JP2005074671A - Head cleaning device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove deposits from a nozzle surface with a cleaning device using only a blade or a brush, and to remove unevenness of wiping, causing droplet ejection bending and density unevenness.
A rotatable brush 55 that scrapes and cleans deposits in a nozzle surface Na and a nozzle N of a head 14 and a direction parallel to the nozzle surface Na while the brush 55 is in contact with the nozzle surface Na. Brush moving means 56 for advancing and retreating, a blade 58 for wiping off and cleaning the deposits on the nozzle surface Na of the head 14, and a blade movement for moving the blade 58 back and forth in a direction parallel to the nozzle surface Na while being in contact with the nozzle surface Na Means 59.
[Selection] Figure 4

Description

  The present invention relates to a head cleaning device and an image forming apparatus, and more particularly to a head cleaning device that removes deposits on a nozzle surface of a droplet discharge head that discharges droplets and an image forming apparatus including this device.

  Inkjet recording devices used as various image forming devices such as printers, facsimiles, copying machines, plotters, etc., form (record) images by mounting a droplet discharge head that discharges liquid recording liquid (ink) from fine nozzles. )

  Since the ink used in this ink jet recording apparatus contains volatile liquid such as water, the volatile liquid evaporates and thickens or aggregates when it is not used for a long period of time. May occur. If clogging occurs, ink cannot be ejected, resulting in an image defect.

  Therefore, in general, in order to recover the clogging of the nozzle, suction is performed in a state where the nozzle surface is sealed with a cap or the like to discharge the ink.

  However, when an ink containing a pigment that easily aggregates (so-called pigment ink) is used, when the ink dries, it becomes a highly aggregated state that cannot be recovered by ink suction. In addition, when a thermal head is used, continuous printing promotes evaporation of volatile components due to heating of the head, resulting in faster drying. Again, a highly agglomerated state that cannot be recovered by ink suction. turn into.

Therefore, in order to solve this problem, for example, a recording head cleaning device including a roller for removing unnecessary materials from the recording head and a means for rotating the roller has been proposed.
JP-A-10-217491

Further, there has been proposed a liquid ejection apparatus including a wiping means for wiping the liquid ejection portion on the outer peripheral surface of a cylindrical rotating wiping member having liquid impregnation property and a cleaning liquid supply means for supplying a cleaning liquid to the wiping member.
JP-A-11-334095

Further, there has been proposed a cleaning device for an ink discharge unit that has a roller that contacts and rotates with the ink discharge unit, an elastic body is disposed on the roller surface, and a cleaning liquid supply unit that supplies a cleaning liquid to the elastic body.
JP 2002-172895 A

Furthermore, the cleaner is sprayed from the cleaner spray that faces the ink nozzles of the ink jet printer head, and the ink in the ink nozzles flows into the ink reservoir, and the ink nozzle opening is cleaned by the rotating brush. Nozzle cleaning devices have been proposed.
Japanese Utility Model Publication No. 7-16433

Also, there is provided an inkjet head cleaning mechanism including a cleaning unit that moves the brush roller in a direction opposite to the rotation direction of the brush roller while bringing the brush roller into contact with the plurality of nozzles arranged in the inkjet head and the peripheral surface portion thereof. Proposed.
JP 2002-19131 A

Other head cleaning devices include the following.
JP 2002-79681 A

  In the apparatus of Patent Document 1, there is a problem that even if a part of the thickened material can be scraped off, a portion that cannot be removed remains when the inside of the nozzle or the nozzle is uneven.

  In the devices of Patent Documents 2 and 3, the waste liquid can be removed by supplying the cleaning liquid to the roller and wiping the nozzle surface. There is a problem that will remain.

  Even in the devices of Patent Documents 4 and 5, thickening and agglomerates on the nozzle surface are removed by rotating the brush, but since the brush is always rotated and brushed, the nozzle surface is damaged by excessive brushing. There is. In addition, if there is a thickened material or agglomerated material in a recess where the brush tip does not reach only by rotating in a certain direction, such an unnecessary material cannot be removed.

  Furthermore, in the apparatuses of Patent Documents 4 and 5, as described above, the thickened matter and aggregates on the nozzle surface are removed by the rotation of the brush, but the adhered matter cannot be completely removed from the nozzle surface. Wiping unevenness will remain. For this reason, the uneven wiping may cause droplet ejection bends and uneven density.

  The present invention has been made in view of the above problems, and is a head cleaning device that can effectively remove the thickened or agglomerated liquid in the nozzle surface or the nozzle and eliminate wiping unevenness on the nozzle surface, In addition, a head cleaning device that can remove the liquid thickened or agglomerated in the nozzle surface or in the nozzle without damaging the nozzle surface, and by providing any one of these head cleaning devices, a clear image formation without image defects is performed. An object of the present invention is to provide an image forming apparatus that can perform the above-described process.

  A head cleaning device according to the present invention is a head cleaning device that removes deposits adhering to a nozzle surface of a droplet discharge head that discharges droplets from a nozzle, and includes a brush and a blade that are in contact with the nozzle surface of the head. It is what it has.

  Here, it is preferable that the brush rotates.

  Another head cleaning device according to the present invention is a head cleaning device that removes adhering matter adhering to a nozzle surface of a droplet discharge head that discharges droplets from a nozzle by bringing the brush into contact therewith, and the image quality of an output image The operation of the brush can be selected according to the condition.

  Here, it is preferable that an operation of rotating the brush and an operation of not rotating the brush can be selected, or an operation of rotating the brush, an operation of not rotating the brush, and an operation of vibrating the brush can be selected.

  Further, it is preferable that the operation of the brush is selected based on the detection result of the image quality of the output image, and the operation of the brush can be manually selected based on the detection result of the image quality of the output image. preferable. Furthermore, it is preferable that a part of the outer peripheral surface of the brush is formed of a porous body.

  In the head cleaning device according to each of the present invention, it is preferable to apply the cleaning liquid when the brush is brought into contact with the nozzle surface.

  An image forming apparatus according to the present invention includes a droplet discharge head for discharging a droplet from a nozzle to form an image on a recording medium, and a head cleaning according to the present invention for cleaning the nozzle surface of the droplet discharge head. And a device.

  Here, it is preferable that the droplet discharge head discharges droplets by utilizing film boiling generated in the liquid by the thermal energy generated by the electrothermal conversion means. The liquid is preferably a recording liquid containing a color material, and the color material of the recording liquid is preferably a pigment.

  In addition, it is preferable to include a liquid droplet discharge head that discharges a recording liquid containing a coloring material and a processing liquid that does not contain a coloring material and generates aggregates or insolubles by contacting the recording liquid. .

  According to the head cleaning device and the image forming apparatus provided with the head cleaning device according to the present invention, since the brush and the blade are provided, the liquid thickener and aggregates in the recesses in the nozzle interior and the nozzle surface are removed. Further, the uneven wiping of the nozzle surface can be eliminated, the non-discharge of the liquid and the discharge bend can be completely eliminated, and a clear image with no density unevenness can be formed.

  Further, according to another head cleaning device according to the present invention and an image forming apparatus equipped with the head cleaning device, since the operation of the brush can be selected, it is possible to remove liquid thickeners and aggregates generated on the nozzle surface. Further, it is possible to effectively suppress the damage to the nozzle surface, and to prevent the occurrence of image defects.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of a mechanism portion of an ink jet recording apparatus as an image forming apparatus according to the present invention, and FIG. 2 is a side view of the mechanism portion.

  The ink jet recording apparatus includes a carriage that is movable in the main scanning direction inside the recording apparatus main body 1, a recording head that includes an ink jet head mounted on the carriage, an ink cartridge that supplies ink to the recording head, and the like. 2 and the like, the paper 3 fed from the paper feed cassette 4 or the manual feed tray 5 is taken in, a required image is recorded by the printing mechanism unit 2, and then discharged to the paper discharge tray 6 mounted on the rear side. Make paper.

  The printing mechanism unit 2 holds the carriage 13 slidably in the main scanning direction (vertical direction in FIG. 2) with a main guide rod 11 and a sub guide rod 12 which are guide members horizontally mounted on left and right side plates (not shown). doing.

  As shown in FIG. 3, the carriage 13 receives ink droplets, which are recording liquid droplets containing color materials of yellow (Y), cyan (C), magenta (M), and black (Bk). Four droplet discharge heads 14y, 14m, 14c, and 14k (collectively referred to as “recording head 14a”) having a nozzle row composed of a plurality of nozzles N to be discharged, ink containing no coloring material, and ink A processing liquid head 14 s composed of a droplet discharge head that discharges a processing liquid that generates aggregates or insolubles by contact is mounted, and the recording head 14 a and the processing liquid head are disposed above the carriage 13. Each liquid cartridge 15 for supplying each color ink or processing liquid to 14s is replaceably mounted.

  The ink cartridge containing the ink to be supplied to the recording head 14a in the liquid cartridge 15 is filled with ink in the upper atmosphere port which communicates with the atmosphere, the lower supply port which supplies ink to the head, and the inside. It has a porous body, and the ink supplied to the head is maintained at a slight negative pressure by the capillary force of the porous body.

  Here, the carriage 13 is slidably fitted to the main guide rod 11 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 12 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 13 in the main scanning direction, a timing belt 20 is stretched between a driving pulley 18 and a driven pulley 19 that are rotationally driven by a main scanning motor 17. The carriage 13 is reciprocally driven by forward and reverse rotation of the main scanning motor 17.

  Further, although the recording head 14a for ejecting ink droplets uses a head for each color, it may be a single head having nozzles for ejecting ink droplets for each color. The droplet discharge head constituting the recording head 14 is preferably a thermal head that discharges droplets by utilizing film boiling generated in the liquid by the thermal energy generated by the electrothermal conversion means. A head configuration using means may be used.

  On the other hand, in order to convey the paper 3 set in the paper feed cassette 4 to the lower side of the recording head 14a and the processing liquid head 14s, a paper feed roller 21 and a friction pad 22 for separating and feeding the paper 3 from the paper feed cassette 4; The guide member 23 for guiding the paper 3, the transport roller 24 for reversing and transporting the fed paper 3, the transport roller 25 pressed against the peripheral surface of the transport roller 24, and the transport roller 24 from the transport roller 24 A leading end roller 26 for defining the feed angle is provided. The transport roller 24 is rotationally driven by a sub-scanning motor 27 through a gear train.

  A printing receiving member 29, which is a paper guide member for guiding the paper 3 fed from the transport roller 24 corresponding to the movement range of the carriage 13 in the main scanning direction, below the recording head 14a and the processing liquid head 14s. Provided. A conveyance roller 31 and a spur 32 that are rotationally driven to send the paper 3 in the paper discharge direction are provided on the downstream side of the printing receiving member 29 in the paper conveyance direction, and the paper 3 is further delivered to the paper discharge tray 6. A roller 33 and a spur 34, and guide members 35 and 36 that form a paper discharge path are disposed.

  At the time of recording, the recording head 14a and the treatment liquid head 14s are driven according to the image signal while moving the carriage 13, thereby ejecting ink onto the stopped sheet 3 to record one line, After the predetermined amount is conveyed, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 3 has reached the recording area, the recording operation is terminated and the sheet 3 is discharged.

  Here, the recording on the paper 3 is performed by ejecting the processing liquid from the processing liquid head 14 s according to the image to be recorded on the paper 3, and then ejecting ink droplets from the recording head 14 a according to the image to be recorded on the paper 3. This is done by discharging. Note that a configuration without a droplet discharge head for discharging the treatment liquid may be employed.

  Further, a recovery device 37 including a head cleaning device according to the present invention for recovering defective ejection of the recording head 14a and the treatment liquid head 14s is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 13. ing. The recovery device 37 includes a cap unit, a suction unit, and a cleaning unit. During printing standby, the carriage 13 is moved to the recovery device 37 side, the recording head 14a and the treatment liquid head 14s are capped by the capping means, and the discharge port (nozzle hole) is kept in a wet state, thereby discharging by ink drying. Prevent defects. Further, by ejecting (purging) ink not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  When a discharge failure occurs, the capping unit seals the discharge ports (nozzles) of the recording head 14a and the processing liquid head 14s, and sucks out bubbles and the like from the discharge port through the tube with the suction unit. Adhering ink, dust, etc. are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

Next, the cleaning liquid that can be used in the head cleaning device according to the present invention will be described.
The cleaning liquid contains a surfactant. The surfactant has an effect of fragmenting and dispersing the aggregate due to the surface active effect between the cleaning liquid and the aggregate. Further, since it has a function of lowering the surface tension of the cleaning liquid, the cleaning liquid easily enters between the aggregate and the nozzle surface, and there is an effect of easily separating the aggregate from the nozzle surface.

  As the surfactant, any compound having a hydrophilic part and a hydrophobic part in the same molecule can be preferably used.

  As specific examples, those represented by the following formulas (I) to (IV) are preferable. That is, a polyoxyethylene alkylphenyl ether surfactant of the following formula (I), an acetylene glycol surfactant of the formula (II), a polyoxyethylene alkyl ether surfactant of the following formula (III) and the formula (IV ) Polyoxyethylene polyoxypropylene alkyl ether surfactants.

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｋ：５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k: 5 to 20)

（ｍ、ｎ≦２０，０＜ｍ＋ｎ≦４０）

(M, n ≦ 20, 0 <m + n ≦ 40)

（Ｒは分岐してもよい炭素数６〜１４の炭化水素鎖、ｎは５〜２０）

(R is a C6-C14 hydrocarbon chain which may be branched, n is 5-20)

（Ｒは炭素数６〜１４の炭化水素鎖、ｍ、ｎは２０以下の数）

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

  Other than the compounds of the above formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl Use alkyl and aryl ethers of polyhydric alcohols such as ethers, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol However, diethylene glycol monobutyl ether is particularly preferable.

  As the antifoaming agent, any component having an antifoaming effect can be used, and among them, a silicon-based antifoaming agent is preferably used. Since foaming can be suppressed by adding an antifoaming agent, it is preferable to use it together with a surfactant. If no defoaming agent is added, once foaming occurs, foaming does not disappear easily, and bubbles of cleaning agent remain around the brush and around the head. In some cases, this foam interferes with printing and causes image defects. Will lead to.

  Thus, by adding an antifoaming agent to the cleaning liquid, it is possible to suppress foaming of the cleaning liquid, it is possible to prevent foaming around the head, and it is possible to prevent foam from inhibiting the ejection of the recording liquid, Generation of image defects can be prevented.

  In general, silicone type antifoaming agents include oil type, compound type, self-emulsifying type, emulsion type, etc., but considering the use in water system, it is reliable to use self-emulsifying type or emulsion type. Desirable in securing. Further, modified silicon-based antifoaming agents such as amino-modified, carbinol-modified, methacryl-modified, polyether-modified, alkyl-modified, higher fatty acid ester-modified, alkylene oxide-modified, etc. may be used.

  Commercially available silicone-based antifoaming agents include silicone antifoaming agents from Shin-Etsu Chemical Co., Ltd. (KS508, KS531, KM72, KM85, etc.) and silicone antifoaming agents from Toray Dow Corning Co., Ltd. (Q2-3183A, SH5510, etc.), Nippon Unicar Co., Ltd. silicone antifoaming agents (SAG30, etc.), Asahi Denka Kogyo Co., Ltd. antifoaming agents (Adecanol series), and the like.

  The amount of these antifoaming agents added to the ink may be the minimum amount that is effective, but generally it is preferably in the range of 0.001% to 3% by weight, more preferably 0.005% to 0.5%. It is the range of mass%.

  Examples of antiseptic / antifungal agents include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, isothiazoline-based compounds, sodium benzoate, and sodium pentachlorophenol. By adding an antiseptic / antifungal agent, it is possible to suppress the occurrence of corrosion and soot even when the cleaning liquid is stored for a long period of time.

  In this way, by adding antiseptic and antifungal agents to the cleaning liquid, it is possible to prevent the occurrence of corrosion and wrinkles even when the cleaning liquid is stored for a long period of time. Can be prevented.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite and the like. By adding a rust preventive agent, it is possible to prevent rusting of a metal member such as around the head.

  In this way, by including a rust inhibitor in the cleaning solution, corrosion of metal parts such as the head can be prevented, the head can be operated normally over a long period of time, and image defects can be prevented. Can do.

  Examples of the humectant include the following specific examples. By adding a moisturizing agent, it is possible to suppress the drying of the recording liquid leading to nozzle clogging and to prevent the occurrence of image defects due to aggregates.

  Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,5-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1 Polyhydric alcohols such as 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monophenyl ether, ether Including polyhydric alcohol aryl ethers such as lenglycol monobenzyl ether, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, etc. Nitrogen heterocyclic compounds, amides such as formamide, N-methylformamide, N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, dimethyl sulfoxide, sulfolane, thio Sulfur-containing compounds such as diethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Of these, diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petriol, 1,5 are particularly preferable. -Pentanediol, N-methyl-2-pyrrolidone, N-hydroxyethylpyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone. By using these compounds, the high solubility of the present compound and the jetting properties due to water evaporation An excellent effect for prevention of defects is obtained. In particular, pyrrolidone derivatives such as N-hydroxyethyl-2-pyrrolidone are preferable as a solvent for obtaining the dispersion stability of the compound (I).

  Next, ink as a recording liquid used in the image forming apparatus according to the present invention will be described.

  Here, an example of ink that is a liquid used in the image forming apparatus according to the present invention will be described, but it is needless to say that the present invention is not limited thereto.

  The ink contains a color material. The coloring material may be contained in a dissolved state or may be contained in a dispersed state. In this case, a dye is preferable as the coloring material used in a dissolved state. Examples of the color material used in a dispersed state include pigments and dyes having low solubility in solvents. By using a pigment, high light resistance and water resistance can be obtained.

  In these, it is preferable to contain a coloring material in the disperse | distributed state. In other words, when the coloring material is contained in a dispersed state, the pH change occurs at the moment of landing on the recording medium (paper) and the dispersion of the coloring material is destroyed and the coloring material aggregates, or the coloring material is a fiber of the recording medium. The phenomenon of being caught in the eyes and not flowing far away occurs. As a result of such a phenomenon, feathering and color bleeding can be suppressed, and a clear image can be obtained.

  On the contrary, if the coloring material is contained in a dissolved state, the dissolved coloring material does not easily precipitate even if a pH change occurs at the moment of landing on the recording medium, so that the coloring material does not aggregate. Further, in a state where the color material is dissolved, when the ink permeates the recording medium, the ink flows out far without being caught in the eyes of the fibers. As a result of such a phenomenon, feathering or color bleeding may occur, resulting in an unclear image.

  Examples of the dye that can be used include dyes that are classified into acid dyes, direct dyes, reactive dyes, and food dyes in the color index, and that have excellent water resistance and light resistance. These dyes may be used as a mixture of a plurality of types, or may be used as a mixture with other dyes such as pigments. These are added as long as the effect is not inhibited.

If these dyes are specifically mentioned, as acid dyes and food dyes,
C. I. Acid Yellow 17, 23, 42, 44, 79, 142,
C. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289,
C. I. Acid Blue 9, 29, 45, 92, 249
C. I. Acid Black 1, 2
And so on.

As a direct dye,
C. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144,
C. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227,
C. I. Direct Orange 26, 29, 62, 102,
C. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202,
C. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171
And so on.

As reactive dyes,
C. I. Reactive Black 3, 4, 7, 11, 12, 17,
C. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67,
C. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97,
C. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95
And so on.

  In particular, acid dyes and direct dyes can be preferably used.

  Specific examples of the pigment that can be used include the following. In this case, these pigments may be used by mixing a plurality of types, or may be used by mixing with other pigments such as dyes.

  Examples of organic pigments include azo, phthalocyanine, anthraquinone, dioxazine, indico, thioindico, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black.

  The pigment is preferably used in the form of particles having a particle diameter of 0.01 to 0.15 μm.

  Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder. Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.

  Further, the particle diameter of these pigments is preferably 0.01 to 0.15 μm. If it is 0.01 μm or less, the hiding power is lowered, the density is low, the light resistance is lowered, and the light resistance of the ink when mixed with the polymer dye system becomes equivalent to that of the conventional dye system. On the other hand, if the thickness is 0.15 μm or more, clogging of the head or clogging with a filter may occur, and it may not be possible to obtain ejection stability.

  Ink is used for the purpose of making the ink have the desired physical properties, preventing drying of the ink by preventing discharge failure, and improving the dissolution stability and dispersion stability of the coloring material. It is preferable to use a water-soluble organic solvent.

  That is, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,5-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol Polyhydric alcohols such as 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene Polyhydric alcohol alkyl ethers such as glycol monoethyl ether, ethylene glycol monophenyl ether Ter, polyhydric alcohol aryl ethers such as ethylene glycol monobenzyl ether, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-capro Nitrogen-containing heterocyclic compounds such as lactam, amides such as formamide, N-methylformamide, N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, dimethyl sulfoxide Sulfur-containing compounds such as sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Of these, diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petriol, 1,5 are particularly preferable. -Pentanediol, N-methyl-2-pyrrolidone, N-hydroxyethylpyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone. By using these, an excellent effect can be obtained for preventing poor jetting characteristics due to high solubility or high dispersibility of the coloring material and water evaporation.

The ink preferably contains a penetrant.
The penetrant is added for the purpose of improving the wettability between the ink and the recording medium and adjusting the penetrating speed. As the penetrant, those represented by the following formulas (I) to (IV) are preferable. That is, a polyoxyethylene alkylphenyl ether surfactant of the following formula (I), an acetylene glycol surfactant of the formula (II), a polyoxyethylene alkyl ether surfactant of the following formula (III) and the formula (IV The polyoxyethylene polyoxypropylene alkyl ether-based surfactant (1) can reduce the surface tension of the liquid, so that the wettability can be improved and the penetration rate can be increased.

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｋ：５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k: 5 to 20)

（ｍ、ｎ≦２０，０＜ｍ＋ｎ≦４０）

(M, n ≦ 20, 0 <m + n ≦ 40)

（Ｒは分岐してもよい炭素数６〜１４の炭化水素鎖、ｎは５〜２０）

(R is a C6-C14 hydrocarbon chain which may be branched, n is 5-20)

（Ｒは炭素数６〜１４の炭化水素鎖、ｍ、ｎは２０以下の数）

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

  Other than the compounds of the above formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl Use alkyl and aryl ethers of polyhydric alcohols such as ethers, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol However, diethylene glycol monobutyl ether is particularly preferable.

  Further, it is preferable to add a pH adjusting agent or a rust preventive agent to the ink for the purpose of preventing elution and corrosion of the member in contact with the ink. As the pH adjuster, any substance can be used as long as the pH can be adjusted to 6 or more without adversely affecting the prepared ink. For example, amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide Products, alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate. Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Further, it is preferable to add an antiseptic / antifungal agent to the ink for the purpose of antiseptic / antifungal. As the antiseptic / antifungal agent, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, isothiazoline-based compound, sodium benzoate, sodium pentachlorophenol and the like can be used.

  Furthermore, it is preferable to add an antifoaming agent to the ink in order to suppress unnecessary foaming. As the antifoaming agent, a silicon-based antifoaming agent is preferably used. In general, there are oil type, compound type, self-emulsification type, emulsion type, etc. for silicone antifoaming agent, but considering the use in water system, use of self-emulsification type or emulsion type ensures reliability. This is preferable. Further, modified silicon-based antifoaming agents such as amino-modified, carbinol-modified, methacryl-modified, polyether-modified, alkyl-modified, higher fatty acid ester-modified, alkylene oxide-modified, etc. may be used.

  Commercially available silicone-based antifoaming agents include silicone defoaming agents from Shin-Etsu Chemical Co., Ltd. (KS508, KS531, KM72, KM85, etc .: trade names), silicone from Toray Dow Corning Co., Ltd. Defoamers (Q2-3183A, SH5510, etc .: trade names), Silicone defoamers (SAG30, etc .: trade names) from Nihon Unicar Co., Ltd., Defoamers from Asahi Denka Kogyo Co., Ltd. ) And the like.

  The ink preferably has a viscosity at 20 ° C. of 4 mPa · sec or more. By setting it in the range of 4 mPa · sec, it is possible to prevent mist due to ink rebound, to ensure ejection stability, and to obtain a clearer image.

Next, an embodiment of a head cleaning device according to the present invention will be described with reference to FIGS. 4 is a schematic configuration diagram of the cleaning device, and FIG. 5 is an explanatory diagram for explaining its operation.
With respect to the nozzle surface Na that also serves as a cleaning liquid splash prevention chamber for capping the nozzle surface Na (see FIG. 3) formed by the nozzle plate 14A of the recording head 14a or the processing liquid head 14s (this is referred to as “head 14”). The cap 41 disposed so as to be able to advance and retreat in the facing direction, the cleaning liquid spray 42 for spraying the cleaning liquid in the cap 41, the cleaning liquid cartridge 43 containing the cleaning liquid containing the surfactant, and the cleaning liquid in the cleaning liquid cartridge 43 as the cleaning liquid A cleaning liquid injection pump 44 and cleaning liquid supply tubes 45 and 46 for supplying and spraying to the spray 42 are provided.

  Further, a waste liquid suction pump 51 that sucks waste liquid from the cap 41, a waste liquid tank 52 that stores the waste liquid, a suction tube 53, and a waste liquid tube 54 are provided.

  Furthermore, a rotatable brush 55 that scrapes and cleans the deposits (thickened matter and aggregates) in the nozzle surface Na of the head 14 and the nozzle N, and the nozzle in a state where the brush 55 is in contact with the nozzle surface Na. Brush moving means 56 is provided for moving back and forth in a direction parallel to the surface Na.

  Here, the brush can be suitably used as long as it has an uneven shape on the outer periphery. That is, a thickened material or an aggregate can be scraped off by the presence of protrusions or depressions.

  For example, as shown in FIG. 6, the plurality of fibers 55a is a brush 55A projecting radially outward from the circumferential surface of the roller-like member 55b, and as shown in FIG. 7, the plurality of fibers 55a are flat. Brush 55B planted in member 55c and protruding outward in the same direction, as shown in FIG. 8, brush 55C with a fine protrusion 55e on the surface of roller member 55d, as shown in FIG. An example is a brush 55D having a fine protrusion 55g on the surface of the rolled porous body 55f.

  In this case, by using the fiber 55a having a diameter equal to or smaller than the nozzle diameter, it is possible to scrape thickeners and aggregates within the nozzle diameter.

  Further, as described above, the brush may be cylindrical or plate-shaped, and the shape is not particularly limited. In the case of a cylindrical shape, it may be rotated to rub the nozzle surface, or may be fixed and rubbed to the nozzle surface.

  Returning to FIG. 4, a blade 58 that wipes and cleans deposits (thickened matter and aggregates) on the nozzle surface Na of the head 14, and is parallel to the nozzle surface Na while the blade 58 is in contact with the nozzle surface Na. Blade moving means 59 for advancing and retreating in any direction.

  The blade 58 can be suitably used as long as one end face has a smooth shape. That is, since the end face is smooth, it is possible to wipe away thickened materials and aggregates that cannot be removed by the brush 55, and to achieve a state without uneven wiping. Since it is convenient to apply a uniform pressure to the nozzle surface Na, it is most preferable that the blade 58 has a plate shape.

  The material of the blade 58 can be made of rubber, metal, plastic, etc. Among them, elastic rubber is most preferable. The elasticity allows the blade 58 to bend evenly and apply a uniform pressure to the nozzle surface. Also, the elasticity allows the blade 58 to deform and conform to the slight irregularities of the nozzle surface Na. Therefore, the cleaning property is improved.

  Since it comprised in this way, when performing the recovery | restoration operation | movement of the nozzle N of the head 14, the nozzle surface Na of the head 14 is first capped by the cap 41 which also serves as the cleaning liquid scattering prevention chamber. Thereafter, the inside of the cap 41 is made negative pressure by the waste liquid suction pump 51, whereby the ink or the processing liquid is sucked from the nozzle N of the head 14 and stored in the waste liquid tank 52.

  Next, the cleaning liquid stored in the cleaning liquid cartridge 43 is transferred to the cleaning liquid injection spray 42 by the cleaning liquid injection pump 44, and the cleaning liquid is discharged from the cleaning liquid injection spray 42 with the cap 41 in close contact with the nozzle surface Na as shown in FIG. Let spray. As a result, the cleaning liquid adheres to the nozzle surface Na and the nozzle N.

  Thereafter, the brush 55 is moved by the brush moving means 56 while rotating, and the nozzle surface Na is brushed. Further, the blade 58 is moved by the blade moving means 59 to wipe the nozzle surface Na.

  By this series of operations, the ink thickened material and the ink aggregate on the nozzle surface are removed.

  As described above, by providing the brush and the blade, it is possible to remove the ink thickened material and the ink agglomerate in the concave portion of the nozzle interior and the nozzle surface, and to completely eliminate the uneven wiping of the nozzle surface. As a result, non-discharge of liquid and discharge bend can be completely eliminated, and a clear image without density unevenness can be obtained.

  That is, the aggregate of ink is a material in which a coloring material such as a dye or a pigment forms an aggregate, and adheres to the nozzle surface more firmly than the thickened product. For this reason, it is more difficult to remove ink agglomerates than to remove ink thickeners. In particular, an ink using a pigment tends to form a thickened product or an agglomerate, so that an image defect due to nozzle clogging is likely to occur. In addition, it is difficult to remove the recesses when there are irregularities in the nozzle or on the nozzle surface.

  Here, the head cleaning device according to the present invention can effectively remove ink thickeners and ink agglomerates remaining in the nozzles and in the recesses of the nozzle surfaces by rubbing the nozzle surfaces with a brush. In addition, although wiping unevenness remains on the nozzle surface with the brush, the head cleaning device according to the present invention includes a blade in addition to the brush, so that no wiping unevenness remains on the nozzle surface.

  Furthermore, by applying a cleaning liquid when the brush rubs the nozzle surface, the aggregated color material can be easily dispersed or peeled off. By rubbing with a brush having a protrusion, the tip of the brush reaches the inside of the nozzle or the concave portion of the nozzle surface, so that aggregates can be effectively removed.

  On the other hand, as in the past, in a head cleaning device that has only blades or only brushes, waste is left inside the nozzles, or uneven wiping of the nozzle surface remains. And discharge bends are not completely eliminated.

  Also, by applying a cleaning liquid containing a surfactant, the aggregate can be dispersed by the action of the surfactant, and the peelability between the aggregate and the nozzle surface can be improved. The effect of removing unnecessary materials in the recesses is further improved.

  In this case, by directly spraying the cleaning agent onto the nozzle surface, it is possible to apply a cleaning liquid during brushing, and it is possible to prevent the occurrence of image defects by removing aggregates and to cool the head. And the formation of aggregates can be suppressed.

  In particular, the head 14 is cooled by spraying the cleaning liquid onto the nozzle surface Na, and this also has the effect of suppressing ink drying due to head heating when a thermal head is used.

  As described above, by using the head cleaning device according to the present invention, it is possible to reliably remove unwanted materials from the nozzle, and by using the image forming apparatus equipped with this head cleaning device, it is stable over a long period of time. A clear image can be obtained.

  In the image forming apparatus including the head cleaning device according to the present invention, a head that ejects droplets by thermal energy can be used. Since this head is excellent in that it can form nozzles at high density and can be manufactured at low cost, a clear image can be obtained with high resolution.

  However, when the discharge operation is continuously performed, the head that discharges by heat energy gradually accumulates heat and generates high heat. For this reason, the volatile components of the recording liquid and the processing liquid near the nozzles evaporate, resulting in thickening and aggregation, and non-ejection and ejection bending are likely to occur.

  For this reason, in the image forming apparatus including the conventional head cleaning device in which only the blade or only the brush is mounted, it is not possible to completely remove unnecessary objects, so that the non-ejection and the ejection bending cannot be solved. On the other hand, by providing the cleaning device according to the present invention, it is possible to effectively remove the thickened material and aggregates in and around the nozzle with a brush, and then wipe the surface uniformly with a blade to completely remove unnecessary materials. Therefore, non-ejection and ejection bending can be suppressed.

  An image forming apparatus provided with the head cleaning device according to the present invention can use a recording liquid containing a pigment. By using a pigment as the color material, a printed matter having a high image density, no bleeding, and high water resistance can be obtained.

  However, when a recording liquid containing a pigment is used, when a volatile component in the recording liquid evaporates, the pigment is likely to be deposited inside or near the nozzle, and non-ejection or ejection bend is likely to occur.

  For this reason, in the image forming apparatus including the conventional head cleaning device in which only the blade or only the brush is mounted, it is not possible to completely remove unnecessary objects, so that the non-ejection and the ejection bending cannot be solved. On the other hand, by providing the cleaning device according to the present invention, it is possible to effectively remove the thickened material and aggregates in and around the nozzle with a brush, and then wipe the surface uniformly with a blade to completely remove unnecessary materials. Therefore, non-ejection and ejection bending can be suppressed.

  The image forming apparatus provided with the head cleaning device according to the present invention can use a processing liquid that generates aggregates or insolubles when contacted with a recording liquid. By using the treatment liquid, it is possible to obtain a printed matter having a higher image density, a wider color reproduction range, and higher water resistance than using the recording liquid alone.

  However, once the processing liquid comes into contact with the recording liquid, an aggregate is instantaneously generated. If this agglomerate is generated inside or in the vicinity of the nozzle, non-ejection or ejection bending is likely to occur.

  For this reason, in the image forming apparatus including the conventional head cleaning device in which only the blade or only the brush is mounted, it is not possible to completely remove unnecessary objects, so that the non-ejection and the ejection bending cannot be solved. On the other hand, by providing the cleaning device according to the present invention, it is possible to effectively remove the thickened material and aggregates in and around the nozzle with a brush, and then wipe the surface uniformly with a blade to completely remove unnecessary materials. Therefore, non-ejection and ejection bending can be suppressed.

Next, specific examples will be described.
<Production example of cleaning liquid>
The following components were mixed to produce a cleaning liquid.
Surfactant (I) (R = C9H19, k = 12) 1.0 part humectant (glycerin) 10.0 parts silicone-based antifoaming agent (KM72, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part antiseptic / antifungal agent (Produced by Avicia, PROXEL LV (s)) 0.5 parts Rust inhibitor (sodium thiosulfate) 0.5 parts Remaining amount of ion-exchanged water

<Example of production of recording liquid>
The following components were mixed to produce a recording liquid.
Carbon black (Cabot Jet, Cabot Jet 300) 10 parts moisturizer 1 (1,3-butanediol) 22.5 parts moisturizer 2 (glycerin) 7.5 parts moisturizer 3 (2-pyrrolidone) 2.0 parts interface Activator (I), R = C9H19, k = 12 1.0 part Antirust agent (sodium thiosulfate) 0.2 part Antiseptic / antifungal agent (Avicia, PROXEL LV (s)) 0.4 part ion exchange The remaining amount of water was further adjusted to pH 10.5 with an aqueous LiOH solution.

<Example of treatment liquid production>
The following components were mixed to produce a treatment liquid.
Cationic colloidal silica (manufactured by Nissan Chemical Co., Ltd .: Snowtex AK) 15.0 parts humectant 1 (2-pyrrolidone) 12.5 parts humectant 2 (diethylene glycol) 12.5 parts penetrant (octanediol) 0 parts cationic surfactant (manufactured by Sanyo Chemical Co., Ltd .: Cation G50) 2.0 parts antiseptic / antifungal agent (Avicia, PROXEL LV (s)) 0.2 parts ion-exchanged water remaining amount and pH 4 with acetic acid .3 to be used.

<Example>
(1) Example 1
When the brush 55 is attached to the image forming apparatus shown in FIGS. 1 and 2 and the cleaning device shown in FIG. 4 having the shape shown in FIG. 6 is attached, the cleaning liquid and the recording liquid are filled, and printing is performed, a clear image can be obtained. did it.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image with white streaks was obtained. Therefore, the nozzle surface was brushed while rotating the brush, and the nozzle surface was wiped with a blade to perform a cleaning operation. Thereafter, when printing was performed again, there was no white streak and a clear image with no density unevenness could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

(2) Example 2
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning device shown in FIG. 4 having the shape of the brush 55 shown in FIG. 6, filled with the cleaning liquid and the recording liquid of the manufacturing example, and printed. I was able to get it.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image with some image defects was obtained. Therefore, after spraying the cleaning liquid onto the nozzle surface by spraying, the nozzle surface was brushed while rotating the brush, and the nozzle surface was wiped with a blade to perform a cleaning operation. Thereafter, when printing was performed again, there was no white streak and a clear image with no density unevenness could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

(3) Comparative Example 1
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning device shown in FIG. 10 having the shape of the brush 55 shown in FIG. When printing was performed, a clear image could be obtained.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image with some image defects was obtained. Therefore, after the cleaning liquid was sprayed onto the nozzle surface, the cleaning operation was performed by brushing the nozzle surface while rotating the brush. After printing again, it was confirmed that the white streaks were greatly reduced, but there was slight density unevenness. When the nozzle surface was observed with an optical microscope, it was confirmed that ink thickeners and aggregates remained on the nozzle surface.

Next, another embodiment of a head cleaning device according to the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the head cleaning device.
This head cleaning device is provided with vibration generating means 61 for vibrating the brush 55. Here, as the brush 55, since the rotation operation is performed, the brush 55 shown in FIGS. 6, 8, and 9 can be used. Further, although the blade 58 and the blade moving means 59 of the embodiment are not provided, they can be provided together.

  Here, as the operation (movement) of the brush 55, as shown in FIG. 12, without rotating (fixing) the rotatable brush 55, it is brought into contact with the nozzle surface Na of the head 14 and reciprocated by the brush moving means 56. Operation for movement (non-rotation operation mode), as shown in FIG. 13, an operation for reciprocating the brush 14 by contacting the nozzle surface Na of the head 14 while rotating the rotatable brush 55 (rotation operation mode). As shown in FIG. 14, the rotatable brush 55 is brought into contact with the nozzle surface Na of the head 14 in a non-rotating manner (or can be rotated), and the brush 55 is moved forward and backward by the vibration generating means 61. Reciprocating in a direction (vertical direction in the figure) and in a direction parallel to the nozzle surface Na (nozzle alignment direction: the front-rear direction in the figure and the direction orthogonal thereto: the left-right direction in the figure) Vibration mode of operation) and there is.

  With this configuration, when performing the recovery operation of the nozzle N of the head 14 as in the above embodiment, the nozzle surface Na of the head 14 is first capped by the cap 41 that also serves as a cleaning liquid splash prevention chamber. Thereafter, the inside of the cap 41 is made negative pressure by the waste liquid suction pump 51, whereby the ink or the processing liquid is sucked from the nozzle N of the head 14 and stored in the waste liquid tank 52.

  Next, the cleaning liquid stored in the cleaning liquid cartridge 43 is transferred to the cleaning liquid injection spray 42 by the cleaning liquid injection pump 44, and from the cleaning liquid injection spray 42 with the cap 41 in close contact with the nozzle surface Na as shown in FIG. Spray the cleaning solution. As a result, the cleaning liquid adheres to the nozzle surface Na and the nozzle N.

  Thereafter, the brush 55 is operated in a required operation mode. That is, if the adhering material adhering to the nozzle surface Na is a simple adhering material, the brush 55 is fixed without rotating as shown in FIG. The kimono can be removed. By rubbing without rotating the brush 55, it is possible to minimize damage to the nozzle surface Na.

  On the other hand, when the deposit is firmly attached to the nozzle surface Na, the deposit cannot be removed unless it is rubbed many times. However, if the brush 55 is fixed and moved left and right, cleaning cannot be performed in a short time.

  Therefore, when the deposits are firmly fixed, the deposits can be removed in a short time by operating in the rotational operation mode in which the brush 55 is rotated as shown in FIG.

  Further, when the deposit adheres firmly to the inside of the nozzle N or the concave portion of the nozzle surface Na, even if the brush 55 is fixed and moved left and right, the deposit is strong and cannot be removed. In some cases, the attached matter cannot be removed because the tip of the brush 55 does not reach the inside of N or a specific portion of the concave portion of the nozzle surface Na.

  In this case, as shown in FIG. 14, the brush 55 can be inserted to a portion that has not been reached by operating in a vibration operation mode in which vibration is applied to the front and rear, left and right, or up and down while fixing the brush 55. The deposits in the recesses in the nozzle N and the nozzle surface Na can be completely removed.

  That is, as described above, the aggregate of ink is an aggregate of color materials such as dyes and pigments, and adheres to the nozzle surface more firmly than the thickener. For this reason, it is more difficult to remove ink agglomerates than to remove ink thickeners. In particular, an ink using a pigment tends to form a thickened product or an agglomerate, so that an image defect due to nozzle clogging is likely to occur. In addition, it is difficult to remove the recesses when there are irregularities in the nozzle or on the nozzle surface.

  On the other hand, the head cleaning device and the image forming apparatus according to the present invention remain in the recesses when the inside of the nozzle and the nozzle surface are uneven by selecting and controlling the operation of the brush according to the image quality of the printed matter. Ink thickeners and ink aggregates can be effectively removed, and damage to the nozzle surface can be minimized.

  Here, the selection control of the rotation operation mode, the non-rotation (fixed) operation mode, and the vibration operation mode can be performed by automatically detecting the image quality of the printed material. It can also be made by visually judging and giving a selection instruction to the apparatus.

  For automatic detection of image quality of printed matter, it is preferable to print a test chart including a solid image such as a solid image and optically detect the image density value or the image density distribution. Any method can be used as long as it can detect non-ejection, and a test chart and detection means suitable for the method can be used.

  In addition, when the user visually determines the image quality of the printed matter, based on the result, it is executed by selecting and instructing the optimum mode from, for example, the rotation operation mode, fixed operation mode, and vibration operation mode through the operation panel. To be.

  Accordingly, an example of control by automatic detection will be described with reference to FIG. 15. First, a test chart is printed to obtain image data. This image data is automatically detected by the method as described above to determine whether or not there is an image defect. If there is no image defect, printing is continued. If there is an image defect, the defect level is determined.

  Here, an operation mode for cleaning is selected according to the level of image defects, and cleaning is executed in the selected operation mode.

  Thereafter, the test chart is printed again to obtain image data, the presence / absence of a defect is determined by detecting an image defect, and if the image defect is eliminated, the cleaning is terminated and the printing is continued. If the image defect is not resolved, it is determined that the defect level is high, an operation mode with a higher cleaning effect is selected, and cleaning is executed in the selected operation mode.

  In this way, the deposit on the nozzle is determined, and cleaning is performed by operating the brush in the optimum operation mode.

  Next, an example of processing when the user selects the operation mode will be described with reference to FIG. 16. When the image forming apparatus is instructed to start the cleaning mode, it prints a test chart and outputs image data. . Here, the user visually checks the output image, determines whether or not there is an image defect, determines the presence or absence of the image defect, and the level of the defect when there is an image defect. To give operation instructions.

  Therefore, on the image forming apparatus side, if the input operation instruction is printing continuation (cancellation), this process is exited. On the other hand, if the printing is not continued, the operation mode selected and input by the user is taken in and cleaning is executed in the selected operation mode. Thereafter, the test chart is printed again and an image is output.

  In this way, the deposit on the nozzle is determined, and cleaning is performed by operating the brush in the operation mode selected by the user.

Next, another embodiment of the head cleaning device according to the present invention will be described with reference to FIGS. FIG. 17 is a schematic configuration diagram of the head cleaning device, and FIG. 18 is an explanatory diagram of a brush of the device.
In this embodiment, a brush 65 in which a part of the outer peripheral surface of the brush 55 shown in FIG. 6 is formed of a porous body 66 such as a sponge is used.

  That is, as described above, the nozzle surface Na is rubbed in the non-rotating operation mode for normal simple deposits. In this case, the porous body 66 is rotated and brought into contact with the nozzle surface Na. By rubbing the surface Na, damage to the nozzle surface Na can be further reduced. In addition, a strong deposit can be removed by rotating or applying vibration.

  As described above, in this head cleaning device, by controlling the movement of the brush, it is possible to effectively remove ink thickeners and ink aggregates generated on the nozzle surface and suppress damage to the nozzle surface. Can be compatible.

  Further, by applying a cleaning liquid when cleaning with a brush, the aggregated colorant can be easily dispersed or peeled off. By rubbing with a brush having a protrusion, the tip of the brush reaches the inside of the nozzle or the concave portion of the nozzle surface, so that aggregates can be effectively removed.

  On the other hand, with the conventional device that rotates the brush in a certain direction, there is a risk of rubbing more than necessary for simple deposits and scratching the nozzle surface. A place where the brush tip does not reach the deposit on the concave portion of the surface is generated, and the deposit cannot be completely removed.

  An image recording apparatus provided with another head cleaning apparatus according to the present invention can use a head that discharges by thermal energy. Since this head is excellent in that it can form nozzles at high density and can be manufactured at low cost, a clear image can be obtained with high resolution. However, when the discharge operation is continuously performed, the head that discharges by heat energy gradually accumulates heat and generates high heat. For this reason, the volatile components of the recording liquid and the processing liquid near the nozzles evaporate, resulting in thickening and aggregation, and non-ejection and ejection bending are likely to occur.

  However, other cleaning devices according to the present invention can effectively remove thickening and agglomerates in and near the nozzle with a brush, and thus can suppress non-ejection and ejection bending.

  In another image forming apparatus including the head cleaning device according to the present invention, a recording liquid containing a pigment can be used. By using a pigment as the color material, a printed matter having a high image density, no bleeding, and high water resistance can be obtained.

  However, when a recording liquid containing a pigment is used, when a volatile component in the recording liquid evaporates, the pigment is likely to be deposited inside or near the nozzle, and non-ejection or ejection bend is likely to occur. However, other cleaning devices according to the present invention can effectively remove thickening and agglomerates in and near the nozzle with a brush, and thus can suppress non-ejection and ejection bending.

  An image forming apparatus provided with a head cleaning device according to another aspect of the present invention can use a processing liquid that generates aggregates or insolubles when contacted with a recording liquid. By using the treatment liquid, it is possible to obtain a printed matter having a higher image density, a wider color reproduction range, and higher water resistance than using the recording liquid alone.

  However, once the processing liquid comes into contact with the recording liquid, aggregates are instantaneously generated. If this agglomerate is generated inside or in the vicinity of the nozzle, non-ejection or ejection bending is likely to occur. However, other cleaning devices according to the present invention can effectively remove thickening and agglomerates in and near the nozzle with a brush, and therefore can suppress non-ejection and ejection bending.

Specific examples will be described below.
<Production example of cleaning liquid>

The following components were mixed to produce a cleaning liquid.
Surfactant (I) (R = C9H19, k = 12) 1.0 part humectant (glycerin) 10.0 parts silicone-based antifoaming agent (KM72, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part antiseptic / antifungal agent (Produced by Avicia, PROXEL LV (s)) 0.5 parts Rust inhibitor (sodium thiosulfate) 0.5 parts Remaining amount of ion-exchanged water

<Example of production of recording liquid>
The following components were mixed to produce a recording liquid.
Carbon black (Cabot Jet, Cabot Jet 300) 10 parts moisturizer 1 (1,3-butanediol) 22.5 parts moisturizer 2 (glycerin) 7.5 parts moisturizer 3 (2-pyrrolidone) 2.0 parts interface Activator (I) R = C9H19, k = 12 1.0 part Antirust agent (sodium thiosulfate) 0.2 part Antiseptic / antifungal agent (Avicia, PROXEL LV (s)) 0.4 part ion exchange water The remaining amount was further adjusted to pH 10.5 with an aqueous LiOH solution.

<Example of treatment liquid production>
The following components were mixed to produce a treatment liquid.
Cationic colloidal silica (manufactured by Nissan Chemical Co., Ltd .: Snowtex AK) 15.0 parts humectant 1 (2-pyrrolidone) 12.5 parts humectant 2 (diethylene glycol) 12.5 parts penetrant (octanediol) 0 parts cationic surfactant (manufactured by Sanyo Chemical Co., Ltd .: Cation G50) 2.0 parts antiseptic / antifungal agent (Avicia, PROXEL LV (s)) 0.2 parts ion-exchanged water remaining amount and pH 4 with acetic acid .3 to be used.

<Example>
(1) Example 3
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning unit shown in FIG. 11 using the brush 55 having the shape shown in FIG. 6, filled with cleaning liquid and recording liquid, and printed. I was able to get an image. As the washing liquid, a 1: 1 mixture of water and ethanol was used.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image with some image defects was obtained. Therefore, as shown in FIG. 12, the cleaning operation was performed by moving the brush to the left and right while fixing the rotation of the brush and bringing the tip of the brush into contact with the nozzle surface. Thereafter, when the image was printed again, a clear image free from image defects could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

(2) Example 4
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning unit shown in FIG. 11 using the brush 55 having the shape shown in FIG. 6, filled with cleaning liquid and recording liquid, and printed. I was able to get an image. As the washing liquid, a 1: 1 mixture of water and ethanol was used.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image with some image defects was obtained. Therefore, as shown in FIG. 12, the cleaning operation was performed by moving the brush to the left and right while fixing the rotation of the brush and bringing the tip of the brush into contact with the nozzle surface. Thereafter, when printing was performed again, it was confirmed that image defects remained although image defects were reduced. When the nozzle surface was observed with an optical microscope, it was confirmed that ink thickeners and aggregates adhered to the nozzle surface and the nozzle was clogged.

  Further, as shown in FIG. 13, the cleaning operation was performed by rotating the brush while bringing the tip of the brush into contact with the nozzle surface. Thereafter, when printing was performed again, it was confirmed that image defects remained although image defects were further reduced. When the nozzle surface was observed with an optical microscope, it was confirmed that ink aggregates adhered to the nozzle surface and the nozzle was clogged.

  Further, as shown in FIG. 14, the cleaning operation was performed by vibrating the brush up and down and left and right while bringing the brush tip into contact with the nozzle surface. Thereafter, when the image was printed again, a clear image free from image defects could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

(3) Example 5
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning unit shown in FIG. 11 using the brush 55 having the shape shown in FIG. 6, filled with cleaning liquid and recording liquid, and printed. I was able to get an image. As the washing liquid, a 1: 1 mixture of water and ethanol was used.

  After printing, it was left for 1 week at room temperature and normal humidity without capping. When printing was performed without cleaning, an image having image defects on the entire surface was obtained. Therefore, as shown in FIG. 13, the cleaning operation was performed by rotating the brush while bringing the tip of the brush into contact with the nozzle surface. Thereafter, when the image was printed again, a clear image free from image defects could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

(4) Example 6
The image forming apparatus shown in FIGS. 1 and 2 is attached with the cleaning unit shown in FIG. 11 using the brush 55 having the shape shown in FIG. 6, filled with cleaning liquid and recording liquid, and printed. I was able to get an image. As the washing liquid, a 1: 1 mixture of water and ethanol was used.

  When 100 sheets were printed continuously, white streaks occurred. When the nozzle surface was observed with an optical microscope without performing the cleaning operation, the nozzle surface had agglomerates that were thought to be generated due to the reaction between the recording liquid and the processing liquid bounced off the recording surface. It was confirmed that clogging occurred. Therefore, as shown in FIG. 13, the cleaning operation was performed by rotating the brush while bringing the tip of the brush into contact with the nozzle surface. Thereafter, when the image was printed again, a clear image free from image defects could be obtained. When the nozzle surface was observed with an optical microscope, it was confirmed that there were no ink thickeners and aggregates on the nozzle surface, and the nozzles were not clogged.

  In the above-described embodiment, the present invention has been described with reference to an example in which the present invention is applied to an ink jet recording apparatus.

1 is a configuration diagram showing an outline of a mechanism part of an ink jet recording apparatus as an embodiment of an image forming apparatus according to the present invention including a head cleaning apparatus according to the present invention. It is side surface explanatory drawing of the mechanism part. FIG. 2 is an explanatory plan view of a head configuration of the recording apparatus. FIG. 3 is a schematic explanatory diagram for explaining one embodiment of a head cleaning device according to the present invention. FIG. 5 is an explanatory diagram for explaining the operation of FIG. 4. It is explanatory drawing explaining the 1st example of the brush of the head cleaning apparatus which concerns on this invention. It is explanatory drawing explaining the 2nd example of the brush of the head cleaning apparatus which concerns on this invention. It is explanatory drawing explaining the 3rd example of the brush of the head cleaning apparatus which concerns on this invention. It is explanatory drawing explaining the 4th example of the brush of the head cleaning apparatus which concerns on this invention. It is a typical explanatory view of a head cleaning device concerning a comparative example. It is a schematic block diagram which shows one Embodiment of the head cleaning apparatus which concerns on other this invention. It is explanatory drawing with which it uses for description of the non-rotation (fixed) operation mode of the head cleaning apparatus. It is explanatory drawing with which it uses for description of the rotation operation mode of the head cleaning apparatus. It is explanatory drawing with which it uses for description of the vibration operation mode of the head cleaning apparatus. It is a flowchart explaining an example of the process which performs the operation mode selection by automatic detection. It is a flowchart explaining an example of the process which performs operation mode selection by manual operation. It is a schematic block diagram which shows other embodiment of the head cleaning apparatus which concerns on other this invention. It is explanatory drawing of the brush of the head cleaning apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 ... Carriage 14 ... Head 14a ... Recording head 14s ... Processing liquid head 15 ... Liquid cartridge 37 ... Subsystem 41 ... Cap 42 ... Cleaning liquid injection spray 43 ... Cleaning liquid cartridge 44 ... Cleaning liquid injection pump 55, 65 ... Brush 56 ... Brush moving means 58 ... Blade 59 ... Blade moving means 60 ... Cleaning liquid 61 ... Vibration generating means

Claims (14)

  A head cleaning device for removing deposits adhering to a nozzle surface of a droplet discharge head that discharges droplets from a nozzle, comprising a brush and a blade that contact the nozzle surface of the head. Head cleaning device.   The head cleaning apparatus according to claim 1, wherein the brush rotates.   A head cleaning device that removes adhering matter adhering to a nozzle surface of a droplet discharge head that discharges droplets from a nozzle by bringing the brush into contact therewith, and the operation of the brush can be selected according to the image quality of an output image An image forming apparatus.   4. The head cleaning device according to claim 3, wherein an operation of rotating the brush and an operation of not rotating the brush can be selected.   4. The head cleaning device according to claim 3, wherein an operation of rotating the brush, an operation of not rotating the brush, and an operation of vibrating the brush can be selected.   6. The head cleaning device according to claim 3, wherein an operation of the brush is selected based on an image quality detection result of an output image.   7. The head cleaning device according to claim 3, wherein the operation of the brush can be manually selected based on the detection result of the image quality of the output image.   8. The head cleaning device according to claim 3, wherein a part of the outer peripheral surface of the brush is formed of a porous body.   9. The head cleaning device according to claim 1, wherein a cleaning liquid is applied when the brush is brought into contact with the nozzle surface.   An image forming apparatus comprising: a droplet discharge head for discharging droplets from a nozzle to form an image on a recording medium; and a head cleaning device for removing deposits on the nozzle surface of the droplet discharge head. An image forming apparatus, wherein the head cleaning device is the head cleaning device according to claim 1.   The image forming apparatus according to claim 10, wherein the liquid droplet ejection head ejects liquid droplets using film boiling generated in the liquid by thermal energy generated by electrothermal conversion means.   12. The image forming apparatus according to claim 10, wherein the liquid is a recording liquid containing a color material.   13. The image forming apparatus according to claim 12, wherein the color material of the recording liquid is a pigment. 12. The image forming apparatus according to claim 10, wherein a recording liquid containing a color material and a treatment liquid that does not contain a color material and generates an aggregate or an insoluble material by contact with the recording liquid are discharged. An image forming apparatus comprising a droplet discharge head that performs the above operation.

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