Patent Application
20210221138
The present disclosure relates to a wiping device, a recording apparatus, and a method of wiping an ejection port surface.
An inkjet recording apparatus is required to cause ejected ink droplets to land on desired positions to generate an excellent recording image. If ink or dust adheres to an ejection port surface of a recording head, normal ejection may be inhibited. U.S. Pat. No. 8,342,638 discusses wiping operation performed while a web is pressed against the ejection port surface, thereby cleaning the ejection port surface. U.S. Pat. No. 8,342,638 further discusses a technique to impregnate the web with polyethylene glycol (PEG) for cleaning performance improvement.
In the technique discussed in U.S. Pat. No. 8,342,638, the web is impregnated with 60 g/m2 to 90 g/m2 of PEG. A PEG having a relatively low molecular weight of 400 or less is in a liquid state. In contrast, a PEG having relatively high molecular weight of 600 or more is in a solid state at room temperature. U.S. Pat. No. 8,342,638 discusses that the web can be impregnated with a PEG, such as PEG300 and PEG400, which is in a liquid state and has a low molecular weight.
An ink, such as pigment ink used in an inkjet recording apparatus, contains fine particles of a coloring material, such as pigment. The fine particles are dispersed into the ink without dissolving. The diameter of each of the particles of the pigment coloring material is about 20 to 30 nm. In wiping operation, if the coloring material in the ink adheres to a surface of a cleaning member and the ejection port surface is wiped by the cleaning member in this state, the wiping is performed in a state where the coloring material is in contact with the ejection port surface. At this time, PEG impregnated in the cleaning member is smaller in particle diameter than the coloring material since the PEG is in a liquid state. Depending on a material of the ejection port surface, the fine particles of the coloring material therefore may function as abrasive grains to shave the ejection port surface, and ejection performance may be deteriorated.
The present disclosure is directed to prevention of deterioration of the ejection port surface caused by the wiping operation of the ejection port surface with the cleaning member.
According to an aspect of the present disclosure, a wiping device includes a cleaning member configured to perform wiping operation to wipe an ejection port surface of a recording head, wherein the recording head includes the ejection port surface on which an ejection port, for ejecting ink containing particles of a coloring material, is formed, and a control unit configured to control the cleaning member to perform the wiping operation in a state where particles are imparted to a surface of the cleaning member, wherein the imparted particles are different in type from the coloring material particles and each imparted particle has a particle diameter greater than a diameter of each of the coloring material particles.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A first exemplary embodiment of the present disclosure will now be described.
The carriage guide 13 supports the carriage 2. More specifically, the carriage guide 13 movably supports the carriage 2 in a main scanning direction (X direction).
The carriage 2 performs reciprocal scanning in the X direction by rotation of a carriage motor (not illustrated) while being guided by a carriage rail 12. The carriage 2 is mounted with a recording head 11. The recording head 11 includes an ejection port surface 11a (illustrated in
The platen 10 supports a recording medium 5 in an area where an image is formed by ejecting the ink from the recording head 11. On an upstream side of the platen 10 in a conveyance direction (Y direction), an LF roller 4 and pinch rollers 6 are provided to convey the recording medium 5.
In recording operation to record an image on the recording medium 5, the LF roller 4 and the pinch rollers 6 are driven with intermittent rotation of a conveyance motor (not illustrated). The recording medium 5 is thereby intermittently conveyed on the platen 10 in the Y direction. The carriage 2 is reciprocally scanned in the X direction while the recording medium 5 is stopped in the intermittent conveyance. During the reciprocal scanning, the ink of colors is ejected to the recording medium 5 from the ejection ports provided in the recording head 11 of the carriage 2, and the image and the like are recorded on the recording medium 5. After the intermittent conveyance of the recording medium 5 and ejection of the ink during the reciprocal scanning of the carriage 2 are repeated a predetermined number of times, recording of the image is completed, and the recording operation to the recording medium 5 ends.
In the present exemplary embodiment, a heater (not illustrated) is built in the platen 10. During the recording operation, the heater is driven, and the recording medium 5 is heated from a rear surface (surface on side opposite to surface where image, etc. are recorded) through the platen 10. When thermosetting ink is used, it is thereby possible to cure the ink ejected to the recording medium 5 by heating the ink immediately after the ink lands on the recording medium 5. Thus, the present exemplary embodiment makes it possible to fix the image and the like formed on the recording medium 5 even when the recording medium 5 is made of a nonabsorbable material, such as vinyl chloride.
A wiping unit 100 is provided at one of end in the X direction of a scanning area scanned by the carriage 2. The wiping unit 100 is a wiping mechanism including a cleaning member to wipe the ejection port surface 11a of the recording head 11. At the other end, the recovery unit 16 is provided. The recovery unit 16 includes a cap 31 that covers the ejection port surface 11a of the recording head 11 to prevent the ink near the ejection ports from drying.
A central processing unit (CPU) 600 controls each of units described below via a main path line 605, and performs data processing. More specifically, the CPU 600 performs head driving control, a carriage driving control, and the data processing through units described below based on programs stored in a read only memory (ROM) 602.
A random access memory (RAM) 601 is used as a work area for the data processing and the like performed by the CPU 600. In place of the RAM 601, a storage device, such as a hard disk, may be used. An image input unit 603 includes an interface with a host computer (not illustrated), and temporarily holds an image input from the host computer. An image signal processing unit 604 performs various kinds of data processing to convert input image data into data to be recorded by the recording head 11.
A head driving control unit 615 controls driving of an ink ejection electrothermal converter of the recording head 11, and causes the recording head 11 to perform preliminary ejection and to eject the ink for recording. A carriage driving control unit 616 controls movement of the carriage 2 based on a program. Likewise, a conveyance control unit 617 controls, based on a program, a motor configured to drive the rollers, such as the LF roller 4 relating to conveyance of the recording medium. Likewise, a wiping unit control unit 618 controls the wiping unit 100 based on a program.
The recording head 11 according to the present exemplary embodiment is configured to eject yellow ink, magenta ink, cyan ink, black ink, light cyan ink, and light magenta ink. Each of the ejection port arrays 21 to 26 ejects each color of the inks. Each of the ejection port arrays 21 to 26 includes a plurality of ejection ports 110 arranged in the Y direction. In the present exemplary embodiment, centers of the ejection ports are at an interval of 1/1200 inches, and 1280 ejection ports 110 are arranged in the Y direction. In the present exemplary embodiment, the recording head 11 includes six ejection port arrays 21 to 26; however, the configuration is not limited thereto.
Each of the ejection ports 110 individually communicate with respective liquid paths (not illustrated). Each of the liquid paths includes an energy generation device generating ejection energy to eject ink from the corresponding ejection port 110. In the present exemplary embodiment, an electrothermal converter is used for the energy generation device. The electrothermal converter locally heats the ink to cause film boiling, and ejects the ink by pressure of the film boiling. In the following description, one ejection port 110 and one liquid path are collectively referred to as one nozzle. The ink is supplied to each of the ejection ports 110 of the recording head 11 from an ink tank (not illustrated) through a tube.
As described herein, water repellency may be imparted to the surface of the ejection port surface 11a. As an example to impart the water repellency, the ejection port surface can be made of a water-repellent negative epoxy resin (cationic polymerization). The water-repellent negative epoxy resin is typically obtained by previously mixing a silane water repellent containing a perfluoropolyether group, an organic acid, a fluorine solvent, and water. Alternatively, solution of partial hydrolysate obtained by partially hydrolyzing the silane water repellent containing a perfluoropolyether group can also be used as a material of a water-repellent film. The silane water repellent containing a perfluoropolyether group is partially hydrolyzed at a time of application. Thus, reactivity with a photosensitive resin layer is high, and the obtained water-repellent film has high water repellency.
Alternatively, hydrophilicity may be imparted to the surface of the ejection port surface 11a as described herein. As an example of a method of imparting hydrophilicity to the ejection port surface, a method using ultraviolet irradiation will now be described. When an ultraviolet ray (waveform of 185 nm) is applied to oxygen (O2) in the atmosphere, ozone (O3) is generated. When the ultraviolet ray (waveform of 254 nm) is absorbed by the ozone, the ozone is decomposed to generate active oxygen (O) in an excited state. The active oxygen reacts with a molecule whose molecular chain on the surface layer of the molecule is cleaved by the ultraviolet ray, and forms a new functional group (e.g., OH, CHO, and COOH) on the surface. These functional groups express hydrophilicity. Alternatively, other methods are used in some cases: discharge treatment (e.g., plasma treatment, corona treatment, and frame treatment), and surface oxidation by chemicals.
The ink used in the present exemplary embodiment will now be described. In the following, “part” and “%” are based on mass unless otherwise noted.
Color ink containing pigment and clear ink containing no or little pigment used in the present exemplary embodiment each contain a water-soluble organic solvent. The water-soluble organic solvent preferably has a boiling point of 150° C. or more and 300° C. or less in terms of wettability and moisture retaining property of a head orifice face. Further, a heterocyclic compound including a lactam structure is especially preferable in terms of a function of a film forming auxiliary to fine resin particles and swelling/solubility properties to the recording medium on which the resin layer is formed. The heterocyclic compound is represented by a ketone compound, a propylene glycol derivative, N-methyl-pyrrolidone, and 2-pyroolidone. In terms of ejection performance, a content of the water-soluble organic solvent is preferably 3 wt % or more and 30 wt % or less. Specific examples of the water-soluble organic solvent include: alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol and ethyl alcohol; amides, such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols, such as acetone and diacetone alcohol; ethers, such as tetrahydrofuran and dioxane; polyalkylene glycols, such as polyethylene glycol and polypropylene glycol; ethylene glycol or alkylene glycols whose alkylene groups have 2 to 6 carbon atoms; lower alkyl ether acetates, such as polyethylene glycol monomethyl ether acetate; glycerol; lower alkyl ethers of polyhydric alcohols, such as ethylene glycol monomethyl (or ethyl) ether; polyhydric alcohols, such as trimethylolpropane and trimethylolethane; and N-methyl-2-pyrrolidone, 2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. The above-described water-soluble organic solvents can be used either singly or in any combination thereof. Deionized water is desirable for the water. The content of the water-soluble organic solvent contained in a reactant used in the exemplary embodiment of the present disclosure is not particularly limited. However, besides the above-described components, a surfactant, an antifoaming agent, a preservative, a mildew-proofing agent, and other components may be suitably added to the color ink and the clear ink used in the exemplary embodiment of the present disclosure as needed, to realize desired physical property values.
The wiping unit 100 that operates as a wiping device wiping the ejection port surface 11a of the recording head 11 will now be described. The wiping unit 100 is disposed in a maintenance area B adjacent to the recording area A in the X direction on a side opposite to the maintenance area C.
The wiping operation of the wiping unit 100 will now be described.
In the present exemplary embodiment, a diameter of the particles of the coloring material, such as pigment, contained in the pigment ink used in the inkjet recording apparatus 1 is about 20 to 30 nm. I contrast, the cleaning member 104 according to the present exemplary embodiment is a non-woven fabric. The non-woven fabric used herein is a sheet web or a pad-like fabric obtained by bonding or intertwining fibers through fusion, mechanical action, or chemical action. The ink adhering to the ejection port surface 11a is instantaneously absorbed in the cleaning member 104 along with the wiping operation by the capillary pressure of fine pores of the cleaning member 104.
In the present exemplary embodiment, the wiping operation is therefore performed in a state where particles each having a particle diameter greater than the diameter of each of the particles of the coloring material are applied on the cleaning member 104. In this example, as the particles each having the particle diameter greater than the diameter of each of the particles of the coloring material, fine resin particles are used. In the present exemplary embodiment, the cleaning member 104 is previously impregnated with the fine resin particles.
The “fine resin particles” according to the present exemplary embodiment are fine particles made of a resin and having a particle diameter dispersible to an aqueous medium. Specific examples of the resin forming the fine resin particles include: fine acrylic resin particles synthesized by emulsion polymerization of a monomer, such as alkyl (meth) acrylate and (meth) acrylic acid alkylamide; fine styrene-acrylic resin particles synthesized by emulsion polymerization of alkyl (meth) acrylate or (meth) acrylic acid alkylamide with a styrene monomer; and fine polyethylene resin particles, fine polypropylene resin particles, fine polyurethane resin particles, and fine styrene-butadiene resin particles. The examples further include, fine core-shell resin particles each including a core and a shell made of polymers having different compositions, and fine resin particles produced by emulsion polymerization using fine acrylic particles synthesized in advance as seeds for controlling the particle size. The examples further include fine hybrid resin particles produced by chemically bonding different types of fine resin particles, for example, fine acrylic resin particles and fine urethane resin particles. One or more types of fine resin particles can be impregnated.
As illustrated in
As described above, since the fine resin particles function as the spacers and the cushion materials, the wiping operation is performed in the state where the fine resin particles are in contact with the ejection port surface 11a as illustrated in
HR=130−500h, (1)
where HR is Rockwell hardness, and h is actual depression depth (mm) when a reference load is defined as zero point.
A plastic material the material of the ejection port surface typically has hardness of about R70 to about R120. If the hardness of the fine resin particles is greater than or equal to R60, the hardness of the fine resin particles becomes substantially equivalent to the hardness of the ejection port surface 11a. Rubbing of the materials having the same hardness is disadvantageous to shaving. Further, when the hardness is less than R20, the crushed amount increases and the fine resin particles become crushed, which may bring the coloring material into contact with the ejection port surface 11a.
The particle diameter of each of the fine resin particles is not limited to the above-described particle diameter as long as the particle diameter is greater than the diameter of each of the particles of the coloring material. To further prevent the coloring material from coming into contact with the ejection port surface 11a during the wiping operation, the particle diameter of each of the fine resin particles is preferably five times or more of the diameter of each of the particles of the coloring material. Further, the hardness of the fine resin particles can be less than R20 as long as the fine resin particles have a size not bringing the coloring material into contact with the fine resin particles when the fine resin particles are crushed by the wiping operation.
With the above-described configuration, the fine resin particles function as the spacers and the cushion materials, even in the case where the ejection port surface 11a is wiped by the cleaning member 104, and therefore the coloring material is difficult to be dragged on the ejection port surface 11a, as illustrated in
A second exemplary embodiment will now be described. The configuration other than the wiping unit is similar to the configuration described in the first exemplary embodiment. Thus, only the detail of the wiping unit will be described.
The wiping unit 200 according to the present exemplary embodiment externally includes a fine-resin-particle supply tank 220. The fine-resin-particle supply tank 220 is disposed at a position higher than the wiping unit 200, and the fine-resin-particle supply tank 220 houses solution 221 in which a predetermined amount of fine resin particles described in the first exemplary embodiment is dispersed into an aqueous medium. Between the third rotary member 201a and the fourth rotary member 201b, a pressing member 203 made of a porous body and a cam 202 configured to elevate and lower the pressing member 203 are disposed. A motor (not illustrated) to rotate the cam 202 is disposed on a center axis of the cam 202. The pressing member 203 is movable in a vertical direction by own weight. The cleaning member 204 can take two positions illustrated in
The above-described fine-resin-particle supply tank 220 includes a supply flow path 230 to supply, to the porous pressing member 203, the solution 221 in which the fine resin particles are dispersed into the aqueous medium. The solution 221 is supplied from the fine-resin-particle supply tank 220 to the pressing member 203 through the supply flow path 230. Since the fine-resin-particle supply tank 220 is disposed at the position higher than the wiping unit 200, the solution 221 is successively supplied to the pressing member 203 by water head difference. Since the pressing member 203 is made of a porous body, the pressing member 203 absorbs the solution 221 up to an allowable holding range. The solution 221 does not leak from the pressing member 203. Unless the solution 221 is completely exhausted, the pressing member 203 constantly holds the solution 221, and the pressing member 203 is maintained moisturized with the solution 221, accordingly.
The wiping operation of the wiping unit 200 according to the second exemplary embodiment will now be described.
In the above-described manner, it is possible to supply the solution 221 to the area of the cleaning member 204 abutting on the ejection port surface 11a at timing of the wiping operation.
A third exemplary embodiment will now be described. The configuration other than the wiping unit is similar to the configuration described in the first exemplary embodiment. Thus, only details of the wiping unit will be described.
The wiping unit 300 according to the present exemplary embodiment externally includes a fine-resin-particle tank 320. The fine-resin-particle tank 320 is disposed at a position higher than the wiping unit 300, and the fine-resin-particle tank 320 houses solution 321 in which a predetermined amount of fine resin particles described in the first exemplary embodiment is dispersed into an aqueous medium. The wiping unit 300 according to the present exemplary embodiment further includes a solution absorbing member 350 made of a porous body and disposed at a position lower than the fine-resin-particle tank 320. The fine-resin-particle tank 320 includes a supply flow path 330 to supply the solution 321 to the solution absorbing member 350. Since the fine-resin-particle tank 320 is disposed at the position higher than the solution absorbing member 350, the solution 321 is successively supplied to the solution absorbing member 350 by water head difference. Since the solution absorbing member 350 is made of a porous body, the solution absorbing member 350 absorbs the solution 321 up to an allowable holding range. The solution 321 does not leak from the solution absorbing member 350. Unless the solution 321 is completely exhausted, the solution absorbing member 350 holds the solution 321 inside the porous body and on a surface of the porous body.
At an upper end of the wiping unit 300 on the downstream side in the wiping direction, a transfer member 340 is provided. The transfer member 340 is configured to transfer the solution 321 to the ejection port surface 11a of the recording head 11. The transfer member 40 contains an elastic material, such as a rubber member. The transfer member 340 is disposed at a position in which the transfer member 340 rubs on the recording head 11 while abutting on the recording head 11, and a part of the transfer member 340 comes into contact with the ejection port surface 11a while being elastically deformed, in the wiping operation of the wiping unit 300. On the upstream side of the solution absorbing member 350 in the wiping direction, a scraper 360 is provided. The scraper 360 comes into contact with a part of the transfer member 340, to scrape foreign substances on the surface of the transfer member 340. The scraper 360 includes a resin member. The scraper 360 is provided to scrape foreign substances adhering to the transfer member 340 through the wiping operation.
The wiping operation of the wiping unit 300 according to the third exemplary embodiment will now be described.
When the wiping unit 300 does not perform the wiping operation, the recording head 11 stands by at a standby position in an area other than the maintenance area B.
As described above, in the present exemplary embodiment, the cleaning member 304 wipes the ink after a predetermined amount of fine resin particles dispersed into the aqueous medium is transferred to the ejection port surface 11a. This makes it possible to wipe the ejection port surface 11a in a state where the predetermined amount of fine resin particles is present between the ejection port surface 11a and the cleaning member 304. At this time, the ejection port surface 11a is put into the state as illustrated in
In the recording apparatus 1 according to the above-describe exemplary embodiments, the wiping unit performs the wiping operation by moving in the Y direction; however, the wiping method is not limited thereto. It may be sufficient to perform the wiping by relative movement in the Y direction, and thus the recording head may move in the Y direction.
Further, the pressing member according to the above-described exemplary embodiments is a member having a width enough to wipe the ejection port surface in the X direction. Alternatively, the pressing member may have a width enough to wipe the ejection port surface in the Y direction, and the wiping operation may be performed by relative movement in the X direction. Further, the wiping unit may be disposed such that the cleaning member is wound up in the X direction, and the wiping operation may be performed by relative movement in the X direction.
As described above, the ejection port surface is wiped in the state where the particles each having the particle diameter greater than the diameter of each of the particles of the coloring material are present between the ejection port surface and the cleaning member, which makes it possible to prevent deterioration of the ejection port surface by the wiping operation.
Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may include one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read-only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-007823, filed Jan. 21, 2020, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-007823 | Jan 2020 | JP | national |
