JP5148311B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that suppresses thickening of ink stored in a nozzle of an ink jet recording head.

  Ink jet recording apparatuses that are generally popular are configured to match the properties of the ink used. In particular, in the maintenance system of the recording head, when the ink to be used is an ink containing a volatile component such as water such as a water-based ink, it is essential to include a cap for sealing the nozzle portion of the recording head. . For example, in water-based ink, a phenomenon called thickening occurs in which the viscosity of the ink increases due to evaporation of water, which is a main component. When this ink thickening occurs inside a nozzle composed of a large number of fine holes for ejecting ink provided in the recording head, the nozzle is clogged and proper ejection of ink droplets is hindered. Droplet ejection and flight bends occur.

  In order to cope with this ink thickening, the evaporation of moisture is suppressed by covering the nozzle portion with a cap at the time of non-ejection. This cap is made of an elastic body such as rubber, and has a nozzle plate peripheral part including a number of nozzles provided in the recording head and a mask part disposed in the vicinity of the peripheral part to generate a thickening. Sealed to prevent water evaporation.

  However, it is difficult to secure a perfect seal by contacting the elastic rubber against the rigid nozzle plate or mask plate due to the shape of the mounting surface and the elastic deterioration of the rubber. When air enters and exits from the water, moisture escapes from the gap to the outside of the cap. Further, since the sealing performance is not certain, the amount of moisture retention changes depending on the elapsed time of the cap attachment, and variations in image quality at the start of printing may occur.

  Several approaches have been proposed to improve these problems. For example, Patent Document 1 proposes a technique in which a cap filled with ink is applied to the nozzle forming surface of a recording head and sealed when the recording head does not eject over a long period of time. The ink in the cap maintains the moisture retention of the ink around the nozzle and prevents thickening. If the amount of ink adhering to the periphery of the nozzle when the cap is removed is small, the process can proceed to image formation as it is, but if the amount of adhesion is large, it must be removed by wiping or suction.

As a conventional technique different from this, for example, Patent Document 2 discloses an example in which the nozzle portion is sealed by a guide portion that forms an ink liquid film around the nozzle portion of the recording head to prevent the nozzle portion from thickening. Have been described. Furthermore, Patent Document 3 describes that a rib is provided inside the cap and the gap between the bottom ink discharge port is made small, so that the discharge port is closed with ink by capillary action, thereby preventing thickening. ing.
JP 2003-291359 A JP 2002-254665 A Japanese Patent No. 2878214

  As described above, for water-based inks, various methods have been proposed to prevent the reduction of volatile components and to prevent ink thickening by sealing the nozzle and its surroundings. It is important to ensure sealing so as to prevent ventilation with outside air.

  Since the method of filling the cap with ink is performed every time the cap is mounted, a large amount of wasted ink is generated. Accordingly, if it is used in a high-speed color ink jet recording apparatus using a large number of fixed type long line heads, it consumes a considerable amount of ink, which increases the running cost.

  Since the technique proposed in Patent Document 2 has a special structure in the recording head, selection restrictions and structural restrictions occur in the recording head that can be employed. Moreover, since the protrusion is provided around the nozzle, the normal wiping process cannot be used. Even if the nozzle plate is provided with water repellency so as to cope with this, it is technically difficult to secure it over a long period of time, and if it is replaced, it will affect the running cost.

  Further, in the technique proposed in Patent Document 3, a method in which a rib is provided inside the cap and the discharge port is closed with ink by a capillary phenomenon causes a capillary phenomenon when a pressure change occurs due to a temperature change in the cap. It is expected that it is difficult to secure an ink thin film over a long period of time. Moreover, the conventional problem remains about the adhesiveness of a cap.

  Accordingly, an object of the present invention is to provide an ink jet recording apparatus that can suppress ink thickening in a nozzle portion of a recording head and can always obtain a high-quality image.

An ink jet recording apparatus according to the present invention includes a recording head including a nozzle plate in which a plurality of nozzles for forming an image by ejecting ink onto a recording medium are formed in a row, and has an elevating function. An ink guide part that is separated from the nozzle and the ink guide by allowing the ink to flow out of the nozzle when the ink guide part approaches the recording head. An ink liquid column for sealing is formed.

The nozzle plate is further sealed to prevent ink thickening inside the nozzle, and when the cap is in close contact with the nozzle plate, a sealed space is formed in the cap. The ink liquid column is formed in the sealed space.

  According to the present invention, it is possible to provide an ink jet recording apparatus capable of stably suppressing ink thickening inside a nozzle of a recording head with a small amount of ink and always performing high-quality image formation. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of a recording head and a cap in the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram showing a cross-sectional configuration of the recording head and the cap. In the present embodiment, it is assumed that components of a normal image forming apparatus (a recording medium supply mechanism, a transport mechanism, a discharge mechanism, a maintenance mechanism, etc.) are mounted. The recording head related to the cap will be illustrated and described.

In the recording head 1 according to the present embodiment, a rectangular main body 10 having a hollow inside and formed of a metal material or a resin material, and nozzles 11 made of a large number of fine holes and ejecting ink are arranged in a row (nozzle row). A nozzle plate 12 provided on a surface facing a recording medium (not shown) and a common ink chamber 13 for storing ink in a cavity provided in the head body 10 and supplying ink to each nozzle 11. An ink supply port 14 that supplies ink 3 into the common ink chamber 13 from an ink supply system, which will be described later, and an ink discharge port that discharges ink 3 that has not been used for image formation from the common ink chamber 13 and returns to the ink supply system 15 and the piezo part 6 provided in each nozzle 11.
The recording head 1 of the present embodiment is an example in which the ink supply port 14 and the ink discharge port 15 are provided, but two of them may be used as the ink supply port 14. Pressurization to the ink 3 in the common ink chamber 13 described later closes the ink path of the ink discharge port 15 or closes the air release valve of the return ink tank 52 described later and stops the pump.

  For example, the recording head 1 has a length equal to or larger than the width of the recording medium, is fixed to a frame or the like of an image forming apparatus (not shown), is transported, and the ink 3 is ejected onto a recording medium that passes in front of the nozzle. Form. Further, a plurality of short recording heads shorter than the width of the recording medium may be used, and the recording heads may be arranged to be longer than the width of the recording medium.

  The cap 2 is formed of an elastic member such as rubber and includes a cap exterior portion 21 that constitutes an exterior; a Y-shaped ink guide 22 that is provided inside the cap exterior portion 21 and receives the purge ink discharged from the nozzle 11; An ink discharge pipe 24 is provided integrally with the ink guide 22 and discharges the purge ink to an external waste liquid bottle (not shown). The cap 2 forms a sealed space that becomes a cap internal space 23 when the cap exterior portion 21 is brought into close contact with the recording head 1.

  As shown in FIG. 2, the ink 3 supplied from an ink supply system (not shown) fills the common ink chamber 13 through the ink supply port 14 of the recording head 1. The nozzle plate 12 is provided so as to close the lower surface of the common ink chamber 13, and the piezo unit 6 is disposed in each nozzle 11. A channel 7 formed by a hole opened in the piezo part 6 is formed to constitute a nozzle 11. In the present embodiment, as shown in FIG. 2, two nozzle rows are formed as an example. In each nozzle 11, a meniscus is formed by the ink 3. At the time of image formation, the ink 3 pressurized by the driving of the piezo 6 flies linearly as ink droplets from the nozzle 11 and lands on the recording medium.

  The ink guide 22 in the cap 2 is disposed at a position close to the ink ejection direction of the nozzle 11 (directly below in FIG. 2). The ink guides 22 are arranged so as to be opposed to the two rows of nozzles 11. In the present embodiment, the ink guides 22 are substantially Y-shaped and symmetrical when viewed from the cross section.

  The ink guide 22 is narrowed downward, and at least one discharge pipe 24 is connected to the lower part. The ink 3 received from the nozzle 11 flows down on the inner wall of the ink guide 22, gathers at the center, and is discharged from the ink discharge pipe 24 to waste ink (not shown).

  The surface of the ink guide 22 in this embodiment has two levels of inclination. The upper stage has a brim shape so that the purge ink can be easily held, has a gentle inclination, and the lower stage tends to cause ink to flow down. Has a steep slope.

  In this embodiment, when the cap 2 is mounted so as to be in contact with the recording head 1, the nozzle 11 and the ink guide 22 are brought into a close state. Here, the ink 3 flows out from the nozzle 11 and bridges the nozzle 11 and the ink guide 22 to form a liquid column, or a plurality of liquid columns are connected to form a wall and are held. Accordingly, the nozzle 11 is blocked from the atmosphere in the cap by the ink. Although the upper limit of the distance between the nozzle 11 and the ink guide 22 varies depending on the ink characteristics (for example, viscosity), an ink liquid column can be formed if it is about 3 mm or less, and preferably about 2 mm or less. The lower limit of the distance may be a distance that does not contact, and is about 0.05 mm in consideration of mechanical accuracy. Therefore, the distance between the nozzle 11 and the ink guide 22 is about 0.05 to 3 mm. Preferably, it is about 0.05 to 2 mm. The closer the distance, the smaller the amount of purge ink used can be reduced. However, the purge ink is at least in contact with the atmosphere in the cap, so the viscosity increases slightly. The distance (ink amount) may be adjusted.

  In the ink guide 22, the position (region) that faces the nozzle 11 and forms the ink liquid columnar shape (or the ink liquid wall) is subjected to hydrophilic processing (or non-water-repellent processing) to hold the ink. The other surface may be water-repellent and the surface processed so that the ink can easily flow down. Alternatively, the position (area) where the ink liquid columnar shape (or ink liquid wall) is formed is reversely water repellent to increase the contact angle of the ink so that the ink becomes a nearly spherical droplet, and the nozzle 11 may be easily contacted. Further, in the present embodiment, the distance between the nozzle 11 and the ink guide 22 is illustrated as being fixed, but the present invention is not limited to this. For example, an elevating mechanism that raises and lowers only the ink guide 22 within the cap 2 is provided, and image formation stop time, for example, about 1 hour stop time, about 1 day stop time, and about several days stop time, etc. Accordingly, it is possible to selectively change the distance between the nozzle 11 and the ink guide 22 to change the amount of ink retained. Of course, the cap 2 at this time is in close contact with the nozzle plate 12.

Next, a procedure for forming an ink liquid column or an ink liquid wall between the recording head 1 and the cap 2 will be described with reference to FIGS.
As shown in FIG. 3A, along with the end of image formation, a cap exterior portion 21 that is an exterior of the cap 2 is mounted in contact with the nozzle plate 12 of the recording head 1 by an elevating mechanism (not shown). 23 is formed. At this time, the nozzle 11 faces the ink guide 22 so as to be close to the inside of the cap 2.

  Next, the sealing ink 3 flows out from the nozzle 11. The sealing ink 3 flows out by pressurizing the common ink chamber 13 with a pressurization source (not shown) or connecting a negative pressure source (not shown) to the cap 2 to cause the internal space 23 of the cap 2 to have a negative pressure. By doing so, any of the suctions for discharging the ink 3 from the nozzle 11 may be used.

  Next, the ink 31 that has flowed out is received by the ink guide 22 that is located immediately below the nozzle 11. The ink 31 flows down from the symmetrical flange portion and concentrates in the center thereof, does not overflow or hardly overflows in the internal space 23 of the cap 2, and concentrates in the ink discharge pipe 24. Stored. At this time, the pressure in the internal space 23 of the cap 2 is preferably a negative pressure by a pump or the like (not shown) from the viewpoint of preventing contamination due to ink scattering. However, if the discharged ink has a high discharge capability and does not spill out of the cap 2, the internal space 23 may be in an atmospheric pressure state.

  Thereafter, supply of pressure to the recording head by a pressure source or a negative pressure source (not shown) is stopped, the water head value is reset to the same as that at the time of image formation, and the outflow of the sealing ink 31 from the recording head 1 is stopped. . FIG. 3B shows a noise sealed state by the ink liquid column 33 after the outflow of the ink 31 is stopped.

  Most of the sealed ink 31 that has flowed out is discharged through the discharge pipe 24, and only the ink that bridges between the nozzle 11 and the ink guide 22 remains in a columnar shape. These become columnar due to the surface tension of the ink, and the ink liquid column 33 is formed. The distance between the ink guide 22 and the nozzle plate 12 is sufficiently small across the nozzle rows, and the interval between adjacent nozzles is narrow, so that the ink liquid columns 33 extend along the nozzle rows 11 and are scattered in rows. become. At this time, when the amount of ink is large, the adjacent ink liquid columns 33 are connected to form a wall state (ink liquid wall).

  The nozzle 11 is sealed by the ink liquid column 33 and is isolated from the atmosphere (air) in the cap, and the ink thickening in the nozzle 11 is suppressed. In the case of the water-based ink used in the present embodiment, the ink liquid column 33 is strong because the surface tension of water, which is a main component, is very large, and is easily dropped from between the nozzle plate 12 and the ink guide 22. It will not fall off and disappear.

  Further, since the ink liquid column 33 is also only exposed to the limited atmosphere in the cap, the ink liquid column can be easily destroyed over a long period of time without evaporation to the extent that the moisture of the sealing ink disappears ( It will not be lost.

  Therefore, since the nozzle 11 closed in the ink liquid column 33 is closed twice with the cap 2 and the ink liquid column 33, the thickening is further suppressed. Furthermore, since the nozzle plate 12 and the ink guide 22 are arranged very close to each other, the amount of ink forming the ink liquid column 33 is the ink used to fill the ink in the conventional cap. A small amount compared to the amount.

  In FIG. 3C, when starting (or resuming) image formation, the cap 22 descends and leaves the mounted state. The ink liquid column 33 is broken by this separation, and is divided into a residual ink 35 on the ink guide 22 side and a residual ink 34 on the nozzle plate 12 side and remains. The residual ink 35 on the ink guide 22 is collected in a waste liquid bottle (not shown) through the ink discharge pipe 24. The ink 35 remaining as it is is washed away by the next outflow of the sealing ink 31. Further, the ink 34 remaining on the nozzle plate 12 is gradually recovered and disappears in the recording head 1 by the negative pressure that is the water head value in the recording head 1. At this time, the pressure applied to the ink 3 in the recording head 1 is made smaller than that during ejection of the ink 3 (image formation). That is, by reducing the pressure in the recording head 1 as an absolute value from the water head value, the suction speed of the residual ink 34 to the nozzle 11 is further increased, and the remaining time on the nozzle plate 12 can be shortened.

  Furthermore, by increasing the negative pressure in the recording head 1, the ink liquid column 33 can be sucked and removed into the nozzle 11 in the cap state. As shown in FIG. 2, a meniscus is formed on the nozzle 11 of the recording head 1, and the image can be quickly returned to a state where it can be formed. The formation and disappearance of the ink liquid column 33 can be freely performed.

  According to the present embodiment, the nozzle 11 is hermetically sealed by the ink liquid column 33 formed so as to block the nozzle 11, and is isolated from the atmosphere (air) in the cap, thereby suppressing ink thickening in the nozzle 11. It becomes possible to do. In addition, since the ink liquid column 33 is only exposed to the limited atmosphere in the cap, the water evaporation of the ink is very small, and the ink liquid column can be maintained for a long time. Further, since the ink liquid column 33 is blocked from the outside air by the cap 2, the nozzle 11 is closed twice with the cap 2 and the ink liquid column 33, and the viscosity increase is further suppressed. Furthermore, since the nozzle plate 12 and the ink guide 22 are arranged very close to each other, the amount of ink that forms the ink liquid column 33 is the amount of ink that is used to fill the conventional cap with ink. A small amount of consumption is required.

Next, a second embodiment will be described.
4A is a diagram illustrating a cross-sectional configuration of the ink jet recording apparatus according to the present embodiment in a state where the recording head and the cap are mounted, and FIG. 4B is a perspective view illustrating a schematic configuration of the cap 2. . In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, the components (recording medium supply mechanism, transport mechanism, discharge mechanism, maintenance mechanism, etc.) of a normal image forming apparatus are also mounted, and the cap is the characteristic part of the present invention. An ink guide and a recording head related to the cap will be described with reference to the drawings.

  The ink guide 25 of this embodiment is different in shape from that of the first embodiment described above. The ink guide 22 of the first embodiment has a two-step inclination, and the ink received from the nozzles 11 is formed on the liquid column on the surface at the upper flange portion. In contrast, as shown in FIGS. 4A and 4B, the ink guide 25 of the present embodiment has one surface with a uniform inclination, and flows out from the nozzle 11 at the upper end portion (line cross-sectional shape portion). The sealed ink 3 is received and an ink liquid column (ink liquid wall) 33 is formed.

  In the present embodiment, since the ink liquid column 33 is held in a line cross-sectional shape, there is a possibility that the ink will easily flow down. However, by continuously exuding, the ink liquid column 33 can be generated between the linear member at the tip of the ink guide 25 and the nozzle plate 12, as shown in FIG. In addition, since the ink is held at the upper end of the ink guide 25 according to the present embodiment, the unnecessary ink flows down on both the inner surface and the outer surface of the ink guide 25, so that the ink guide 25 has an inner surface from the outer surface. An ink discharge hole 28 penetrating the nozzle is opened. Note that a counterbore (outflow path) may be provided at the bottom of the inner surface of the cap exterior portion 21 so that the ink can easily enter the ink discharge hole 28.

  According to the present embodiment, the ink for sealing can be realized with a smaller ink consumption by forming the ink liquid column (ink liquid wall) on the line cross-sectional shape portion at the upper end of the ink guide 25. By the ink liquid column 33 formed in this manner, the nozzle 11 can be sealed so as to be shielded from the outside air, as in the first embodiment. Further, in the present embodiment, the cap exterior portion 21 that accommodates the ink guide 25 is in contact with the nozzle plate to form a sealed space 23, the evaporation of the ink liquid column 33 is suppressed, and the ink in the nozzle 11 is kept for a long time. Thus, it is possible to suppress the thickening.

Next, a third embodiment will be described.
FIG. 5A is a diagram illustrating a cross-sectional configuration of the ink jet recording apparatus according to the third embodiment in a state where the recording head and the cap are mounted. FIG. 5B is a perspective view illustrating a schematic configuration of the cap 2. It is. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, the components (recording medium supply mechanism, transport mechanism, discharge mechanism, maintenance mechanism, etc.) of a normal image forming apparatus are also mounted, and the cap is the characteristic part of the present invention. An ink guide and a recording head related to the cap will be described with reference to the drawings.

  In the present embodiment, the shape of the ink guide 26 is different from the first embodiment described above. As shown in FIG. 5B, the ink guide 26 is an ink guide 26 made of, for example, a metal wire. As shown in FIG. 5A, the ink that exudes from the nozzle 11 is received by a member having a cross-sectional shape when viewed from the cross section.

  Further, the blocking effect of the nozzle 11 by the ink liquid column 33 is the same as that of each of the embodiments described above, and furthermore, the ink in the nozzle 11 can be suppressed from increasing in viscosity for a long time with a very small amount of ink. . When the ink liquid column 33 is formed, excess ink 3 is dropped from the ink guide 26 to the bottom of the cap exterior portion 21, and the dropped ink 3 is discharged from the discharge pipe 24 to a waste liquid bottle (not shown).

  The wires constituting the ink guide 26 are not limited to metal, and can be formed of resin or other materials as long as tension is satisfied. Further, the wire may be a single core or may be a multicore having a large number of thin wire rods. However, the multi-core wire can take a larger tension and can also improve the ink retention.

  According to the present embodiment, as in the second embodiment described above, the ink liquid column 33 can be formed with a very small amount of hermetically sealed ink with the nozzle plate 12 disposed in proximity.

Next, a fourth embodiment will be described.
FIG. 6 is a diagram illustrating a cross-sectional configuration of an ink supply system, a recording head, and a cap in an ink jet recording apparatus according to the fourth embodiment. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, the components (recording medium supply mechanism, transport mechanism, discharge mechanism, maintenance mechanism, etc.) of a normal image forming apparatus are also mounted, and the cap is the characteristic part of the present invention. An ink guide and a recording head related to the cap will be described with reference to the drawings.

  FIG. 6 shows the recording head 1, the cap 2, the ink supply mechanism 4, and the blade mechanism 5. The ink supply mechanism 4 of the present embodiment is roughly divided into a supply ink tank 51 for supplying the ink 3 to the recording head, a return ink tank 52 for collecting ink that has not been used for image formation, and a circulation pump 45. These are connected by an ink path 4 to form an ink circulation path. For details of the path, the supply ink tank 51 and the ink supply port 14 of the recording head 1 are connected by an ink supply path 43. The ink discharge port 15 of the recording head 1 and the return ink tank 52 are connected by an ink return path 44. The ink return path 44 and the supply ink tank 51 are connected by an ink circulation path 46 with the circulation pump 45 interposed therebetween.

  The supply ink tank 51 and the return ink tank 52 are equipped with air opening ports 53 and 54 and ink level detections 55 and 56, respectively, and are detected and controlled by a control device (not shown). In the present embodiment, the ink path 4 is a circulating ink path, and the ink supply port 14 of the recording head 1 serves as an ink inlet 41 and the ink discharge port 15 serves as an ink outlet 42.

The operation of the ink path 4 in this embodiment will be described.
When the ink path 4 does not circulate, the air opening ports 53 and 54 of the supply ink tank 51 and the return ink tank 52 are closed, and the ink 3 does not leak from the nozzle 11. Alternatively, only the air opening 54 of the return ink tank 52 is opened, and the water head value is applied to the inside of the recording head 1.

  On the other hand, at the time of ink circulation, first, the air opening port 54 of the return ink tank 52 is closed, the circulation pump 45 is operated, the ink 3 is sent to the supply ink tank 51, and the negative pressure inside the return ink tank 52 is increased. Due to this negative pressure, the ink 3 is drawn from the common ink chamber 13 of the recording head 1, and the inside of the common ink chamber 13 becomes negative pressure. Further, by opening the atmosphere opening 53 of the supply ink tank 51, a pressure difference is generated between the ink inlet 41 and the ink outlet 42 of the recording head 1, and ink circulation is started. The ink circulation amount is determined by the magnitude of the negative pressure in the return ink tank 52 by the circulation pump 45, and the ink circulation amount increases as the negative pressure increases. The effect of circulating ink is that a normal head value is statically applied when the cap 2 is lowered to recover the ink liquid column 33 and the residual ink 34 on the nozzle plate 12 is collected in the nozzle 11. Can be completed earlier than if. This is because the ink circulation has a higher effect of making the pressure distribution inside the recording head 1 more uniform by the ink circulation.

  Further, by increasing the rotation speed R of the ink circulation pump 45 and increasing the negative pressure inside the return ink tank 52, the negative pressure inside the recording head 1 also increases, and the residual ink 34 on the nozzle plate 12 is further reduced. , It flows into the nozzle 11 sooner and is recovered. However, if the negative pressure in the return ink tank 52 is increased too much in order to increase the residual ink recovery speed, the negative pressure inside the recording head 1 increases and the air bubbles 36 are sucked from the nozzles 11, so the magnitude of the negative pressure is increased. Need to be set empirically.

  FIG. 7 shows a state in which bubbles 36 are entrained from the nozzle 11 because the negative pressure on the ink outlet 42 side is too large. The ink inlet 41 side, which is the upstream side of the nozzle 11, is in the positive direction, and the downstream ink outlet 42 side is in the negative pressure direction. By applying a negative pressure greater than the meniscus holding force on the negative pressure side, Inhalation occurs. In the present embodiment, since the ink path is an ink circulation path, even if the bubbles are recovered and removed from the ink outlet 42 through the ink return path 44 and then returned to the ink tank 52, there is no serious problem. .

  Therefore, according to the present embodiment, the ink jet recording apparatus using the ink path 4 by ink circulation can shift to the image forming state more quickly.

  Furthermore, the residual ink 35 is quickly and reliably sucked and removed into the nozzle 11, and the residual liquid droplet 34 on the nozzle plate 12 becomes extremely small, so that the entire surface of the nozzle plate 12 of the recording head 1 is immersed in ink. Thus, it is possible to avoid a state in which image formation cannot be performed due to a large amount of residual droplets. Accordingly, the wiping operation for removing the residual droplets on the nozzle plate 12 by the blade mechanism 6 can be omitted, and it is possible to shift to the image forming state more quickly.

  Next, a fifth embodiment will be described.

  FIG. 8A is a diagram showing a cross-sectional configuration of the ink jet recording apparatus according to the fifth embodiment with the recording head and the cap attached thereto, and FIG. 8B is a perspective view of the cap.

  This embodiment is an example in which the ink guide 27 provided in the cap 2 has a flat plate shape close to and facing the nozzle plate. The ink guide 27 is formed of the same material as that of the first embodiment described above, and is fixed by a support member 30 provided at the bottom of the cap exterior portion 21.

  The ink guide 27 has a dish shape with an edge around a flat plate, and is provided with at least one ink collecting tube 29 on the central back surface and opened. As shown in FIG. 8A, the ink collecting tube 29 has a length that does not reach the bottom of the cap exterior portion 21 when attached to the cap exterior portion 21. In order to efficiently discharge ink, it is desirable that the ink collecting pipe 29 and the ink discharging pipe 24 provided at the bottom of the cap exterior portion 21 are coaxial, and the inner diameter of the ink collecting pipe 24 is the inner diameter of the ink collecting pipe 29. It is desirable to be larger.

  In this configuration, the inside of the common ink chamber 13 is pressurized by the method described above, and the sealing ink 3 is dropped from the nozzle 11 and reaches the ink guide 27. The ink 3 forms an ink liquid column 33 (or ink liquid wall) between the nozzle 11 and the ink guide 27 that are close to each other. Excess ink 3 flows on the surface of the ink guide 27, flows into the ink collecting pipe 29 from the opening, and is accommodated in a waste liquid bottle (not shown) through the ink discharge pipe 24. The ink 3 overflowing from the ink guide 27 is received at the bottom of the cap exterior portion 21 and similarly accommodated in the waste liquid bottle via the ink discharge pipe 24 opened at the bottom.

  According to the present embodiment, it is possible to obtain the same operational effects as those of the first embodiment described above. In addition, since the ink liquid column 33 is formed on the flat ink guide 27, the ink liquid column 33 can be moved even when there is an external impact, as compared with other embodiments in which the ink guide 27 has an inclination. Less likely to occur.

Next, a sixth embodiment will be described.
The present embodiment is a simplified ink guide 61 in which the ink guide is provided with a lifting and lowering function and the cap 2 is omitted. As shown in FIG. 9, a wedge shape having an open upper surface is formed, and a contact edge member 62 made of an elastic member is provided around the tip of the flange portion 61 a of the ink guide 61. The ink guide 61 has a shape in which, for example, the side surface of the ink guide 22 shown in FIG.

Also in this embodiment, the surface of the ink guide 61 has two levels of inclination, the upper stage is shaped so that the purge ink is easily held, has a gentle inclination, and the lower stage has ink flowing down. It has a steep slope to make it easier.

  The received ink 3 is stored in a waste liquid bottle (not shown), as in the above-described embodiment. The contact edge member 62 acts to regulate the distance between the stopper and the nozzle plate 12 and the ink guide 61 when contacting the nozzle plate 12. Further, by forming a groove in the center of the surface of the contact edge member 62 that contacts the nozzle plate 12, ink is prevented from leaking outside the ink guide. Further, by providing the groove, the contact surface becomes thinner and can be more closely attached.

  In the present embodiment, the elevating mechanism (not shown) causes the border member 62 to abut on the location of the recording head 1 where the cap exterior portion 21 abuts in the first embodiment described above, and the ink guide 22 serves as the recording head 1. Close contact with the nozzle plate. In this state, an ink liquid column (ink liquid wall) is formed, and the nozzle 11 is sealed.

  According to this embodiment, ink thickening can be suppressed by forming an ink liquid column and sealing the nozzle. In addition, since the cap exterior portion is a simple configuration, the collar portion is extended, and the contact edge member 62 is provided around it, so that the same effect as that of the cap exterior portion for preventing ink from scattering to the outside is obtained. be able to. Since the cap exterior part is not required, further miniaturization can be realized, and the space where the ink liquid column is exposed becomes the ink guide internal space, and the sealed space can be reduced.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. In each of the embodiments described above, the example of the water-based ink has been described. However, the present invention is not limited to this, and other types of ink may be used. The recording head has been described by taking a piezo type as an example, but is not limited to this as well. Further, the structure and shape of the recording head and cap are not limited to this.

 The recording head is not limited to a fixed head, and is mounted with a removable ink tank for storing a small amount of ink, or an ink chamber having a function capable of filling ink, and is moved by scanning. The present invention can also be applied to a scanning recording head.

Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

FIG. 2 is a perspective view of a recording head and a cap unit used in the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a cross-sectional configuration of a recording head and a cap according to the first embodiment illustrated in FIG. 1. FIGS. 3A to 3C are views for explaining a procedure for forming the ink liquid column of the recording head and the cap according to the first embodiment. It is a perspective view of the recording head and cap part which are used for the inkjet recording device which concerns on 2nd Embodiment. It is a perspective view of the recording head and cap part which are used for the inkjet recording device which concerns on 3rd Embodiment. It is a figure which shows the structure of the recording head, cap part, and ink supply path which are used for the inkjet recording device which concerns on 4th Embodiment. FIG. 4 is a diagram illustrating a state where air bubbles are sucked into a recording head. FIG. 8A is a diagram showing a cross-sectional configuration of the ink jet recording apparatus according to the fifth embodiment with the recording head and the cap attached thereto, and FIG. 8B is a perspective view of the cap. FIG. 9A is a diagram illustrating an external configuration of an ink guide in an ink jet recording apparatus according to the sixth embodiment, and FIG. 9B is a diagram illustrating a cross-sectional configuration of a recording head and a cap.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Recording head, 2 ... Cap, 3 ... Ink, 4 ... Ink supply mechanism, 5 ... Blade mechanism, 6 ... Piezo part, 7 ... Channel, 10 ... Head main body, 11 ... Nozzle, 12 ... Nozzle plate, 13 ... Common Ink chamber, 14 ... ink supply port, 15 ... ink discharge port, 21 ... cap exterior, 22 ... ink guide, 23 ... cap internal space, 24 ... ink discharge tube.

Claims (9)

A recording head comprising a nozzle plate in which a plurality of nozzles for ejecting ink onto a recording medium to form an image are formed in a line;
An ink guide portion that has an elevating function, faces the nozzle, and approaches or separates, and causes the ink to flow out of the nozzle when the ink guide portion approaches the recording head. the ink jet recording apparatus characterized by between the ink guide and the nozzle to form an ink liquid column for sealing the nozzle.   A cap for sealing the nozzle plate to prevent ink thickening inside the nozzle is further included. When the cap is in close contact with the nozzle plate, a sealed space is formed in the cap. The ink jet recording apparatus according to claim 1, wherein the ink liquid column is formed in the space. The ink guide portion is configured such that the upper end is configured in a line cross-sectional shape, and the upper end is close to the nozzle when the cap is in close contact with the nozzle plate,
An ink liquid column that seals the nozzle is formed between the nozzle and the upper end portion of the ink guide by dropping the ink from the nozzle onto the upper end portion of the ink guide. The ink jet recording apparatus according to claim 2. A recording head comprising a nozzle plate in which a plurality of nozzles for ejecting ink onto a recording medium to form an image are formed in a line;
A cap for raising and lowering, forming a sealed space when in close contact with the nozzle plate, and preventing ink thickening inside the nozzle;
The nozzle is provided in the cap, extends along the row of the nozzles, and is arranged so as to approach or leave the nozzle. When the cap is in close contact with the nozzle plate, the nozzle And an ink guide part that forms an ink liquid column that seals the nozzle between the nozzle and the wire by dropping the ink on the wire. A recording head comprising a nozzle plate in which a plurality of nozzles for ejecting ink onto a recording medium to form an image are formed in a line;
A cap for raising and lowering, forming a sealed space when in close contact with the nozzle plate, and preventing ink thickening inside the nozzle;
An ink guide portion provided in the cap, having a flat plate-like surface facing directly in parallel along the row of the nozzles, and being formed close to or away from the nozzle and integrally formed with the ink discharge pipe; Have
An ink liquid column that seals the nozzle is formed between the nozzle and the flat plate-like surface by dropping the ink from the nozzle onto the flat plate-like surface. Recording device. The ink guide portion is configured such that an upper end of the contact guide member made of an elastic member is provided at an upper end of the ink guide portion, and the contact contact edge member is close to the nozzle.
An ink liquid column for sealing the nozzle is formed between the nozzle and the contact edge member by dropping the ink from the nozzle onto the upper end portion of the ink guide. Item 2. An ink jet recording apparatus according to Item 1.   7. The ink jet recording according to claim 3, wherein when the cap is detached from the nozzle plate, a pressure applied to the ink in the recording head is made smaller than a water head value at the time of ink ejection. apparatus.   Furthermore, a blade mechanism for wiping and removing ink remaining on the nozzle plate is provided, and a wiping operation by the blade mechanism is performed after the cap is detached from the nozzle plate until image formation is started on the recording medium. The inkjet recording apparatus according to claim 7, wherein the inkjet recording apparatus is not implemented.   3. The ink jet recording apparatus according to claim 2, wherein the ink liquid column is an ink liquid wall in which a plurality of adjacent ink liquid columns are connected to form a wall shape.

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