JP6225867B2 - Recording head maintenance method and ink jet recording apparatus - Google Patents

Description

  The present invention relates to a recording head maintenance method and an ink jet recording apparatus.

  A purge / wipe operation is known as a process for maintaining a recording head equipped in an ink jet recording apparatus. The purge / wipe operation is a process of executing a wipe operation following the purge operation. The purge operation is an operation in which ink is supplied to the recording head and ink (purge ink) is forcibly pushed out (purged) from a nozzle (ink ejection port) of the recording head. The wiping operation is an operation of cleaning the nozzle surface by wiping (wiping or wiping) the nozzle surface (surface on which the nozzle is formed) of the recording head with a cleaning blade. Therefore, when the purge / wipe operation is executed, the purge ink is pushed out from the nozzle, and the purge ink attached to the nozzle surface is wiped off by the cleaning blade.

  However, the purge ink wiped off by the cleaning blade remains on the cleaning blade. The purge ink remaining on the cleaning blade comes into contact with air to dry and thicken until the next wiping operation. The purge ink remaining on the cleaning blade is rubbed against the nozzle surface during the next wiping operation. As a result, the thickened purge ink adheres as a thin film to the nozzle surface (see, for example, Patent Document 1).

  The purge ink adhering to the nozzle surface is further dried by contact with air and further thickened until the next purge / wipe operation. For this reason, the purge ink adhering to the nozzle surface may not be removed by a normal wipe operation. For this reason, by repeating the purge / wipe operation, the purge ink remaining on the cleaning blade is repeatedly rubbed on the purge ink adhering to the nozzle surface, and the purge ink on the nozzle surface is repeatedly rubbed. There is a possibility that the thickness of the purge ink increases as the thin film accumulates little by little. As the thickness of the purge ink increases, the possibility that the purge ink adheres to a recording medium such as a sheet passing under the recording head increases.

  The purge ink adheres to the recording medium particularly easily when cockling or curling occurs on the recording medium. For example, when the thickness of the purge ink is 0.5 mm or more, the purge ink tends to adhere to a recording medium on which cockling or curling has occurred. The purge ink adhering to the recording medium causes deterioration in image quality.

Japanese Patent Application Laid-Open No. 6-079880

  As a method for removing the purge ink adhering to the nozzle surface, a method in which a cleaning liquid for dissolving ink (purge ink) is immersed in a porous pad such as a sponge and the pad is brought into close contact with the nozzle surface can be considered. According to this method, the purge ink adhering to the nozzle surface can be returned to a liquid state and dropped from the nozzle surface.

  The method of bringing the pad soaked with the cleaning liquid into close contact with the nozzle surface requires a certain amount of time in order to dissolve the dried and thickened purge ink. Further, the longer the time for which the pad is brought into close contact with the nozzle surface, the higher the effect of removing the purge ink.

  However, when the pad is brought into close contact with the nozzle surface for a long time, the cleaning liquid enters from the nozzle into the fine flow path inside the recording head, and mixing of the cleaning liquid and the ink occurs. Mixing of the cleaning liquid and the ink causes ink aggregation. Then, the aggregation of ink in the fine flow path inside the recording head causes a defective ejection of ink from the recording head (nozzle).

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a recording head maintenance method and an ink jet recording apparatus capable of suppressing purge aggregation adhering to a nozzle surface and suppressing aggregation of ink in the recording head. Objective.

  A recording head maintenance method according to the present invention includes the following steps. A step of pressing a pad member into which the cleaning liquid has penetrated against the nozzle surface of the recording head; And a purge operation for supplying ink to the recording head while the pad member is pressed against the nozzle surface.

  An ink jet recording apparatus according to the present invention includes a recording head having a nozzle surface, a pump mechanism, and a supply channel. The pump mechanism supplies ink to the recording head. The supply flow path connects the recording head and the pump mechanism. The ink flows through the supply flow path from the pump mechanism toward the recording head by the operation of the pump mechanism. Further, while the pad member infiltrated with the cleaning liquid is pressed against the nozzle surface, the pump mechanism applies a pressure to the supply flow path to perform a purge operation for supplying the ink to the recording head. Done.

  According to the present invention, it is possible to reduce the purge ink adhering to the nozzle surface and to suppress the aggregation of ink in the recording head.

1 is a diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a nozzle surface included in the recording head according to the embodiment of the invention. FIG. 3 is a flowchart illustrating a recording head maintenance method according to the first embodiment of the invention. It is a figure which shows the structure of the inkjet recording device which concerns on Embodiment 2 of this invention, and operation | movement of the inkjet recording device. It is a figure which shows the structure of the 1st maintenance unit with which the inkjet recording device which concerns on Embodiment 2 of this invention is provided. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. It is a figure which shows operation | movement of the inkjet recording device which concerns on Embodiment 2 of this invention. FIG. 9 is a flowchart illustrating a recording head maintenance method according to a second embodiment of the invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated. In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. .

[Embodiment 1]
[Inkjet recording apparatus 1]
FIG. 1 is a diagram illustrating a configuration of an inkjet recording apparatus 1 according to the first embodiment. Specifically, FIG. 1 shows a state during maintenance of the recording head 2 provided in the inkjet recording apparatus 1. FIG. 2 is a diagram illustrating a nozzle surface included in the recording head 2. Specifically, FIG. 2 shows a state of the nozzle surface 11 before the recording head 2 is maintained. As shown in FIG. 2, the nozzle surface 11 is provided with a nozzle region R in which a large number of nozzles 12 (ink discharge ports) are arranged. Further, purge ink 10a thickened by drying adheres to the nozzle surface 11 of the recording head 2 before maintenance.

  As shown in FIG. 1, at the time of maintenance of the recording head 2, the pad member 3 into which the cleaning liquid has permeated is pressed across the entire nozzle surface 11 of the recording head 2. The pad member 3 is held by the holding member 4. In this embodiment, for example, a maintenance person holds the holding member 4 with his hand and presses the pad member 3 against the nozzle surface 11 of the recording head 2. For easy understanding, the pad member 3 and the holding member 4 are shown in cross section.

  The pad member 3 is preferably made of a porous material. As the porous material, for example, a material that has a continuous pore structure therein and can absorb and permeate liquid, such as continuous foam, woven fabric, and non-woven fabric, is preferably used. In particular, as a material for forming the pad member 3, it is preferable to use a material having elasticity so that it is difficult to damage the object even if it comes into contact with the object and can maintain its own shape. Examples of such materials include so-called continuous foams such as urethane, polystyrene, polypropylene, and polyethylene, and other sponge-like materials.

  By forming the pad member 3 from a porous material, the cleaning liquid can easily penetrate into the pad member 3. Further, since the pad member 3 is formed of an elastic material, the pad member 3 can be easily adhered to the nozzle surface 11. In the present embodiment, the pad member 3 is compressed when the pad member 3 is pressed against the nozzle surface 11.

  The ink jet recording apparatus 1 includes a pump mechanism 5 for supplying ink 10 to the recording head 2. The pump mechanism 5 includes a hollow cylinder 51 and a piston 52. A part of the piston 52 is inserted into the hollow part of the cylinder 51. The piston 52 can be moved in the longitudinal direction of the cylinder 51 by a driving device. An inlet and an outlet are formed at the bottom of the cylinder 51.

  The ink jet recording apparatus 1 includes an ink tank 6 that stores ink 10. Further, the ink jet recording apparatus 1 includes a first flow path 7, a second flow path 8, and electromagnetic valves 9a and 9b.

  One end of the first flow path 7 is connected to the ink tank 6, and the other end of the first flow path 7 is connected to the inlet of the pump mechanism 5 (cylinder 51). That is, the first flow path 7 connects the ink tank 6 and the pump mechanism 5. The first flow path 7 is provided with an electromagnetic valve 9a. The ink 10 stored in the ink tank 6 flows through the first flow path 7 toward the cylinder 51 of the pump mechanism 5 when the piston 52 of the pump mechanism 5 operates.

  One end of the second flow path 8 (an example of the supply flow path) is connected to the outlet of the pump mechanism 5 (cylinder 51), and the other end of the second flow path 8 is connected to the recording head 2. Yes. That is, the second flow path 8 connects the recording head 2 and the pump mechanism 5. The second flow path 8 is provided with an electromagnetic valve 9b. The ink 10 stored in the cylinder 51 of the pump mechanism 5 flows through the second flow path 8 toward the recording head 2 when the piston 52 of the pump mechanism 5 operates.

[Ink 10]
As the ink 10, a known ink jet ink can be used. The ink 10 contains a colorant, a resin (dispersion stabilizer), and a solvent as main components, and various kinds of surfactants, penetrants, compatibility agents, humectants, viscosity modifiers, and the like as necessary. Contains additives. The resin is not particularly limited, and for example, polymers and copolymers such as polystyrene, acrylic resin, polyester, polyethylene, and polyamide, low molecular weight polyethylene, and polypropylene can be used.

For example, water-based pigment inks having the compositions shown in Table 1 and Table 2 below can be used as the ink 10. Table 1 shows the composition of the pigment dispersion contained in the aqueous pigment ink, and Table 2 shows the composition of the aqueous pigment ink.

  The pigment dispersion having the composition shown in Table 1 contains a resin as a dispersion stabilizer and contains Olfine E1010 as a surfactant. The resin is water-soluble (for example, an alkali-available resin) and is used after being neutralized with an equivalent amount by KOH. For example, a styrene-acrylic resin can be used as the resin.

  The styrene-acrylic resin can be produced by a macromonomer synthesis method. Specifically, first, an oligomer (AS-6, manufactured by Toa Gosei Co., Ltd., number average molecular weight (Mn) 6000), a methacrylic acid, and a methyl methacrylate, having a (meth) acryloyl group bonded to one of molecular ends of polystyrene. And butyl acrylate are polymerized in methyl ethyl ketone (organic solvent). Then, styrene-acrylic resin can be obtained by distilling off methyl ethyl ketone under reduced pressure (vacuum distillation). For the polymerization reaction, a known polymerization initiator such as an azo compound can be used. As the azo compound, for example, 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile) can be used.

  In Table 2, the amount of pigment (15% by mass) enclosed in parentheses indicates the ratio of the pigment to the total amount of the pigment dispersion. The amount of the pigment dispersion is adjusted so that the ratio of the pigment to the total amount of the ink is 4% by mass or more and 9% by mass or less.

  Ink 10 (water-based pigment ink) having the composition shown in Table 2 contains Orphine E1010 as a surfactant, triethylene glycol monobutyl ether as a penetrant, 2-pyrrolidone as a compatibility agent, and moisturizing As an agent, 1,2-octanediol and glycerin are contained. When the water-based pigment ink contains a penetrant (triethylene glycol monobutyl ether), the penetrability of the ink into the recording medium is improved. Glycerin also has a function as a viscosity adjusting agent. For example, the amount of glycerin and the amount of ion-exchanged water are adjusted so that the viscosity of the ink is 6 mPa / sec.

[Cleaning liquid]
The cleaning liquid is not particularly limited as long as the ink 10 can be dissolved. For example, when the ink 10 is a water-based pigment ink having the composition shown in Tables 1 and 2, the cleaning liquid contains triethylene glycol monobutyl ether as a penetrant and 2-pyrrolidone as a compatibility agent, You may contain 1, 3- propanediol as a viscosity modifier. In addition, the cleaning liquid may contain ion exchange water for adjusting the viscosity. The cleaning liquid easily penetrates into the pad member 3 by containing a penetrant (triethylene glycol monobutyl ether).

Table 3 below shows composition examples (compositions 1 to 6) of the cleaning liquid. Table 3 also shows the viscosity of each cleaning liquid. In Table 3, glycerin is used as a humectant and viscosity modifier.

[Maintenance method of recording head 2]
Next, a maintenance method for the recording head 2 will be described with reference to FIGS. FIG. 3 is a diagram illustrating a flow of a maintenance method for the recording head 2.

  During maintenance of the recording head 2, first, the pad member 3 into which the cleaning liquid has permeated the nozzle surface 11 of the recording head 2 is pressed, for example, by a maintenance person (step S1 in FIG. 3). A purge operation is performed while the pad member 3 is pressed against the nozzle surface 11 of the recording head 2 (step S2 in FIG. 3).

  Specifically, first, the piston 52 provided in the pump mechanism 5 performs a pulling operation in a state where the electromagnetic valve 9a is opened and the electromagnetic valve 9b is closed. Thereby, the ink 10 accommodated in the ink tank 6 is drawn into the cylinder 51 provided in the pump mechanism 5 through the first flow path 7.

  Next, the solenoid valve 9a is closed and the solenoid valve 9b is opened. Thereby, the cylinder 51 communicates with the fine flow path formed in the recording head 2. In this state, the piston 52 performs a pushing operation. As a result, the ink 10 accommodated in the cylinder 51 is supplied to the fine flow path inside the recording head 2 via the second flow path 8.

  According to the maintenance method of the recording head 2 according to the present embodiment, the pad member 3 infiltrated with the cleaning liquid that dissolves the purge ink 10 a (ink 10) is pressed against the nozzle surface 11 of the recording head 2. As a result, the purge ink 10a (see FIG. 2) adhering to the nozzle surface 11 of the recording head 2 returns to a liquid state. The pump mechanism 5 applies pressure to the second flow path 8 while the pad member 3 is pressed against the nozzle surface 11 of the recording head 2. Thereby, a pressure for pushing the ink 10 to the outside of the nozzle 12 is applied to the ink 10 inside the recording head 2. The pressure can suppress the intrusion of the cleaning liquid into the fine flow path formed inside the recording head 2. Therefore, according to this embodiment, the removal of the purge ink 10a adhering to the nozzle surface 11 of the recording head 2 and the mixing of the cleaning liquid and the ink 10 and the suppression of ink aggregation in the recording head 2 are suppressed. Can be achieved.

  The purge operation is preferably started simultaneously with the pressing of the pad member 3 against the nozzle surface 11 in order to suppress the penetration of the cleaning liquid into the fine flow path inside the recording head 2. However, the purge operation may be started after a predetermined time has elapsed since the pad member 3 was pressed against the nozzle surface 11 (for example, after 1 minute has elapsed). The predetermined time is determined according to the ease with which the cleaning liquid enters the fine flow path inside the recording head 2.

  In addition, the purge pressure (the pressure that the pump mechanism 5 applies to the second flow path 8) is adjusted to a size that can prevent the cleaning liquid from entering the fine flow path inside the recording head 2. preferable. Specifically, in the meniscus of the ink 10 formed at the nozzle 12 (ink discharge port), the pressure applied to the ink 10 by the pump mechanism 5 and the osmotic pressure at which the cleaning liquid tries to enter the nozzle 12 are in an equilibrium state. Thus, the purge pressure is preferably adjusted. Alternatively, a pressure higher than the osmotic pressure of the cleaning liquid is applied to the ink 10 by the pump mechanism 5, but the ink 10 does not move (the meniscus of the ink 10 is destroyed and the ink 10 is pushed outside the nozzle 12. It is preferable that the purge pressure is adjusted so as to be in a state of not being released).

  The purge ink 10 a that has returned to the liquid state can be removed from the nozzle surface 11 by penetrating the pad member 3. Alternatively, the wiping operation may be performed after the pad member 3 is separated from the nozzle surface 11 of the recording head 2. Accordingly, the purge ink 10a that has returned to the liquid state can be wiped off by the cleaning blade.

  In the present embodiment, the pad member 3 is pressed against the nozzle surface 11 during the purge operation (step S2). Therefore, the nozzle 12 of the recording head 2 is in a state covered with the pad member 3. For this reason, even if the purge operation is executed, the ink 10 (purge ink) is not pushed out from the nozzle 12 as in the normal purge operation. That is, the flow of the ink 10 that tries to move to the outside of the nozzle 12 does not occur. However, if the purge pressure is too high, the ink 10 may be slightly pushed out of the nozzle 12 even if the pad member 3 is pressed against the nozzle surface 11. In this case, the purge ink 10 pushed out from the nozzle 12 may permeate into the pad member 3 and the function of the cleaning liquid may be impaired. Therefore, it is preferable that the purge pressure is adjusted to such a level that the ink 10 is not pushed out of the nozzle 12 in a state where the pad member 3 is pressed against the nozzle surface 11.

  In addition, as a time for pressing the pad member 3 against the nozzle surface 11 of the recording head 2, a time during which the purge ink 10 a attached to the nozzle surface 11 of the recording head 2 can be sufficiently dissolved is set. The pressing time of the pad member 3 depends on the composition of the purge ink 10a and the composition of the cleaning liquid, but is set to 5 minutes or more, for example. The longer the time during which the pad member 3 is pressed against the nozzle surface 11 of the recording head 2, the more reliably the purge ink 10a returns to the liquid state, so the effect of removing the purge ink 10a is enhanced.

  Preferably, the pad member 3 is brought into close contact with the nozzle surface 11 of the recording head 2. Thereby, the purge ink 10a can be more reliably returned to the liquid state.

  Further, the purge operation is preferably performed in such a manner that the purge pressure is continuously generated. That is, it is preferable that the pump mechanism 5 continuously applies pressure to the second flow path 8 while the pad member 3 is pressed against the nozzle surface 11 of the recording head 2. Thereby, pressure is always applied to the ink 10 inside the recording head 2, and the penetration of the cleaning liquid into the fine flow path formed inside the recording head 2 can be more reliably suppressed.

  Further, depending on the purge pressure, the cleaning liquid may enter the recording head 2. Further, the higher the viscosity of the cleaning liquid, the easier it is for the cleaning liquid to enter the recording head 2. If the cleaning liquid enters the fine flow path formed inside the recording head 2, the cleaning liquid and the ink 10 may be mixed in the recording head 2 (fine flow path), and the ink 10 may be aggregated. Aggregation of the ink 10 in the recording head 2 causes a discharge failure of the ink 10 from the recording head 2 (nozzles 12) (an image density defect).

  Therefore, the purge / wipe operation may be performed after the pad member 3 is separated from the nozzle surface 11 of the recording head 2. As a result, the cleaning liquid and the ink 10 (including the agglomerated ink 10) can be pushed out of the nozzle 12 and wiped off by the cleaning blade, thereby suppressing the ejection failure of the ink 10.

  In addition, it is necessary to enable the ink 10 to be ejected from all the nozzles 12 (in order to restore the density of the image) as the cleaning liquid enters the deeper side of the fine flow path formed inside the recording head 2. Increases the number of purge / wipe operations. As the number of executions of the purge pipe operation increases, the amount of ink 10 necessary to enable ink 10 to be ejected from all nozzles 12 increases. In particular, when the ink 10 aggregates in the back side of the fine flow path formed inside the recording head 2, the number of times of performing the purge / wipe operation necessary to enable the ink 10 to be discharged from all the nozzles 12 is large. Become.

  On the other hand, according to the present embodiment, when the pad member 3 is pressed against the nozzle surface 11 of the recording head 2, the pressure to push the ink 10 to the outside of the nozzle 12 by the purge operation is 2 is applied to the ink 10 inside. Therefore, it is possible to suppress the penetration of the cleaning liquid into the back side of the fine flow path formed inside the recording head 2. Therefore, the number of executions of the purge / wipe operation necessary to enable the ink 10 to be discharged from all the nozzles 12 (to restore the state of the recording head 2 to the state where the ink 10 is discharged from all the nozzles 12) and The amount of ink 10 can be suppressed. For example, the number of executions of the purge / wipe operation can be suppressed to 3 times or less.

  The upper limit value (maximum allowable value) of the purge pressure is determined by the strength of the fine structure or fine mechanism (for example, a fine flow path having a minute step or a minute gap) provided in the recording head 2. That is, the upper limit value of the purge pressure is set to such an extent that the fine structure or fine mechanism provided in the recording head 2 is not destroyed. On the other hand, if the viscosity of the cleaning liquid is too high with respect to the upper limit value of the purge pressure (if the osmotic pressure of the cleaning liquid is too high), the cleaning liquid is applied when the pad member 3 is pressed against the nozzle surface 11 of the recording head 2. There is a possibility that the cleaning liquid may easily permeate into the fine flow path inside the recording head 2, and the cleaning liquid may enter the back side of the fine flow path formed inside the recording head 2. Therefore, the upper limit value of the purge pressure is one factor for determining the viscosity of the cleaning liquid. For example, when the upper limit value of the purge pressure is 2 cc / sec, the viscosity of the cleaning liquid is set to 20 mPa / sec or less. Thereby, it is possible to suppress the penetration of the cleaning liquid into the back side of the fine flow path formed inside the recording head 2. Among the cleaning liquids (compositions 1 to 6) shown in Table 3, the viscosity of the cleaning liquids of compositions 1 to 4 is 20 mPa / sec or less.

[Embodiment 2]
[Inkjet recording apparatus 1a]
Subsequently, regarding the maintenance method of the inkjet recording apparatus 1a and the recording head 2 according to the second embodiment, matters different from those of the first embodiment will be described, and descriptions of items that overlap with the first embodiment will be omitted. The ink jet recording apparatus 1a according to the second embodiment is different from the ink jet recording apparatus 1 according to the first embodiment in that a pad member 3 is provided.

  First, the configuration of the ink jet recording apparatus 1a will be described with reference to FIG. 1, FIG. 2, FIG. 4, and FIG. FIG. 4A is a side view showing the configuration of the inkjet recording apparatus 1a, and FIG. 4B is a front view showing the configuration of the inkjet recording apparatus 1a. FIG. 5 is a diagram showing the configuration of the first maintenance unit 40 provided in the inkjet recording apparatus 1a.

  As shown in FIGS. 4A and 4B, the inkjet recording apparatus 1a includes a first transport unit 20, a recording unit 30, a first maintenance unit 40, a second transport unit 60, and a second transport unit. And a maintenance unit 70. In FIG. 4B, the recording medium S is omitted.

  The first transport unit 20 includes a first drive roller 21, a first driven roller 22, and a first transport belt 23. The first conveyor belt 23 is stretched between the first drive roller 21 and the first driven roller 22. The recording medium S held on the first conveyance belt 23 is conveyed in the conveyance direction X by the first drive roller 21 being rotated in the clockwise direction on the paper surface of FIG.

  The recording unit 30 is disposed above the first transport unit 20. Specifically, the recording unit 30 is supported at a height at which the nozzle surface 11 of the recording head 2 is separated from the conveying surface of the first conveying belt 23 by a predetermined distance (for example, 1 mm).

  The recording unit 30 includes the recording head 2. The recording unit 30 includes the pump mechanism 5, the ink tank 6, the first flow path 7, the second flow path 8, the electromagnetic valve 9a, and the electromagnetic valve 9b described with reference to FIG.

  As described with reference to FIG. 2, the nozzle surface R of the recording head 2 is provided with the nozzle region R in which a large number of nozzles 12 (ink discharge ports) are arranged. Further, purge ink 10a thickened by drying adheres to the nozzle surface 11 of the recording head 2 before maintenance.

  The recording head 2 is a line head in this embodiment, and has a recording area in which the width in the direction orthogonal to the transport direction X (main scanning direction) is equal to or larger than the maximum width of the recording medium S. That is, the nozzle 12 (nozzle region R) is provided over the maximum width of the recording medium S that can be printed by the inkjet recording apparatus 1a in the longitudinal direction of the nozzle surface 11 (main scanning direction). As a result, ink can be ejected from the nozzles 12 corresponding to the printing position to the recording medium S conveyed on the first conveying belt 23.

  The first maintenance unit 40 is disposed below the first transport unit 20 during normal times (periods other than during maintenance). The first maintenance unit 40 includes a pad member 3 and a holding member 4. The first maintenance unit 40 moves upward so that the pad member 3 is in close contact with the nozzle surface 11 of the recording head 2 during maintenance.

  Further, as shown in FIG. 5, the first maintenance unit 40 includes a pump mechanism 41 for supplying a cleaning liquid 48 for dissolving the ink 10 (purge ink 10 a) to the pad member 3. The pump mechanism 41 includes a hollow cylinder 42 and a piston 43. A part of the piston 43 is inserted into the hollow portion of the cylinder 42. The piston 43 can be moved in the longitudinal direction of the cylinder 42 by a driving device. An inlet and an outlet are formed at the bottom of the cylinder 42.

  Further, the first maintenance unit 40 includes a tank 44 that stores the cleaning liquid 48. Further, the first maintenance unit 40 includes a third flow path 45, a fourth flow path 46, and electromagnetic valves 47a and 47b.

  One end of the third flow path 45 is connected to the tank 44, and the other end of the third flow path 45 is connected to the inlet of the pump mechanism 41 (cylinder 42). That is, the third flow path 45 connects the tank 44 and the pump mechanism 41. The third flow path 45 is provided with an electromagnetic valve 47a. The cleaning liquid 48 stored in the tank 44 flows through the third flow path 45 from the tank 44 toward the cylinder 42 of the pump mechanism 41 when the piston 43 of the pump mechanism 41 operates.

  One end of the fourth flow path 46 is connected to the outlet of the pump mechanism 41 (cylinder 42), and the other end of the fourth flow path 46 is connected to the pad member 3. That is, the fourth flow path 46 connects the pad member 3 and the pump mechanism 41. The fourth flow path 46 is provided with an electromagnetic valve 47b. The cleaning liquid 48 accommodated in the cylinder 42 of the pump mechanism 41 flows through the fourth flow path 46 toward the pad member 3 when the piston 43 of the pump mechanism 41 operates.

  Returning to FIG. 4A and FIG. 4B, the second transport unit 60 is disposed on the downstream side of the first transport unit 20 with respect to the transport direction X. The second transport unit 60 includes a second drive roller 61, a second driven roller 62, and a second transport belt 63. The second transport belt 63 is stretched between the second drive roller 61 and the second driven roller 62. The recording medium S held by the second transport belt 63 is transported in the transport direction X by the second drive roller 61 being rotated in the clockwise direction on the paper surface of FIG.

  The recording medium S on which an image is recorded by the recording unit 30 is sent from the first transport unit 20 to the second transport unit 60. While the recording medium S passes through the second transport unit 60, the ink ejected on the surface of the recording medium S is dried.

  The second maintenance unit 70 is disposed below the second transport unit 60 during normal times (a period other than during maintenance). The second maintenance unit 70 includes a cleaning blade 71 and a tray 72. The cleaning blade 71 has a width equal to or larger than the width of the nozzle surface 11 in the transport direction X. For easy understanding, the tray 72 is shown in cross section.

  The second maintenance unit 70 moves below the recording unit 30 so that the tip of the cleaning blade 71 contacts the nozzle surface 11 when performing the purge / wipe operation. Then, the second maintenance unit 70 cleans the nozzle surface 11 by wiping the nozzle surface 11 with the cleaning blade 71. The tray 72 receives the ink 10 (or purge ink) dropped from the recording head 2 by the purge / wipe operation.

[Maintenance method of recording head 2]
Next, a maintenance method for the recording head 2 according to the second embodiment will be described with reference to FIGS. 1, 2, and 4 to 12. 6 to 11 are diagrams showing the operation of the ink jet recording apparatus 1a during maintenance of the recording head 2. FIG. Specifically, FIG. 6A, FIG. 7A, FIG. 8A, FIG. 9, FIG. 10A, and FIG. 11A show the operation of the inkjet recording apparatus 1a from the side. 6 (b), FIG. 7 (b), FIG. 8 (b), FIG. 10 (b), and FIG. 11 (b) each show the operation of the ink jet recording apparatus 1a from the front. FIG. 12 is a flowchart illustrating a maintenance method for the recording head 2 according to the second embodiment.

  During maintenance of the recording head 2, first, the cleaning liquid 48 is supplied to the pad member 3 (step S11 in FIG. 12).

  Specifically, as shown in FIG. 5, first, the piston 43 included in the pump mechanism 41 performs a pulling operation in a state where the electromagnetic valve 47a is opened and the electromagnetic valve 47b is closed. Accordingly, the cleaning liquid 48 stored in the tank 44 is drawn into the cylinder 42 provided in the pump mechanism 41 through the third flow path 45.

  Next, the solenoid valve 47a is closed and the solenoid valve 47b is opened. In this state, the piston 43 performs a pushing operation. As a result, the cleaning liquid 48 accommodated in the cylinder 42 is supplied to the pad member 3 through the fourth flow path 46, and the cleaning liquid 48 penetrates into the pad member 3.

  Thereafter, the pad member 3 into which the cleaning liquid 48 has penetrated is pressed against the nozzle surface 11 of the recording head 2 (step S12 in FIG. 12).

  Specifically, as shown in FIGS. 4A and 4B, the first transport unit 20 moves in the direction of the arrow 101 and retracts from below the recording head 2. Further, the first maintenance unit 40 moves in the direction of arrow 102 (upward), and the second maintenance unit 70 moves in the direction of arrow 103. As a result, as shown in FIGS. 6A and 6B, the pad member 3 is in close contact with (pressed against) the nozzle surface 11 of the recording head 2 in a compressed state. Further, the second maintenance unit 70 moves below the recording head 2 (first maintenance unit 40).

  Then, a purge operation is performed while the pad member 3 is pressed against the nozzle surface 11 of the recording head 2 (step S13 in FIG. 12). Since the purge operation while the pad member 3 is pressed against the nozzle surface 11 has already been described in the first embodiment, the description here is omitted.

  After execution of the purge operation, the first maintenance unit 40 (pad member 3) moves and retreats from below the recording head 2 (step S14 in FIG. 12).

  Specifically, as shown in FIGS. 6A and 6B, first, the first maintenance unit 40 moves in the direction of arrow 104 (downward). As a result, as shown in FIGS. 7A and 7B, the pad member 3 is separated from the nozzle surface 11 of the recording head 2.

  Next, as shown in FIGS. 7A and 7B, the first transport unit 20 moves in the direction of the arrow 105, the first maintenance unit 40 moves in the direction of the arrow 106, and the first The maintenance unit 40 is retracted from below the recording head 2. Further, the second maintenance unit 70 moves in the direction of the arrow 107 (upward). As a result, the tip of the cleaning blade 71 contacts the bottom surface of the recording head 2 as shown in FIGS. Specifically, the cleaning blade 71 is pressed against the position outside the nozzle surface 11 from a substantially vertical direction. Thereafter, a purge / wipe operation is executed (step S15 in FIG. 12).

  Specifically, first, a purge operation is performed. As a result, the ink (purge ink) 10 is pushed out from the recording head 2. A part of the extruded ink 10 is dropped onto the tray 72, and the remaining ink 10 adheres to the nozzle surface 11 as shown in FIG.

  Next, a wiping operation is performed. That is, as shown in FIG. 9, the cleaning blade 71 moves over the entire area in the longitudinal direction of the nozzle surface 11 in the direction of the arrow 108 (direction orthogonal to the transport direction X), and the ink 10 adhered to the nozzle surface 11. Wipe off (mainly purge ink). At this time, if the purge ink 10 a remains on the nozzle surface 11, the purge ink 10 a is also wiped off by the cleaning blade 71. A part of the wiped ink 10 is dropped onto the tray 72, and the remaining ink 10 remains (adheres) on the cleaning blade 71. The ink 10 dropped on the tray 72 is guided to a waste liquid tank (not shown).

  When the cleaning blade 71 moves over the entire length of the nozzle surface 11, the second maintenance unit 70 moves in the direction of arrow 109 (downward) and moves away from the recording head 2 as shown in FIG. 10. During this time, the cleaning blade 71 moves in the direction of the arrow 110 and returns to the position at the start of the wiping operation. Further, the first maintenance unit 40 moves in the direction of arrow 111, and the first transport unit 20 moves in the direction of arrow 112. As a result, the first maintenance unit 40 moves downward of the recording head 2 as shown in FIGS.

  Thereafter, the first transport unit 20, the first maintenance unit 40, and the second maintenance unit 70 each return to the position before the maintenance of the recording head 2. Thereby, the maintenance of the recording head 2 is completed.

  Specifically, as shown in FIGS. 11A and 11B, the second maintenance unit 70 moves in the direction of the arrow 113, the first maintenance unit 40 moves in the direction of the arrow 114, One transport unit 20 moves in the direction of arrow 115. As a result, as shown in FIGS. 4A and 4B, the second maintenance unit 70 moves below the second transport unit 60, and the first transport unit 20 is connected to the recording head 2 and the first maintenance. Move to and from the unit 40.

  According to the second embodiment described above, as in the first embodiment, the recording liquid is mixed with the cleaning liquid 48 and the ink 10 together with the removal of the purge ink 10a attached to the nozzle surface 11 of the recording head 2. 2 can suppress aggregation of the ink 10.

  In the second embodiment, the case where the purge / wipe operation is performed once after the pad member 3 is separated from the nozzle surface 11 of the recording head 2 has been described. However, the purge / wipe operation may be performed a plurality of times. Good. Further, when the cleaning liquid 48 does not enter the fine flow path formed inside the recording head 2, the purge / wipe operation may be omitted. In this case, the wiping operation may be executed once after the pad member 3 is separated from the nozzle surface 11 of the recording head 2.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

  For example, in the embodiment of the present invention, the inkjet recording apparatuses 1 and 1a that form a monochrome image on the recording medium S have been described. However, the present invention is applied to an inkjet recording apparatus that forms a color image on the recording medium S. Is also possible.

[Example]
Examples of the present invention will be described below, but the present invention is not limited to the following examples.

  In Examples 1 and 2 and Comparative Examples 1 and 2, water-based pigment inks having the compositions shown in Tables 1 and 2 were used. As the pigment, phthalocyanine blue (P.B-15: 3) was used. As the resin, a styrene-acrylic resin produced by macromonomer synthesis was used. When the mass average molecular weight (Mw) of the styrene-acrylic resin was confirmed using gel filtration chromatography (HLC-8020GPC (manufactured by Tosoh Corporation)) under the following conditions, it was about 50,000. Moreover, it was 150 when the acid value (mgKOH / g) of the styrene-acrylic resin was confirmed by titration.

<Mass average molecular weight measurement conditions>
Column: TSKgel, Super Multipore HZ-H (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm)
Number of columns: 3 Eluent: Tetrahydrofuran Flow rate: 0.35 ml / min Sample injection volume: 10 μl
Measurement temperature: 40 ° C
Detector: IR detector calibration curves are F-40, F-20, F-4, F-1, A-5000, A-2500, A from standard samples (TSK standard, polystyrene, manufactured by Tosoh Corporation). -1000 and 8 types of n-propylbenzene were selected and prepared.

  In Examples 1 and 2 and Comparative Examples 1 and 2, after the pad member was pressed against the recording head for 5 minutes, a purge / wipe operation was performed. When the pad member was pressed against the recording head, the recording head was bitten into the pad member by 0.5 mm. During the purge / wipe operation, the purge operation was performed at a purge pressure of 0.3 cc / sec.

[Example 1 and Comparative Example 1]
In Example 1 and Comparative Example 1, using a recording unit of an ink jet printer (prototype), a purge / wipe operation was performed after pressing the pad member infiltrated with the cleaning liquid against the nozzle surface of the recording head. Then, the number of executions of the purge / wipe operation necessary to allow ink to be ejected from all nozzles (to restore the state of the recording head to a state where ink is ejected from all nozzles) was measured.

In Example 1 and Comparative Example 1, the cleaning liquid having composition 1 among the cleaning liquids shown in Table 3 was used. In Example 1, the purge operation was performed at a purge pressure of 0.3 cc / sec when the pad member was pressed against the nozzle surface of the recording head (with pressurization). On the other hand, in Comparative Example 1, no purge operation was performed when the pad member was pressed against the nozzle surface of the recording head (no pressurization). The results are shown in Table 4 below.

  In Table 4, evaluation A indicates that all nozzles have recovered to a state where ink can be ejected by purging and wiping operations three times or less, and evaluation B indicates that all nozzles have ink ejected by four or more purging and wiping operations. Indicates that the ink has returned to a dischargeable state.

[Examples 1 and 2 and Comparative Example 2]
In Example 2 and Comparative Example 2, using a recording unit of an ink jet printer (prototype), a purge / wipe operation was performed after pressing the pad member infiltrated with the cleaning liquid against the nozzle surface of the recording head. Then, the number of executions of the purge / wipe operation necessary to allow ink to be ejected from all nozzles (to restore the state of the recording head to a state where ink is ejected from all nozzles) was measured.

In Example 2, the cleaning liquid having the composition 3 among the cleaning liquids shown in Table 3 was used. In Comparative Example 2, a cleaning liquid having composition 6 among the cleaning liquids shown in Table 3 was used. In Example 2 and Comparative Example 2, a purge operation was performed at a purge pressure of 0.3 cc / sec when the pad member was pressed against the nozzle surface of the recording head (with pressurization). The results are shown in Table 5 below. Table 5 also shows the results of Example 1.

  In Table 5, evaluation A indicates that all nozzles have recovered to a state where ink can be ejected by purging and wiping operations three times or less, and evaluation B indicates that all nozzles have ink ejected by purging and wiping operations four times or more. Indicates that the ink has returned to a dischargeable state.

  The present invention is useful for maintenance of a recording head that discharges ink onto a recording medium.

1, 1a Inkjet recording apparatus 2 Recording head 3 Pad member 5 Pump mechanism 8 Second flow path 10 Ink 11 Nozzle surface 48 Cleaning liquid

Claims (8)

A step of pressing a pad member infiltrated with a cleaning liquid against the nozzle surface of the recording head;
Performing a purge operation for supplying ink to the recording head while the pad member is pressed against the nozzle surface ,
An ink discharge port is formed on the nozzle surface,
The purge operation is performed when a pump mechanism applies pressure to a supply channel that supplies ink to the recording head.
When the pad member is pressed against the nozzle surface, the pump mechanism continuously applies pressure to the supply flow path,
The pump mechanism so that the pressure applied to the ink by the pump mechanism and the osmotic pressure at which the cleaning liquid tries to enter the discharge port are in an equilibrium state in the ink meniscus formed at the discharge port. A method for maintaining a recording head, in which applies pressure to the supply flow path . Separating the pad member from the nozzle surface;
The print head maintenance according to claim 1, further comprising: performing at least one time each of the purge operation and a wiping operation to wipe the nozzle surface after the pad member is separated from the nozzle surface. Method. The pressure applied by the pump mechanism to the supply flow path is 2 cc / sec or less;
The recording head maintenance method according to claim 1 , wherein the cleaning liquid has a viscosity of 20 mPa / sec or less. The pad member comprises a porous material, a maintenance method of the recording head according to any one of claims 1 to 3. The pad member includes a material having elasticity,
The pad member is pressed against the nozzle surface in a compressed state, a maintenance method of the recording head according to any one of claims 1 to 4. The pad member, 5 minutes or more, pressed against the nozzle surface, the maintenance method of the recording head according to any one of claims 1 to 5. A recording head having a nozzle surface;
A pump mechanism for supplying ink to the recording head;
The recording head and the pump mechanism are connected, and a supply flow path through which the ink flows from the pump mechanism toward the recording head by the operation of the pump mechanism,
An ink discharge port is formed on the nozzle surface,
A purge operation in which the pump mechanism continuously applies pressure to the supply flow path to supply the ink to the recording head while a pad member having a cleaning liquid infiltrated against the nozzle surface. Is done ,
In the meniscus of ink formed at the ejection port, the pump mechanism so that the pressure applied to the ink by the pump mechanism and the osmotic pressure at which the cleaning liquid tries to enter the ejection port are in equilibrium. An ink jet recording apparatus that applies pressure to the supply flow path . The inkjet recording apparatus according to claim 7 , further comprising the pad member.

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