JP4799331B2 - Inkjet head cleaning method and inkjet recording apparatus - Google Patents

Description

  The present invention relates to an ink jet head cleaning method and an ink jet recording apparatus. Specifically, the present invention efficiently removes ink residues and the like attached to the surface (hereinafter also referred to as an ejection surface) of an inkjet head (hereinafter also referred to as a recording head or simply a head). It is related to the technology to make it.

  Since the ink jet recording system is a system that converts input image data into an output image through liquid ink as a medium, a cleaning technique for a recording head that ejects ink is a very important factor. The main problems that require cleaning are briefly described as follows.

  A recording head for ink ejection records from a fine nozzle (hereinafter collectively referred to as an ejection port, a liquid path communicating therewith, and an element for generating energy used for ink ejection unless otherwise specified). Ink is directly discharged onto a medium. Accordingly, the ejected ink may hit the recording medium and bounce off, or when ink is ejected, fine ink droplets (satellite) may be ejected in addition to the main ink involved in recording and drift in the atmosphere. Then, these may become ink mist and adhere around the ink discharge port of the recording head. In addition, dust or the like drifting in the air may adhere. As a result, the attached ink pulls the ejected main ink droplets, thereby changing the ink ejection direction, that is, preventing the straight travel of the main ink droplets.

  Therefore, as a cleaning technique for solving this problem, in the ink jet recording apparatus, the ejection surface of the recording head is swept with a wiping member (wiper blade) made of an elastic material such as rubber at a predetermined timing to remove the deposits. What is called wiping is adopted.

  On the other hand, recently, ink (pigment-based ink) containing a pigment component as a coloring material has been increasingly used for the purpose of improving the recording density, water resistance, light resistance and the like of recorded matter. The pigment-based ink is obtained by dispersing a color material that is originally solid in water by introducing a functional group on the surface of the pigment or the pigment. Therefore, the dried pigment ink, which is dried by evaporation of the water in the ink on the ejection surface, causes more damage to the ejection surface than the dry fixed matter of the dye-based ink in which the coloring material itself is dissolved at the molecular level. . In addition, there is a property that the polymer compound used for dispersing the pigment in the solvent is easily adsorbed to the ejection surface. This is a problem that occurs in addition to pigment-based inks when a high molecular compound is present in the ink as a result of adding a reaction liquid to the ink for the purpose of adjusting the viscosity of the ink, improving light resistance, or the like.

  In response to these problems, various proposals have been made regarding a mechanism for cleaning the ejection surface accompanied by wiping.

  For example, in Patent Documents 1 and 2, a non-volatile solvent head liquid is applied to the ejection surface during wiping of the recording head, thereby reducing wear of the wiper and dissolving ink residues accumulated in the recording head. Discloses a technique for removing accumulated substances. Further, by forming a thin film of the head liquid on the recording head, it is possible to prevent foreign matter from adhering to the recording head, thereby improving the wiping property. The head liquid used for wiping is stored inside the printer body.

  Japanese Patent Application Laid-Open No. 2003-228561 discloses a content in which a wiping operation is performed on a discharge surface of a head after a head liquid made of a non-volatile solvent is applied to a wiper.

  Patent Document 4 discloses a content in which a solution is sprayed on a discharge surface, and insolubilized substances adhering to the discharge surface are removed with a wiper.

  Further, Patent Document 5 discloses the content of performing the wiping operation by dissolving the ink residue on the head in a non-volatile ink solvent held on the wiper.

Japanese Patent Laid-Open No. 10-138503 JP 2000-203037 A JP-A-10-138502 JP-A-10-151759 JP-A-11-254692

  As described above, all of Patent Documents 1 to 5 according to the related art disclose that the head liquid is applied to the ejection surface in relation to wiping. However, no consideration is given to the amount of head liquid applied.

  A sufficient amount of head liquid should be supplied to the ejection surface. This is because when the supply amount of the head liquid is small, the ejection surface is not sufficiently cleaned, and a situation in which the occurrence of ejection failure cannot be effectively prevented occurs.

  The present inventors examined the operation of transferring the head liquid to the wiper by bringing the wiper into contact with the head liquid holding member, and wiping the discharge surface with the wiper. It was found that it varies depending on the conditions, especially the environmental temperature. This is because the usage environment of the recording apparatus main body varies from high temperature to low temperature, and the physical property (viscosity) of the head liquid changes, so that the amount of transfer of the head liquid to the wiper varies first. That is, depending on the environmental temperature, a sufficient amount of head liquid does not transfer to the wiper, and as a result, a sufficient amount of head liquid cannot be supplied to the ejection surface.

  Therefore, it is conceivable to obtain a sufficient transfer amount or supply amount under any temperature condition, but when the temperature is high, an excessive amount of head liquid is transferred or supplied. In this case, the head liquid is not stored before the end of the life of the recording apparatus main body, and frequent replenishment of the head liquid is required, or the head liquid is used if the replenishment is not possible. Since it cannot be performed, there is a risk that cleaning will not be performed. Further, in order to avoid this, a large container for storing a considerable amount of head liquid is required, and there is a problem that the recording apparatus is increased in size.

  In view of the above, the present invention makes it possible to supply a necessary and sufficient amount of head liquid regardless of environmental conditions, thereby efficiently and surely removing ink residues from the ejection surface and sufficiently cleaning the ink. The goal is to achieve. Thereby, the change in the surface characteristics of the ejection surface is suppressed, and the initial performance of the recording head is maintained.

To this end, the present invention provides an ink jet recording apparatus comprising: a wiper for wiping the discharge port surface of the ink jet head; and a liquid storage portion for storing a head liquid supplied to the wiper by contacting the wiper. In
The liquid container has a first absorber made of a porous material and a second absorber made of a porous material having a pore size different from that of the first absorber material,
According to an environmental condition, the absorber that contacts the wiper is switched.
According to another aspect of the present invention , there is provided a method for cleaning an inkjet head in an inkjet recording apparatus, comprising: a wiper for wiping the discharge port surface of the inkjet head ; and a liquid storage portion for storing a liquid for the head.
Supplying the head liquid to the wiper by bringing the wiper into contact with the liquid container; and
A wiping step of wiping the discharge port surface with the wiper supplied with the head liquid;
With
The liquid container has a first absorber made of a porous material and a second absorber made of a porous material having a pore size different from that of the first absorber material,
In the supplying step, the absorber that contacts the wiper is switched according to environmental conditions.

  According to the present invention, a necessary and sufficient amount of head liquid is stably transferred to the wiper regardless of environmental conditions such as temperature, thereby supplying a necessary and sufficient amount of head liquid to the ejection surface of the head. Will be able to. As a result, it is possible to efficiently and effectively clean the head discharge surface, and it is possible to suppress deterioration of the discharge surface such as scraping of the discharge surface due to pigment agglomerates due to repeated wiping operations.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(Embodiment of the device)
FIG. 1 is a schematic perspective view of a main part of an ink jet recording apparatus according to an embodiment of the present invention.

  In the illustrated ink jet recording apparatus, the carriage 100 is fixed to the endless belt 5 and is movable along the guide shaft 3. The endless belt 5 is wound around a pair of pulleys 503, and one pulley 503 is connected to a drive shaft of a carriage drive motor (not shown). Therefore, the carriage 100 is reciprocally main-scanned in the left-right direction in the drawing along the guide shaft 3 as the motor is driven to rotate. On the carriage 100, a cartridge-type recording head 1 that detachably holds the ink tank 2 is mounted.

  FIG. 2 is a perspective view showing a configuration example of the recording head 1 that can be mounted on the carriage 100 in FIG. 1, and FIG. 3 is an exploded perspective view showing a configuration example of a head unit that is a component of the recording head 1.

  The recording head 1 according to this example includes a head unit 400 having an array of ejection ports that eject ink, and an ink tank 410 that stores ink and supplies ink to the head unit 400. In the recording head 1, the ink ejection port array provided in the head unit 400 faces the paper 6 as a recording medium, and the arrangement direction is different from the main scanning direction (for example, sub-scanning in which the recording medium 6 is transported). Is mounted on the carriage 100 so as to coincide with the direction). The number of sets corresponding to the ink color to be used can be provided as a set of the ink discharge port arrays and the ink tanks 410. In the illustrated example, six sets are provided corresponding to six colors (for example, black (Bk), cyan (C), magenta (M), yellow (Y), light cyan (PC), and light magenta (PM)). . In the recording head 1 shown here, an ink tank 410 independent for each color is prepared, and each is detachable from the head unit 400.

As shown in FIG. 3, the head unit 400 includes a recording element substrate 420, a first plate 430, an electric wiring substrate 440, a second plate 450, a tank holder 460, and a flow path forming member 470. A recording element substrate 420 having an ejection port array for each color ink is bonded and fixed onto a first plate 430 made of aluminum oxide (Al ₂ O ₃ ), and ink is supplied to the recording element substrate 420 here. An ink supply port 431 for this purpose is formed. Further, a second plate 450 having an opening is bonded and fixed to the first plate 430. The second plate 450 holds the electrical wiring board 440 so that the electrical wiring board 440 for applying an electrical signal for ejecting ink and the recording element board 420 are electrically connected. On the other hand, a flow path forming member 470 is ultrasonically welded to a tank holder 460 that holds the ink tank 410 in a detachable manner, thereby forming an ink flow path (not shown) extending from the ink tank 410 to the first plate 430.

  FIG. 4 is a perspective view showing a partially broken structure in the vicinity of the ejection port array for one color in the recording element substrate 420 shown in FIG. In FIG. 4, reference numeral 421 denotes a heating element (heater) that generates thermal energy that causes film boiling in the ink in response to energization as energy used to eject the ink. On the base 423 on which the heater 421 is mounted, a temperature sensor 428 for detecting the temperature of the head unit 400 and a sub-heater (not shown) for keeping the head or ink in accordance with the detected temperature are provided. It is done. Reference numeral 422 denotes an ink discharge port, and 426 denotes an ink flow path wall. Reference numeral 425 denotes an ejection port plate in which an ink ejection port 426 is formed in a state of facing each heater, and is disposed on the substrate 423 through a resin coating layer 427. In addition, a desired water repellent material is provided on the surface of the discharge port plate 425 (discharge surface facing the recording medium).

  In this example, two rows of heaters 421 to discharge ports 422 are arranged, and the heaters 421 to discharge ports 422 between the rows are arranged so as to be shifted by a half of the arrangement pitch in the arrangement direction, that is, the sub-scanning direction. Yes. Here, a resolution of 1200 dpi per color ink is realized by arranging 128 heaters 421 to ejection ports 422 per row at a density of 600 dpi. Then, the recording element substrate configuration corresponding to the six colors is arranged on the first plate 430.

  A method for creating the recording element substrate and the ejection surface will be described with reference to FIGS.

  FIGS. 5A and 5B are a schematic perspective view of the recording element substrate 420 and a schematic cross-sectional view taken along the line bb ′, respectively, and the base 1 in which the plurality of heaters 421 are made of silicon or the like. Arranged above (electrodes and the like for energizing the heater are not shown).

  FIG. 5C is a diagram in which an ink flow path pattern forming material 433 is arranged on the base 423 shown in FIG. 5B by a positive resist. The ink flow path pattern forming material 433 includes a common liquid chamber for temporarily holding ink to be supplied to each ejection port, and an ink flow path that branches into a plurality from the common liquid chamber and causes film boiling by the heater. It corresponds to the pattern for composition.

  FIG. 5D shows a nozzle forming material 434 made of a negative resist on the ink flow path pattern forming material 433 shown in FIG. 5C and a water repellent material 435 which is a negative resist containing fluorine and siloxane molecules. It is a figure which shows the state which formed. In the present embodiment, the discharge port plate 425 is formed of these materials. By using the water repellent material 435 in this way, it becomes possible to impart water repellency to the ejection surface. Alternatively, in this step, it is possible to change the discharge surface to a desired surface characteristic by changing the material combined with the nozzle forming material. Further, when the discharge surface does not require water repellency, it is possible to form the discharge surface without water repellency by using only the nozzle material without using the water repellent material.

  FIG. 5E shows a state in which an ink ejection port 422 and an ink path leading to the ink ejection port 422 are formed by a photolithography method with respect to the state of FIG. Further, in FIG. 5F, an ink supply port 424 is formed by anisotropic etching of silicon from the back surface side of the substrate 423 while appropriately protecting the discharge port forming surface side and the like with respect to the state of FIG. It is a figure which shows the state which carried out. FIG. 5G shows a state where the ink flow path pattern forming material 4333 is eluted with respect to the state of FIG. The recording element substrate 420 thus completed is placed on the first plate 430, and further connected to each part, electrically mounted, and the like, thereby obtaining the configuration shown in FIG.

  Referring again to FIG. 1, the recording medium 6 is intermittently conveyed in a direction orthogonal to the scanning direction of the carriage 100. The recording medium 6 is supported by a pair of roller units (not shown) provided on the upstream side and the downstream side in the transport direction, and is transported in a state where a certain tension is applied and flatness with respect to the ink ejection port is ensured. Then, recording on the entire recording medium 6 is performed while alternately repeating recording of a width corresponding to the array width of the ejection ports of the head unit 1 accompanying the movement of the carriage 100 and conveyance of the recording medium 6. The illustrated apparatus is provided with a linear encoder 4 for the purpose of detecting the movement position of the carriage in the main scanning direction.

  The carriage 100 stops at the home position as necessary at the start of recording or during recording. A maintenance mechanism 7 including a cap and a cleaning device described later with reference to FIG. 6 is installed in the vicinity of the home position. The cap is supported so as to be movable up and down, and in the raised position, the ejection surface of the head unit 1 can be capped to protect it during non-recording operation or to perform suction recovery. During the recording operation, the lower position is set to avoid interference with the head unit 1, and preliminary ejection can be received by facing the ejection surface.

(Configuration of cleaning device)
FIG. 6 is a schematic side view showing an example of the cleaning device according to the present invention as seen from the direction of the arrow in FIG.

  Wiper blades 9A and 9B made of an elastic member such as rubber are fixed to the wiper holder 10, and the wiper holder 10 is in the horizontal direction in the figure (the direction in which the ink discharge ports are arranged orthogonal to the main scanning direction of the recording head 1). It is movable. The wiper blades 9A and 9B have different heights. When the wiper blades 9A and 9B are in sliding contact with the ejection surface 11 of the recording head 1, the former is bent relatively large and the side (abdomen) is bent, and the latter is bent relatively small and the tip The part (edge part) comes into sliding contact.

  Reference numeral 12 denotes a liquid storage portion for transferring the head liquid by contact with the wiper blade, and can be configured to store the head liquid in a tank (container). Also, a transfer amount stabilizing member 50 including an absorber that holds a predetermined amount of head liquid and exudes an appropriate amount of head liquid in response to contact with the wiper blade, at least in the contact portion It is.

  In the cleaning operation, first, the head liquid is transferred by bringing the wiper blade into contact with the liquid storage unit 12 in a state where the recording head 1 is not in the position shown in the drawing. Then, the wiper holder 10 and the recording head 1 are set to the illustrated positions, and the wiper holder 10 is moved in the arrow direction. In the course of this movement, the relatively long wiper blade 9A first comes into sliding contact with the discharge surface 11, and the relatively short wiper blade 9B follows.

  That is, the wiper blade 9A is bent relatively large, and its side portion (abdomen) is in sliding contact with the ejection surface 11, and the head liquid 16 is efficiently transferred and applied (supplied) to the ejection surface 11. Even if there is an ink residue 1104 on the ejection surface 11, it is dissolved by the application of the head liquid 16. In this state, the tip end (edge) of the wiper blade 9B abuts on the ejection surface 11, whereby the dissolved ink residue is efficiently scraped, and the recording head is cleaned.

  As a result of the wiping, a dissolved ink residue is adhered on the wiper blade 9B. When this is caused to flow down along the wiper blade according to the action of gravity, a member for receiving this can be provided below the position of the illustrated wiper holder 10.

  However, a means (sponge, scraper, etc.) or a process for positively receiving the melt from the wiper blade by abutting against the wiper blades 9A and 9B in the vicinity of the liquid storage unit 12 to clean the wiper blade is provided. It is desirable. If the head liquid is transferred after the wiper blades 9A and 9B are in a clean state, it is possible to immediately prepare for the next wiping operation.

  Next, the transition amount stabilizing member 50 according to the main part of the present embodiment will be described.

  The head liquid is transferred from the absorber to the wiper blade due to the interfacial tension of the meniscus of the head liquid formed at the contact portion between the absorber and the wiper blade. However, as a drag force, a pressure loss occurs in the head liquid storage unit 12 and the viscosity of the head liquid increases particularly in a low temperature environment. The pressure tends to increase, and the liquid for the head is not smoothly exuded.

  Therefore, by providing the transition amount stabilizing member 50 as a mechanism for controlling the dynamic negative pressure in the liquid storage unit 12, the amount of head liquid leaching is made constant, and the head liquid is transferred to the wiper blade. As a result, the supply amount to the discharge surface 11 is stabilized.

  FIG. 7 is a plan view showing a configuration example of the transition amount stabilizing member 50, and FIGS. 8A and 8B are schematic side sectional views for explaining the operation. The transition amount stabilizing member 50 of the present example has a plate shape having two absorbers 51 and 52 with different capillary forces. The member 50 is attached so as to be movable (slidable) with respect to the liquid storage portion 12, and as shown in FIGS. 8A and 8B, any one of the members 50 is connected to the head liquid outlet 12 A of the liquid storage portion 12. The absorber can be selectively positioned. Therefore, when a wiper blade (only the wiper blade 9A is shown in FIG. 8) contacts with a constant force, an amount of head liquid corresponding to the capillary force is absorbed from the absorber facing the outlet 12A. It exudes and metastasizes.

  The reason why the two absorbers having different capillary forces are provided is to transfer a certain amount of head liquid regardless of the environmental temperature. That is, the reference for which absorber is switched so as to face the outlet 12 is a predetermined environmental temperature. For example, when the predetermined temperature is set to 20 ° C. and the temperature is lower than 20 ° C., an absorption body having a small capillary force, that is, leaching easily occurs (for example, the absorbent body 51). A body (eg, absorber 52) may be used. Here, it is conceivable that the standard use environment is 20 ° C. or higher, and the absorbent body 52 has a capillary force set so that an appropriate amount of exudation occurs in this standard use environment. On the other hand, the absorbent body 51 has a capillary force set so that an amount of exudation equivalent to that in a normal use environment can be obtained even in a relatively low temperature (less than 20 ° C.) environment. As a result, it is possible to prevent the transfer amount of the head liquid to the wiper blade from being reduced in a low-temperature environment, and to obtain a stable transfer amount, and hence a given amount to the ejection surface.

  Note that the moving direction of the transition amount stabilizing member 50 shown in FIG. 8A is merely an example, and the two absorbers are juxtaposed in a direction orthogonal to the drawing and moved in the same direction. May be. In addition, the absorber may be switched by rotating, for example, rotating the transition amount stabilizing member 50 instead of moving (sliding) in the linear direction.

  In addition, by providing three or more absorbers having different capillary forces, it is possible to stabilize the amount of transition in response to changes in environmental temperature.

  Furthermore, as shown in FIG. 9, a porous absorbent body 53 having a capillary force changed continuously or stepwise by changing the pore size is provided so that the amount of movement of the transition amount stabilizing member 50 can be adjusted. Thus, it is possible to stabilize the amount of transition in response to changes in environmental temperature.

  In addition, instead of providing multiple absorbers with different capillary forces or absorbers with continuously changing capillary forces, a mechanism for appropriately compressing the absorber according to temperature is provided to adjust the pore size in the absorber. It is also possible to do.

  In addition, factors other than the temperature condition can be taken into account as a factor for changing the amount of transfer of the head liquid to the wiper blade. For example, if the physical properties of the liquid for the head change with respect to conditions such as humidity, and this changes the amount of transfer, the capillary force may be changed in accordance with other conditions instead of or together with the temperature condition. Is possible.

(Details of cleaning operation and suitable conditions)
The cleaning operation will be described with reference to FIGS. 10 (a) to 10 (c) and FIG.
In the cleaning operation, first, the head liquid is transferred by bringing the recording head 1 into a standby state at a position away from the home position or by bringing a wiper blade into contact with the liquid storage unit 12 before moving to the home position ( FIG. 10 (a)). At this time, the necessary and sufficient amount of the liquid for the head is stably transferred by the wiper blade coming into contact with the absorber or the absorber portion having an appropriate capillary force according to the environmental temperature.

  Then, the wiper holder 10 is returned to the position shown in FIG. 6, the recording head is set to the home position, and then the wiper holder 10 is moved again in the direction of the arrow. In the course of this movement, first, a relatively long wiper blade 9A is brought into sliding contact with the ejection surface 11 in advance. At this time, the head liquid 16 that has been transferred to the wiper blade 9A is applied to the ejection surface 11, where And mixed with the ink residue adhering to the ink. Then, by continuing the movement of the wiper holder 10, the subsequent wiper blade 9B scrapes off the mixture of the head liquid and the ink residue (FIGS. 10B and 11).

  At this time, the wiper blade 9A is bent relatively large, and its side portion (abdomen) is in sliding contact with the ejection surface 11, and the head liquid 16 is efficiently transferred, applied, or supplied to the ejection surface 11. At this time, since a necessary and sufficient amount of head liquid is held by the wiper blade, the amount of head liquid applied to the ejection surface is also necessary and sufficient. Therefore, even if there is an ink residue 1104 on the ejection surface 11, it is efficiently dissolved by the application of the head liquid 16.

  In this state, the tip end (edge) of the wiper blade 9B contacts the ejection surface 11 to efficiently scrape the dissolved ink residue and clean the recording head (FIG. 10C). , FIG. 11). At this time, the surface characteristic of the wiper blade 9B is made higher than the surface tension of the ejection surface 11 (wetting with respect to ink is made higher than that of the ejection surface). As a result, the dissolved ink residue easily moves from the ejection surface 11 to the wiper blade 9B, and the dissolved ink residue can be efficiently removed from the ejection surface.

  In the above configuration, the head liquid transfer wiper blade 9A is compared by increasing the amount of penetration (height from the position corresponding to the ejection surface to the tip of the wiper blade) so as not to have ink scraping ability. The abdomen is slidably in contact with the discharge surface. As a result, the head liquid 16 passes through the ink residue. At this time, even if a slight movement occurs in the ink residue 1104 on the ejection surface 11, it is not substantially removed.

  Thus, when the liquid 16 for head is apply | coated to the discharge surface 11 with the wiper blade 9A, and mixing agitation with the ink residue etc. which adhered to the discharge surface 11, it is preferable to set it as abdominal part sliding contact. The wiper blade 9A has such a wiping condition and is configured to slip through the ink residue together with the head liquid, so that the head liquid can be uniformly applied to the ink residue. Easier to dissolve in liquid. That is, by performing the abdomen sliding contact of the wiper blade 9A, the head liquid passes between the wiper blade 9A and the ejection surface 11, and the ink residue and the head liquid are rubbed against the ink residue at that time. Agitation occurs. As a result, the mixing is promoted, and the ink residue is taken in the head liquid.

  Here, it is preferable that the relationship of the surface tension of the ejection surface 11 <the surface tension of the ink <the surface tension of the head liquid is satisfied. When this condition is satisfied, the ink residue having a lower surface tension than the head liquid dissolves in the head liquid having a higher surface tension. That is, since the surface tension is higher than that of the ink residue alone, the surface tension difference from the ejection surface 11 is larger than that of the ink residue alone. Accordingly, the wetness of the discharge surface is reduced, so that the ink residue mixed liquid can be easily moved on the discharge surface. For this reason, the ink residue mixed liquid can be easily removed (scraped) from the ejection surface 11 by being pushed by the subsequent movement of the wiper blade 9B.

  Such an effect is preferably exhibited in a state where a large amount of head liquid is applied. Specifically, a range of 0.1 to 100 times the amount of ink residue on the ejection surface is preferable. If it says from the result using the printer of the Example mentioned later, the application amount of 0.05-0.5g is preferable. And this embodiment can maintain the application quantity set appropriately in a necessary and sufficient quantity irrespective of environmental temperature.

  As the head liquid, any suitable liquid can be adopted as long as it can be used for effective dissolution of ink residues. For example, glycerin may be used alone, or a glycerin aqueous solution may be used.

  For the wiper blade 9B, in order to improve the scraping property of the ink on the ejection surface 11, the amount of penetration is adjusted so that the edge portion of the tip abuts on the ejection surface so that the remaining wiping hardly occurs. . By performing the edge contact in this manner, the mixture of the head liquid and the ink residue is smoothly removed, unlike the application and mixing stirring function of the wiper blade 9A.

  With the above configuration, it is possible to reliably apply the head liquid to the ejection surface 11 and mix and agitate it with the ink residue. Therefore, it is possible to easily remove the ink residue and the like adhered to the ejection surface. Become. With this effect, the initial surface characteristics (for example, water repellency) of the ejection surface can be maintained even after a large number of wiping operations, and stable recording performance can be maintained over a long period of time. Further, the effect of the present invention is that no wiping residue occurs even when an ink containing a polymer is used to disperse a pigment as a color material, or when an ink containing a dye is used as a color material. The head can be cleaned. These are effective because the stability of the recording performance is improved.

  In order to give the preceding wiper blade 9A a function of applying, mixing and stirring the head liquid, and to give the subsequent wiper blade 9B a scraping function, the amount of intrusion is adjusted as described above. The material and shape of the seed wiper blade may be appropriately changed. In addition, the number of wiper blades is not limited to two as long as both functions can be effectively performed, and may be a single wiper blade or three or more wiper blades.

  In this embodiment, wiping is performed in a direction parallel to the nozzle arrangement direction (left and right direction in FIG. 4). However, the direction can be determined as appropriate, and wiping may be performed in a direction perpendicular to the nozzle arrangement direction.

(Control system configuration)
A configuration of a control system and a control procedure that can be preferably applied in carrying out the present invention will be described.

FIG. 12 is a block diagram illustrating a configuration example of a control system of the ink jet recording apparatus.
In the figure, reference numeral 1005 denotes a control unit. The control unit 1005 includes an MPU 1000 that controls each unit when a control procedure described later with reference to FIG. 13 is executed. A ROM 1001 stores a program corresponding to the control procedure, other fixed data, and the like. Further, the control unit 1005 includes a RAM 1002 used as a work area at the time of execution of a control procedure executed by the MPU 1000, a nonvolatile memory 1004 such as an EEPROM for holding necessary information even when the apparatus is turned off, and the like. .

  An operation unit 1107 is connected to the control unit 1010, and the operation unit 1107 includes a switch (power switch or the like) that receives a user operation, a display unit for presenting information to the user, and the like. In addition, a host device 1200 such as a computer or a digital camera is connected to the control unit 1010. From the host device 1200, a recording information signal including a recording instruction signal (command) and recording data can be received. Further, status information on the recording device side can be sent to the host device 1200 as necessary.

  A printer unit 1023 is connected to the control unit 1005 via an interface unit 1003. The printer unit 1023 includes each part of the recording apparatus shown in FIGS. In the printer unit 1023, reference numeral 1025 denotes a head driver for driving the recording head 1. Reference numeral 1010 denotes a carriage motor serving as a driving source for movement (main scanning) of the carriage 100, and 1027 denotes a motor driver for driving the carriage motor. Reference numeral 1011 denotes a conveyance motor serving as a driving source for conveyance (sub-scanning) of the recording medium, and 1028 denotes a motor driver for driving the conveyance motor.

  Reference numeral 1029 denotes a maintenance mechanism, which includes a cap 7, a head liquid storage unit 12, and wiper blades 9A and 9B. Reference numeral 1030 denotes a driving unit for driving each part of the maintenance mechanism 1029, and includes a lifting mechanism for the cap 7, a moving mechanism for the transition amount stabilizing member 50, a moving mechanism for the wiper holder 10, and the like.

  Reference numeral 1032 denotes a temperature sensor for detecting the environmental temperature. The arrangement site can be determined as appropriate, but from the viewpoint of stabilizing the amount of transfer of the head liquid to the wiper blade, it is preferably provided in the head liquid storage portion 12 or in the vicinity thereof.

  FIG. 12 shows only main parts related to the processing of this embodiment. In practice, however, it is of course possible to include a sensor group such as a carriage home position sensor and a capping sensor which are used as a reference when controlling each part, and other necessary means.

  FIG. 19 is a flowchart illustrating an example of a control procedure that can be executed prior to the wiping process described with reference to FIGS. When this procedure is activated, first the environmental temperature is detected by the temperature sensor 1032 (step S1). Then, based on the temperature information, the absorber (the absorber 51 or 52 in FIG. 7) or the absorber portion (the portion on the absorber 53 in FIG. 9) from which the head liquid is leached is determined (step S3). Then, the transfer amount stabilizing member 50 is moved so that the determined absorber or absorber portion is positioned at the ink outlet 12A of the liquid storage unit 12 (step S5), and the execution of the wiping operation as described above is permitted. (Step S7).

  The determination of the absorber or the driving of the transition amount stabilizing member as described above may be performed not only by a combination of software processing but also by a hardware configuration. For example, this may include a comparator that compares the detected temperature with the reference temperature and an actuator that is displaced to a position corresponding to the comparison output.

(Example)
Hereinafter, the effects of the present invention will be verified by giving more specific examples.

Surface tension First, the surface tension related to the cleaning property will be described.
In measuring the surface tension of the discharge surface (solid surface tension), first, a wetting test standard solution (wetting reagent) described in JIS K6768-1971 was applied to the discharge surface with a cotton swab. And it was performed by observing the degree of repelling of the wet reagent in the state immediately after application (the state of “tailing” of the wet reagent accompanying the movement of the cotton swab during application). The measurement method was determined to be “repelling” when the wet reagent formed a round droplet immediately after application, and “wet” when the immediately following droplet was not a perfect circle. The measurement is performed in order from the wetting reagent with the lowest surface tension, and the surface tension of the wetting reagent applied immediately before the wetting reagent applied when it was first judged to be “played” was defined as the surface tension of the measured object, that is, the discharge surface. .

  A surface tension meter “CBVP-A3” manufactured by Kyowa Interface Science was used for measuring the surface tension of the ink and the head liquid.

  The surface tensions of the recording head ejection surface, ink, and head liquid applied to the examples described below are as follows.

Discharge surface tension: Fγs = 22 dyn / cm
Ink surface tension: Iγs = 28 to 40 dyn / cm
Liquid surface tension for head: Rγs = 64 dyn / cm
Wiping endurance test Using the following head liquid and ink, the wiping endurance test was conducted at different environmental temperatures. Here, assuming an actual use environment, the discharge surface cleaning operation is continuously performed 5000 times in combination with the recording operation using a printer, and the recording state before and after the test is evaluated to evaluate the discharge surface characteristics. The change was confirmed.

The main body used for the evaluation main body evaluation was obtained by modifying the recovery system of an inkjet printer “PIXUS850i” manufactured by Canon Inc. as shown in FIG.

The recording head used for the evaluation head evaluation was a recording head made of a water-repellent material whose discharge surface is a negative resist containing fluorine and siloxane molecules.

Evaluation ink was evaluated by mounting an ink having the composition shown in Table 1 at the color tank position of the recording head.

10 parts of carbon black having a specific surface area of 210 m ² / g and a DBP oil absorption of 74 ml / 100 g and a 10% sodium hydroxide neutralized aqueous solution of a styrene-acrylic acid copolymer having an acid value of 200 and a weight average molecular weight of 10,000. Furthermore, after mixing 70 parts of ion-exchanged water and dispersing for 1 hour using a sand grinder, coarse particles are removed by centrifugation, and pressure filtration is performed with a micro filter (made by Fuji Film) having a pore size of 3.0 μm. Thus, a pigment dispersion 1 containing a resin-dispersed pigment was obtained. The physical properties of the obtained pigment dispersion 1 were a solid content of 10%, pH = 10.0, and an average particle size of 120 nm.

The liquid for liquid head head with glycerin.

Wiping conditions The following two wiper blades were used.

・ First wiper blade (corresponding to wiper blade 9A whose abdomen is in sliding contact with the discharge surface)
Material: Urethane, Hardness: 75 °, Thickness: 0.5mm, Width: 9mm
Free length: 6 mm, penetration depth: 1.75 mm
・ Second wiper blade (corresponding to wiper blade 9B whose edge is in sliding contact with the discharge surface)
Material: Urethane, Hardness: 75 °, Thickness: 0.5mm, Width: 9mm
Free length: 5 mm, penetration depth: 0.6 mm
Evaluation results are evaluated by the change in the recording state before and after the endurance test when the temperature condition is 30 ° C. (using an absorber having a relatively high capillary force) and 15 ° C. (using an absorber having a relatively low capillary force). It was done by confirming. At this time, the nozzle check pattern built in the printer main body was recorded on a high-quality exclusive paper, and the deviation of the dot formation position was observed. Evaluation was made in the following three stages.
○: The nozzle check pattern is not twisted and printed well (no change from recording when genuine ink is used in an unmodified printer).
Δ: Twist has occurred in part of the nozzle check pattern.
X: A twist has occurred in the entire nozzle check pattern.

  As a result, even after the wiping operation was continuously performed 5000 times for all the combinations of the examples, the recording performance was maintained at a level at which there is no problem in practical use in all the combinations as in the initial case. That is, substantial image deterioration such as a large number of pigment particles adhering to the ejection surface, non-ejection or twisting due to a decrease in water repellency was not confirmed. Furthermore, when the environment was variously changed in the temperature range of 15 ° C. to 30 ° C. and the humidity range of 10% to 90% and the wiping operation was continuously performed 1000 times, no deterioration was observed in any case.

  In addition, the amount of transfer of the liquid for the head to the wiper blade is stabilized against changes in the environmental temperature, and the desired amount of transfer can be obtained even at a low temperature (15 ° C.). By adjusting so that there was not, it was possible to consume the head liquid efficiently. That is, for the same number of wiping operations, the consumption of the liquid for the head could be made almost uniform at any temperature.

As described above, by using the configuration shown in the embodiment or the example of the present invention, the amount of the liquid for the head can be adjusted, and the wiper blade or the recording head can be fixed regardless of the environmental temperature condition. An amount of head liquid can be supplied. As a result, even when pigment ink is used, the head ejection surface can be cleaned, so that no wiping residue that adversely affects the ink ejection operation occurs. As a result, it is possible to suppress deterioration of the discharge surface, such as polymer adhesion to the discharge surface 11 and scraping of the discharge surface due to pigment agglomerates associated with repeated wiping operations.

1 is a schematic perspective view of a main part of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration example of a recording head that can be mounted on a carriage of the ink jet printer of FIG. FIG. 2 is an exploded perspective view illustrating a configuration example of a recording head that is a component of the recording head in FIG. 1. FIG. 4 is a perspective view showing a partially broken structure near a discharge port array for one color in a recording element substrate applied to the recording head of FIG. 3. (A)-(g) is explanatory drawing of the manufacturing process of the recording element board | substrate of FIG. It is a typical side view which shows an example of the cleaning apparatus applied to the recording device of FIG. FIG. 7 is a plan view illustrating a configuration example of a transfer amount stabilizing member in a head liquid storage portion of the cleaning device of FIG. 6. (A) And (b) is a typical sectional side view for demonstrating operation | movement of the transition amount stabilization member of FIG. FIG. 8 is a plan view showing another configuration example of the transfer amount stabilizing member in the head liquid storage portion of the cleaning device of FIG. 6. (A)-(c) is a schematic diagram for demonstrating operation | movement of the cleaning apparatus of FIG. It is a schematic diagram for demonstrating operation | movement of the cleaning apparatus of FIG. 1 is a block diagram illustrating a configuration example of a control system of an ink jet recording apparatus to which the present invention is applicable. 13 is a flowchart illustrating an example of a control procedure before wiping processing by the control system configuration of FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording head 9A, 9B Wiper blade 10 Wiper holder 11 Discharge surface 12 Liquid storage part for heads 50 Liquid transfer amount stabilization apparatus for heads 51-53 Absorber 1032 Temperature sensor

Claims (6)

In an ink jet recording apparatus comprising: a wiper for wiping the discharge port surface of an ink jet head; and a liquid storage portion for storing a head liquid supplied to the wiper by contacting the wiper.
The liquid container has a first absorber made of a porous material and a second absorber made of a porous material having a pore size different from that of the first absorber material,
An ink jet recording apparatus, wherein the absorber that contacts the wiper is switched according to environmental conditions. The inkjet recording apparatus according to claim 1, wherein the second absorber has a larger pore size than the first absorber. The inkjet recording apparatus according to claim 2, wherein the environmental condition is a temperature of a use environment . When the temperature of the usage environment is equal to or higher than the predetermined temperature, the wiper is brought into contact with the first absorber, and when the temperature of the usage environment is lower than the predetermined temperature, the wiper is applied to the second absorber. The inkjet recording apparatus according to claim 3, wherein the inkjet recording apparatus is in contact with the inkjet recording apparatus. The ink jet recording apparatus according to claim 1, wherein the ink ejected from the ink jet head includes a pigment as a coloring material . In a method for cleaning an ink jet head in an ink jet recording apparatus, comprising: a wiper for wiping the discharge port surface of the ink jet head; and a liquid storage portion for storing a liquid for the head.
Supplying the head liquid to the wiper by bringing the wiper into contact with the liquid container; and
A wiping step of wiping the discharge port surface with the wiper supplied with the head liquid;
With
The liquid container has a first absorber made of a porous material and a second absorber made of a porous material having a pore size different from that of the first absorber material,
A method for cleaning an ink jet head, characterized in that, in the supplying step, the absorber that contacts the wiper is switched according to environmental conditions.

Images