JP5712757B2 - Head cleaning device - Google Patents

Description

  The present invention relates to a head cleaning device that cleans a head that discharges a recording liquid such as ink, and an inkjet image forming apparatus that includes the head cleaning device and forms an image using a recording liquid discharged from a head.

  Conventionally, a recording liquid such as ink is ejected from a plurality of micro nozzles in accordance with image information using a movable actuator system typified by a piezo system or a heated film boiling system typified by a thermal system. An image forming apparatus that employs an inkjet image forming technique such as an ink jet printer that includes a head attached to a recording medium such as an ink jet recording is known (for example, [Patent Document 1] and [Patent Document 2]). reference). Such an inkjet image forming apparatus is expanding its application range to printers, facsimiles, copiers, and the like because of the simplicity of the apparatus configuration compared to the electrophotographic system. It is also expected to develop into new fields such as electrical circuit formation and biotechnology applications. In addition, an ejection device that ejects ink from a head is known (see, for example, [Patent Document 3]).

  In these image forming apparatuses, if the ink attached to the nozzle and its surroundings thickens or dries, or if foreign matter such as dust or paper dust adheres to the nozzle, ejection failure, mist, or disturbance in the ink droplet flight direction will occur. And the image quality deteriorates. Therefore, a head cleaning method has been conventionally proposed in which a nozzle surface is wiped with a member made of a flexible material such as rubber, a wiper, or the like and wiped to remove deposits around the nozzle (for example, [Patent Documents] 1] to [Patent Document 3]).

  However, mechanical contact of a member such as a blade with the nozzle surface causes deterioration of the nozzle surface and deterioration of the member itself in the long term. In particular, in an inkjet head, the surface of the nozzle surface is often treated with a water-repellent film in order to increase the ink ejection performance and meniscus retention, and such mechanical contact damages the water-repellent film. . Damage to the water-repellent film causes flying bends, mist generation, and dispersion of the ejected droplets, which significantly deteriorates the image quality. Further, when the blade is deteriorated, the wiping performance is deteriorated, so that mist, foreign matter and the like adhering to the nozzle surface cannot be removed well, and the image quality is also deteriorated.

  Therefore, a technique for cleaning the nozzle surface, particularly a water-repellent film, without damaging the head is desired in order to stably operate an inkjet image forming apparatus for a long period of time. Has previously proposed a technique for cleaning the head without using such a member as a blade (Japanese Patent Application No. 2011-044600).

  On the other hand, in the configuration for cleaning the head, it is necessary to determine whether or not the head has actually been cleaned after the head cleaning operation. This is because when the head cleaning is insufficient, it is necessary to perform an operation such as repeating the head cleaning operation.

However, the technique of cleaning the head with a member such as a blade as described above has disadvantages in this determination.
That is, for example, when such a technique is adopted, if a large amount of ink adheres to such a member, the ink may only repeatedly adhere between the head and the member, and cleaning may not succeed. This is a problem that occurs when there is no mechanism for measuring the unwiped state of the nozzle surface. In this regard, a configuration employing such a mechanism (see, for example, [Patent Document 1] and [Patent Document 2]) has been proposed, and according to this configuration, such a problem can be solved. However, such a configuration leads to complication of the apparatus. For this reason, when such a technique is adopted, the wiping is often performed by controlling the blade and other members so that there is no deposit. In this case, unless the wiping state of the nozzle surface is measured, the nozzle surface is wiped. It cannot be controlled so that there is no residue, resulting in the above-mentioned problem.

  Therefore, a configuration has been proposed in which the state of the nozzle surface is not measured and a mechanism that removes deposits on members such as blades is employed (for example, see [Patent Document 3]). However, in this configuration, since the state of the nozzle surface and the state of such a member are not controlled, there is a possibility that cleaning must be repeated, and due to the above-described problem, that is, due to mechanical contact of a member such as a blade with the nozzle surface, There is a possibility of promoting the problem of causing deterioration of the nozzle surface and the member itself.

  In view of the circumstances as described above, in the technology for cleaning the head without using a member such as a blade, at least the progress of the cleaning of the head is easily determined as to whether or not the head has been cleaned. Is desirable.

  The present invention cleans a head that discharges a recording liquid such as ink without using a member such as a blade that contacts the head, and makes it possible to easily determine the progress of head cleaning. It is an object of the present invention to provide an image forming apparatus of an ink jet type that includes the apparatus and the head cleaning device and forms an image with a recording liquid discharged from the head.

  In order to achieve the above object, the invention according to claim 1 is a cleaning member to which a recording liquid discharged from the nozzle is applied in a state of facing a head having a nozzle member having a nozzle for discharging a recording liquid; Based on voltage application means for applying a voltage between the nozzle member and the cleaning member, and a transition of an energization state in a state where a voltage is applied between the nozzle member and the cleaning member by the voltage application means. The head cleaning apparatus includes a cleaning determination unit that determines a progress of cleaning of the nozzle member.

  According to a second aspect of the present invention, in the head cleaning device according to the first aspect, the cleaning member and the head are arranged so that the recording liquid applied to the cleaning member moves while contacting the surface of the nozzle member. The cleaning determination means includes a moving means for relatively moving the cleaning member and the head relative to each other by the moving means, and the voltage applying means between the nozzle member and the cleaning member. The progress of the cleaning of the nozzle member is determined based on the transition of the energization state with the voltage applied.

  The present invention provides a cleaning member to which a recording liquid discharged from the nozzle is applied in a state of being opposed to a head having a nozzle member provided with a nozzle for discharging a recording liquid, and between the nozzle member and the cleaning member. A progress state of cleaning of the nozzle member is determined based on a voltage application means for applying a voltage, and a transition of an energization state in a state where a voltage is applied between the nozzle member and the cleaning member by the voltage application means. Since the head cleaning device has a cleaning determination means, the head can be cleaned using the recording liquid without using a blade or other member that comes into contact with the head, and the current state of the cleaning can be determined based on the progress of the cleaning. PROBLEM TO BE SOLVED: To provide a head cleaning device capable of easily judging based on the transition of Door can be.

  The cleaning member includes a moving unit that relatively moves the cleaning member and the head so that the recording liquid applied to the cleaning member moves while contacting the surface of the nozzle member. The cleaning member and the head are moved relative to each other by a moving unit, and a voltage is applied between the nozzle member and the cleaning member by the voltage applying unit. If the progress of the cleaning is judged, the head can be cleaned using the recording liquid, and the progress of the cleaning is determined based on the transition of the energization state that changes due to the relative movement. It is possible to provide a head cleaning device that can be easily determined.

  The cleaning determination means determines the progress status based on the transition as a case where the recording liquid applied to the cleaning member is poorly discharged between the nozzle member and the cleaning member; Then, the head can be cleaned using the recording liquid, and the progress of the cleaning is easily determined as such a discharge failure based on the transition of the energization state that changes due to the relative movement. It is possible to provide a head cleaning device that can be used.

  The cleaning determination unit applies a voltage between the nozzle member and the cleaning member by the voltage application unit at least at a timing when the recording liquid discharged from the nozzle bridges between the head and the cleaning member. If it is determined that the progress of cleaning of the nozzle member is based on the current-carrying state in that state, it is determined that the recording liquid discharge from the nozzle is defective. The head cleaning device can perform the cleaning of the head without using the recording liquid and can easily determine the progress of the cleaning as an ejection failure based on the transition of the energization state. Can be provided.

  When the cleaning determination means determines that the progress is a discharge failure of the recording liquid from the nozzle, the moving means relatively moves the cleaning member and the head to apply the voltage. If the state of progress of the cleaning of the nozzle member is determined based on the transition of the energization state in a state where a voltage is applied between the nozzle member and the cleaning member by means, such as a blade that contacts the head The head can be cleaned using the recording liquid without using a member, and the progress of the cleaning can be easily determined as an ejection failure based on the transition of the energization state. When this decision is made, further cleaning is performed, By determining the progress of the cleaning, enhanced reliability of cleaning, it is possible to provide the possibility and the head cleaning device to perform a good cleaning.

  If the voltage application means applies a voltage to the anionic recording liquid so that the nozzle member functions as a cathode and the cleaning member functions as an anode, a member such as a blade that contacts the head is provided. Without using it, the recording liquid can be used to clean the head by generating hydroxide ions on the nozzle member side and dispersing the aggregation component of the recording liquid inside the recording liquid. It is possible to provide a head cleaning device that can easily determine the progress status based on the transition of the energization status.

  If the cleaning member functions as an intermediate transfer body in which the recording liquid discharged and applied from the nozzle is transferred to a recording medium, the cleaning member can be applied to the intermediate transfer body without using a member such as a blade that contacts the head. The head can be cleaned using the applied recording liquid, and the progress of this cleaning can be easily judged based on the transition of the energization status. It is possible to provide a head cleaning device whose price is suppressed or prevented.

  Since the present invention is in an image forming apparatus having such a head cleaning device, the cleaning of the head is performed using the recording liquid without using a member such as a blade abutting on the head, and the progress of the cleaning is energized. By making a simple determination based on the transition of the situation, it is possible to provide an image forming apparatus that can perform good image formation over time.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a conceptual diagram illustrating a state in which a recording liquid is applied from a head to an intermediate transfer member in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic plan view illustrating the arrangement of nozzles in a head provided in the image forming apparatus shown in FIG. 1. FIG. 2 is a conceptual diagram illustrating a state in which colorants in recording liquid discharged from a head in the image forming apparatus illustrated in FIG. 1 are aggregated via protons. FIG. 2 is a conceptual diagram illustrating a state of a liquid column by a recording liquid formed between a cathode and an anode in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a conceptual diagram illustrating an operation for cleaning a nozzle portion in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic front view showing a state when a nozzle portion is cleaned in the image forming apparatus shown in FIG. 1. 2 is a flowchart illustrating a part of an operation when a nozzle portion is cleaned in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a conceptual diagram for explaining a principle in which a progress status of cleaning of a nozzle member is grasped based on an energization status in the image forming apparatus shown in FIG. 1. FIG. 7 is a conceptual diagram illustrating an operation of cleaning the nozzle portion in another mode in the image forming apparatus illustrated in FIG. 1. 1 is a schematic view of an image forming apparatus to which the present invention is applied and having an intermediate transfer member in a belt shape. FIG. 12 is a conceptual diagram illustrating an operation when the nozzle unit is cleaned in the image forming apparatus illustrated in FIG. 11. FIG. 12 is a schematic diagram of a modification of the image forming apparatus illustrated in FIG. 11.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a printer as an ink jet printer and can perform full-color image formation. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside.

  The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is. The image forming apparatus 100 is a single-sided image forming apparatus that can form an image on one side of a transfer sheet S that is a recording medium as a recording medium that is a recording medium. It may be an image forming apparatus.

  The image forming apparatus 100 ejects a recording liquid, which is a conductive recording liquid as ink of that color, capable of forming an image as an image corresponding to each color separated into yellow, magenta, cyan, and black. It has heads 61Y, 61M, 61C and 61BK which are ink jet heads as recording heads which are ink heads as recording liquid discharge bodies.

  The heads 61Y, 61M, 61C, and 61BK are disposed at positions facing the outer peripheral surface of the intermediate transfer body 37 that is an intermediate transfer drum disposed at a substantially central portion of the main body 99 of the image forming apparatus 100. The heads 61Y, 61M, 61C, 61BK are arranged in this order from the upstream side in the A1 direction, which is the moving direction of the intermediate transfer body 37 and is the clockwise direction in FIG. In the drawing, Y, M, C, and BK added after the numerals of the reference numerals indicate members for yellow, magenta, cyan, and black.

  The heads 61Y, 61M, 61C, and 61BK are respectively ink ejection devices 60Y, 60M, which are recording liquid ejection devices for forming yellow (Y), magenta (M), cyan (C), and black (BK) images. It is provided in 60C and 60BK. Each of the heads 61Y, 61M, 61C, and 61BK is provided in the ink ejection devices 60Y, 60M, 60C, and 60BK in such a manner that a plurality of the heads 61Y, 61M, 61C, and 61BK are arranged in parallel in the direction perpendicular to the paper surface of FIG.

  The intermediate transfer body 37 is rotated in the A1 direction and is recorded in yellow, magenta, cyan, and black from the heads 61Y, 61M, 61C, and 61BK in an area facing the heads 61Y, 61M, 61C, and 61BK. The liquids are ejected and applied in such a manner that they are sequentially superimposed, and an image is formed on the surface. As described above, the image forming apparatus 100 has a tandem structure in which the heads 61Y, 61M, 61C, and 61BK are opposed to the intermediate transfer member 37 and are arranged in parallel in the A1 direction.

  The recording liquid is ejected or applied to the intermediate transfer member 37 by the heads 61Y, 61M, 61C, 61BK upstream of the A1 direction so that the image areas of yellow, magenta, cyan, and black are overlapped at the same position on the intermediate transfer member 37. The timing is shifted from the side toward the downstream side.

  The image forming apparatus 100 includes ink discharge devices 60Y, 60M, 60C, and 60BK that are provided with heads 61Y, 61M, 61C, and 61BK, and an intermediate transfer member 37 that is transferred as the intermediate transfer member 37 rotates in the A1 direction. A transport unit 10 serving as a paper transport unit for transporting the paper S, and a feeding unit that can load a large number of transfer sheets S and feeds only the top transfer sheet S among the stacked transfer sheets S toward the transport unit 10. It has a paper unit 20 and a paper discharge tray 25 on which a large number of printed transfer papers S that have been transported by the transport unit 10 can be stacked.

  In the image forming apparatus 100, as shown in FIG. 2B, the liquid column of the recording liquid immediately after being ejected from the heads 61Y, 61M, 61C, 61BK is changed to the heads 61Y, 61M, 61C, 61BK, the intermediate transfer body 37, and the like. The electrode oxidation reaction is performed inside the recording liquid in such a liquid column so that a potential difference is formed between the intermediate transfer member 37 and the heads 61Y, 61M, 61C, 61BK in a state where the space between the intermediate transfer body 37 and the head 61Y, 61M, 61C, 61BK. Alternatively, it has energization means 33 as voltage application means for energizing the recording liquid in a state where the current component resulting from the electrode reduction reaction is applied and promoting aggregation of the colorant contained in the recording liquid as described later.

  As shown in FIG. 1, the image forming apparatus 100 also removes the recording liquid remaining on the intermediate transfer body 37 from the intermediate transfer body 37 after the recording liquid is transferred to the transfer paper S. The cleaning means 34 that is a residual ink removing means as a cleaning means for cleaning, a carriage 50 as a head support that integrally supports the heads 61Y, 61M, 61C, and 61BK, and the carriage 50 are shown in FIG. The heads 61Y, 61M, 61C, 61BK are brought into contact with the intermediate transfer body 37 and the positions shown in FIG. And the drive unit 35 as contact / separation means for contacting / separating the heads 61Y, 61M, 61C, 61BK and the intermediate transfer body 37, and the overall operation of the image forming apparatus 100. Your to CPU, and a controller 40 as control means including a memory and the like.

  In addition to the intermediate transfer member 37, the transport unit 10 is disposed so as to face the intermediate transfer member 37, and when the transfer sheet S passes through the transfer unit 31 that is an area between the transfer unit S and the intermediate transfer member 37. The transfer means 64 for transferring the image of the recording liquid carried thereon onto the transfer paper S and the transfer paper S fed from the paper supply unit 20 are guided to the transfer unit 31 and passed through the transfer unit 31. A guide plate 39 that guides the transfer sheet S to the paper discharge table 25, a motor 32 that is an intermediate transfer body rotation drive motor as a drive unit that rotationally drives the intermediate transfer body 37 in the A1 direction, and the like. As described above, the image forming apparatus 100 is an indirect image forming apparatus that indirectly forms an image on the transfer sheet S using the intermediate transfer body 37.

  The transfer means 64 includes a transfer roller 38 that rotates following the intermediate transfer body 37, a spring (not shown) as a pressure means that presses the transfer roller 38 against the intermediate transfer body 37 and causes the transfer roller 38 to function as a pressure roller, A separation portion 36 is provided as a separation means for separating the transfer roller 38 from the intermediate transfer body 37 against the biasing force of the spring, and the transfer sheet S is conveyed under pressure between the intermediate transfer body 37 and the transfer roller 38. It has become.

  As shown in FIG. 2, the intermediate transfer member 37 includes a support 37a made of aluminum, which is a conductive substrate, and a surface layer 37b made of silicone rubber formed on the support 37a. The material of the support 37a is not limited to aluminum, and may be formed of a metal such as an aluminum alloy, copper, or stainless steel as long as it has mechanical strength. The material of the surface layer 37b is not limited to silicone rubber. For the advantage of high releasability of the recording liquid, any elastic material having low surface energy and high followability to the transfer paper S may be used. It may be formed of rubber, urethane rubber, fluorine rubber or the like, or may be resin.

  The surface layer 37b is a conductive rubber in which metal fine particles such as carbon, platinum, and gold as a conductive agent are dispersed and mixed in the rubber material in order to impart conductivity to the intermediate transfer member 37. It has become. However, increasing the number of conductive fine particles improves the conductivity, but a trade-off relationship that lowers the releasability, so adjustment is necessary as appropriate.

As will be described later, in order to form a desired potential difference in the liquid column of the recording liquid temporarily bridged by the heads 61Y, 61M, 61C, 61BK and the intermediate transfer body 37, the volume resistivity of the conductive rubber is 10 ^3. It is preferably less than Ω · cm, and preferably smaller than the volume resistivity of the recording liquid.

  The material of the surface layer 37b is silicone rubber, nitrile rubber, urethane rubber, or fluorine rubber as described above, and is made of a material having high wettability with respect to the recording liquid as described later. From the viewpoint of safety, the surface layer 37b may include an elastomer having a fluorine-based coating on the surface of the material.

  The thickness of the surface layer 37b is preferably about 0.1 to 1 mm, and preferably 0.2 to 0.6 mm. Further, the intermediate transfer member 37 is not in a drum shape but may be in an endless belt shape as will be described later, or in a sheet shape if possible.

  As shown in FIG. 1, the paper feeding unit 20 transports only the uppermost transfer paper S among the paper feed tray 21 on which a large number of transfer papers S can be stacked and the transfer paper S stacked on the paper feed tray 21. The sheet feeding roller 22 fed toward the unit 10, the casing 23 supporting the sheet feeding tray 21 and the sheet feeding roller 22, and the sheet feeding roller 22 are ejected from the recording liquid in the heads 61Y, 61M, 61C, 61BK. It has a motor or the like as a driving means (not shown) that rotates and feeds the transfer paper S so as to match the timing.

  The carriage 50 can be replaced with a new one when the heads 61Y, 61M, 61C, 61BK are deteriorated, and in order to facilitate maintenance, the heads 61Y, 61M, 61C, 61BK can be replaced. And can be attached to and detached from the main body 99. Each of the heads 61Y, 61M, 61C, 61BK can be independently attached to and detached from the main body 99 so that it can be replaced with a new one when deterioration or the like occurs and for easy maintenance. ing. This facilitates replacement work and maintenance work.

  The ink discharge devices 60Y, 60M, 60C, and 60BK have substantially the same configuration with respect to the other points although the colors of the recording liquid to be used are different. The ink ejection devices 60Y, 60M, 60C, 60BK and the image forming apparatus 100 are a head-fixed full line type.

  The ink ejection devices 60Y, 60M, 60C, and 60BK are ink cartridges 81Y, 81M, and 81C that are recording liquid cartridges as main tanks that store the recording liquids of the corresponding colors supplied to the plurality of heads 61Y, 61M, 61C, and 61BK. , 81BK and a supply pump that feeds and feeds the recording liquid stored in the ink cartridges 81Y, 81M, 81C, 81BK toward the heads 61Y, 61M, 61C, 61BK. The recording liquid feed paths between the pumps 82Y, 82M, 82C, and 82BK as the pumps and the ink cartridges 81Y, 81M, 81C, and 81BK and the heads 61Y, 61M, 61C, and 61BK are pumps 82Y, 82M, 82C, and 82BK. And a pipe (not shown) that is formed together.

  The ink cartridges 81Y, 81M, 81C, 81BK are replaced with new ones when the internal recording liquid is consumed and the remaining amount is low or no longer used, and in order to facilitate maintenance. 99 is removable.

  The pumps 82Y, 82M, 82C, and 82BK are types that feed the recording liquid into the heads 61Y, 61M, 61C, and 61BK. The pumps 82Y, 82M, 82C, and 82BK may be piston pumps or the heads 61Y, 61M, and 61C. , 61BK may be used to suck the recording liquid.

  The operations of the pumps 82Y, 82M, 82C, and 82BK are controlled by the controller 40. In this respect, the control unit 40 functions as an ink supply control unit that is a recording liquid supply control unit. The control unit 40 controls the driving of the image forming apparatus 100 even when not specifically described.

  The recording liquid contains at least a colorant corresponding to yellow, magenta, cyan, and black, an anionic dispersant that is a dispersant for the colorant, and a solvent. Due to the colorant and the dispersant, the ink component of the recording liquid has an anionic group. The solvent contains water from the viewpoint of safety and the conductivity from the viewpoint of causing electrolysis to be described later, and the recording liquid is a water-soluble recording liquid that is a conductive ink and a water-soluble ink. The recording liquid is desirably alkaline from the viewpoint of storage stability.

The pigment that is a colorant used in the recording liquid is not particularly limited, but as a pigment for orange or yellow, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.
Further, as a pigment for red or magenta, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
Further, as a pigment for green or cyan, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
Further, as a pigment for black, C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.
The content of the pigment in the recording liquid is usually 0.1 to 40% by mass, preferably 1 to 30% by mass, and more preferably 2 to 20% by mass.

  Examples of the anionic dispersant include, but are not limited to, fatty acid salt, alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonate formalin condensate, poly Examples thereof include oxyethylene alkyl sulfate esters, and two or more of them may be used in combination.

From the viewpoint of transferability, the recording liquid preferably further contains a resin having an anionic group in which a carboxyl group, a sulfonic acid group, a phosphonic acid group or the like is neutralized with a base.
The recording liquid may further contain a solvent soluble in water. Solvents that are soluble in water are not particularly limited, but are polyvalent such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. Alcohols: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene oxide adduct of diglycerin Polyhydric alcohol derivatives such as pyrrolidone, N-methyl-2-pyrrolidone, Nitrogen-containing solvents such as hexylpyrrolidone and triethanolamine; alcohols such as ethanol, isopropyl alcohol, butyl alcohol and benzyl alcohol; sulfur-containing solvents such as thiodiethanol, thiodiglycerol, sulfolane and dimethyl sulfoxide; propylene carbonate, ethylene carbonate and the like These may be used in combination of two or more.

  For example, the recording liquid for black, that is, the black ink has the following composition. 35.0% by mass of sulfonic acid group-bonded carbon black pigment dispersion CAB-O-JET-200 (Cabot Specialty Chemicals Inc.) having a solid content of 20% by mass, 10.0% by mass of 2-pyrrolidone, 14.0% by mass of glycerin, 0.9% by mass of propylene glycol monobutyl ether, 0.1% by mass of sodium dehydroacetate and distilled water (residue).

  As shown in FIG. 2, each of the heads 61Y, 61M, 61C, 61BK includes a nozzle plate 61a as a nozzle plate that is a conductive nozzle member disposed on the recording liquid discharge side facing downward in the figure, and a nozzle An ink chamber that is a liquid chamber that is supplied with recording liquid from the ink cartridges 81Y, 81M, 81C, and 81BK by the nozzle 61b formed on the plate 61a and pumps 82Y, 82M, 82C, and 82BK, and holds the recording liquid. 61c and an ink discharge means (not shown) for discharging the recording liquid in the ink chamber 61c from the nozzle 61b. The nozzle plate 61a, the nozzle 61b, the ink chamber 61c, and the ink discharge means are provided as a set, and each head 61Y, 61M, 61C, 61BK is provided in large numbers, but only one of them is shown in FIG. Is illustrated.

  Although detailed illustration is omitted, the nozzle plate 61 a includes a conductive substrate and a water repellent film formed on the surface of the substrate facing the intermediate transfer body 37. The water-repellent film may be formed by applying a fluorine-based water repellent or a silicon-based water repellent, or may be formed by plating a fluorine-based polymer or a fluorine-metal compound eutectoid, Any film having water repellency is not particularly limited. The nozzle plate 61a includes a surface on the ink chamber 61c side as an interface forming portion that forms an interface with the recording liquid in the ink chamber 61c, and functions as a cathode as will be described later.

  The entire nozzle plate 61a may be conductive, or may be a member in which only the surface on the ink chamber 61c side is subjected to conductive treatment, or an intermediate member between the conductive member disposed on the ink chamber 61c side. You may comprise by the insulating member arrange | positioned by the transfer body 37 side.

  Since the conductive portion of the nozzle plate 61a is provided as a cathode as will be described later, it does not need to be made of a material resistant to metal elution, and has a high conductivity such as SUS alloy, metal such as nickel, and carbon. What is necessary is just to be comprised with material.

The nozzle plate 61a is set so that the gap with the intermediate transfer member 37 is 50 to 600 μm during image formation. If the gap is less than 50 μm, it may be difficult to maintain the gap between the intermediate transfer member 37, which is a rotating body, and the nozzle plate 61a. If the gap exceeds 600 μm, the liquid injection described later may be performed. This is because it may be difficult to form a bridge. However, there is no particular problem even if the gap is less than 50 μm as long as the gap can be maintained.
The nozzle plate 61a is a nozzle portion provided with a nozzle 61b, and in particular, a nozzle surface 61d that is a surface facing the intermediate transfer member 37 is a nozzle portion.

  The ink discharge means has a piezoelectric element as an actuator for applying pressure for discharging the recording liquid from each nozzle 61 b to be discharged and landed on the intermediate transfer body 37, and is applied to the piezoelectric element by the control of the control unit 40. The recording liquid is ejected from the nozzle 61b according to the voltage pulse. In this regard, the control unit 40 functions as an ink ejection control unit. The control unit 40 functioning as an ink ejection control unit inputs a voltage pulse for driving the piezoelectric element to each of the piezoelectric elements with a predetermined signal waveform. The control unit 40 functioning as an ink ejection control unit drives each piezoelectric element in time series so that an arbitrary pattern, that is, an image is formed by the recording liquid ejected from each nozzle 61b. In this regard, the control unit 40 functions as an image control device. The pressure in the ink chamber 61c is maintained at a negative pressure except when the recording liquid is discharged and discharged from the nozzle 61b.

  The actuator of the ink discharge means may be a movable actuator of another type that is a shape deforming element type, such as a piezo type, or the nozzle 61b by boiling of the recording liquid by a heating means that employs a heater type such as a thermal type. The recording liquid may be ejected from the recording liquid, or the recording liquid may be ejected by electrostatic attraction by a voltage application means. Any apparatus that ejects the recording liquid by any method may be employed.

  As described above, the image forming apparatus 100 is a head-fixed full line type. FIG. 3 illustrates the configuration of the heads 61Y, 61M, 61C, and 61BK. In the heads 61Y, 61M, 61C, 61BK shown in FIG. 6A, the nozzle plate 61a has a large number of nozzles 61b in a line along the main scanning direction corresponding to the horizontal direction in FIG. A full line type ink jet head is obtained by providing two rows of nozzles along the direction corresponding to the vertical direction in the figure perpendicular to the sub-scanning direction, that is, the main scanning direction. The main scanning direction corresponds to a direction perpendicular to the paper surface in FIG. Heads 61Y, 61M, 61C, 61BK shown in FIG. 6B are nozzle plates 61a having a number of nozzles 61b in the same manner as shown in FIG. By arranging a plurality of nozzle plates 61a smaller than the nozzle plate 61a shown in a grid, a full-line inkjet head is obtained. In any of FIGS. 6A and 6B, the heads 61Y, 61M, 61C, and 61BK are line-type heads that are two-dimensionally provided with nozzles 61b, but the heads 61Y, 61M, 61C, and 61BK are provided. May be a one-dimensional line-type head provided with a plurality of nozzles 61b in the main scanning direction. The heads 61Y, 61M, 61C, and 61BK may be serial scan type ink jet heads.

  The energizing means 33 is realized as a part of the function of the power source 33a, a not-shown electric circuit in which the power source 33a is connected to the support 37a and the nozzle plate 61a, and a part of the function of the control unit 40. Voltage application control means for controlling time. The controller 40 as voltage application control means also functions as voltage changing means for changing the voltage of the power supply 33a.

  The power source 33a has an anode connected to the support 37a and a cathode connected to the nozzle plate 61a by an electric circuit. Therefore, the energizing unit 33 includes the intermediate transfer member 37 as an anode and the nozzle plate 61a as a cathode.

  Although not shown, the cleaning means 34 scrapes off the recording liquid that has not been transferred to the transfer paper S from the surface of the intermediate transfer body 37 from the recording liquid constituting the image formed on the intermediate transfer body 37 as residual ink. A cleaning blade which is a rubber blade as a cleaning member formed of rubber as an elastic body, which is in contact with the intermediate transfer body 37 in a so-called counter contact manner, and the cleaning blade is pressed against the intermediate transfer body 37 It has a pressing means for hitting and a waste liquid bottle for collecting foreign matter such as recording liquid and dust scraped off from the surface of the intermediate transfer member 37 by the cleaning blade. The cleaning unit 34 may include a cleaning roller as a cleaning member together with the cleaning blade.

  The portion of the intermediate transfer member 37 on which the recording liquid is applied and carried, that is, the surface, desirably has a receding contact angle smaller than that of the nozzle surface 61d. The receding contact angle is a characteristic indicating wettability. Generally speaking, the wettability refers to the static contact angle, surface tension, and the like of the substrate, here the intermediate transfer member 37 or the nozzle surface 61d, and the liquid, here the recording liquid. Of these, the receding contact angle is measured as a value in which the influence of the viscosity of the liquid is added in addition to the affinity. When this was applied to the image forming apparatus 100, it was confirmed that the recording liquid was well released from the member having a large receding contact angle, and the recording liquid was more adsorbed to the member having a small receding contact angle. As a condition that the releasability is particularly good, the receding contact angle of the nozzle surface 61d is 60 ° or more, preferably 75 ° or more with respect to pure water, and the receding contact angle of the surface of the intermediate transfer member 37 is less than 70 °, more desirably. It was when it was 60 ° or less. By using a material with a receding contact angle smaller than that of the nozzle surface 61d as the material of the surface of the intermediate transfer body 37, the recording liquid, which is a liquid component typified by ink mist attached on the nozzle surface 61d, is efficiently removed. It becomes possible.

  Further, it is desirable that the surface of the intermediate transfer member 37 has higher tack than the nozzle surface 61d. The tackiness is a characteristic showing a sticky feeling. The larger the tack value, the higher the sticky feeling. In order to efficiently remove a dried product of the recording liquid on the nozzle surface 61d, that is, a solid matter such as a high-viscosity component such as an ink dried body and dust and paper powder, from the nozzle surface 61d with the recording liquid on the intermediate transfer member 37. The tackiness is more important than the receding contact angle. By making the material of the surface of the intermediate transfer body 37 higher in tackiness than the nozzle surface 61d, it is possible to efficiently move the solid material from the nozzle surface 61d to the intermediate transfer body 37, and it is more stable. High image formation is possible.

  The receding contact angle was measured at 23 ° C. using an automatic contact angle meter DM500 (manufactured by Kyowa Interface Science) and analysis software FAMAS (manufactured by Kyowa Interface Science). The tack value is a stress applied when pulling out a cylinder-shaped stainless steel probe having a diameter of 5 mm with a compressive load of 200 gf for 1 second and then pulling out at 120 mm / min. . Furthermore, the hardness is a value measured using a JIS-A hardness meter.

  In the image forming apparatus 100 having such a configuration, the intermediate transfer body 37 rotates in the A1 direction while facing the heads 61Y, 61M, 61C, 61BK in response to the input of a predetermined signal indicating the start of image formation. In the process, the yellow, magenta, cyan, and black recording liquids are transferred from the heads 61Y, 61M, 61C, and 61BK so that the image areas of the respective colors of yellow, magenta, cyan, and black overlap with the same position on the intermediate transfer body 37. The images are ejected in such a manner that they are sequentially overlapped from the upstream side toward the downstream side in the A1 direction, and an image is temporarily carried on the intermediate transfer member 37.

At this time, the energizing unit 33 is driven by the control unit 40 as the voltage application control unit, and a voltage is applied between the support 37a and the nozzle plate 61a from the power source 33a.
In this state, the recording liquid is applied from the heads 61Y, 61M, 61C, 61BK onto the intermediate transfer body 37. At that time, first, the heads 61Y, 61M, 61C, 61BK are used as shown in FIG. As shown in FIG. 2B, the recording liquid forming a meniscus in the nozzle 61b moves toward the intermediate transfer body 37 as shown in FIG. 2B, and the recording liquid is recorded between the nozzle 61b and the intermediate transfer body 37. A bridge of a liquid column made of liquid is temporarily formed, and then, as shown in FIG. 2C, the bridge of the liquid column made of recording liquid is divided so as to be carried on the intermediate transfer body 37, and the intermediate transfer. An image of the recording liquid is formed on the body 37.

In the state where the liquid injection bridge made of the recording liquid is formed as shown in FIG. 2B, the colorant component in the recording liquid is subjected to an aggregating action by the energizing means 33. Specifically, the voltage application of the energizing means 33 causes the following electrode reactions to occur in the nozzle plate 61a serving as the cathode and the intermediate transfer member 37 serving as the anode, respectively, and the water contained in the bridge of the liquid column of the recording liquid. Electrolyzed.
^{_{Cathode: 4H 2 O + 4e - →}} 2H 2 + 4OH - ··· reaction formula (1)
_{^{Anode: 2H 2 O → 4H + +}} O 2 + 4e - ··· reaction formula (2)

  According to the reaction formula (1), hydroxide ions are generated on the side of the nozzle surface 61d functioning as the cathode, and as a result, alkalinity is exhibited. Since the colorant of the recording liquid is an anionic pigment, it exhibits high dispersibility under such alkaline conditions, and the recording medium attached to the nozzle surface 61d is easily dissolved. Further, according to the reaction formula (2), water contained in the bridge of the liquid column of the recording liquid is oxidized on the surface of the intermediate transfer member 37 functioning as the anode, and protons (H +) that are hydrogen ions are generated. As shown in FIG. 4, the pigment P dispersed by the anionic dispersant D aggregates via protons. That is, since the colorant of the recording liquid is an anionic pigment, the positive charge of hydrogen ions and the negative charge of the anionic pigment cancel each other, and electrostatic repulsion is reduced, causing phenomena such as aggregation, thickening and solidification. This occurs in the vicinity of the intermediate transfer member 37, particularly the surface of the intermediate transfer member 37 that is the electrode interface. Thereby, the occurrence of bleeding between adjacent dots is suppressed, and a high-definition image is formed. In addition, there is an advantage that clogging of the nozzle 61b is prevented by such voltage application. The time for forming such a bridge can be controlled by the peak voltage and pulse width of the electromagnetic pulse applied to the piezoelectric element.

Here, the bridge of the liquid column formed between the cathode and the anode will be described with reference to FIG. Inside the bridge B of the liquid column, cations and anions move in the vicinity of the cathode C and the anode A, respectively. As a result, the surface of the cathode C and the anode A, the electric double layer E _C and E _A respectively is formed, the charging speed of the electric double layer E _C and E _A is the conductivity of the bridge B of the liquid column, recording It is almost determined by the concentration of ions contained in the liquid. At this time, when the voltage of the electric double layer E _A reaches several V, Faraday current flows water is electrolyzed. As a result, on the surface of the anode A, water is oxidized to generate protons, and the pigment dispersed by the anionic dispersant is aggregated. That is, at the moment when such a bridge is formed, ions that cause an aggregation action of the pigment are efficiently generated in the bridge, so that the pigment is aggregated simultaneously with the landing of the recording liquid on the intermediate transfer body 37. As a result, pigment bleeding does not occur between adjacent recording liquid dots, and a very high-definition solute image is formed.

  As described above, the energizing means 33 includes the intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK, specifically the nozzle plate 61a for electrolyzing the recording liquid forming the bridge B of the liquid column. It is the structure for performing the voltage application between.

  The time from the formation of the bridge B of the liquid column to the separation is usually several microseconds to several tens of microseconds, and the conductivity of the recording liquid is usually several tens mS / m to several hundreds mS / second. m. For this reason, in order to form an image of the recording liquid on the intermediate transfer member 37, the voltage applied by the energizing means 33 is 1.23 V, which is the theoretical decomposition voltage of water, or a number that is a general condition for electrolysis of water. V to several tens of volts is insufficient, and it is preferably several tens of volts to several hundreds of volts.

  The state where the bridge B of the liquid column is formed is observed with a high-speed camera. From this observation, after the voltage pulse is input to the piezoelectric element of the ink ejection means by the control unit 40 functioning as the ink ejection control means, the recording liquid is ejected from the nozzle 61b, and the intermediate transfer is performed after the recording liquid is ejected. The timing until the bridge B is formed with the body 37 and the duration of the bridge can be measured in units of μsec for each nozzle 61b.

  In addition to the reaction formulas (1) and (2), an oxidation-reduction reaction of the electrode itself occurs simultaneously. What reaction occurs depends on the electrode material, the electrode potential, and the pH of the cleaning liquid in addition to the recording liquid when the recording liquid and the cleaning liquid described later are used, but the potential-pH state diagram (Pourbaix Diagram) It can be easily inferred by reference.

  In synchronization with the timing at which the leading edge of the image carried on the intermediate transfer body 37 reaches the transfer unit 31, a single sheet of transfer paper S fed from the paper supply unit 20 is supplied to the transfer unit 31, and the transfer roller 38. , The image carried on the intermediate transfer body 37 is transferred to the transfer sheet S passing through the transfer unit 31, and an image is formed on the surface of the transfer sheet S. The transfer sheet S on which the image is formed is guided to the paper discharge tray 25 and stacked on the paper discharge tray 25.

  When the image is transferred to the transfer paper S in this way, the recording liquid containing the aggregation component is transferred to the transfer paper S. Therefore, by forming an image with the colorant aggregated by the above-described aggregation action, even when the transfer paper S is plain paper, high image density can be achieved at high speed while preventing or suppressing feathering and bleeding. High-quality image formation is possible.

  In order to perform high-speed image formation, since the recording liquid needs to be quick-drying, the recording liquid generally has high absorbability to the transfer paper S. In this case, the recording liquid is deep in the transfer paper S. Penetrating to the surface and causing so-called offset, making it unsuitable for double-sided image formation. However, since the aggregating action reduces the absorbability of the recording liquid onto the transfer paper S, such a set-off is prevented or suppressed, which is suitable for double-sided image formation. Furthermore, since the absorbability of the recording liquid to the transfer paper S is reduced, deformation of the transfer paper S such as cockling and curling is suppressed or prevented, and thereby the transfer paper S carrying an image is conveyed. The handling of the transfer sheet S is facilitated, for example, the property is improved and jamming is prevented or suppressed.

  Almost no components due to the recording liquid remain on the intermediate transfer member 37 that has passed through the transfer unit 31 due to the transfer in the transfer unit 31, but the intermediate transfer member 37 is subjected to cleaning by the cleaning unit 34, thereby recording. Liquid offset is highly prevented or suppressed, and even when image formation is repeatedly performed, background contamination due to offset is prevented or suppressed, image deterioration and deterioration of the intermediate transfer body 37 are suppressed or prevented, and the time is good. Image formation can be performed.

  At the time of performing the image forming operation as described above or at the time of non-image forming, the heads 61Y, 61M, 61C, 61BK are caused by ink mist or the like due to the scattering of the recording liquid as shown in FIG. The recording liquid may adhere to the nozzle surface 61d of the nozzle plate 61a. The recording liquid adhering to the nozzle surface 61d may adsorb foreign matter such as dust and paper dust in the atmosphere. In addition, foreign matters such as dust and paper dust can directly adhere to the nozzle surface 61d. When contamination due to the recording liquid or foreign matter adhering to the nozzle surface 61d progresses particularly in the vicinity of the nozzle 61b, the recording liquid ejected from the nozzle 61b has an adverse effect on precise image formation, and such contamination causes the nozzle 61b. If it adheres to the surface, it may cause image formation failure due to clogging of the nozzle 61b, which may adversely affect image formation.

  Therefore, in the image forming apparatus 100, when the number of transfer sheets S on which image formation has been performed reaches a predetermined number, the wiping operation of the nozzle surface 61d by the recording liquid carried on the intermediate transfer body 37, in other words, the cleaning operation. It is designed to perform cleaning. The cleaning operation of the nozzle surface 61d in the image forming apparatus 100 will be described with reference to FIGS.

  In addition to the time when the number of transfer sheets S on which image formation has been performed reaches a predetermined number, the timing for performing such a cleaning operation is that a timer is provided in the image forming apparatus 100, in other words, a non-printing time. A sensing mechanism that measures the formation time with a timer and senses the discharge state of the recording liquid from the heads 61Y, 61M, 61C, and 61BK is disposed in the image forming apparatus 100 when the non-printing time becomes a predetermined time or more. This sensing mechanism causes nozzle down, that is, discharge failure of the recording liquid ejected from the heads 61Y, 61M, 61C, and 61BK and ejection of the recording liquid ejected from the heads 61Y, 61M, 61C, and 61BK. Is detected. The sensing mechanism includes a one-dimensional or two-dimensional light receiving sensor that recognizes and acquires an image pattern formed on the intermediate transfer body 37, and an analysis unit that analyzes the image pattern acquired by the light receiving sensor. Can be used. After the cleaning operation is performed, the recording liquid is discharged from the heads 61Y, 61M, 61C, and 61BK by the sensing mechanism, and the cleaning operation and the sensing are repeated until the discharge state is sufficiently good. May be.

  When performing the cleaning operation, the head 61Y, 61M, 61C, 61BK and the intermediate transfer body 37 are separated from the home position in the normal printing state, that is, the image forming state shown in FIG. 6 (b), as shown in step S801 in FIGS. 7 and 8, the control unit 40 controls the drive unit 35 to bring the heads 61Y, 61M, 61C, 61BK close to the intermediate transfer member 37 and the nozzle surface 61d. As shown in FIG. 7, the transfer roller 38 is separated from the intermediate transfer body 37 by controlling the separation section 36 by the control section 40 as shown in FIG. State.

  Next, while maintaining this state, as shown in step S802 of FIG. 6C and FIG. 8, the control unit 40 drives the pumps 82Y, 82M, 82C, and 82BK, so that the inside of the ink chamber 61c is reduced from the negative pressure. The recording liquid contained in the heads 61Y, 61M, 61C, and 61BK is forcibly discharged from each nozzle 61b and applied to the intermediate transfer member 37 that faces the heads 61Y, 61M, 61C, and 61BK in close proximity. To do. As a result, when foreign matters such as bubbles, recording liquid aggregates, paper dust, and dust are present in each nozzle 61b, these are discharged from each nozzle 61b. As described above, the pumps 82Y, 82M, 82C, and 82BK function as a recording liquid discharging unit that discharges the foreign matter together with the recording liquid from the nozzle 61.

  In other words, the distance between the nozzle surface 61d and the intermediate transfer member 37, that is, the gap between the heads 61Y, 61M, 61C, and 61BK at the cleaning position is the same as the recording surface applied to the intermediate transfer member 37 as shown in FIG. The gap between 61d and the intermediate transfer member 37 is bridged to fill these gaps, and the gap is small, and is set appropriately in accordance with the characteristics of the recording liquid. In this embodiment, since the recording liquid is aqueous, the gap is set to a predetermined value in the range of 10 to 500 μm.

  When the recording liquid discharged from the nozzle 61b bridges between the nozzle surface 61d and the intermediate transfer member 37, the control unit 40 controls the motor 32 as shown in step S803 of FIG. 6C and FIG. Then, the intermediate transfer member 37 is rotationally driven in the A1 direction to relatively move the nozzle surface 61d and the surface of the intermediate transfer member 37. In this state, as shown in step S804 in FIG. The controller 40 drives the energizing means 33, and a voltage is applied between the nozzle plate 61a and the intermediate transfer member 37 in the same manner as in the image forming operation described above. The applied voltage value at this time is constant. Further, the control unit 40 detects the amount of current flowing between the nozzle plate 61 a and the intermediate transfer body 37 by applying such a voltage. In this regard, the control unit 40 functions as a current detection unit.

  When the rotation of the intermediate transfer member 37 is continued in this state, the recording liquid between the nozzle surface 61d and the intermediate transfer member 37 is moved by the movement of the surface of the intermediate transfer member 37 having high wettability, and FIG. As shown in (), it starts to move by being pulled in the A1 direction. At this time, the recording liquid is not divided between the nozzle surface 61d side and the intermediate transfer member 37 side due to the surface tension and viscosity, and the nozzle surface 61d from the highly water-repellent nozzle surface 61d, particularly in the vicinity of the nozzle 61b. It is peeled off together with the foreign matter adhering to In this manner, the nozzle surface 61d is rubbed with the recording liquid to be in a wiping state, and the recording liquid adhering to the nozzle surface 61d moves to the intermediate transfer body 37 side by the movement of the intermediate transfer body 37. During movement, the foreign matter is wiped and removed by the recording liquid, particularly in the vicinity of the nozzle 61b, and the nozzle surface 61d is cleaned.

  In performing such cleaning, the intermediate transfer body 37 functions as a cleaning member as a cleaning body to which the recording liquid ejected from the nozzle 61b is applied in a state of facing the heads 61Y, 61M, 61C, and 61BK. To do. The motor 32 moves the surface of the intermediate transfer member 37 and the nozzle surface 61d so that the recording liquid applied to the intermediate transfer member 37 functioning as a cleaning member moves while contacting the nozzle surface 61d and wipes the nozzle surface 61d. The intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK function as a moving means that relatively moves in a manner in which they move relative to each other while maintaining a parallel state. The relative movement between the intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK is such that the recording liquid applied to the intermediate transfer body 37 functioning as a cleaning member moves so as to wipe the nozzle surface 61d. It only has to be done.

  In this way, such cleaning is different from cleaning that is generally known in the past, such as cleaning the surface of the nozzle using a blade made of a flexible material such as rubber, a wiper, or the like. Wiping is performed in a non-contact manner, so there is no problem with cleaning using such a member that the water-repellent effect is lost due to wear of a very thin water-repellent film, leading to defective discharge. Compared with conventional cleaning, the water-repellent film has a longer life and contributes to extending the product life that depends on the life of the water-repellent film.

  This cleaning is advantageous because it is a non-contact method as described above, but is performed by physically wiping the nozzle surface 61d by the recording liquid in other words. Further, such cleaning is performed chemically as well as physically.

  That is, the energization means 33 is driven and voltage is applied between the nozzle plate 61a and the intermediate transfer member 33, so that the reaction formula (1), the reaction formula (2), FIG. 4 and FIG. Since the reaction described above also occurs due to electrolysis of the components of the recording liquid adhering to the nozzle surface 61d, specifically the ink components, the pigment of the recording liquid is concentrated on the surface of the intermediate transfer body 37 which is the counter electrode. In addition, since the ink concentration in the recording liquid interposed between the nozzle surface 61d and the intermediate transfer member 37 is lowered, the dissolution of the recording liquid adhering matter adhering to the nozzle surface 61d is promoted.

  In this way, in such cleaning, utilizing the fact that the recording liquid is anionic, the energizing means 33 allows the nozzle plate 61a to function as a cathode and the intermediate transfer member 37 to function as an anode. Thus, the recording liquid functions as a cleaning liquid that acts not only physically but also chemically.

  The recording liquid carried on the intermediate transfer body 37, that is, the recording liquid removed from the nozzle surface 61d, the foreign matter, and the aggregation component of the recording liquid aggregated on the intermediate transfer body 37 are directed toward the A1 direction of the intermediate transfer body 37. As it rotates, it reaches the cleaning means 34 and is removed from the intermediate transfer member 37. As a result, the intermediate transfer member 37 is kept clean. Therefore, the cleaning of the nozzle plate 61a highly prevents or suppresses the offset of the recording liquid or foreign matter adhering to the intermediate transfer body 37, and even if image formation is performed thereafter, the background stain due to the offset is prevented or suppressed, and the image is deteriorated. The deterioration of the intermediate transfer member 37 is suppressed or prevented, and good image formation can be performed over time.

  As described above, in the image forming apparatus 100, the cleaning of the nozzle surface 61 d promotes chemical re-dispersion of the ink aggregate simultaneously with the physical cleaning, that is, the intermediate transfer body 37 is subjected to the above-described aggregation action. Since the cleaning is performed by aggregating the colorant, the nozzle surface 61d is kept highly clean.

  The control unit 40 uses the amount of current flowing between the nozzle plate 61a and the intermediate transfer body 37 detected by the control unit 40 functioning as a current detection unit to determine the progress of the cleaning. Function as.

  Specifically, from the start of energization described in step S804 of FIG. 8, the control unit 40 that functions as a cleaning determination unit monitors the amount of current detected by the control unit 40 that functions as a current detection unit, that is, monitoring. The progress of the cleaning of the nozzle plate 61a, specifically the nozzle surface 61d, is determined based on the transition of the energization state when the voltage is applied between the nozzle plate 61a and the intermediate transfer member 37 by the energization means 33. To do.

  That is, the control unit 40 functioning as a cleaning determination unit is in a state where the nozzle surface 61d and the surface of the intermediate transfer member 37 are relatively moved as shown in FIGS. 6 (c) and 6 (d). Based on the transition of the energization state, as shown in steps S805 and S806 in FIG. 8, it is determined whether or not energization has occurred until the specified time has elapsed, and no energization has occurred until the specified time has elapsed. When the cleaning progress is determined as shown in step S807 in FIG. 8 as the cleaning of the nozzle surface 61d is completed, the energization does not occur until the specified time elapses, that is, the specified time. When the energization has occurred even after the elapse of time, the progress of the cleaning is indicated by the heads 61Y, 61M, 61 as shown in step S808 of FIG. , The 61BK specifically determines as a recording liquid is in the defective discharging from between the nozzle surface 61d and the intermediate transfer member 37.

The reason why these determinations are made based on the transition of the energization status until the specified time elapses is as follows.
When a voltage is applied by the energizing unit 33 in a state where the recording liquid is filled between the nozzle surface 61d and the intermediate transfer member 37, a current flows through the recording liquid, so that the current functions as a current detecting unit. As shown in FIG. 9, the amount of current, that is, the energization amount is gradually decreased when the nozzle surface 61d is normally cleaned.

  This is because there is a correlation between the amount of the recording liquid sandwiched between the nozzle surface 61d and the intermediate transfer member 37 and the energization amount. Therefore, by monitoring the amount of current detected by the control unit 40 functioning as current detection means when the intermediate transfer member 37 is rotated and the recording liquid is peeled off from the nozzle surface 61d, the intermediate transfer member 37 and the nozzle surface 61d are in the middle. Either the determination that the discharge of the recording liquid from the transfer body 37 is completed and the cleaning of the nozzle surface 61d is completed, or the determination that the discharge is not performed normally and an error occurs is performed. .

  More specifically, since the gap between the nozzle surface 61d and the intermediate transfer member 37 and the voltage value applied by the energizing means 33 are constant, the recording liquid is supplied from the nozzle 61b as shown in FIG. In the initial stage immediately after being discharged, the amount of the recording liquid sandwiched between the nozzle surface 61d and the intermediate transfer body 37 is large, and the contact area between the recording liquid, the nozzle surface 61d and the intermediate transfer body 37 is large. As shown in FIG. 6D, the recording liquid is discharged from between the nozzle surface 61d and the intermediate transfer body 37 as the intermediate transfer body 37 is rotated. As a result, the amount of the recording liquid sandwiched between them decreases, and the contact area between the recording liquid, the nozzle surface 61d, and the intermediate transfer body 37 decreases accordingly, and the resistance due to the recording liquid is reduced. big Therefore, the amount of energization decreases as shown in FIG. 9, and the discharge of the recording liquid further advances, so that recording from between the nozzle surface 61d and the intermediate transfer member 37 is performed as shown in FIG. 6 (e). When the removal of the liquid is completed, the energization amount becomes 0 as shown in FIG.

  On the other hand, when the recording liquid is not discharged from between the nozzle surface 61d and the intermediate transfer body 37, the amount of the recording liquid sandwiched between them does not gradually decrease, as shown in FIG. Unstable behavior without decreasing energization amount. The reason why the recording liquid is not discharged from between the nozzle surface 61 d and the intermediate transfer member 37 is a mechanical defect such as the rotation of the intermediate transfer member 37 being stopped.

  When the determination in step S807 in FIG. 8 or the determination in step S808 in FIG. 8 is made, in both cases, as shown in steps S809 and S810 in FIG. The driving of the means 33 is stopped, the voltage application between the nozzle plate 61a and the intermediate transfer body 37 is stopped, and the motor 32 is controlled by the control unit 40 as shown in steps S811 and S812 of FIG. Is stopped, the rotation of the intermediate transfer member 37 is stopped, the relative movement between the nozzle surface 61d and the surface of the intermediate transfer member 37 is stopped, and step S813 in FIG. As shown in S814, the control unit 40 controls the drive unit 35 to separate the heads 61Y, 61M, 61C, and 61BK from the intermediate transfer body 37, and from the cleaning position. To return to the over-time position.

  Note that these operations in the case where the determination in step S807 of FIG. 8 is performed have a time loss until the start thereof is reduced as much as possible. This is because in step S805 in FIG. 8, even if the specified time has not elapsed, if energization stops, the determination in step S807 in FIG. 8 is performed immediately. If this determination is made, these operations are performed immediately. Because it is started.

  After these operations, when the determination in step S808 in FIG. 8 is made, the cleaning operation is terminated. In this case, when the image forming apparatus 100 includes a display unit such as a liquid crystal display device, error display may be performed on the display unit.

  On the other hand, when the determination in step S807 of FIG. 8 is performed, as shown in step S816 of FIG. 8, the recording liquid is ejected from each nozzle 61b by the control unit 40 functioning as an ink ejection control unit.

  At this time, the energization unit 33 is driven by the control unit 40 as the voltage application control unit, and the recording liquid discharged from the nozzle 61b is transferred between the nozzle plate 61a and the intermediate transfer member 37 in the same manner as in the image forming operation described above. At the timing of bridging between them, a voltage is applied between them.

  Also in this case, the control unit 40 functions as a current detection unit and a cleaning determination unit. That is, the control unit 40 uses the amount of current flowing between the nozzle plate 61a and the intermediate transfer body 37, which is detected by the control unit 40 functioning as a current detection unit, to determine the cleaning progress status. It functions as a judgment means. Note that the transfer roller 38 is kept away from the intermediate transfer member 37.

  Specifically, as shown in step S816 of FIG. 8, the control unit 40 functioning as a cleaning determination unit detects the current of each nozzle 61b at least at such timing by the control unit 40 functioning as a current detection unit. However, when there is a nozzle 61b at which current is not detected at least at such timing, the recording liquid is not discharged from the nozzle 61b, so that the recording liquid is normally discharged from all the nozzles 61b. Assuming that the condition is not satisfied, the progress of the cleaning of the nozzle plate 61a is determined to be a discharge failure of the recording liquid from the nozzle 61b as shown in step S817 of FIG.

  If this determination is made, the process returns to step S801 in FIG. 8, and the above-described control is repeated. This repetitive operation is not executed when the discharge failure determination in step S808 of FIG. 8 is performed, so that waste of the recording liquid due to repeated unnecessary cleaning operations is avoided.

  On the other hand, in step S816 in FIG. 8, when the current is detected by the control unit 40 functioning as the current detection means at least at all the timings for all the nozzles 61b, in other words, the recording liquid is normal from all the nozzles 61b. As shown in step S818 of FIG. 8, the cleaning progress of the nozzle plate 61a is completed, that is, the cleaning of the nozzle surface 61d and the nozzle 61b is completed. And the cleaning operation is terminated.

  Note that the recording liquid applied to the surface of the intermediate transfer body 37 by the discharge of the recording liquid is removed from the surface of the intermediate transfer body 37 by the cleaning unit 34. At the end of the cleaning operation, the control unit 40 controls the separation unit 36 to bring the transfer roller 38 into contact with the intermediate transfer body 37, so that the original position shown in FIG. In other words, the home position is restored.

  As described above, the control unit 40 functioning as the cleaning determination unit is in a state in which the energization unit 33 is driven by the control unit 40 as the voltage application control unit and a voltage is applied between the nozzle plate 61 a and the intermediate transfer body 37. The cleaning of the nozzle plate 61a, specifically, the nozzle surface 61d, based on the transition of the energization state between the nozzle plate 61a and the intermediate transfer body 37 detected by the control unit 40 functioning as a current detection unit. The progress of cleaning of the nozzle 61b is determined.

  The control unit 40 functioning as a cleaning determination unit may monitor the transition of the energization state from before the recording liquid is discharged in step S802 shown in FIG. In this case, as the progress of the cleaning, whether or not the recording liquid is discharged from the nozzle 61b by the operation of the pumps 82Y, 82M, 82C, and 82BK, the nozzle surface 61d is discharged from the nozzle 61b. It is possible to determine whether or not a sufficient amount of recording liquid is filled between the intermediate transfer member 37 and the intermediate transfer member 37.

  As shown in FIG. 1, the image forming apparatus 100 includes at least the intermediate transfer member 37, the energizing unit 33, the motor 32, the drive unit 35, the pumps 82Y, 82M, 82C, and 82BK, and the control unit 40 among the configurations described above. And a head cleaning device 41 for cleaning the heads 61Y, 61M, 61C, and 61BK to perform normal image formation by cleaning the nozzle plate 61a as described above. In this regard, the control unit 40 functions as a head cleaning control unit that controls head cleaning.

  As described above, the head cleaning device 41 is configured by a configuration provided for performing image formation in the image forming apparatus 100. For example, the intermediate transfer body 37 not only functions as a cleaning member but also the nozzle 61b. The common use of the components is highly realized, for example, the recording liquid ejected from the recording medium functions as a member to be transferred to the transfer paper S. Therefore, in the image forming apparatus 100, the increase in size and cost of the apparatus due to the provision of the head cleaning device 41 are highly suppressed.

  Since the cleaning device 41 performs cleaning by electrolysis of foreign matters derived from the components of the recording liquid attached to the nozzle plate 61a by applying a voltage using the energization means 33, the recording liquid after electrolysis is removed from the nozzle plate 61a. For example, if the recording liquid removing means for removing by suction is provided between the intermediate transfer body 37 and the intermediate transfer body 37, the moving means for relatively moving the nozzle plate 61a and the intermediate transfer body 37 may be omitted. Is possible.

  However, the relative movement between the nozzle plate 61a and the intermediate transfer member 37 is preferably provided with such moving means in order to promote cleaning. The motor 32 functioning as a moving unit performs the relative movement by moving the intermediate transfer member 37 side. The moving unit moves the relative direction by moving the heads 61Y, 61M, 61C, and 61BK. It may be what performs.

  Therefore, the image forming apparatus 100 can perform such relative movement also by the driving unit 35, and in addition to the above-described operation described with reference to FIGS. 6 to 9, as shown in FIG. The heads 61Y, 61M, 61C, and 61BK are moved relative to the nozzle surface 61d to perform the relative movement.

  Specifically, as shown in FIG. 10D, the intermediate transfer member 37 rotates in the A1 direction, and the recording liquid between the nozzle surface 61d and the intermediate transfer member 37 is moved to the intermediate position by the movement of the intermediate transfer member 37. When the nozzle surface 61d is cleaned by the recording liquid during the movement, the drive unit 35 moves the heads 61Y, 61M, 61C, 61BK toward the upstream side in the A1 direction. Such a relative movement is performed by moving substantially parallel to 61d. Regarding other operations, FIGS. 6A to 6F correspond to FIGS. 10A to 10F, respectively, and are performed in the same manner.

  Thereby, cleaning is performed in a wider range of the nozzle surface 61d than in the case shown in FIG. Further, the cleaning performance is improved by increasing the speed of the relative movement due to the movement of the heads 61Y, 61M, 61C, and 61BK. Due to the fact that the surface of the intermediate transfer member 37 is curved, in the operation shown in FIG. 6, for example, as shown in FIGS. There is a possibility that the component of the recording liquid grows in an ice column shape in a portion relatively far from the surface, and when this component grows further, this component comes into contact with the intermediate transfer member 37 or separates from the nozzle surface 61d to contaminate the inside of the apparatus. Then, the image may be attached to the transfer paper S and disturb the image. However, in the case shown in FIG. 10, the cleaning is performed over a wide range of the nozzle surface 61d. As shown in f), such icicle-like components are also removed, and this is prevented or suppressed.

Thus, the drive unit 35 also relatively moves the intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK in such a manner that the recording liquid applied to the intermediate transfer body 37 moves while contacting the nozzle surface 61d. It functions as a moving means.
In this embodiment, the moving means is constituted by the motor 32 and the driving unit 35, but only the driving unit 35 may be used as the moving means.

  As long as the drive unit 35 and the separation unit 36 can displace the intermediate transfer body 37 and the heads 61Y, 61M, 61C, and 61BK as described above, a cam, a motor that drives the cam, and the like are adopted as the configuration. It may be a thing, the thing which employ | adopted the motor etc. which drive a pinion, a rack, and a pinion, the thing which employ | adopted the solenoid etc. may be used. The heads 61Y, 61M, 61C, and 61BK in the present embodiment are full line type as described above, but the cleaning mechanism is prevented or suppressed from increasing in size, and is relatively low-cost and space-saving.

  In the case where no foreign matter is generated due to aggregation due to the characteristics of the recording liquid, the application of voltage by the energizing means 33 monitors the transition of the energization state described above that is necessary for judging the progress of cleaning of the nozzle plate 61a. Therefore, the applied voltage value may be set to a level sufficient to determine the progress status, but a moving means is essential because chemical cleaning is not performed.

  In any case, since the recording liquid has different prescriptions depending on the color, model, etc., and the characteristic values such as surface tension and viscosity are different, the gap between the nozzle surface 61d and the surface of the intermediate transfer body 37 at the cleaning position, the cleaning The relative movement speed between the nozzle surface 61d and the intermediate transfer body 37 during operation, that is, the movement speed of the intermediate transfer body 37 and the nozzle surface 61d may be set so that optimum cleaning is performed according to the characteristic value. Further, it is desirable that these gaps and speeds are variable depending on the configuration of the drive unit 35 and the motor 32 so that optimum cleaning is performed according to the characteristic values.

The case where the cleaning member is the roller-shaped intermediate transfer member 37 has been described above. However, as shown in FIG. 11, the intermediate transfer member 37 may have an endless belt shape.
The configuration shown in FIG. 11 will be described mainly with respect to the differences from the above-described configuration shown in FIG.

  Along with the intermediate transfer body 37 having a belt shape, the transport unit 10 includes rollers 42, 43, and 44 around which the intermediate transfer body 37 is wound, and a spring (not shown) that biases the roller 43. . The motor 32 rotates the roller 42, and the roller 42 is a driving roller. The roller 43 is a tension roller that is displaced by a spring so as to keep the tension of the intermediate transfer body 37 integral. The roller 44 is disposed at a fixed position facing the transfer roller 38 with the intermediate transfer member 37 interposed therebetween, and serves as a transfer counter roller.

  The heads 61Y, 61M, 61C, 61 are provided in a manner that they are arranged in parallel so as to face the portion of the intermediate transfer member 37 that is stretched between the roller 42 and the roller 43. The advantage of the intermediate transfer member 37 having a belt shape is that the heads 61Y, 61M, 61C, 61BK can be arranged in parallel, as in this embodiment, and the degree of freedom in arrangement of the heads 61Y, 61M, 61C, 61. In the configuration in which the heads 61Y, 61M, 61C, and 61BK are provided in such a manner, the entire surface of the nozzle surface 61d is moved without moving the heads 61Y, 61M, 61C, and 61 parallel to the nozzle surface 61d. It is to be able to be cleaned. However, if the intermediate transfer member 37 is in the form of a drum, it is not easy to process the belt-like intermediate transfer member 37 into an endless shape, fluttering occurs during driving, and multiple winding rollers are required. There is an advantage that there is no circumstance. Accordingly, whether the intermediate transfer member 37 is in the form of a drum or a belt is appropriately selected by comparing and examining various matters.

  In addition, in the form shown in FIG. 11, the image forming apparatus 100 includes a guide member 45 disposed inside the intermediate transfer body 37 at a position facing each of the heads 61Y, 61M, 61C, and 61BK. Yes.

The cleaning operation of the nozzle surface 61d in the image forming apparatus 100 having such a configuration will be described with reference to FIGS.
When performing the cleaning operation, the drive unit 35 is controlled by the control unit 40 from the home position shown in FIGS. 11A and 12A as shown in FIGS. 11B and 12B. Thus, the heads 61Y, 61M, 61C, 61BK are moved to the intermediate transfer member 37 side, and the gaps between the heads 61Y, 61M, 61C, 61BK and the intermediate transfer member 37 are the same as those shown in FIG. At this time, the transfer roller 38 is separated from the intermediate transfer member 37 by controlling the separation portion 36 by the control portion 40 as shown in FIG. The subsequent operations shown in FIGS. 12C to 12F are the same as the operations shown in FIGS. 6C to 6F described above.

  In the embodiment described above, the drive unit 35 is configured to simultaneously drive the heads 61Y, 61M, 61C, and 61BK to contact and separate from the intermediate transfer member 37. However, the heads 61Y, 61M, 61C, and 61BK have different colors. Since the recording liquid is discharged, if these are simultaneously cleaned by the intermediate transfer body 37, the recording liquid of one color removed from the nozzle surface 61d by the intermediate transfer body 37 discharges the recording liquid of another color. There is a possibility of color mixing when adhering to 61b and subsequent recording liquid discharge, and there is also a possibility of color mixing by flowing backward from the nozzle 61b into the ink chamber 61c connected thereto. Color mixing is a factor that degrades the color quality of image formation. Therefore, in order to avoid such a problem of color mixing, the drive unit 35 can make the heads 61Y, 61M, 61C, 61BK independently contact and separate from the intermediate transfer member 37, and the control unit 40 serving as a cleaning control unit is described above. It is desirable to perform the cleaning operation independently on the nozzle surfaces 61d of the heads 61Y, 61M, 61C, and 61BK. Color mixing can be avoided by sequentially and independently cleaning the nozzle surfaces 61d of the heads 61Y, 61M, 61C and 61BK of the respective colors. In this case, cleaning positions for the respective color heads 61Y, 61M, 61C, and 61BK are sequentially and independently formed by the drive unit 35. In addition, the transfer roller 38 is brought into contact with and separated from the intermediate transfer member 37 by the separating unit 36. Is performed before and after the cleaning operation for all the color heads 61Y, 61M, 61C and 61BK, the time required for the cleaning operation is minimized by minimizing the number of times the transfer roller 38 contacts and separates from the intermediate transfer body 37. Is suppressed.

  In each embodiment described above, the heads 61Y, 61M, 61C, 61BK and the intermediate transfer body 37 are brought close to each other by moving the heads 61Y, 61M, 61C, 61BK to the intermediate transfer body 37 side, thereby obtaining a cleaning position. However, as shown in FIG. 13, the intermediate transfer member 37 is moved toward the heads 61Y, 61M, 61C, 61BK, so that the heads 61Y, 61M, 61C, 61BK and the intermediate transfer member 37 are brought close to each other to perform the cleaning position. You may make it.

With respect to the form shown in FIG. 13, portions different from the above-described form shown in FIG. 11 will be mainly described.
In the form shown in the figure, the driving unit 35 supports the guide members 45 and the guide members 45 from below, and pushes the guide members 45 together toward the heads 61Y, 61M, 61C, 61BK to perform intermediate transfer. A support member 46 is provided in which the body 37 is brought close to the heads 61Y, 61M, 61C, and 61BK to serve as a cleaning position.

  In this embodiment, the driving member 35 displaces the support member 46 during the cleaning operation so that the intermediate transfer body 37 is brought close to the heads 61Y, 61M, 61C, 61BK to be the cleaning position. The remaining points are shown in FIG. It is the same as the above-mentioned form shown.

  The drive unit 35 is configured to simultaneously drive the guide members 45 to contact and separate the heads 61Y, 61M, 61C, and 61BK. However, as described above, in order to avoid color mixing, the guide members 45 45 may be driven independently, and the heads 61Y, 61M, 61C, and 61BK may be sequentially cleaned.

  In this embodiment, since the tension of the intermediate transfer member 37 is increased at the cleaning position, the intermediate transfer member 37 flutters during the cleaning operation or occurs at a portion wound around the rollers 42, 43, and 44 when left for a long time. The deformation of the intermediate transfer body 37 is corrected. Therefore, there is an advantage that the flatness of the intermediate transfer body 37 in the portion stretched between the roller 42 and the roller 43 is improved, and stable and satisfactory cleaning is performed.

  In the embodiment having the roller-shaped intermediate transfer body 37 shown in FIG. 1 and the like, a configuration in which the intermediate transfer body 37 is brought close to the heads 61Y, 61M, 61C, and 61BK to be the cleaning position may be employed. Further, a configuration may be adopted in which the intermediate transfer member 37 and the heads 61Y, 61M, 61C, 61BK are both brought close to each other to be used as a cleaning position.

  Here, the control unit 40 records in the memory the recording ejected from the nozzle 61b in a state of facing the heads 61Y, 61M, 61C, 61BK having the nozzle plate 61a having the nozzle 61b for ejecting the recording liquid as described above. A voltage is applied between the nozzle plate 61a and the intermediate transfer body 37 by the power supply means 33, and an energizing means 33 for applying a voltage between the nozzle plate 61a and the intermediate transfer body 37. A head cleaning program for executing a head cleaning method using the control unit 40 that determines the progress of the cleaning of the nozzle plate 61a based on the transition of the energization state in the applied state is stored. In this respect, the control unit 40 or the memory functions as a head cleaning program storage unit. Such a head cleaning program includes not only a memory provided in the control unit 40 but also a semiconductor medium (for example, ROM, non-volatile memory), an optical medium (for example, DVD, MO, MD, CD-R, etc.), a magnetic medium. (For example, a hard disk, a magnetic tape, a flexible disk, etc.) It can be stored in other storage media, and when such a memory and other storage media store such a head cleaning program, the computer read that stores such a head cleaning program Configure possible recording media.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the pigment in the conductive recording liquid may be dispersed with a cationic dispersant and aggregated via hydroxide ions generated on the surface of the intermediate transfer member functioning as a cathode.

  The image forming apparatus to which the present invention is applied is not limited to the above-described type of image forming apparatus, but may be other types of image forming apparatuses, that is, a shuttle type with respect to the head, or a copying machine or a facsimile alone. Alternatively, these multifunction peripherals, multifunction peripherals such as monochrome machines related thereto, other image forming apparatuses used for forming electric circuits, and image forming apparatuses used for forming predetermined images in the biotechnology field may be used. . The number of heads is increased or decreased according to the application of the image forming apparatus, and may be plural or one.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

32 Moving means 33 Voltage applying means 35 Moving means 37 Cleaning member, intermediate transfer member 40 Cleaning determination means 41 Head cleaning device 61a Nozzle member 61b Nozzle 61Y, 61M, 61C, 61BK Head 100 Image forming apparatus

JP 2008-132786 A Japanese Patent No. 4507213 JP 2009-018249 A

Claims (2)

A cleaning member to which a recording liquid discharged from the nozzle is applied in a state of facing a head having a nozzle member having a nozzle for discharging the recording liquid;
Voltage applying means for applying a voltage between the nozzle member and the cleaning member;
A head cleaning apparatus comprising: a cleaning determination unit that determines a progress of cleaning of the nozzle member based on a transition of an energization state in a state where a voltage is applied between the nozzle member and the cleaning member by the voltage applying unit. . The head cleaning device according to claim 1,
Moving means for relatively moving the cleaning member and the head so that the recording liquid applied to the cleaning member moves while contacting the surface of the nozzle member;
The cleaning determination means is a state of energization in a state where the cleaning means and the head are relatively moved by the moving means and a voltage is applied between the nozzle member and the cleaning member by the voltage applying means. A head cleaning device that determines the progress of cleaning of the nozzle member based on the above.

Images