JP2007276394A - Shutter apparatus and liquid droplet delivering apparatus equipped with this shutter apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent ink in a nozzle when it is not operated from being dried. <P>SOLUTION: When an inkjet recording apparatus 110 is not operated, a nozzle row 23 is covered by a part except a slit 94 of a shutter 92 by sliding the shutter 92. It is possible thereby to prevent water content of the ink in the nozzle 22 from being evaporated as the ink in the nozzle 22 becomes hardly exposed to open air. Therefore, it is possible to prevent the nozzle 22 from clogging. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a shutter device provided in a droplet discharge head that discharges droplets from a nozzle, and a droplet discharge device including the shutter device.

  In an inkjet recording apparatus that prints on a recording medium by ejecting ink droplets from a recording head, ink is ejected from a plurality of nozzles formed on a nozzle plate, and the ink is attached to a recording medium such as paper to perform printing. ing.

  In such an ink jet recording apparatus, nozzle clogging may be caused by drying and thickening of the ink during non-operation. As a result, dot missing occurs during printing, resulting in a problem that print quality is deteriorated or printing becomes impossible. In particular, when ink containing a pigment system or a resin additive is used to ensure print quality, there is a risk that ink drying and thickening may remarkably occur during maintenance.

  The mechanism by which the ink thickening progresses is experimentally and analyzed by simulation, and a progress model from both sides of gas permeation from the ink supply side and air drying from the nozzle side is considered. Although it depends on the head structure, the nozzles are directly open to the atmosphere and have many nozzles and are also outlets, so they are easily affected by ink thickening, and the progress of ink thickening from the nozzle side is dominant. The results are also serious.

  For this reason, the cap for sucking the ink of the nozzle is pressed against the nozzle plate when the ink jet recording apparatus is not operating, thereby preventing the ink in the nozzle from drying. However, since a sealing member (for example, an O-ring) attached around the opening of the cap is only pressed against the nozzle plate, air enters the cap from this sealing member, and the moisture of the ink in the nozzle May evaporate.

In addition, there is a shutter provided between an ink chamber and a nozzle (see Patent Document 1). In the configuration of Patent Document 1, it is possible to prevent the ink in the ink chamber from being exposed to the outside air by closing the shutter. However, since the ink in the nozzle remains exposed to the outside air, the ink is dried in the nozzle. There is a risk of clogging the nozzle. In addition, providing a movable mechanism in a fine ejector is not practical because of problems such as ink leakage and ejection pressure leakage.
Japanese Patent No. 2746703

  In view of the above problems, an object of the present invention is to prevent drying of ink in a nozzle when not operating.

  The present invention according to claim 1 is used in a droplet discharge head that discharges droplets from nozzles, and is slidably attached to a nozzle plate in which a plurality of nozzles are formed, and an opening that exposes the nozzles is formed. And a slide means that slides the shutter and covers the nozzle or exposes the nozzle.

  According to the first aspect of the present invention, when the shutter that is slidably attached to the nozzle plate is slid by the sliding means, and the opening formed in the shutter reaches the position of the nozzle, the nozzle is exposed, and other than the opening When the part reaches the position of the nozzle, the nozzle is covered with a shutter.

  For example, during operation of the apparatus, droplets can be ejected from the nozzle by sliding the shutter to expose the nozzle. In addition, when the apparatus is not in operation, the shutter is slid to cover the nozzle, thereby making it difficult for the liquid droplets in the nozzle to be exposed to the outside air. As a result, the evaporation of the moisture in the droplets in the nozzle can be prevented, and nozzle clogging is prevented. This eliminates the need for droplet suction means for sucking the dried droplets in the nozzle, thereby simplifying the configuration of the entire apparatus.

  Further, since the shutter slides on the nozzle plate, foreign matters such as dust are not pushed into the nozzle when the shutter is slid to cover the nozzle.

  Furthermore, since the shutter is in close contact with the nozzle, there is no air layer between the shutter and the nozzle. For this reason, the ink in the nozzle is difficult to dry.

  The present invention according to claim 2 is characterized in that the shutter is slidably attached to a counterbore plate which is stacked on the nozzle plate and protects the nozzle.

  In the invention described in claim 2, counterbore plates for protecting the nozzle are stacked on the nozzle plate, and a shutter is slidably attached to the counterbore plate.

  That is, since the shutter does not slide on the nozzle plate but slides on the counterbore plate, the nozzle plate is not damaged by sliding the shutter. Therefore, there is no possibility that the droplet discharge port of the nozzle is damaged.

  The present invention described in claim 3 is characterized in that the shutter is slidably attached to the counterbore plate by a magnetic force.

  In the invention according to claim 3, the shutter is slidably attached to the counterbore plate by the magnetic force. Thus, the shutter can be attached with a simple configuration in close contact with the counterbore plate. Further, since the shutter and the counterbore plate are in close contact with each other, it is difficult for foreign matters such as dust to enter from between the shutter and the counterbore plate.

  According to a fourth aspect of the present invention, when the magnet is attached to the shutter, the counterbore plate is a magnetic plate, and when the magnet is attached to the counterbore plate, the shutter is a magnetic plate. It is a feature.

  In the invention described in claim 4, the counterbore plate is used as a magnetic plate, and a magnet is attached to the shutter. Moreover, a magnet is attached to the counterbore plate, using the shutter as a magnetic plate. That is, by attaching at least one of the counterbore plate and the shutter as a magnetic plate and attaching a magnet to the other plate, the shutter is attached to the counterbore plate so as to be slidable by magnetic force.

  According to a fifth aspect of the present invention, the opening of the shutter is a slit capable of exposing the row of nozzles arranged in one direction, and a pitch at which the slits are arranged is a pitch of the row of nozzles. It is characterized by being identical.

  According to the fifth aspect of the present invention, the shutter is provided with slits at the same pitch as the pitch of the nozzle rows arranged in one direction, and the nozzle rows can be exposed from the slits. Thus, if the shutter is slid with a movement amount that is half the pitch of the nozzle row, the nozzle can be exposed or covered.

  According to a sixth aspect of the present invention, there is provided a droplet discharge device including the shutter device according to any one of the first to fifth aspects, wherein the droplet is discharged from the opening of the shutter during the droplet discharge. The nozzle is exposed, and the nozzle is covered with the shutter after completion of the ejection.

  In the invention described in claim 6, when ejecting a droplet from the nozzle, the nozzle is exposed from the opening of the shutter so that the droplet can be ejected from the nozzle. In addition, when a droplet is not discharged from the nozzle, the nozzle is covered with a shutter so that the droplet in the nozzle is not easily exposed to the air. This makes it difficult for the water in the droplets in the nozzles to evaporate when the droplets are not ejected from the nozzles, and prevents the droplets from drying in the nozzles. Therefore, nozzle clogging does not occur.

  Since the present invention is configured as described above, drying of the ink in the nozzles during non-operation is prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an ink jet recording apparatus 110.

  As shown in FIG. 1, a paper feed tray 116 is provided in the lower part of the casing 114 of the ink jet recording apparatus 110, and the sheets P stacked in the paper feed tray 116 are picked up one by one by a pickup roller 118. It is. The taken paper P is transported by a plurality of transport roller pairs 120 constituting a predetermined transport path 122.

  Above the paper feed tray 116, an endless transport belt 128 stretched around a driving roller 124 and a driven roller 126 is disposed. A recording head array 130 is disposed above the conveyor belt 128 and faces the flat portion 128F of the conveyor belt 128. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 130. The sheet P conveyed on the conveyance path 122 is held by the conveyance belt 128 and reaches the conveyance area SE, and ink droplets corresponding to image information are attached from the recording head array 130 in a state of facing the recording head array 130. The

  Within the recording head array 130, four long inkjet recording heads 10 corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) are provided in the transport direction. And a full color image can be recorded.

  Four maintenance units 134 corresponding to the respective inkjet recording heads 10 are arranged in the vicinity of the recording head array 130 (in this embodiment, both sides in the transport direction). The maintenance unit 134 performs a predetermined maintenance operation (vacuum, dummy jet, wiping, etc.).

  A charging roll 136 is disposed on the upstream side of the recording head array 130. The charging roll 136 is driven between the driven roller 126 while sandwiching the conveyance belt 128 and the paper P, and moves between a pressing position for pressing the paper P against the conveyance belt 128 and a separation position separated from the conveyance belt 128. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roller 126 and the sheet P can be charged and electrostatically attracted to the transport belt 128.

  A peeling plate (not shown) is disposed on the downstream side of the recording head array 130 so that the paper P is peeled from the transport belt 128. The peeled paper P is conveyed by a plurality of discharge roller pairs 142 constituting a discharge path 144 and discharged to a paper discharge tray 146 provided at the upper part of the housing 114.

  A reversing path 152 composed of a plurality of reversing roller pairs 150 is provided between the paper feed tray 116 and the conveying belt 128, and the sheet P on which an image is recorded on one side is reversed and held on the conveying belt 128. By doing so, it is possible to easily record images on both sides of the paper P.

  Between the transport belt 128 and the paper discharge tray 146, an ink tank 154 is provided for storing each of the four color inks. The ink in the ink tank 154 is supplied to the recording head array 130 through an ink supply pipe (not shown).

  Such an ink jet recording apparatus 110 includes four ink jet recording heads 10 each containing four color inks. Therefore, the head width in the transport direction of the paper P can be reduced, and a small recording head can be obtained. An array 130 can be implemented.

  Next, the ink jet recording head 10 will be described. FIG. 2 is a schematic perspective view showing the inkjet recording head 10.

  As shown in FIG. 2, the ink jet recording head 10 includes a head bar (not shown) set to a length corresponding to the maximum width of the recording medium P. This head bar is fixedly supported by a support (not shown) in the ink jet recording apparatus 110 (see FIG. 1).

  The head bar is provided with a plurality of head units 14 connected in a row. Each head unit 14 is configured to print on a sheet P conveyed at a predetermined pitch in the direction of arrow A in the figure. That is, it is possible to print the entire width of the paper P without scanning the ink jet recording head 10 by passing under the head unit 14 once.

  Here, the configuration of the head unit 14 will be described. FIG. 3 shows a cross-sectional view of the head unit 14.

  As shown in FIG. 3, the head unit 14 includes a nozzle plate 30, and a communication hole plate 32 and a damper member 34 are stacked above the nozzle plate 30. Above the damper member 34, the pool plates 36, 38, 40, the communication hole plate 42, the flow path plate 44, the communication hole plate 46, the pressure chamber plate 48, and the vibration plate 50 are aligned. Laminated and joined by a joining means such as an adhesive.

  As shown in FIG. 4, nozzles 22 that eject ink droplets are formed at a predetermined pitch on the nozzle plate 30 to form nozzle rows 23. The nozzle rows 23 are arranged at a predetermined pitch obliquely with respect to the transport direction of the paper P. Thereby, ink can be ejected with high density along a direction orthogonal to the transport direction of the paper P.

  As shown in FIG. 3, the communication hole plate 32 is formed with a communication hole 54 communicating with the nozzle 22, and the damper member 34 is formed with a communication hole 56. The pool plates 36, 38, and 40 are formed with communication holes 58, 60, and 62, respectively, and the communication hole plate 42 is formed with a communication hole 64. Further, a communication hole 66 is formed in the flow path plate 44, and a communication hole 68 is formed in the communication hole plate 46. These nozzles 22 and communication holes 54, 56, 58, 60, 62, 64, 66, 68 communicate with each other and are connected to a pressure chamber 70 formed in the pressure chamber plate 48.

  On the other hand, the communication hole plate 32 has a cavity 72 formed below the damper member 34 so that the damper member 34 can be deformed. Ink pools 74, 76, and 78 are formed on the pool plates 36, 38, and 40, respectively, and are connected to each other to form one space. In these ink pools 74, 76 and 78, ink supplied from an ink supply hole (not shown) is stored. Further, the communication hole plate 42 is formed with a supply hole 80 so as to be connected to the ink pool 78, and the flow path plate 44 is formed with an ink flow path 82 communicating with the supply hole 80. Further, a supply hole 84 is formed in the communication hole plate 46 so as to be connected to the ink flow path 82 on the opposite side of the supply hole 80. The ink pools 74, 76, 78, the supply hole 80, the ink flow path 82, the supply hole 84, and the pressure chamber 70 are in communication with each other, and ink is supplied from the ink pools 74, 76, 78 into the pressure chamber 70. Is supplied.

  In addition, a piezoelectric element 86 as a pressure generating unit is attached above the diaphragm 50 above the pressure chamber 70. The piezoelectric element 86 is provided with an electrode 87 so that a driving voltage is applied from a flexible wiring board (not shown). These piezoelectric elements 86 are respectively provided above the pressure chambers 70 communicating with the individual nozzles 22, and a piezoelectric element group constituted by a large number of piezoelectric elements 86 includes element substrates 16 and 18 shown in FIG. It has become.

  As shown in FIGS. 3 and 4, a counterbore plate 88 is attached to the ink ejection surface side of the nozzle plate 30. FIG. 4 shows the positional relationship between the nozzle row 23 and a slit 94 of a shutter 92 described later, and the nozzle row 23 is expressed in a simplified manner.

  In the counterbore plate 88, circular openings 90 that are slightly larger than the nozzles 22 are formed in rows corresponding to the nozzles 22, and the nozzles 22 are exposed from the openings 90. In other words, a counterbore plate 88 having openings 90 is provided around each nozzle 22 to provide a step, and the paper P that has been lifted during printing is transferred to the nozzle 22 and the nozzle plate 30. It is configured to prevent contact with the nozzle surface. Thereby, damage to the nozzle 22 due to paper jam or the like is prevented.

  A shutter 92 is provided on the surface of the counterbore plate 88 (the surface on the ink discharge side). The shutter 92 is formed of a magnetic member, and has a plate shape that is sized across the entire head unit 14 as shown in FIGS. 2 and 5.

  A movable iron core 95A of a solenoid 95 is attached to one end of the shutter 92 in the longitudinal direction. The solenoid 95 is connected to a control device (not shown), and when the solenoid 95 is energized by a signal from the control device, the movable iron core 95A protrudes and the shutter 92 is perpendicular to the transport direction of the paper P (arrow B in the figure). It is configured to slide in the opposite direction).

  A thin plate-like plate material 96 is extended in a direction perpendicular to the plate thickness direction of the shutter 92 at the other end in the longitudinal direction of the shutter 92. One end of a coil spring 98 is attached to the plate material 96. The other end of the coil spring 98 is attached to a frame of the apparatus main body (not shown), and the shutter 92 is urged in the direction of arrow B in the figure.

  The side surface near the other end of the shutter 92 is supported by a plate 97 provided on the frame. With such a configuration, when the solenoid 95 is energized and the movable iron core 95A protrudes, the shutter 92 slides in a direction orthogonal to the transport direction of the paper P while being supported by the plate 97. Then, when the energization of the solenoid 95 is stopped, it slides in the direction of arrow B in the figure by the urging force of the coil spring 98.

  The shutter 92 is in close contact with the surface of the counterbore plate 88 by the magnetic force of a plurality of magnets 93 provided in the gap between the head units 14. The magnetic force of the magnet 93 is determined by the biasing force of the coil spring 98 when the shutter 92 is pushed out by the movable core 95A when the movable core 95A of the solenoid 95 protrudes, and when the energization of the solenoid 95 is stopped. The thing of the magnitude | size which can be slid to a position (position before pushing out by 95 A of movable iron cores) is used.

  A slit 94 is formed in the shutter 92 along the conveyance direction of the paper P. The slits 94 are sized such that the row of openings 90 formed in the nozzle row 23 and the counterbore plate 88 can be exposed, and a plurality of slits 94 are formed at the same pitch as the pitch of the nozzle row 23.

  As a result, if the shutter 92 is slid by a movement amount that is half the pitch of the nozzle row 23, the nozzle 22 can be exposed or covered. That is, during operation such as ink ejection, the shutter 92 is moved until the slit 94 reaches the position of the nozzle row 23 and the nozzle 22 is exposed from the slit 94 as shown in FIG. 4B, the shutter 92 is moved until a portion other than the slit 94 reaches the position of the nozzle row 23, and the nozzle 22 is covered with the shutter 92.

  Next, the operation of the embodiment of the present invention will be described.

  During operation of the inkjet recording apparatus 110, the shutter 92 is slid in a direction orthogonal to the transport direction of the paper P with a movement amount that is half the pitch of the nozzle row 23. As a result, the nozzle row 23 is exposed from the slit 94 formed in the shutter 92, and ink can be ejected from the nozzle 22.

  Further, when the ink jet recording apparatus 110 is not operating, the shutter 92 is slid by a movement amount that is half the pitch of the nozzle row 23. As a result, the nozzle row 23 is covered with a portion other than the slit 94 of the shutter 92, and the ink in the nozzle 22 becomes difficult to be exposed to the outside air, so that evaporation of the moisture of the ink in the nozzle 22 can be prevented. Therefore, clogging of the nozzle 22 is prevented, and there is no need to operate the maintenance unit 134 (see FIG. 1) to suck the dried ink in the nozzle 22.

  Further, since the nozzle array 23 is covered with the shutter 92 by sliding the shutter 92 in a direction perpendicular to the conveyance direction of the paper P, there is no possibility that foreign matters such as dust are pushed into the nozzle 22.

  Furthermore, since the shutter 92 is provided in close contact with the counterbore plate 88 by a magnetic force, it is difficult for foreign matter such as dust to enter between the shutter 92 and the counterbore plate 88 and between the shutter 92 and the nozzle 22. The ink in the nozzle 22 is difficult to dry because there is only a minute space corresponding to the counterbore plate thickness.

  In the present embodiment, the shutter 92 is formed of a magnetic member, and the shutter 92 is brought into close contact with the counterbore plate 88 by the magnetic force of the magnet 93 provided in the gap between the head units 14. Is not necessarily provided in the gap between the head units 14 and may be embedded in the counterbore plate 88. Moreover, even if the counterbore plate 88 is formed of a magnetic member and a magnet is embedded on the shutter 92 side, the counterbore plate 88 can be brought into close contact with the shutter 92 by magnetic force. Further, as a method of bringing the shutter 92 into close contact, a sealed space may be formed in the gap between the head units 14 regardless of the magnetic force, and the inside may be sucked with a negative pressure.

  Further, in the present embodiment, the nozzle 22 is wiped using the maintenance unit 134. However, when the wiper blade or brush is attached to the opening edge of the slit 94 of the shutter 92 and the shutter 92 is slid, The nozzle 22 may be wiped with a wiper blade or a brush, and the ink attached to the nozzle 22 may be removed.

  In this embodiment, the counter plate 88 is provided on the ink ejection surface side of the nozzle plate 30 and the shutter 92 is disposed on the surface of the counter plate 88. However, the nozzle plate 30 is not provided with the counter plate. The shutter 92 may be arranged directly on the ink ejection surface side.

1 is a schematic configuration diagram of an inkjet recording apparatus according to an embodiment of the present invention. It is a perspective view which shows the inkjet recording head mounted in the inkjet recording device. It is a fragmentary sectional view showing a head unit of an ink jet recording head. FIG. 4 is a partial perspective view of the nozzle plate, counterbore plate, and shutter of the head unit as viewed from the nozzle side, where (A) shows the state during ink ejection and (B) shows the state during non-ink ejection. Has been. It is the partial top view which looked at the inkjet recording head from the nozzle side.

Explanation of symbols

10 Inkjet recording head (droplet ejection head)
22 Nozzle 23 Nozzle row (nozzle row)
30 Nozzle plate 88 Counterbore plate 90 Opening 92 Shutter (shutter device)
93 Magnet 94 Slit (Opening)
95 Solenoid (shutter device, slide means)
110 Inkjet recording device (droplet ejection device)

Claims (6)

Used in a droplet discharge head that discharges droplets from a nozzle,
A shutter in which a plurality of the nozzles are slidably attached to a nozzle plate, and an opening for exposing the nozzles is formed;
Sliding means for sliding the shutter and covering the nozzle or exposing the nozzle;
A shutter device, comprising:   The shutter device according to claim 1, wherein the shutter is slidably attached to a counterbore plate that is stacked on the nozzle plate and protects the nozzle.   The shutter device according to claim 2, wherein the shutter is slidably attached to the counterbore plate by a magnetic force.   4. The counterbore plate is a magnetic plate when a magnet is attached to the shutter, and the shutter is a magnetic plate when a magnet is attached to the counterbore plate. The shutter device described in 1.   The opening of the shutter is a slit that can expose the row of nozzles arranged in one direction, and a pitch at which the slit is arranged is the same as a pitch of the row of nozzles. The shutter device according to any one of claims 2 to 4.   A droplet discharge device comprising the shutter device according to any one of claims 1 to 5, wherein the nozzle is exposed from an opening of the shutter during droplet discharge, and the discharge is completed after the discharge is completed. A droplet discharge apparatus, wherein the nozzle is covered with a shutter.

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