JP2008195017A - Recovery method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recovery method which requires shorter recovery time and reduces an ink waste quantity in the time of recovery. <P>SOLUTION: When nozzles 22Kn continuously discharge ink droplets, a nozzle 22Kn-1 filled with air bubbles inside is generated as shown in (b). When a recovery operation is carried out, at first, as shown in (b), a face surface 22Ks where ink outlets of the respective nozzles 22Kn are formed is covered with a cap 52 to be sealed. A space outside an ink discharge outlet 154 is thereby sealed by the cap 52. In this state, a pump 51 is driven so that it sends air into inside the cap 52, and then a valve 66 is closed in the timing when the insides of the nozzles 22Kn are not in positive pressure. The pressure inside the cap 52 is increased through the operation of the pump 51, and as shown in (c), ink I in all the ink nozzles 22Kn is pushed back to a shared liquid chamber 22Kr. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recovery method for recovering an ink discharge state from a nozzle of a recording head to an initial state.

  Paper, cloth, plastic sheets based on recorded information as recording devices with functions such as printers, copiers, facsimiles, etc., or as recording devices used as output devices such as composite electronic devices including computers and word processors and workstations Inkjet recording apparatuses (inkjet image forming apparatuses) that perform recording (form images) by ejecting ink onto a recording medium such as an OHP sheet have become widespread. Among these, in the inkjet recording apparatus used for industrial use, there are a wide variety of recording media used for recording, and there are various requirements for the material of these recording media. In recent years, development for these various requirements has progressed, and in addition to normal recording media such as paper and resin thin plates, recording devices that use cloth, leather, nonwoven fabric, metal, etc. as recording media are also used. It has become. Such an ink jet recording apparatus is now widely applied to printers, copiers, facsimiles, etc. from the viewpoints of low noise, low running cost, easy miniaturization of the apparatus, and easy colorization. Yes.

  As an ink jet recording head (hereinafter referred to as a recording head) used in an ink jet recording apparatus, one that ejects ink droplets from nozzles by various methods is known. Above all, a recording head that uses heat as the energy used to eject ink can achieve high-density multi-nozzle formation relatively easily, enabling high-resolution, high-quality, and high-speed recording. It is a method. In this method, heating elements are arranged in the ink flow paths respectively connected to a large number of ink ejection ports formed in the recording head, and electric energy or power corresponding to the recording signal is selectively supplied to these heating elements. Utilizing the thermal energy generated by the application, the ink in contact with (and in the vicinity of) the heat-generating element is rapidly heated to cause film boiling. Ink is ejected.

As described above, ink droplets are ejected by the pressure of bubbles in the recording head described above, so there are piles of fine bubbles that cannot be removed when printing continuously, and extraction of dissolved gas from the ink due to heat. Many bubbles may remain inside the nozzle. For this reason, ink ejection becomes impossible, paper dust of recording media, dust in the atmosphere, etc. may be mixed into the face surface (surface on which the ink ejection port of the nozzle is formed) or the nozzle, This may adversely affect ink ejection. Accordingly, various ink recording apparatuses are provided with a recovery unit that restores the ink ejection state from the recording head to an initial state in order to clean and remove those that adversely affect ink ejection. The recovery unit includes a pressure recovery unit type that applies pressure from the inside of the recording head to discharge bubbles together with ink from the nozzle, and a recovery member by sealing the ink discharge port with a recovery member (generally a rubber cap). Is a suction recovery unit type that sucks ink from the nozzles by making the internal pressure of the nozzle negative (see, for example, Patent Document 1). In any recovery unit type, there is a wiping means for wiping off ink adhering to the periphery of the nozzle, and dust adhering to the face surface, fixed ink, etc. can be wiped off.
Japanese Patent Laid-Open No. 02-000525

  In the ink jet recording apparatus equipped with the above-described suction recovery unit, ink is simultaneously sucked from all nozzles, so when there are a large number of nozzles that need to be recovered, the suction pressure per unit time must be increased, I have to keep sucking for a long time. For this reason, there is a problem that the amount of ink discharged increases and the recovery time becomes longer.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a recovery method that can shorten the recovery time and reduce the amount of ink discarded during recovery.

In order to achieve the above object, the recovery method of the present invention provides an ink ejection state from the nozzle in an initial state in an ink jet image forming apparatus that forms an image by ejecting ink from a nozzle of a recording head onto a recording medium. In the recovery method to recover,
(1) The nozzle is not filled with ink,
(2) A predetermined amount of ink is sucked through the nozzle.

here,
(3) When the ink is not filled in the nozzle, the ink meniscus may not be formed in the nozzle.

Also,
(4) When the ink is not filled in the nozzle, the ink discharge port of the nozzle is closed with a cap and the inside of the cap is pressurized so that the ink in the nozzle is placed inside the recording head. You may push back.

further,
(5) When the nozzle is not filled with ink, the recording head and the ink tank may be moved relative to each other to use a water head difference.

Furthermore,
(6) Prior to making the ink not filled in the nozzle, the face surface on which the ink discharge port of the nozzle is formed may be wiped off.

  In the present invention, before the ink is sucked through the nozzles, the ink is kept in the nozzles, so that the ink starts to be sucked through the nozzles under the same conditions. For this reason, when applying a suction pressure for sucking ink through each nozzle, a uniform suction pressure acts on each nozzle. In addition to the state where each nozzle is not filled with ink, a uniform suction pressure acts on each nozzle, so the suction pressure at the time of recovery can be lowered and the amount of ink sucked from each nozzle is reduced. As well as the recovery time. As a result, the amount of ink to be discarded can be reduced.

  The present invention has been realized in an ink jet printer that forms an image by ejecting ink onto a recording medium from a plurality of nozzles formed on a recording head.

  An example of a printer in which the recovery method of the present invention is executed will be described with reference to FIG.

  FIG. 1 is a front view schematically showing an example of a printer in which the preliminary ejection method of the present invention is executed.

  The printer 10 is connected to a host PC (personal computer) 12 that sends image information to the printer 10. In the printer 10, four (four) recording heads 22K, 22C, 22M, and 22Y are arranged side by side in the conveyance direction (arrow A direction) of the recording medium (roll paper in this case). The four recording heads 22K, 22C, 22M, and 22Y eject black, cyan, magenta, and yellow inks, respectively. These four recording heads 22K, 22C, 22M, and 22Y are so-called line heads, and extend in a direction orthogonal to the paper surface of FIG. 1 (a direction orthogonal to the arrow A direction). The lengths of these four recording heads 22K, 22C, 22M, and 22Y are slightly longer than the maximum width (the length in the direction perpendicular to the paper surface of FIG. 1) of the recording media that can be printed by the printer 10. Further, these four recording heads 22K, 22C, 22M, and 22Y are fixed and do not move during image formation (are in a non-moving state).

  A recovery unit 40 is incorporated in the printer 10 so that ink can be stably ejected from the four recording heads 22K, 22C, 22M, and 22Y. By the recovery unit 40, the ink ejection state from the recording heads 22K, 22C, 22M, and 22Y is restored to the initial ink ejection state. The recovery unit 40 includes a capping mechanism 50 that removes ink from the ink discharge port formation surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four recording heads 22K, 22C, 22M, and 22Y during the recovery operation. The capping mechanism 50 is provided independently for each of the recording heads 22K, 22C, 22M, and 22Y. In the example of FIG. 1, six colors (that is, six capping mechanisms 50) are shown. The color component is a preliminary mechanism when the recording head is added. The capping mechanism 50 includes a rubber cap 52 for sealing the ink discharge port forming surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four recording heads 22K, 22C, 22M, and 22Y, a known blade, an ink removing member, and a blade holding member. Etc.

  The roll paper P is supplied from the roll paper supply unit 24 and is conveyed in the direction of arrow A by the conveyance mechanism 26 incorporated in the printer 10. The transport mechanism 26 includes a transport belt 26a for loading and transporting the roll paper P, a transport motor 26b for rotating the transport belt 26a, and a roller 26c for applying tension to the transport belt 26a.

  When forming an image on the roll paper P, after the recording start position of the roll paper P being conveyed reaches below the black recording head 22K, the recording head is based on the recording data (image information). Black ink is selectively ejected from 22K. Similarly, each color ink is ejected in the order of the recording head 22C, the recording head 22M, and the recording head 22Y to form a color image on the roll paper P. In the printer 10, in addition to the components and members described above, main tanks 28K, 28C, 28M, 28Y for storing ink supplied to the recording heads 22K, 22C, 22M, 22Y, and recording heads 22K, 22C, 22M. , 22Y are provided with various pumps (see FIG. 2 and the like) for supplying ink and performing a recovery operation.

  With reference to FIG. 2, a part of the ink supply mechanism and the recovery unit incorporated in the printer 10 will be described.

  FIG. 2 is a schematic diagram showing a part of an ink supply mechanism and a recovery unit incorporated in the printer. FIG. 2 shows an ink supply device and a recovery unit for supplying ink to the recording head 22K and for recovering the recording head 22K. The other recording heads 22C, 22M, and 22Y have the same configuration. Is provided. In FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

  The printer 10 (see FIG. 1) includes an ink supply device 60 that supplies ink to the recording head 22K, and a recovery unit that restores the ink ejection state from the recording head 22K to the initial ink ejection state (normal ink ejection state). 40 is incorporated.

  The ink supply device 60 includes an ink tank 28K (see FIG. 1) that is detachable from the main body of the printer 10, and a sub tank 23K that is disposed in the middle of the ink supply path that connects the ink tank 28K and the recording head 22K. ing.

  The sub tank 23K and the recording head 22K are connected by two ink flow paths (an ink forward path 62 through which ink flows from the sub tank 23K to the recording head 22K and an ink return path 64 through which ink flows from the recording head 22K to the sub tank 23K) ( Connected). An open / close valve 66 that opens and closes the ink return path 64 at a predetermined timing is attached to the ink return path 64. An end 62a on the sub tank 23K side of the ink forward path 62 is connected to the sub tank 23K. Further, the end 62b on the recording head 22K side in the ink forward path 62 is connected to the common liquid chamber 22Kr (see FIG. 3) of the recording head 22K. For this reason, the ink stored in the sub tank 23K is supplied from the sub tank 23K to the common liquid chamber 22Kr of the recording head 22K through (via) the ink forward path 62. Of the ink forward path 62 and the ink return path 64, filters 67, 68, and 69 for removing dust and bubbles in the ink are provided at a connection portion with the sub tank 23K, a connection portion with the recording head 22K, and an intermediate portion thereof. It is attached.

  A reverse-rotating pump 70 is attached to the ink forward path 62. When the pump 70 rotates forward, ink is sent from the sub tank 23K toward the common liquid chamber 22Kr. When the pump 70 rotates in the reverse direction, ink is sent from the common liquid chamber 22Kr toward the sub tank 23K. The pump 70 does not flow ink when not driven.

  The capping mechanism 50 provided in the recovery unit 40 includes a rubber cap (rubber cap) 52 that covers and seals the face surface 22Ks of the recording head 22K. The rubber cap 52 moves up and down by a known configuration (contacts and separates from the face surface 22Ks).

  The recovery unit 40 is provided with a pump 51 capable of sucking air from the inside of the rubber cap 52 that seals the face surface 22Ks and sending air into the inside. When the pump 51 is operated so as to send air into the rubber cap 52 with the face surface 22Ks sealed, the air enters the nozzle 22Kn of the recording head 22K and the ink moves backward (pushed back to the common liquid chamber 22Kr). Be) On the contrary, when the pump 51 is operated so as to suck air from the inside of the rubber cap 52 with the face surface 22Ks sealed, the ink inside the recording head 22K is sucked through the nozzle 22Kn of the recording head 22K. . An ink discharge path 54 for discharging the ink discharged to the rubber cap 52 from the plurality of nozzles 22Kn formed on the recording head 22K to the outside is connected to the bottom of the rubber cap 52. The ink discharged from the rubber cap 52 is discharged into the waste ink tank 58 and stored.

  The structure of the nozzle 22Kn of the recording head 22K will be described with reference to FIG. The nozzles of the other recording heads 22Y, 22M, and 22C have the same structure. FIG. 3 is a cross-sectional view showing the nozzle and its peripheral portion. Although only one nozzle 22Kn is shown in FIG. 3, the recording head 22K has a large number of nozzles arranged side by side perpendicular to the recording medium conveyance direction.

  In the recording head 22K, a large number of nozzles 22Kn for ejecting ink are formed side by side in the direction perpendicular to the paper surface of FIG. The large number of nozzles 22Kn are connected (communicated) with a common liquid chamber 22Kr in which ink is stored. The common liquid chamber 22Kr is connected to a sub tank 23K (see FIG. 2), and ink is supplied from the sub tank to the common liquid chamber 22Kr.

  The nozzle 22Kn is provided with a heating element 152 for foaming (forming bubbles) in the ink in the nozzle 22Kn. By energizing the heating element 152 to generate heat, bubbles (bubbles) are generated in the ink in the nozzle 22Kn, and ink droplets are pushed out and discharged from the outlet (ink ejection port 154) of the nozzle 22Kn. The ejection of the ink droplet will be described later with reference to FIG.

  The heating element 152 is formed on the silicon element substrate 156 by a known technique. A silicon top plate 158 and a nozzle I160 are formed on the silicon element substrate 156 in order to make the ink wettability uniform in the vicinity of the meniscus M, which will be described later. The silicon top plate 158 and the nozzle I160 serve as nozzles 22Kn. Facing the inner wall. The nozzle I160 is formed on the inner wall in the vicinity of the ink discharge port 154 of the nozzle 22Kn, and narrows the ink discharge port 154.

  The common liquid chamber 22Kr is also formed in the silicon element substrate 156. In addition, a valve 162 that efficiently directs energy in the ink discharge direction (arrow D direction) when foaming is generated by the heating element 152 and a channel wall 164 that extends vertically from the silicon top plate 158 toward the inside of the nozzle 22Kn are also formed on the silicon element substrate. 156. The nozzle I160 is for preventing chipping (chipping) when the silicon top plate 158 is cut when a large number of nozzles 22Kn and the like are manufactured.

  The heating element 152 is formed by patterning an electric resistance layer and wiring. The heating element 152 generates heat by applying a voltage to the electric resistance layer through this wiring and passing a current. Due to this heat generation, the ink on the surface portion of the heating element 152 is foamed, and the ink is pushed out from the ink discharge port 154 and discharged. Further, a Di sensor (not shown) for detecting the temperature of the heat accumulated in the silicon element substrate 156 and the heating element 152 (heat storage temperature) is disposed on the silicon element substrate 156, and this Di sensor detects it. The drive condition of the recording head 22K is determined according to the detected temperature.

  An example of the recovery operation of the present invention will be described with reference to FIGS. Here, the five nozzles 22Kn of the recording head 22K are taken as an example, but in reality, the same state is obtained with a large number of nozzles, and the same applies to the other recording heads 22Y, 22M, and 22C.

  FIG. 4 is a simplified illustration of the same structure as the nozzle shown in FIG. 3, (a) is an explanatory view showing a nozzle in a normal state, and (b) is one nozzle with bubbles. FIG. 4C is an explanatory diagram showing a normal state where other nozzles are satisfied, and FIG. 8C is an explanatory diagram showing an example in which there is no ink in each nozzle prior to suction of ink from each nozzle. FIG. 5 is a flowchart showing the procedure of the recovery operation. In FIG. 4, the same components as those shown in FIGS. 2 and 3 are denoted by the same reference numerals.

  In the recording head 22K in the normal state, as shown in (a), each nozzle 22Kn is filled with ink I, and the common liquid chamber 22Kr communicating with each nozzle 22Kn is also filled with ink. Further, the water head pressure is equally applied to each nozzle 22Kn according to the positional relationship with the sub tank 23K. For this reason, the meniscus M is formed by the surface tension, viscosity, and nozzle shape of the ink. Ink droplets are ejected from the nozzles 22Kn from the normal state under the ejection conditions as described above.

  When ink droplets are continuously ejected from the respective nozzles 22Kn, the nozzle 22Kn-1 in which the inside is filled with bubbles is generated as shown in FIG. Thus, it is difficult to form an image because appropriate ink droplets are not ejected from the nozzle 22Kn-1 filled with bubbles, and in such a case, the recovery operation of each nozzle 22Kn, that is, the recording head, is difficult. A 22K recovery operation is required.

  In the present embodiment, when performing the recovery operation, first, as shown in FIG. 5B, the face surface 22Ks on which the ink outlet (ink ejection port 154) of each nozzle 22Kn is formed is covered with a cap 52 and sealed. (S501 in FIG. 5). As a result, the space outside the ink discharge port 154 is sealed with the cap 52. In this state, the pump 51 is operated so as to send air into the cap 52 (S502 in FIG. 5). Subsequently, the valve 66 (see FIG. 2) is closed at a timing such that the inside of the nozzle 22Kn does not become a positive pressure (atmospheric pressure higher than the outside air) (S503 in FIG. 5). Thereby, it is possible to further reliably prevent bubbles from being mixed into the upstream side (the ink flow paths 62 and 64 (see FIG. 2) side) from the common liquid chamber 22Kr. By the operation of the pump 51, the pressure inside the cap 52 is increased (pressurized), and the ink I in all the nozzles 22Kn is pushed back to the common liquid chamber 22Kr as shown in (c). By predetermining the time for operating the pump 51 at the design stage of the printer 10, the ink I exists in the common liquid chamber 22Kr, but the ink I cannot be filled in the nozzle 22Kn. . The pump 51 is operated for the above time and then stopped (S504 in FIG. 5).

  Since the volume (internal volume) of one nozzle 22Kn is sufficiently smaller than the common liquid chamber 22Kr, the air that has been pushed in (pressed) by the length of the nozzle 22Kn is from the volume (internal volume) of the common liquid chamber 22Kr. The amount is very small and floats as a bubble h in the common liquid chamber 22Kr. However, at the rear end portion of the nozzle 22Kn (the boundary portion between the nozzle 22Kn and the common liquid chamber 22Kr), as shown in (c), the meniscus M is formed at the same position for all the nozzles 22Kn.

  When the pump 51 is operated to increase the pressure inside the cap 52 as described above, the amount of ink I or air in one nozzle 22Kn is pushed back into the common liquid chamber 22Kr, and the inside of the common liquid chamber 22Kr. The moving distance of the ink I is more than several times. Therefore, the common liquid chamber 22Kr is set so as not to have no ink. In addition, since the filter 68 (see FIG. 2) is attached to a portion of the common liquid chamber 22Kr that is close to the ink flow paths 62 and 64 (see FIG. 2), any one of the nozzles 22Kn inside the common liquid chamber 22Kr. Even when the bubbles are pushed in from the common liquid chamber 22Kr, the bubbles are configured not to move outward (to the ink flow paths 62 and 64).

  From the state shown in (c), the pump 51 is operated so as to reduce the pressure inside the cap 52 to a negative pressure (S505 in FIG. 5). In this case, the operation time of the pump 51 is determined in advance at the design stage of the printer 10 so as to suck an amount of ink corresponding to the internal volume of the common liquid chamber 22Kr. Accordingly, in the recovery operation, the amount of ink sucked through the nozzle 22Kn is only an amount corresponding to the internal volume of the common liquid chamber 22Kr, and the amount of ink to be discarded can be reduced. In contrast, conventionally, all the ink in the recording head 22K is sucked by an amount that can be sufficiently sucked, so that the recovery operation can be executed with a smaller amount of ink suction than in the past.

  In addition, before the ink is sucked through the nozzles 22Kn, the inside of all the nozzles 22Kn is filled with air (the ink is not filled). In addition, even when the negative pressure is low, suction recovery can be achieved with a negative pressure sufficient to destroy the meniscus M of the ink shown in (c). In addition, it is desirable to clean the face surface 22Ks of the recording head 22Kn before executing the recovery operation (in a state where the ink is not filled in the nozzles 22Kn). This cleaning is performed by wiping with a known blade. The reason for cleaning prior to the recovery operation is that when the ink is pushed back into the nozzle, if the ink having a high viscosity adheres to the face surface 22Ks, the high-viscosity ink is also pushed into the nozzle. This is because it may be difficult to recover by the suction recovery performed in the above.

  In contrast to the conventional negative pressure such as suction recovery of 1000 to 3000 kPa, according to this embodiment, it is sufficient to destroy the meniscus M shown in FIG. And the suction time (operation time of the pump 51) is also shortened.

  Here, the state where the ink I is not filled in the nozzle 22Kn will be described with reference to FIGS.

  FIG. 6 is a cross-sectional view schematically showing a part of the nozzle and the common liquid chamber, and (a) to (e) show an example in which the nozzle is not filled with ink. FIG. 7 is a diagram when the nozzle is viewed from below, and both (a) and (b) show examples in which the nozzle is not filled with ink.

  The “state in which the nozzles are not filled with ink” in the present invention is not limited to the state in which only a small amount (a small amount) of ink is not present in the nozzles 22Kn, but also the ink meniscus M (see FIG. 4A). For example, as shown in FIG. 6A, a state where a very small amount of ink Is is attached to the side wall of the nozzle 22Kn is a state where there is no ink in the nozzle 22Kn. . Further, as shown in FIGS. 6B and 7B, there is no ink in the upper part of the nozzle 22Kn in the common liquid chamber 22Kr, and a very small amount of ink Is adheres to the side wall of the nozzle 22Kn. The state is a state where there is no ink in the nozzle 22Kn. Further, as shown in FIG. 6C, the state where the meniscus M1 is formed inside the common liquid chamber 22Kr is also a state where there is no ink in the nozzle 22Kn. Furthermore, as shown in FIG. 6D, the state where the ink is convex from the common liquid chamber 22Kr toward the nozzle 22Kn is also a state where there is no ink in the nozzle 22Kn. Furthermore, as shown in FIGS. 6E and 7A, the state in which the ink exists in the nozzle 22Kn and extends over the two surfaces is also the state in which there is no ink in the nozzle 22Kn.

  A second embodiment of the recovery method of the present invention will be described with reference to FIG.

  FIG. 8A is a schematic diagram illustrating a state where ink can be ejected from the nozzles, and FIG. 8B is a schematic diagram illustrating a state when ink in the nozzles is pushed back into the recording head. In these drawings, the same components as those shown in FIG. 2 are denoted by the same reference numerals.

  In the case of forming an image, as shown in (a), the sub tank 23K is positioned at a position that is a water head difference in which ink is supplied from the sub tank 23K to the recording head 22K. When performing the recovery operation, when the ink in the nozzle 22Kn is pushed back into the recording head 22K, the recording head 22K is raised without moving the sub tank 23K to increase the hydraulic head pressure acting on the nozzle 22Kn. As a result, a large negative pressure acts on the nozzle 22Kn, and the state shown in FIG. From this state, the valve 66 is closed as described in S503 of FIG. Subsequently, the recording head 22K is lowered to the position shown in FIG. In this lowered state, the valve 66 is opened. Subsequently, the operation of S505 in FIG. 5 is executed to complete the recovery operation. Thus, in the method of moving the recording head up and down, the pump 51 may not be installed as in the first embodiment.

FIG. 2 is a front view schematically showing an example of a printer in which the preliminary ejection method of the present invention is executed. FIG. 3 is a schematic diagram illustrating a part of an ink supply mechanism and a recovery unit incorporated in a printer. It is sectional drawing which shows a nozzle and its peripheral part. FIG. 3 is a simplified diagram showing the same structure as the nozzle shown in FIG. 3, (a) is an explanatory view showing a nozzle in a normal state, and (b) is a diagram illustrating one nozzle filled with bubbles and the other. These nozzles are explanatory views showing a normal state, and FIG. 8C is an explanatory view showing an example in which no ink is present in each nozzle prior to sucking ink from each nozzle. It is a flowchart which shows the procedure of recovery operation | movement. It is sectional drawing which shows the outline of a nozzle and a part of common liquid chamber, (a) to (e) shows the example of the state by which all are not filled with ink in the nozzle. It is a figure when a nozzle is seen from the bottom, and both (a) and (b) show examples in a state where ink is not filled in the nozzle. (A) is a schematic diagram illustrating a state in which ink can be ejected from a nozzle, and (b) is a schematic diagram illustrating a state when ink in the nozzle is pushed back into the recording head.

Explanation of symbols

10 Printer 22K, 22C, 22M, 22Y Recording head 22Kn Nozzle 22Kr Common liquid chamber 22Ks Face 51 Pump 52 Cap

Claims (5)

In a recovery method for recovering an ink discharge state from the nozzle to an initial state in an inkjet image forming apparatus that forms an image by discharging ink from a nozzle of a recording head to a recording medium.
The nozzle is not filled with ink, and then
A recovery method comprising sucking a predetermined amount of ink through the nozzle. The recovery method according to claim 1, wherein when the ink is not filled in the nozzle, the ink is not formed with a meniscus in the nozzle. When the ink is not filled in the nozzle, the ink ejection port of the nozzle is closed with a cap, the inside of the cap is pressurized, and the ink in the nozzle is pushed back into the recording head. The recovery method according to claim 1 or 2, characterized in that 3. The recovery method according to claim 1, wherein when the ink is not filled in the nozzle, the recording head and the ink tank are relatively moved to utilize a water head difference. 4. 5. The face surface on which the ink discharge port of the nozzle is formed is wiped before the nozzle is not filled with ink. 5. Recovery method described in 1.

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