recovery operation in the initial stage according to the content of the dispersant resin contained in the ink, thereby achieving an appropriate aging recovery state without using excessive energy or ink. It was confirmed that (the state of removing kogation) was obtained.

(Third embodiment)
Next, a third embodiment of the present invention will be described.
In the third embodiment, the number of drive pulses required to recover the discharge speed of each ink in the initial discharge stage was obtained using the ink jet recording apparatus shown in FIGS. 7 and 8 as in the first embodiment. However, it differs from the first embodiment in that the drive pulse signal condition for B ink is a voltage value of 25.0 V and a pulse width of 6.0 μs.

In this third embodiment, the number of drive pulses required to restore the B ink ejection speed is 1.2 × 10 ⁵ , which is approximately the same as the number of drive pulses required for Y ink. became.

  Based on the above results, appropriate aging is achieved while applying electrical energy without excess or deficiency by changing the voltage value and pulse width of the drive pulse signal related to the aging recovery operation according to the thermal decomposition temperature of the dispersant resin contained in the ink. It was confirmed that a recovery state (burnt removal state) was obtained.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.
In the fourth embodiment, as in the first embodiment, the ink jet recording apparatus shown in FIGS. 7 and 8 is used, and in the case shown in FIG. A description will be given of the aging recovery operation when the value begins to decrease.

Conventionally, the aging recovery operation is performed according to the cumulative number of recording dots counted for each nozzle. Specifically, the number of drive pulses is determined by referring to the aging table based on the cumulative recording dot number.
FIG. 11 shows an example of an aging table conventionally used. In this table, the number of drive pulses in the aging recovery operation, that is, the number of ejections is determined for each predetermined range with respect to the cumulative number of recording dots. For example, if the cumulative number of recording dots is 7 × 10 ⁵ or more and less than 8 × 10 ^{5, the} number of drive pulses is 10,000.

  In the fourth embodiment, the start of the aging recovery operation is determined based on the cumulative number of recorded dots as in the conventional case. Further, regarding the end of the aging recovery operation, the aging recovery operation is not performed by managing the sheet resistance value of the outermost layer of the heater unit 102 based on the relationship shown in FIGS. 4 and 5 described above without using the aging table of FIG. The end condition (end timing) was determined.

  FIG. 11 shows the relationship between the ejection speed of the recording head and the sheet resistance value of the outermost layer 205 of the heater unit 102 measured in advance. This sheet resistance value is measured and calculated using the four-terminal method described above. From FIG. 11, it was confirmed that the ejection speed was normal when the sheet resistance value was 300 to 360Ω / □, so the threshold value for determining the end timing of the aging recovery operation was set to 320Ω / □. In the fourth embodiment, the resistance value is measured by a plurality of heater portions, the average value of the measured sheet resistance is calculated, and this is used for determining the end timing of the aging recovery operation.

As a specific value, the cumulative number of recording dots when the aging recovery operation was started was 9 × 10 ⁵ . When the aging recovery operation is started with this cumulative number of dots, conventionally, the aging recovery operation with 12,000 drive pulses has been performed according to FIG.

  In this fourth embodiment, after the aging recovery operation was started, the sheet resistance value of the outermost layer 205 of the heater unit 102 was appropriately measured, and the aging was completed when the threshold value was below 320Ω / □. Thereafter, when a recording operation was performed, it was confirmed that the image was recorded normally. The number of drive pulses during the aging recovery operation at this time is 9000 times for B ink (black ink) and 8000 times for Y ink (yellow ink), and the aging recovery operation can be performed with a smaller number of drive pulses than conventionally performed. I was able to complete. Also, Y ink, which is relatively easier to remove kogation than B ink, can complete the aging recovery operation with a smaller number of drive pulses than B ink, and application with no excess or deficiency depending on the ink characteristics It became possible to give energy.

(5th Example)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the ink jet recording apparatus shown in FIGS. 7 and 8 was used as in the first embodiment.
In the fifth embodiment, as in the fourth embodiment, an aging recovery operation when the discharge speed starts to decrease after a lapse of a certain time from the start of use will be described. However, the fifth embodiment is different from the fourth embodiment in that the start of the aging recovery operation is not determined by the cumulative recording dot number, but is determined by the sheet resistance value of the heater unit 102. The end of the aging recovery operation was determined by detecting the sheet resistance value of the outermost layer 205 of the heater unit 102 as in the fourth embodiment. Based on FIG. 12, the threshold for determining the start of the aging recovery operation (upper limit threshold) was 360Ω / □, and the threshold for determining the end was 320Ω / □ as in the fourth embodiment.

First, during recording, the sheet resistance value of the outermost layer 205 of the heater unit 102 was appropriately monitored, and aging was started when the upper limit threshold of 360Ω / □ was exceeded. The cumulative number of dots recorded at that time was 5 × 10 ^{6 for} B ink and 5.8 × 10 ⁶ for Y ink. When the aging recovery operation is started with this cumulative number of dots, conventionally, the aging recovery operation has been performed with a drive pulse number of 17000 times according to the aging table of FIG.

  On the other hand, in the fifth example, after the start of aging, the aging was completed when the sheet resistance value was below 320Ω / □, as in the fourth example. Thereafter, when a recording operation was performed, it was confirmed that the image was recorded normally. At this time, the number of drive pulses during the aging recovery operation is 14000 times for B ink (black ink) and 13000 times for Y ink (yellow ink), and aging is completed with a smaller number of drive pulses than conventionally performed. I was able to. In addition, Y ink, which is relatively easier to remove kogation than B ink, can complete aging with a smaller number of drive pulses than B ink. It became possible to grant.

(Example 6)
Next, a sixth embodiment of the present invention will be described. In the fifth embodiment, the ink jet recording apparatus shown in FIGS. 7 and 8 was used as in the first embodiment.

In this embodiment, the aging recovery operation is started when the cumulative number of recorded dots is 9 × 10 ⁵ as in the fourth embodiment. However, as a monitoring method for detecting the end of aging, the sheet resistance value of the outermost layer 205 of the heater unit 102 is used. Instead, the reflectance by the reflection of the laser beam was used.

  The laser beam was reflected on the outermost layer of the heater unit 102, and the correlation between the diffuse reflection component (diffuse reflectance), the ejection speed, and the C amount was measured in advance. As a result, it was confirmed that the laser light diffuse reflection component (diffuse reflectance) increases as the amount of C increases and the discharge speed decreases as kogation accumulates. Therefore, since the laser light diffuse reflection component (diffuse reflectance) is reduced by the recovery operation, the threshold is determined in advance by the laser light diffuse reflection component (diffuse reflectance), and the aging recovery operation is performed when the threshold falls below the threshold. Was controlled to end.

After the aging recovery operation was started, the laser light diffuse reflection component (diffuse reflectance) of the outermost layer 205 of the heater unit 102 was appropriately measured, and the aging was terminated when the value was below the threshold. Thereafter, it was confirmed that the image was normally recorded by the recording operation.
The number of drive pulses during the aging recovery operation at this time was 10,000 for B ink and 9000 for Y ink, and aging could be completed with a smaller number of drive pulses than conventionally performed. In addition, Y ink, which is relatively easier to remove kogation than B ink, can complete aging with a smaller number of drive pulses than B ink. It became possible to grant.

(Other embodiments)
In the first to third embodiments, the case where the aging recovery operation corresponding to the thermal decomposition temperature or content of the ink dispersant resin is performed in the initial stage of ejection has been described as an example. However, the aging recovery operation according to the thermal decomposition temperature or content rate can also be performed when the discharge speed starts to decrease after a certain period of time has elapsed from the start of use. In this case, the start time of the aging recovery operation can be determined based on an aging table as shown in FIG. 11, or can be performed based on a measured value of C amount.

  Furthermore, in the fourth to sixth embodiments, the aging recovery operation according to the amount of C of the koge deposited on the heating unit is performed when the discharge speed starts to decrease after a certain time from the start of use. . However, the aging recovery operation corresponding to the C amount can also be performed at the initial stage of discharge.

  Further, an aging recovery operation according to the thermal decomposition temperature or content of the ink dispersant resin and an aging recovery operation according to the amount of C may be appropriately combined.

  In the above embodiment, the aging recovery operation is controlled on the basis of the thermal decomposition temperature or content of the ink dispersant resin. However, the present invention is not limited to the above-described embodiment, and is used for recovery depending on the difficulty of disassembling the kogation deposited on the heating unit (heater unit) or the ease of depositing the kogation deposited. It is also possible to control the electrical energy.

  That is, the effect similar to that of the above-described embodiment can be expected by increasing the electric energy applied to the heater section as the ink is more difficult to decompose the kogation deposited on the heater section 102. The same effect as in the above embodiment can be expected even when the electric energy is increased as the ink discharged from the recording head is more easily deposited on the heater portion.

2A and 2B are diagrams showing one ejection port of the recording head used in the ink jet recording apparatus according to the present invention and its peripheral structure, wherein FIG. 4A is a partially enlarged view seen from the ejection surface side, and FIG. It is a BB sectional view. It is the elements on larger scale of the discharge outlet in the embodiment of the present invention. It is sectional drawing which shows an example of the heating part (heater part) shown in FIG. It is a figure which shows the relationship between the discharge speed in 2 types of ink in embodiment of this invention, and the number of accumulation recording dots. It is a figure which shows the relationship between the discharge speed and the C amount (C / Ta, ratio of atomic%) of a koge part in embodiment of this invention. It is a figure which shows the relationship between the sheet resistance value on the surface of a heater part, and the C amount (C / Ta, ratio of atomic number%) of a koge part in embodiment of this invention. It is explanatory drawing of the four terminal method which is an example of the sheet resistance measuring method in embodiment of this invention. 1 is a perspective view schematically showing a schematic configuration of an ink jet printer used in an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a control system of an ink jet recording apparatus used in an embodiment of the present invention. It is a figure which shows the relationship between four types of ink discharge speeds and the number of accumulation recording dots in the Example of this invention. It is a figure which shows the relationship between two types of ink discharge speeds and the number of accumulation recording dots in the Example of this invention. It is a figure which shows the aging table used in the conventional aging recovery operation | movement demonstrated in the Example of this invention. It is a figure which shows the relationship between the ink discharge speed and the sheet resistance value of the heater part surface in the Example of this invention.

Explanation of symbols

101 Substrate 102 Heating part (heater part)
DESCRIPTION OF SYMBOLS 103 Ink flow path 104 Foaming chamber 105 Discharge port 202 Heating resistor 203 Electrode 204 Protective film 205 Outermost layer 206 Koge 701 Recording head Yellow (Y)
702 Recording head Magenta (M)
703 Recording head Cyan (C)
704 Recording head Black (B)
1701 MPU
1702 ROM
1703 DRAM
1704 Gate array 1726 EEPROM
1730 C amount monitor unit 1731 Laser projector / receiver unit 1732 Resistance measurement unit

Claims (14)

In an inkjet recording apparatus that performs recording using a recording unit that heats and discharges ink including at least a pigment and a pigment dispersant by a heating unit that generates thermal energy according to applied electrical energy.
In order to perform a recovery operation of removing the kog accumulated on the surface of the heating unit by heating ink, the recovery unit includes recovery means for applying recovery electrical energy to the heating unit,
The ink jet recording apparatus, wherein the recovery means changes the electric energy for recovery applied to the heating unit in accordance with characteristics of the ink to be ejected from the recording means. The recording means comprises a plurality of types of recording heads that eject inks having different characteristics,
The ink jet recording apparatus according to claim 1, wherein the recovery unit changes the electrical energy for recovery in accordance with characteristics of ink to be ejected from each recording head.   The recovery means increases the electrical energy for recovery as the characteristics of the ink to be ejected increase the difficulty of disassembling the kogation deposited on the heating unit. Inkjet recording apparatus.   The inkjet according to any one of claims 1 to 3, wherein the recovery means increases the electrical energy for recovery as the characteristics of the ink to be ejected tend to deposit kogation on the heating portion. Recording device.   The said recovery means changes the said electrical energy for recovery according to the characteristic of the pigment dispersant contained in the ink which should be discharged from the said recording means. Inkjet recording device.   6. The ink jet recording apparatus according to claim 5, wherein the recovery means increases the electrical energy for recovery as the pyrolysis temperature of the pigment dispersant contained in the ejected ink is higher.   7. The ink jet recording apparatus according to claim 1, wherein the recovery means increases the electrical energy for recovery as the content of the pigment dispersant contained in the ink to be ejected is higher. A measuring means for measuring the amount of carbon contained in the koge deposited on the electrothermal conversion element;
The inkjet according to any one of claims 1 to 7, wherein the recovery means determines at least one timing of the start and end of the recovery operation according to the amount of carbon measured by the measurement means. Recording device. The measuring means measures a sheet resistance value of a portion where kogation is deposited on the heating unit,
The recovery means determines at least one of a start time and an end time of the recovery operation when the resistance value measured by the measurement means reaches a preset threshold value. 8. The ink jet recording apparatus according to any one of 7 above. The measuring means measures the reflectance of the portion where kogation accumulates on the heating unit,
The recovery means determines at least one of a start time and an end time of the recovery operation when the reflectance measured by the measurement means reaches a preset threshold value. The ink jet recording apparatus according to any one of 8. The electric energy applied to the heating unit is a pulsed electric signal,
The recovery means is characterized in that at least one of a voltage value, a pulse width, or a pulse number of the electric signal applied to the heating unit in one recovery operation is a characteristic of the pigment dispersant contained in the ink. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is determined according to the above. In a recovery method of an ink jet recording apparatus that performs recording using a recording unit that discharges ink containing at least a pigment and a pigment dispersant by applying electric energy to a heating unit,
A recovery step of applying recovery electrical energy to the heating unit in order to perform a recovery operation for removing kogation deposited on the surface of the heating unit by heating ink;
The recovery method of an ink jet recording apparatus, wherein the recovery step determines the electrical energy for recovery to be applied to the heating unit in accordance with characteristics of ink ejected from the recording means.   12. The recovery method of an ink jet recording apparatus according to claim 11, wherein the recovery step increases the recovery electric energy as the thermal decomposition temperature of the pigment dispersant contained in the ejected ink is higher.   The inkjet according to claim 11 or 12, wherein the recovery step increases the electrical energy for recovery applied to the heating unit as the content of the pigment dispersant contained in the ink to be ejected is higher. Recording device recovery method.

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