JP2006312261A - Wiping apparatus and inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently wipe and remove wet ink even when ink wetting due to ink mist or splashing ink droplets adhering to the ejection surface of a recording head progresses, and stable and good ink ejection. Provided are a wiping device and an ink jet recording apparatus that enable the above.
SOLUTION: A plurality of rubber-like elastic wipers that are sequentially brought into sliding contact with a discharge surface H1101 of a recording head H1001, and a contact angle θ1 with respect to the discharge surface of a first wiper 11 that first comes into sliding contact is set to a subsequent second wiper 12. Is selected to be smaller than the contact angle θ2 with respect to the ejection surface.
[Selection] Figure 1

Description

  The present invention relates to a wiping apparatus that wipes and cleans an ejection surface of a recording head that ejects ink and records on a recording medium, and an ink jet recording apparatus using the wiping apparatus.

  An ink jet recording apparatus that performs recording by ejecting ink from a recording head to a recording medium such as recording paper is advantageous in that it is easy to downsize, has low noise, and is inexpensive. Used in devices and various printing devices. A recording head mounted on an ink jet recording apparatus has an ejection surface on which ejection ports for ejecting ink are formed. By selectively driving the ejection ports based on recording information, a desired ink is obtained. An image is recorded by causing droplets to land on a recording medium. In general, an ink jet recording apparatus uses a recording head having a discharge surface (usually the same surface) on which discharge port arrays in which a plurality of discharge ports are arranged at a predetermined pitch are formed.

  In an ink jet recording apparatus, since liquid ink is ejected, a phenomenon in which floating ink mist, ink rebounding from a recording medium, or the like adheres to the ejection surface due to continued ink ejection. In the present application, such a phenomenon is referred to as “wetting” or “ink wetting”. When this wetting (ink wetting) occurs in the vicinity of the ejection port on the ejection surface, the ink in the ejection port is connected to the wetting through the ejection port, or the ink is connected between a plurality of ejection ports. In addition, foreign matters such as paper powder and dust may adhere to the discharge surface through wetting, and the discharge port may be blocked by the attached matter. When the above phenomenon occurs, the ink to be ejected from the ejection port is pulled by wetting, and as a result, the ejection direction of the ejected ink droplet is bent, and the size and landing position of the ink droplet may vary. . Further, the ejection may be impossible. As a result, there arises a disadvantage that normal image formation cannot be performed.

In order to prevent such inconvenience, water repellent treatment is performed on the ejection surface of the recording head, and wetting is prevented by repelling ink droplets to be attached. Furthermore, since wetting may not be completely prevented only by water repellent treatment, a wiping device for wiping (wiping and cleaning) the wetting when the amount of wetting increases is incorporated in the ink jet recording apparatus. Yes. This wiping device generally includes a wiper that slidably contacts the discharge surface, and is configured to perform a slidable contact operation with a wiper at a predetermined timing, thereby wiping and cleaning (wiping) wetness and foreign matter. .
JP-A-8-20112 JP-A-8-187876 Japanese Patent Laid-Open No. 11-78058

  On the other hand, the use of pigments as ink coloring materials has been researched and developed for the purpose of improving the image density and fastness (water resistance, light resistance, etc.) of recorded images (print images). Ink for ink jet recording often uses a dye as a coloring material, but since water is often used as the main solvent of the ink, a water-soluble dye is also frequently used. When water-soluble dyes are used, there are problems such as poor water resistance due to water-soluble properties and poor light resistance, which is known as a general dye property. In order to solve these problems, the use of pigments having excellent water resistance and light resistance has been studied.

  When using a pigment as a coloring material for an inkjet ink, it is necessary to pay attention to the following. That is, since a normal pigment is insoluble in water, it must be dispersed in water due to the presence of a surfactant, a resin, and the like. Furthermore, an ink for inkjet is obtained by adding an appropriate resin, solvent or the like as required. Such a dispersion method itself has been conventionally practiced in the field of paints and printing, but in the case of ink-jet ink, a droplet having a small particle size is caused by discharging droplets from a discharge port having a diameter of several tens of μm. Is required. In general, the particle size of the pigment used in the inkjet ink is 200 nm or less, more preferably 100 nm or less.

  Furthermore, for stable ejection, dispersion stability that does not cause aggregation or sedimentation due to external force or passage of time is required. Further, it is necessary that a strong binding force is developed between the pigment particles and the recording medium after the ink has landed on the recording medium. Since the pigment is insoluble in water as described above, it remains in the form of particles even after landing on the recording medium. In particular, when the recording medium is plain paper, there is no strong binding force between the fibers and the pigment constituting the paper. Therefore, in order to improve the binding force between the recording medium and the pigment, a water-soluble polymer substance is contained in the ink as a binder component. In particular, in order to improve the fixing property and the scratching property after the ink adheres to the recording medium, it is preferable to apply a polymer substance having a low acid value. Here, the acid value is a general term and is defined by the number of mg of potassium hydroxide required to neutralize free fatty acids contained in 1 g of a sample.

  In this way, a polymer material having a relatively low acid value is used to maintain high fixing and scratching characteristics. However, a polymer material having a low acid value is compared with a material having a high acid value. And has a low solubility in water. Therefore, when wetting occurs on the ejection surface when applied to an ink jet ink, the evaporation of a volatile solvent such as water over time in the wetting ink on the ejection surface proceeds partially. Aggregation occurs, or the polymer substance itself precipitates. This is repeated by further wetting, and the wetting is gradually accumulated. As this accumulation of wetting progresses, wetting may not be completely wiped out even if the wiping operation is performed due to the increase in the viscosity of the wet ink portion and solidification accompanying the accumulation of precipitates, which may result in unwiping. .

  FIG. 3 is a diagram schematically illustrating a wet state on the discharge surface, and FIG. 3A is a schematic front view of the state where the scattered ink adheres to the discharge surface and is wet as viewed from the discharge surface. (B) is the typical side view which looked at the state of the discharge surface shown to (a) from the side, (c) is the state after wiping and cleaning the discharge surface shown to (a) with the conventional wiping apparatus It is a typical front view which shows. As shown in FIG. 3A, the wet state is not uniform within the ejection surface, and the size of the ink adhering varies depending on the location within the ejection surface. Further, when the ejection surface of FIG. 3A is viewed from the lateral direction, the thicknesses of the attached ink are different as shown in FIG. 3B.

  In such a state, when sliding contact of the wiper is executed by the conventional wiping method, the remaining wiping state is as shown in FIG. 3C, and it is difficult to wipe off the wetness. That is, the amount of wet ink and its viscosity differ depending on the location where each wet ink adheres, and therefore, the ink resistance to the wiper varies depending on the location on the ejection surface during wiping. As a result, as shown in (c) of FIG. 3, there are scattered portions where wetting cannot be completely removed.

  Further, the sliding contact of the wiper in the state of FIGS. 3A and 3B also means that the wiper comes into contact with a portion where there is not much wet ink on the ejection surface. Since the wet ink spreads while the wiper is in sliding contact with the portion of the ejection surface where the wiper contacts, it can be said that there are actually few opportunities for both the wiper and the ejection surface to contact each other at a location where no ink adheres. However, it cannot be said that there is no opportunity for the wiper and the part of the ejection surface where no ink adheres to contact each other. In the case where the wiper and the discharge surface do not adhere to ink, the contact portions of the wiper are likely to be worn.

  In view of the difficulty of wiping off such wetness, it is conceivable to wipe off the accumulated wetness by frequently performing wiping operations, but in order to perform such operations, the recording head is frequently moved to the wiping position. It is necessary to move or perform a wiping operation for a long time. Therefore, such a solution is not a preferable solution because the operation mechanism of the recording apparatus becomes complicated and the throughput (overall recording speed) of the recording operation decreases.

  On the other hand, when a high-molecular substance having a high acid value is contained in the ink, even if it adheres to the ejection surface as a wet ink, it has a relatively high solubility as described above. Precipitation of the polymer substance is unlikely to occur, and even if a wetting phenomenon occurs, it is easily dissolved again by the next wet ink adhesion. For this reason, accumulation and accumulation of wetting are unlikely to occur, and the liquid is maintained in a behavior similar to that of ink using a dye.

However, since a high-molecular substance having a high acid value has a relatively high water solubility, the ink that has landed on the recording medium easily penetrates in the thickness direction of the recording medium, and as a result, it is difficult to maintain a high image density. Further, since the ink spreads in the thickness direction of the recording medium, the binding force between the pigment particles and the paper cannot be maintained strongly, and the scratching property of the recorded image is lowered.
From the above, when trying to improve image performance, there is a possibility of causing viscosity increase and solidification due to aggregation and precipitation of wet ink on the ejection surface, and these will accumulate on the ejection surface. Therefore, there arises a technical problem that a wiping operation for wiping and cleaning wet ink becomes difficult.

  In order to eliminate the wiping residue during the wiping operation as shown in FIG. 3C, it has been proposed to continuously (sequentially) slidably contact the same portion with a plurality of wipers. For example, in Japanese Patent Laid-Open No. 8-20112, a plurality of wipers are arranged in parallel in a direction perpendicular to the traveling direction of the recording head, and the contact force of the wiper that first contacts the ejection surface is relatively weakened. A configuration in which the contact force of the wiper is sequentially increased in order of contact is disclosed. If the ink is dissolved dye or is an ink that adheres to the ejection surface and evaporates, it is possible to prevent the wet ink from being wiped off as described above. When the ink contained in the ink deposits and accumulates as the ink evaporates, the wiper does not slide enough during wiping, or the wiper oscillates multiple times. There are inconveniences, such as not being able to wipe off the wetness enough only by repeated wiping.

  However, there is a possibility that wetting can be completely removed if the wiper sliding force can be sufficiently wiped out by gradually increasing the contact force of the wiper so as to realize the sliding contact of the wiper. However, when the contact force of the wiper increases, there is a disadvantage that the water repellent agent on the ejection surface is worn, and the degree of ink wetting may further increase as the water repellency decreases. Absent. Moreover, setting the contact force of the wiper higher in this way also leads to an increase in wear of the contact portion with the discharge surface of the wiper.

  On the other hand, JP-A-8-187876 and JP-A-11-78058 disclose a method of applying a water repellent to the discharge surface in order to cope with the above-described decrease in water repellency on the discharge surface. . In JP-A-8-187876, a wiping mechanism having a holding member for holding a water repellent and a wiping mechanism for wiping with the holding member is wiped off after wiping the wet ink on the ejection surface with a wiping pad made of a rubber blade. A configuration is disclosed in which a water repellent holding member is brought into contact with the portion to replenish the water repellent. In JP-A-11-78058, there is provided means for forming a water repellent film on the discharge surface, and after wiping the discharge surface with a wiper, the absorbent member containing a water repellent solution is pressed against the discharge surface. A structure for forming a water-repellent coating layer is disclosed.

  Even in the methods disclosed in these documents, there are restrictions on the types of water repellents that can be used, and it is difficult to form a uniform thickness layer when the water repellent layer is re-formed. There is a technical problem. Furthermore, it is necessary to add a dedicated mechanism to the ink jet recording apparatus in order to re-form the water repellent layer, and there is a technical problem that the apparatus becomes large. Therefore, setting the contact force of the wiper at the time of wiping high by re-applying water repellency to the ejection surface by these methods is not preferable from these viewpoints.

  The present invention has been made in view of the above technical problems, and an object of the present invention is to efficiently wipe and remove wet ink even when ink wetting on the ejection surface of the recording head has progressed. It is possible to provide a wiping apparatus and an ink jet recording apparatus that can discharge ink stably and satisfactorily.

  As a result of repeated investigations on the occurrence state of ink wetting on the ejection surface due to ink ejection and the behavior on the ejection surface due to evaporation of volatile components of ink adhering to ink wetting, the present inventor A novel technique capable of efficiently wiping and removing ink wetting generated on the surface has been found, and the present invention has been completed.

  In order to achieve the above object, a wiping device according to the present invention includes a plurality of wipers that sequentially slide in contact with the ejection surface in a wiping device that wipes and cleans the ejection surface of a recording head that ejects ink and records on a recording medium. The contact angle of the wiper that first comes into sliding contact with the discharge surface is smaller than the contact angle of the other wiper with respect to the discharge surface.

  According to the wiping apparatus and the ink jet recording apparatus of the present invention, a plurality of wipers that are sequentially slidably contacted with the ejection surface of the recording head are used, and the contact angle of the wiper that first slidably contacts the ejection surface of the other wiper Since the configuration is smaller than the contact angle, even when ink wetting progresses on the ejection surface of the recording head, the wet ink can be efficiently wiped off and stable and good ink ejection becomes possible.

  Embodiments of the present invention will be specifically described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 9 is a perspective view showing an appearance of the ink jet recording apparatus according to the embodiment of the present invention. FIG. 10 is a perspective view showing an internal configuration of the ink jet recording apparatus according to the embodiment of the present invention. 11 is a perspective view of the recording means (head cartridge) mounted on the carriage in FIG. 10, and FIG. 12 is a perspective view showing a state in which the recording means of FIG. 11 is disassembled into a recording head and an ink tank. FIG. 13 is an exploded perspective view of the recording head shown in FIG.

  In FIG. 9, the outer shell portion of the apparatus main body M1000 of the ink jet recording apparatus is composed of a lower case M1001, an upper case M1002, an access cover M1003, and a paper discharge tray M1004. It is supported by a chassis M3019 (see FIG. 10). The chassis M3019 is formed of a plurality of plate-like metal members having a predetermined rigidity, forms a skeleton of the recording apparatus, and supports each recording operation mechanism described later. The lower case M1001 forms a substantially lower half of the outer shell part, and the upper case M1002 forms a substantially upper half of the outer shell part, and a hollow having a space for storing each mechanism described later by a combination of both cases. It is a structure. An opening is formed in each of the rear upper surface and the front surface of the apparatus main body M1000.

  An opening formed on the front surface of the lower case M1001 can be opened and closed by a discharge tray M1004. The discharge tray M1004 is rotatably held by the lower case at one end, and is configured to open and close the front opening by the rotation. When executing the recording operation, the discharge tray M1004 is rotated to the front side to open the opening, thereby enabling the recording medium such as recording paper to be discharged from the opening and the discharged recording medium. Can be loaded sequentially. The discharge tray M1004 stores two auxiliary trays M1004a and M1004b, and the recording medium stacking area can be expanded and reduced in three stages by pulling each auxiliary tray forward as necessary.

  One end of the access cover M1003 is rotatably held by the upper case M1002, and can open and close the opening on the rear upper surface. By opening the access cover M1003, the entire head cartridge H1000, the ink tank H1900, or the recording head H1001 can be taken out from the apparatus main body and replaced. When the access cover M1003 is opened and closed, a protrusion formed on the back surface of the access cover M1003 rotates the cover opening / closing lever, and the opening / closing state of the access cover can be detected by detecting the rotation position of the lever with a micro switch or the like. it can.

  On the upper surface of the rear part of the upper case M1002, a power key E0018 and a resume key E0019 are provided so that they can be pressed, and a display lamp E0020 is provided. When the power key E0018 is pressed, the user can be informed that the display lamp E0020 can be turned on and recorded (printed). In addition, the display lamp E0020 has various display functions such as notifying the user of troubles of the recording apparatus or the like by blinking or color change. It is also possible to make a buzzer. When the trouble is solved, the recording operation can be resumed by pressing the resume key E0019.

  In FIG. 10, as a recording operation mechanism in this embodiment, a sheet feeding unit M3022 for automatically feeding a recording medium such as recording paper or a plastic thin plate into the apparatus main body, and one sheet from the sheet feeding unit M3022 are sent out one by one. The recording medium to be transported to a predetermined recording position and the recording medium from the recording position to the discharge unit M3030, and a desired recording (printing) on the recording medium transported to the recording position. And a recovery unit M5000 for performing recovery processing such as ink suction and wiping for maintaining and recovering the ink ejection performance of the recording head H1001 of the recording unit. The recording unit (printing unit) includes a carriage M4001 that is guided and supported so as to be movable along a carriage axis M4021, and a head cartridge H1000 as recording means that is detachably mounted on the carriage M4001. .

  Next, the head cartridge H1000 used in the recording unit will be described with reference to FIGS. As shown in FIG. 11, the head cartridge H1000 in the present embodiment includes an ink tank H1900 that stores ink, and a recording head H1001 that discharges ink supplied from the ink tank H1900 from an ejection port based on recording information. Have. The recording head H1001 is detachably mounted on the carriage M4001.

  The head cartridge H1000 in the present embodiment is capable of forming a photographic image with high image quality. As an ink tank, for example, a plurality of ink tanks H1900 independent of each color of black, light cyan, light magenta, cyan, magenta, and yellow are used. It has. Each ink tank H1900 is detachable individually. As shown in FIG. 13, the recording head H1001 includes a discharge element substrate H1100, a first plate H1200, an electric wiring substrate H1300, a second plate H1400, an ink tank holder H1500, an ink flow path forming member H1600, a filter H1700, and a seal rubber. H1800 and the like.

  The discharge element substrate H1100 is based on a silicon substrate, and on the surface of the discharge element substrate, a plurality of discharge elements for discharging ink and electric wiring such as aluminum for supplying power to each discharge element are formed. It is formed by. Furthermore, a plurality of ink flow paths and a plurality of discharge ports H1100T corresponding to the discharge elements are formed on the surface of the discharge element substrate by a photolithography technique. The ejection element substrate is formed with an ink supply port for supplying ink to the plurality of ink flow paths opened on the back surface. The surface on which the plurality of ejection ports H1100T is formed becomes the ejection surface H1101 of the recording head H1001.

  The ejection element substrate H1100 is bonded and fixed to the first plate H1200, and an ink supply port H1201 for supplying ink to the ejection element substrate H1100 is formed in the plate H1200. Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200. The second plate H1400 holds the electrical wiring board H1300 so that the electrical wiring board H1300 and the ejection element substrate H1100 are electrically connected. The electrical wiring substrate H1300 applies an electrical signal for ejecting ink to the ejection element substrate H1100. The electrical wiring substrate H1300 is located at the end of the electrical wiring corresponding to the ejection element substrate H1100 and the electrical signal from the main body. And an external signal input terminal H1301. The external signal input terminal H1301 is positioned and fixed on the back side of the ink tank holder H1500.

  On the other hand, an ink flow path forming member H1600 is fixed to the ink tank holder H1500 that detachably holds the ink tank H1900 by, for example, ultrasonic welding, and an ink flow path H1501 from the ink tank H1900 to the first plate H1200 is formed. ing. A filter H1700 is attached to the ink tank side end of the ink flow path H1501 that engages with the ink tank H1900 to prevent dust from entering from the outside. A seal rubber H1800 is attached to an engagement portion of the ink flow path H1501 with the ink tank H1900 to prevent ink from evaporating from the engagement portion.

  The ink tank holder is composed of an ink tank holder H1500, an ink flow path forming member H1600, a filter H1700, and a seal rubber H1800, and an ejection element substrate H1100, a first plate H1200, an electric wiring substrate H1300, and a second plate H1400. A recording head H1001 is configured by bonding the ejection element portion with an adhesive or the like.

  Next, ink that is used in the ink jet recording apparatus according to the present embodiment and uses a pigment as a color material will be described. Here, black ink will be described as an example, but the technique of the same content can be applied to other color inks by simply adjusting the type of pigment used to one corresponding to each color ink. First, in preparing an ink, it is necessary to disperse a pigment insoluble in water. This is done in the following way.

That is, styrene / methacrylic acid / 2-hydroxyethyl methacrylate / tetraethylene glycol methacrylate (weight ratio: 75/15/5/5, weight average molecular weight: 20000, acid value: 100) as a water-insoluble polymer substance. A polymer solution containing 50% active ingredient was prepared by dissolving in methyl ethyl ketone. 20 g of this polymer solution, 30 g of carbon black (specific surface area: 220 m ² / g, oil absorption: 120 ml / 100 g), 17.9 g of 1N potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water are prepared. These were sufficiently stirred and then kneaded 20 times with a three-roll mill. The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator.

Thereafter, the ground particles were removed with a centrifugal separator to prepare Pigment Dispersion A having a nonvolatile concentration of 10% by weight. This pigment dispersion A was evaporated to dryness, and the ratio of the pigment (P) to the polymer substance (B) was measured by TG-DTA. P / B = 75/25. The dispersion produced as described above is referred to as “Pigment Dispersion A”, and ink is prepared by mixing with other components with the following contents.
Pigment dispersion A ... 40% by weight
Glycerin ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10% by weight
Polyethylene glycol (molecular weight: 1000) 3% by weight
Acetylenol EH (trade name) ...... 0.15% by weight
These components were finally mixed, stirred well, and then filtered through a membrane filter having a pore size of 1.0 μm to obtain an ink as a target product.

  Next, a carriage M4001 on which the head cartridge H1000 is mounted will be described with reference to FIG. In FIG. 10, the carriage M4001 is engaged with a carriage cover M4002 for guiding the recording head H1001 to a predetermined mounting position on the carriage M4001, and an ink tank holder H1500 of the recording head H1001, so that the recording head H1001 is engaged. A head set lever M4007 is provided for pressing and setting at a predetermined mounting position. The headset lever M4007 is rotatably attached to the upper part of the carriage M4001. A head set plate (not shown) that is biased by a spring is attached to the engaging portion of the head set lever M4007 with the recording head H1001 via a spring, and the carriage M4001 is pressed against the recording head H1001 by the spring force. It is configured to be attached to.

  Further, a contact flexible cable E0011 is provided at another engagement portion of the carriage M4001 with the recording head H1001, and a contact portion on the contact flexible cable and a contact portion (external signal input terminal) H1301 provided on the recording head H1001. Are in electrical contact with each other, and exchange of various information for recording and power supply to the recording head H1001 are performed.

  Here, an elastic member such as rubber (not shown) is provided between the contact portion of the contact flexible cable E0011 and the carriage M4001, and the contact portion is formed by the elastic force of the elastic member and the pressing force by the headset lever spring. And the carriage M4001 can be reliably contacted. The contact flexible cable E0011 is connected to a carriage substrate (not shown) mounted on the back surface of the carriage M4001.

  According to the ink jet recording apparatus configured as described above, an image is formed on a recording medium such as recording paper by ejecting ink from the ejection port H1100T of the recording head H1001 based on the recording information. If ink discharge is continued for this image formation, wetting may occur on the discharge surface. Next, a wiping device for eliminating this wetting will be described. This wiping device is provided in the aforementioned recovery unit M5000.

  FIG. 1 is a side view showing a wiping unit in a first embodiment of a wiping device according to the present invention. In FIG. 1, the wiping unit 10 is provided with two wipers 11 and 12, and the recording means H1000 (recording head H1001) is provided with an ejection surface H1101 in which ejection ports are arranged. The wiping unit 10 is moved in the direction of arrow A with respect to the discharge surface H1101 so as to make sliding contact with the discharge surface H1101, thereby wiping and cleaning the discharge surface H1101.

  The wiping unit 10 is provided with a plurality of (two) blade-like rubber-like elastic wipers 11 and 12 that are in sliding contact with the discharge surface H1101 in sequence. That is, the wiping unit 10 is provided with the first wiper 11 that first comes into sliding contact with the discharge surface H1101 and the second wiper 12 that comes into sliding contact with the discharge surface H1101. These blade-like wipers 11 and 12 are formed of a molded product of polyether urethane having a hardness (rubber hardness) of 70 degrees.

  The first wiper 11 is fixed on the base 13 in a predetermined positional relationship by the fixing member 14 and the second wiper 12 is fixed by the fixing member 15. In the present embodiment, the thickness D1 of the first wiper 11 is 0.5 mm, the thickness D2 of the second wiper 12 is also 0.5 mm, the free length L1 of the first wiper 11 is 8 mm, and the second wiper 12 The free length L2 is selected to be 5 mm. That is, the free length of the wiper 11 that contacts first is selected to be longer than the free lengths of the other wipers 12. By such dimension selection, the relative positional relationship between the head cartridge H1000 and the wiping unit 10 is defined so that the contact angle becomes about 45 degrees when the second wiper 12 is in sliding contact with the discharge surface H1101.

  FIG. 2 is an exploded perspective view showing the attachment structure of the wipers 11 and 12 in the wiping unit 10 of FIG. In FIG. 2, the wiping unit 10 has a base 13, and the base 13 is fitted in mounting holes 111 and 112 provided in the blade-like first wiper 11 made of a rubber-like elastic body. Protruding parts 131 and 132 are provided. Similarly, the base 13 is provided with protrusions 133 and 134 that fit into mounting holes 121 and 122 provided in the blade-like second wiper 12 made of a rubber-like elastic body. The protrusions 131, 132, 133, and 134 are molded integrally with the base 13. The first wiper 11 and the second wiper 12 are positioned on the base 13 by fitting the above-described protrusions into the respective holes from the directions of the arrow B1 and the arrow C1.

  Next, the fixing members 14 and 15 made of stainless steel or the like are attached to the base 13 from the arrow B2 direction and the arrow C2 direction, respectively. That is, the fixing member 14 of the first wiper 11 fits the protrusions 131 and 132 of the base 13 in the holes 141 and 142 and the grooves 135 formed on both sides of the base 13 with the convex ribs 143 and 144. The first wiper 11 is positioned and fixed with respect to the base 13 by being fixed to the base 13 with a predetermined elastic force. Similarly, the fixing member 15 of the second wiper 12 fits the projections 133 and 134 of the base 13 into the holes 151 and 152, and grooves formed on both sides of the base 13 with the convex ribs 153 and 154. By being hooked on 136, the base 13 is positioned and fixed with a predetermined elastic force, whereby the second wiper 12 is positioned and fixed with respect to the base 13.

  FIGS. 4 to 6 are diagrams showing operations when the wiping unit 10 shown in FIGS. 1 and 2 wipes and removes wet ink adhering to the ejection surface H1101 as shown in FIGS. 3A and 3B. It is. FIG. 4 shows a state when the first wiper 11 starts to slidably contact the discharge surface H1101 by moving the wiping unit 10 in the direction of arrow A, and (a) is a schematic front view of the discharge surface H1101. FIG. 4B is a schematic side view of the wiping unit 10 and the recording head H1001.

  FIG. 5 shows a state in which the second wiper 12 following the first wiper 11 starts to slidably contact the discharge surface H1101 by further moving the wiping unit 10 in the direction of arrow A from the state of FIG. Is a schematic front view of the ejection surface H1101, and (b) is a schematic side view of the wiping unit 10 and the recording head H1001. FIG. 6 shows a state when the first wiper 11 has come out of the discharge surface H1101 by further moving the wiping unit 10 in the direction of arrow A from the state of FIG. 5, and (a) is a schematic front view of the discharge surface H1101. (B) is a schematic side view of the wiping unit 10 and the recording head H1001.

Next, with reference to FIGS. 4 to 6, the operation when the wiping unit 10 is used to wipe off and remove the wet ink adhering to the ejection surface H1101 as shown in FIGS. 3A and 3B will be described. To do.
The wiping unit 10 is in a relative positional relationship as shown in FIG. 1 with respect to the ejection surface H1101 of the recording head in the standby state. When the wiping unit 10 is moved in the arrow A direction from such a standby position, first, the first wiper 11 starts to slidably contact the discharge surface H1101 as shown in FIG. 4, and the wiping by the first wiper 11 is performed. At this time, the distal end portion of the first wiper 11 bends as shown in FIG. 4B and contacts with the discharge surface H1101 at a very small angle θ1. The contact angle θ1 at this time is about 10 degrees in the present embodiment.

  In the state of FIG. 4, the curved portion at the tip of the first wiper 11 is close to the discharge surface H1101, and the distance between the wiper 11 and the discharge surface H1101 becomes very small near the ridgeline of the curved portion. Yes. Therefore, the first wiper 11 is in contact with the ejection surface H1101 in a state close to surface contact in a range that is expanded to some extent, not just the ridge line portion. For this reason, it is almost impossible to remove the deposit (wetting ink) on the ejection surface H1101 by the sliding contact of the first wiper 11, but while spreading the wetting ink on the ejection surface H1101, it is a film having a substantially uniform thickness. You can fake.

  As the operation of the wiping unit 10 further proceeds, as shown in FIG. 5, the second wiper 12 follows the first wiper 11 and comes into sliding contact with the discharge surface H1101. Here, the free length of the second wiper 12 is selected to be shorter than the free length of the first wiper 11. For this reason, the second wiper 12 comes into contact with the ejection surface H1101 mainly at the tip ridge line portion, and comes into contact with an angle effective for wiping and removing the wet ink. The contact angle θ2 at this time is larger than the above θ1, and is about 45 degrees in the present embodiment.

  On the other hand, the wet ink in the portion where the second wiper 12 enters is spread on the discharge surface H1101 by the sliding contact of the first wiper 11 and is made to have a substantially uniform thickness. The second wiper 12 having a large diameter can be efficiently wiped off, and the discharge surface H1101 after the second wiper 12 has passed is a clean surface. When the wiping unit 10 further moves in the direction of arrow A while proceeding with such a wiping operation, as shown in FIG. 6, the first wiper 11 comes out of the discharge surface H1101, and the second wiper 12 is also discharged. It will be in the state which has slidably contacted most of the surfaces. Then, when the wiping of the wet ink on the ejection surface H1101 by the second wiper 12 is finished, the entire ejection surface becomes a clean surface.

  According to the embodiment described above, a plurality of rubber-like elastic wipers 11 and 12 that are sequentially brought into sliding contact with the discharge surface H1101 of the recording head H1001 are used, and the contact angle θ1 of the wiper 11 that first comes into sliding contact with the discharge surface θ1. Is smaller than the contact angle θ2 of the other wiper 12 with respect to the ejection surface, so that even when ink wetting on the ejection surface of the recording head progresses, the wet ink can be efficiently wiped off. A wiping apparatus and an ink jet recording apparatus that enable stable and good ink ejection are provided.

  FIG. 7 is a side view showing a wiping unit in the second embodiment of the wiping apparatus according to the present invention. In the present embodiment, of the plural (two) wipers 11 and 16 fixed on the base 13 via the fixing members 14 and 15, the sliding contact with the discharge surface H1101 of the subsequent wiper (second wiper) 16 is made. The tip portion 16a is formed in a spire shape. That is, in this embodiment, instead of the second wiper 12 of the first embodiment described above, the second wiper 16 in which the tip sliding contact portion 16a has a spire shape (or a tip shape) is used. Although this point is different from the first embodiment, the configuration is substantially the same in other points. Corresponding portions are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  According to such a 2nd embodiment, in addition to the same operation effect as a 1st embodiment, tolerance at the time of attachment to base 13 of each wiper 11 and 16 and discharge surface H1101 and wiping unit 10 There is an effect that the instability of the sliding contact due to the variation of the contact angle with respect to the discharge surface H1101 of the second wiper 16 that may occur due to the relative position tolerance or the like can be suppressed. That is, according to the configuration of the present embodiment, even if the contact angle of the second wiper 16 varies to some extent, the discharge surface H1101 can always be slidably contacted with the tip 16a of the second wiper 16. The wet ink can always be removed by using the ridge line at the tip of the second wiper 16. This makes it possible to wipe out wet ink more reliably.

  FIG. 8 is a side view showing a wiping unit in the third embodiment of the wiping apparatus according to the present invention. The wiping unit 10 in the present embodiment produces a wiper unit 17 in which the first wiper 17a and the second wiper 17b are integrally formed using the same polyether urethane as the material of the wipers 11 and 12 in the first embodiment. The wiper unit 17 is fixed (or coupled) to the base 18. Here, the coupling (or fixing) between the wiper unit 17 and the pedestal 18 can be performed by a known fixing means such as adhesion or screw fastening. However, since the wiper unit 17 is formed of polyether urethane, it is necessary to prevent deformation due to frictional resistance when the discharge surface H1101 is slidably contacted. Therefore, the base 18 is made of a material having high rigidity, For example, it is preferably formed of polyacetal or polycarbonate.

  The wiping device according to the present embodiment is different from the above-described first embodiment in the points described above, but has substantially the same configuration in other points. And according to this embodiment, in addition to the effect similar to the above-mentioned 1st Embodiment, the fluctuation | variation of the free length of the wiper which can arise from the dispersion | variation in attachment at the time of attaching a wiper to a base can be suppressed. The effect is obtained.

  In the above embodiment, the case where two blade-like wipers made of a rubber-like elastic body are used and the hardness and thickness (plate thickness) of each wiper are the same has been described. The present invention can be carried out in various forms, and these are also included in the scope of the present invention. For example, by selecting the hardness (rubber hardness) of the first wiper 11 to be lower than the hardness of the second wipers 12, 16, the contact angle at the time of sliding contact of the first wiper 11 can be further reduced (lower). it can. Thereby, the wet ink on the ejection surface H1101 can be made a more uniform film layer. When the configuration of FIG. 1 is taken as an example, specifically, the hardness of the first wiper 11 can be selected to be about 60 degrees, and the hardness of the second wiper 12 can be selected to be about 80 degrees.

  However, when the hardness of the wiper decreases, the contact force (pressure contact force) of the wiper may decrease. In that case, the wiper may be adjusted by appropriately selecting the free length and thickness of the wiper. . Furthermore, changing the hardness of the wiper means that the hardness of the second wiper is relatively high. By changing the hardness of the wiper, the amount of deflection at the time of sliding contact with the second wiper and the fluctuation of the deflection are suppressed. Can also produce further effects.

  In the above embodiment, the case where two (two) wipers are used has been described as an example. However, the present invention is not limited to this number, and corresponds to the first wiper or the second wiper. The wiper may be composed of a plurality of sheets, or both the first and second wipers may be composed of a plurality of sheets, and the present invention includes such a structure. By adopting such a configuration, it is possible to further ensure the uniform film formation of the wet ink on the ejection surface 1101 by the first wiper, and it is possible to more reliably remove the wet ink by the second wiper. Can be. In particular, depending on the selection of a low acid number substance used in the ink, the deposition of the wet ink may be more likely to proceed, and such a configuration is effective at that time.

  Further, the present invention is not particularly limited with respect to the presence or absence of the treatment and the method for making the discharge surface H1101 water-repellent. Regardless of whether the ejection surface H1101 is water-repellent or hydrophilic, wetting ink may adhere to the ejection surface. However, in terms of wiping wet ink using a wiper, it is more effective that the number of contact points between the wet ink and the discharge surface H1101 is as small as possible, and thus water repellency is imparted to the discharge surface H1101 (that is, It is preferable that the discharge surface H1101 has water repellency.

  In the process of completing the present invention as described above, the following technical matters were confirmed. First, an ink in which a pigment is dispersed using a pigment as a colorant and a polymer material having an acid value of 200 or less is ejected from the recording head, and “wetting” on the ejection surface that occurs as the ink is ejected. Observing the adhesion state of the ink that causes the problem, the following technical matters were confirmed. In the polymer material used here, the balance between the hydrophilic group and the hydrophobic group is important. A typical example is a copolymer of polyacrylic acid / polystyrene. From the definition of the acid value, the more the carboxyl group, the higher the acid value.

  Next, technical matters confirmed in the process of completing the present invention will be specifically described. Ink adhesion on the ejection surface occurs in a wide range including the vicinity of the ejection port in the form of fine droplets, and ink adhesion (wetting ink) increases as ink ejection continues. At the same time, evaporation of volatile components in the adhered ink on the ejection surface also occurs, so that the adhered ink gradually increases in viscosity, and further, the deposition of a polymer substance component also occurs. While the ink is in such a state, another ink droplet adheres to the ejection surface, and among these, those adhering to close positions increase in viscosity or merge with the deposited portion. . However, in this coalescence, when the acid value of the polymer substance is low, the already precipitated polymer substance is not easily re-dissolved by ink droplets attached later, so that viscosity increasing components and precipitates are deposited. It will follow.

  Since there is no regularity in adhesion of ink droplets, the adhesion of these ink droplets varies on the ejection surface, and the amount of adhered ink varies depending on the location, and the thickness of the deposited ink component also varies. In this state, when the contact angle is made small (lower) as θ1 in FIG. 4 by the first wiper and the ejection surface is brought into sliding contact, some of the adhered ink may be removed, but most of the ink is removed. The adhered ink remains on the ejection surface without being removed. However, due to the sliding contact of the first wiper, the adhered ink is made to have a substantially uniform thickness and accordingly spreads over a wide area on the ejection surface. Such a phenomenon is attributed to the fact that the contact of the first wiper with the discharge surface is performed in a state close to the surface contact, not the line contact by the ridgeline.

  That is, when the contact angle of the wiper is as small as θ1 in FIG. 4, it is difficult to clearly reveal the ridge line of the wiper at the time of contact with the discharge surface. It also means that the contact area with the wiper increases (close to surface contact). Therefore, the wiper is less likely to swing during sliding contact, and the ink leveled by the wiper spreads over a wide area as a whole with a substantially uniform thickness, and all the ink droplets mix with each other. The difference in viscosity (hardness) disappears.

  Subsequently, when the second wiper (contact angle θ2 in FIG. 5) having a higher contact angle than the first wiper is brought into sliding contact with the discharge surface, the contact between the second wiper and the discharge surface is a line contact. Therefore, the wet ink that has been adjusted to a substantially uniform thickness by the first wiper is easily removed. Here, it is conceivable that the volatile matter in the wet ink further evaporates in the time after the first wiper passes, but since this time is very short, the alteration of the ink here can be ignored. Further, since the adhered ink (wetting ink) is once once almost uniformized as a whole, there is almost no difference in the state of the adhered ink depending on the location. With the above-described configuration and operation, it is possible to wipe off and remove the adhered ink on the ejection surface.

  Of these, the contact angle of the first wiper or another wiper with respect to the ejection surface is preferably selected as follows. First, the contact angle of the first wiper is preferably selected to be approximately 30 degrees or less, which is an appropriate contact angle for realizing sliding contact close to surface contact, and a more preferable contact angle is approximately 0 to It is about 25 degrees. Various studies were conducted in consideration of the elastic modulus and hardness of the material used for the wiper and the shape of the wiper, such as the thickness and the free length. When the contact angle of the first wiper exceeded about 30 degrees, The influence of the contact due to the ridgeline becomes large, and surface contact or a state close thereto cannot be obtained. For the rubber-like elastic wipers of various materials and forms, an appropriate contact angle was experimentally obtained in order to produce an effect of making the adhered ink almost uniform. It was confirmed that the contact angle was suitable. In addition, the contact angle in the case of sufficient or ideal surface contact is about 0 degree.

  On the other hand, with respect to a suitable contact angle of the second wiper that causes the contact of the line contact following the first wiper, as a result of the same investigation as described above, about 25 degrees to about 60 with respect to the discharge surface. It has been confirmed that a contact angle of about 50 degrees is preferable, and a contact angle in the range of about 30 degrees to about 50 degrees is more preferable. If the contact angle of the second wiper exceeds about 60 degrees, the line contact by the ridge line may be insufficient during the wiping operation, and the rocking may occur. In some cases, wiping and removal of the adhering ink after the cleaning becomes insufficient.

  As described above, according to the above-described embodiment, when the ink containing the pigment as the color material and the high molecular substance having an acid value of 200 or less is discharged from the discharge port, wetting on the discharge surface proceeds. Even in such a case, by performing appropriate wiping, stable ink ejection can always be maintained, and stable and good image recording can be performed. That is, according to the present invention, a pigment is used as a coloring material, which causes wetting on the ejection surface that could not be generated with an ink using a dye as a coloring material, and the conventional technology cannot remove the wetting on the ejection surface. Even when the ink used is used, it is possible to efficiently remove the wetting on the ejection surface without the need to change the water repellent layer on the ejection surface or improve the contact force during wiping.

  Further, according to the above-described embodiment, the wet ink can be spread over a wide range to a uniform thickness on the ejection surface by the action of the first wiper, and then the ejection surface is wiped with a wiper (second wiper or the like). Even when sliding, the wiper and the ejection surface do not come into contact with each other at a place where there is no ink adhesion (ink layer). Therefore, the present invention is also effective in preventing wiper wear. This is effective in increasing the degree of freedom in designing the ink, improving the reliability of the image, and further improving the stability of the system of the ink jet recording apparatus.

  In the above embodiment, a serial type ink jet recording apparatus using a recording head mounted on a carriage movable with respect to a recording medium has been described as an example. However, the present invention is a line for recording only in sub-scanning. The present invention can be similarly applied to other recording system ink jet recording apparatuses such as a type of ink jet recording apparatus, and has the same effects. Further, the present invention is an inkjet recording apparatus, an apparatus using one recording head, an apparatus using a plurality of recording heads using different color inks, or a plurality of recording heads using inks of the same color and different densities The present invention can be applied in the same manner to a device using the above, and a device combining these, and the same effect can be achieved.

It is a side view which shows the wiping unit in 1st Embodiment of the wiping apparatus by this invention. It is a perspective view which decomposes | disassembles and shows the attachment structure of the wiper in the wiping unit of FIG. FIG. 2 is a diagram schematically illustrating a wet state on a discharge surface of a recording head, and (a) is a schematic front view of the scattered ink attached to the discharge surface and viewed from the discharge surface. (B) is the typical side view which looked at the state of the discharge surface shown to (a) from the side, (c) is the state after wiping and cleaning the discharge surface shown to (a) with the conventional wiping apparatus It is a typical front view which shows. The state when the first wiper starts to come into sliding contact with the ejection surface by moving the wiping unit is shown, (a) is a schematic front view of the ejection surface, and (b) is a schematic diagram of the wiping unit and the recording head. It is a side view. FIG. 4 shows a state when the second wiper starts to slidably contact the discharge surface following the first wiper by further moving the wiping unit from the state of FIG. 4, (a) is a schematic front view of the discharge surface; FIG. 4B is a schematic side view of the wiping unit and the recording head. FIG. 5 shows a state in which the first wiper has come out of the ejection surface by further moving the wiping unit from the state of FIG. 5, (a) is a schematic front view of the ejection surface, and (b) is a wiping unit and recording. It is a typical side view of a head. It is a side view which shows the wiping unit in 2nd Embodiment of the wiping apparatus by this invention. It is a side view which shows the wiping unit in 3rd Embodiment of the wiping apparatus by this invention. 1 is a perspective view illustrating an appearance of an ink jet recording apparatus according to an embodiment of the present invention. 1 is a perspective view showing an internal configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 11 is a perspective view of recording means (head cartridge) mounted on the carriage in FIG. 10. FIG. 12 is a perspective view illustrating a state in which the recording unit of FIG. 11 is disassembled into a recording head and an ink tank. It is the disassembled perspective view which decomposed | disassembled the recording head in FIG. 12 for every component, and was seen from the downward direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wiping unit 11, 17a 1st wiper 12, 16, 17b 2nd wiper 13 Base 14, 15 Fixing member 16a Tip part 17 Wiper unit 18 Base M1000 Apparatus main body M1001 Lower case M1002 Upper case M1003 Access cover M3022 Paper feed part M3029 Conveying unit M3030 Discharging unit M4001 Carriage M4021 Carriage shaft M5000 Recovery unit H1000 Recording means (head cartridge)
H1001 Printhead H1100T Discharge port H1101 Discharge surface H1900 Ink tank E0018 Power key A Wiping direction θ1, θ2 Contact angle

Claims (10)

In a wiping device that wipes and cleans the ejection surface of a recording head that ejects ink and records on a recording medium,
Having a plurality of wipers that are in sliding contact with the discharge surface sequentially;
A wiping apparatus, wherein a contact angle of a wiper that first comes into sliding contact with the discharge surface is smaller than a contact angle of another wiper with respect to the discharge surface.   The wiping apparatus according to claim 1, wherein the ink contains a pigment as a color material and a polymer substance having an acid value of 200 or less.   The wiping apparatus according to claim 1, wherein the wiper is formed of a blade-like rubber-like elastic body.   The wiping device according to any one of claims 1 to 3, wherein a contact angle of the first wiper with respect to the discharge surface is 30 degrees or less.   The wiping device according to claim 3 or 4, wherein the hardness of the wiper that contacts first is lower than the hardness of another wiper.   The wiping device according to any one of claims 3 to 5, wherein a free length of the wiper that contacts first is longer than a free length of another wiper.   The wiping device according to any one of claims 1 to 6, wherein the plurality of wipers are positioned and fixed to each other.   The wiping device according to any one of claims 1 to 6, wherein the plurality of wipers are integrally formed.   The wiping apparatus according to claim 1, wherein the discharge surface has water repellency. In an inkjet recording apparatus that performs recording by discharging ink from a recording head to a recording medium,
An ink jet recording apparatus comprising the wiping apparatus according to claim 1.

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