JP4691944B2 - Inkjet recording device - Google Patents

Description

The present invention relates to an ink jet recording equipment which performs printing by ejecting ink onto a recording medium.

  In an inkjet printer, a purge operation is performed in which ink is sucked from a nozzle disposed on an ink ejection surface of an inkjet head to recover the ink ejection state. Therefore, such a printer is provided with a substantially box-shaped purge cap capable of covering the nozzles of the inkjet head. The purge cap is connected to a suction pump, and ink is sucked from the nozzle by reducing the pressure in the cavity (closed space) in the purge cap in a state where the nozzle on the ink discharge surface is covered with the purge cap. (For example, refer to Patent Document 1).

Japanese Patent No. 3189532

  However, in the purge operation in the ink jet printer described in Patent Document 1 described above, first, a purge cap is brought into contact with the ink ejection surface of the ink jet head. Then, the purge cap that is in contact with the ink discharge surface forms a closed space with the ink discharge surface. When the closed space is depressurized by the suction pump, bubbles contained in the ink are sucked from the nozzle together with the ink having increased viscosity in the ink jet head. Thereafter, the purge cap is separated from the ink ejection surface. At this time, part of the ink in the purge cap may remain attached to the ink ejection surface. When the ink is discharged from the nozzle into the closed space, the ink foams, that is, contains a large amount of bubbles. On the other hand, since a negative back pressure, that is, a pressure drawn into the ink, is applied to the ink in the ink jet head as is well known, the purge cap is separated from the ink ejection surface by the bubble mixed ink remaining on the ink ejection surface. When drawn, the ink is drawn into the inkjet head from the nozzle. As a result, after the purge operation, the ink in the ink jet head contains more bubbles.

An object of the present invention is that the air bubbles mixed ink adhering to the ink discharge surface during a purge to provide an ink jet recording equipment which hardly drawn into the nozzle.

Means for Solving the Problems and Effects of the Invention

An inkjet recording apparatus of the present invention includes an inkjet head having an ink ejection surface on which a plurality of nozzles for ejecting ink are formed, and ink that is disposed above the inkjet head and is supplied to the inkjet head temporarily. An ink chamber for storing, an air inlet / outlet passage for communicating air stored in the ink chamber with the outside, a buffer tank including a communication valve capable of opening and closing the air inlet / outlet passage, and a first annular protrusion a first cap, a first closed space between the first cap and the ink discharge surface by the first annular protrusion abuts against the ink ejection surface is formed by a recess formed in any of the positions where the a position to be the first annular projection of the first closed space spaced apart from the ink ejection surface is eliminated, A first capping drive mechanism for displacing the serial first cap and a second cap recesses defined by the second annular projection is formed, said second annular projection opening of said air input and passage A position where a second closed space is formed between the lower end surface and the second cap by contacting the lower end surface of the communication valve of the formed buffer tank, and the second annular protrusion A second capping drive mechanism for displacing the second cap at a position separated from the lower end surface and the second closed space is eliminated, and vertically penetrates the second cap. disposed, and the second cap movable independently of one another a valve portion along the vertical direction, a first decompression means for decompressing the first closed space, the ink discharge surface Waist for wiping And par, ink adhering to the ink ejection surface is provided with said wiper and wiping driving mechanism for moving at least one of the ink-jet head to be removed by the wiper. Then, the a first capping control means for the first cap to control said first capping drive mechanism to abut the ink ejection surface, the first cap by the first capping control means the A closed space that stops the pressure-reducing operation by the first pressure-reducing means after depressurizing the first closed space by the first pressure-reducing means until at least ink starts to be discharged from the nozzles when contacting the ink ejection surface. The first valve opening control for opening the communication valve by moving the valve opening / closing portion while the pressure in the first closed space is a pressure at which ink is not drawn into the nozzle. means, when said first valve opening control means opens the communication valve, drive the first capping so that the first cap is spaced apart from the ink ejection surface A first uncapping control means for controlling the mechanism, when the first cap by the first uncapping control means is spaced apart from the ink ejection surface, in order to remove the ink adhering to the ink ejection surface wherein the wiper and the first wiping control means for controlling the wiping driving mechanism to move the one of the ink jet head, the ink adhering to the ink ejection surface is removed by the wiper, the said valve First valve closing control means for moving the opening and closing portion to close the communication valve; and second pressure reducing means for reducing the pressure of the ink chamber via the air inlet / outlet path by reducing the pressure of the second closed space. , A second capping control for controlling the second capping drive mechanism so that the second cap contacts the lower end surface. And a second valve opening control means for opening the communication valve by moving the valve opening / closing portion when the second cap comes into contact with the lower end surface by the second capping control means, When the valve opening control means opens the communication valve, the second pressure reducing means causes the second decompression means to discharge at least part of the air in the ink chamber to the outside through the second closed space and the air inlet / outlet path. An ink chamber decompression control unit that stops the decompression operation by the second decompression unit after decompressing the ink chamber, and the air in the ink chamber is discharged to the outside by leaving a predetermined amount of air by the second decompression unit. Then, a second valve closing control means for closing the communication valve by moving the valve opening / closing part is further provided.

According to this, the ink chamber disposed above the inkjet head is opened by opening the communication valve while the pressure in the first closed space is the pressure at which ink is not drawn into the nozzle due to the pressure reduction during the purge. Becomes atmospheric pressure. Therefore, even if the air pressure on the ink ejection surface subsequently rises to atmospheric pressure, a pressure for ejecting ink from the nozzles is applied to the ink due to the water head difference between the ink chamber and the nozzles. For this reason, it is difficult for the bubble-mixed ink attached to the ink ejection surface during the purge to be drawn into the inkjet head from the nozzle. Further, excess air can be discharged from the ink chamber. Therefore, it is possible to prevent the air from increasing in the ink chamber as air from the outside enters the ink jet head.
In the present invention, the first valve opening control means preferably opens the communication valve by moving the valve opening / closing part in a state where the second cap is separated from the lower end surface.

In the present invention, the time measuring means for measuring the elapsed time from the time when the pressure reducing operation by the first pressure reducing means is stopped, and the elapsed time measured by the time measuring means are such that the pressure in the first closed space is within the nozzle. The apparatus further includes elapsed time determination means for determining whether or not a predetermined time has been reached when the pressure has not increased to the pressure at which ink is drawn. The first valve opening control means preferably opens the communication valve when the elapsed time determining means determines that the elapsed time measured by the time measuring means has reached the predetermined time.

  Thereby, since a communicating valve is opened based on measuring elapsed time, a sensor etc. are unnecessary and an apparatus structure is simplified.

Further, in the present invention, the pre-Symbol first valve closing control means closes the communication valve, the third of said first cap to control said first capping drive mechanism to abut the ink ejecting surface The second valve opening control means can open the communication valve when the first cap comes into contact with the ink ejection surface by the third capping control means. preferable.

Thus, since the forming a first closed space when discharging the surplus air from the ink chamber, comprising a meniscus is hardly destroyed.

At this time, the the second valve closing control means closes the communication valve, the first cap second controlling said first capping drive mechanism so as to be spaced apart from the ink ejection surface When the first cap is separated from the ink ejection surface by the uncapping control means and the second uncapping control means, the wiper and the inkjet head are used to remove ink adhering to the ink ejection surface. And a second wiping control means for controlling the wiping drive mechanism to move any one of the first and second inks, and when the ink adhering to the ink ejection surface is removed by the wiper, ink is preliminarily ejected from the plurality of nozzles. The preliminary ejection control means for controlling the inkjet head, and the preliminary ejection control means When ink from a plurality of nozzles are ejected preliminary, be further provided with a fourth capping control means for said first cap to control said first capping drive mechanism to abut the ink ejecting surface Good.

  As a result, the mixed color ink that has entered the nozzle when the ink attached to the ink discharge surface is removed by the wiper can be discharged.

In the present invention, the first cap, and the atmosphere open passage which communicates with said recess and the outside of the first cap, and a is shut-off valve for opening and closing the atmosphere opening passage Yes. Then, the before the first cap abuts on the ink discharge surface by the first capping control means, a shutoff valve opening control means for opening the shut-off valve, the first by the first capping control means Preferably, the apparatus further includes a shut-off valve closing control unit that closes the shut-off valve when the cap contacts the ink discharge surface.

Thereby, the inside of the 1st closed space can be certainly made into atmospheric pressure at the time of forming the 1st closed space. Therefore, when the first closed space is formed, it becomes difficult for air to enter the nozzle.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view illustrating the internal configuration of a color inkjet printer according to an embodiment of the present invention. In FIG. 1, a head unit 2 is disposed in the color inkjet printer 1. To the holder 3 of the head unit 2, a buffer tank 4 for storing inks of four colors, magenta, yellow, cyan, and black, and an ink jet head 5 (see FIG. 2) for discharging the inks of four colors are fixed. The holder 3 is fixed to a carriage 11 that reciprocates in a linear direction (main scanning direction) by a drive mechanism 10. The platen roller 18 as a conveying means for conveying the paper P as a recording medium is arranged so that its axis is along the reciprocating direction of the carriage 11 and faces the head unit 2.

  The carriage 11 is slidably supported by a guide shaft 12 and a guide plate 13 that are arranged in parallel with the support shaft of the platen roller 18. Pulleys 14 and 15 are supported in the vicinity of both ends of the guide shaft 12, and an endless belt 16 is bridged between the pulleys 14 and 15. The carriage 11 is fixed at an appropriate position of the endless belt 16.

  In such a configuration of the driving mechanism 10, when one pulley 14 rotates forward and backward by driving the motor 17, the carriage 11 reciprocates in the linear direction (main scanning direction) along the guide shaft 12 and the guide plate 13. Accordingly, the head unit 2 also reciprocates.

  The paper P is fed from a paper feed cassette (not shown) provided on the side of the ink jet printer 1, guided to the space between the ink jet head 5 and the platen roller 18, and discharged from the ink jet head 5. The paper is ejected after printing is performed. In FIG. 1, the paper feed mechanism and paper discharge mechanism for paper P are not shown.

  Further, a purge mechanism 20 shown at the lower left in FIG. 1 is provided in the inkjet printer 1. The purge mechanism 20 covers the ink discharge surface 40a (see FIG. 3) of the inkjet head 5 with the purge cap 21 and forcibly sucks and removes defective ink containing bubbles, dust, and the like accumulated inside the inkjet head 5. Is for. The purge cap 21 moves in the vertical direction (vertical direction) with respect to the ink ejection surface 40a of the inkjet head 5 as the cam 22a rotates.

  That is, the cam 22 a is rotated to cover the plurality of nozzles 60 (see FIG. 5) of the inkjet head 5 with the purge cap 21. The ink jet head 5 is recovered by sucking the defective ink containing bubbles or the like accumulated inside the ink jet head 5 by the pump 23 and discarding it into the waste ink reservoir 24.

  Further, a valve opening / closing mechanism 34 and a wiping mechanism 37 are disposed at a right side position adjacent to the purge cap 21. The valve opening / closing mechanism 34 includes four slide bars 35. The slide bar 35 moves up and down in the same manner as the purge cap 21 by the rotation of the cam 22b, and opens the communication valve 26 described later to an open state or a closed state. The wiping mechanism 37 includes a wiper 36a that extends in the same direction as the length of the ink ejection surface 40a in the sub-scanning direction, and a lift 36b that moves the wiper 36a in the vertical direction. The wiper 36a is made of an elastic material such as rubber and moves up and down in the same manner as the slide bar 35 by the elevating part 36b. That is, when the inkjet head 5 is disposed at a position adjacent to the wiper 36a, the lift 36b moves the wiper 36a to a position where it can contact the ink discharge surface 40a, and the tip of the wiper 36a is elastically deformed. Thus, by driving the motor 17 of the drive mechanism 10 and moving the head unit 2 in one direction, it is possible to wipe off the ink adhering to the ink discharge surface 40a. In the wiping mechanism, a mechanism in which the wiper can move in the main scanning direction may be provided. In this case, the ink attached to the ink ejection surface can be wiped off by moving the wiper in the main scanning direction while contacting the ink ejection surface.

  On the other hand, an ink receiving portion 25 is disposed at a left side position adjacent to the purge cap 21. The ink receiving portion 25 is disposed at a position just opposite to the ink discharge surface 40a by moving the inkjet head 5 on the carriage 11 to the left end in the main scanning direction during so-called flushing in which ink is preliminarily discharged from the nozzle 60. ing. As a result, ink preliminarily ejected from the nozzle 60 by flushing can be received by the ink receiving portion 25. The ink received by the ink receiving unit 25 is discarded into the waste ink reservoir 24.

  FIG. 2 is an exploded perspective view of the head unit 2 shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. As shown in FIG. 2, the head unit 2 includes a holder 3 formed in a box shape with a synthetic resin material, an inkjet head 5 fixed to the lower surface side of the bottom plate 3a of the holder 3 via a frame 30, and a bottom plate 3a. And a buffer tank 4 fixed on the upper side.

  As shown in FIG. 3, the buffer tank 4 is formed with four ink chambers 6 in which magenta, yellow, cyan, and black inks are stored in order from the right. As shown in FIG. 2, the ink chamber 6 is connected to one end of the corresponding tube 29. The other end of each tube 29 is connected to an ink cartridge (not shown) disposed below the inkjet head 5, and each color ink is supplied to the ink chamber 6 via the tube 29. It is like that. Each ink chamber 6 is filled with a predetermined amount of air together with the ink, and the dynamic pressure of the ink generated when the head unit 2 reciprocates is absorbed and attenuated by a damper effect of air.

  As shown in FIG. 2, the buffer tank 4 includes four communication valves 26 that communicate with the ink chambers 6. These communication valves 26 are arranged in parallel along the extending direction (sub-scanning direction) of the ink chamber 6. As shown in FIG. 4, a passage 8 communicating with each communication valve 26 is provided immediately below the upper cover 4 a of the buffer tank 4. As shown in FIG. 2, these passages 8 extend in a direction orthogonal to the extending direction of the ink chamber 6, and communicate with each communication valve 26 and the corresponding ink chamber 6.

  As shown in FIG. 2, the frame 30 has a planar rectangular shape, and a through portion 31 penetrating in the thickness direction is formed in the central region. The inkjet head 5 is fixed to the frame 30 such that an actuator unit 42 and a flexible printed circuit (FPC: Flexible Printed Circuit) 50, which will be described later, are disposed in the through portion 31.

  The inkjet head 5 includes a head main body 40 including a flow path unit 41 in which a plurality of ink flow paths are formed for each color, and an actuator unit 42 bonded to the upper surface of the flow path unit 41, and an actuator unit 42. And an FPC 50 joined to the upper side. As shown in FIG. 2, both the flow path unit 41 and the actuator unit 42 have a rectangular planar shape, and are disposed below the buffer tank 4 with the frame 30 interposed therebetween. A plurality of nozzles 60 (see FIG. 5) are arranged on the ink ejection surface 40a of the head body 40 along the extending direction (sub-scanning direction) of the head body 40. Each nozzle 60 is formed downward so as to face the upper surface of the paper P.

  As shown in FIG. 2, four ink supply ports 41 a having an elliptical planar shape are formed on the upper surface of the flow path unit 41, avoiding the actuator unit 42. In the region where these four ink supply ports 41a are formed, a filter 45 (see FIG. 5) is disposed at a position facing each ink supply port 41a. Thus, dust or the like in the ink supplied into the flow path unit 4 from the ink supply port 41 a is captured by the filter 45. The flow path unit 41 is bonded to the frame 30 so that the through holes 33 formed in the frame 30 and the ink supply ports 41 a formed in the flow path unit 41 are connected to each other.

  Further, as shown in FIG. 3, a through portion 3 b penetrating in the thickness direction is formed on the bottom surface 3 a of the holder 3 at a position facing the through hole 33 of the frame 30 and the ink outlet 7 of the buffer tank 4. . An elastic member 44 is disposed in the penetrating portion 3b. In the elastic member 44, four communication holes 43 are formed at positions facing the ink outlet 7 of the buffer tank 4, respectively. The elastic member 44 is screwed into the mounting holes 38a and 38b of the buffer tank 4 and the mounting holes 39a and 39b of the frame 30, and the buffer tank 4 and the frame 30 are fastened to each other. The compressed state is established between the frame 30 and the connection between the ink outlet 7 and the through hole 33 is sealed. With such a configuration, the ink in the buffer tank 4 is supplied into the flow channel unit 41 from the ink supply port 41a of the corresponding flow channel unit 41 through the ink outlet port 7, the communication hole 43, and the through hole 33. Is done.

  As shown in FIG. 3, the FPC 50 joined to the upper surface of the actuator unit 42 is pulled out to one side in the main scanning direction, passed through the through-hole 3c formed in the bottom surface 3a, and pulled upward. The FPC 50 is pulled out along the side surface of the buffer tank 4 through an elastic member 27 such as a sponge, and a driver IC 51 is installed on the FPC 50. On the other hand, the FPC 50 is electrically joined to the actuator unit 42 by soldering so that the drive signal output from the driver IC 51 is transmitted to the actuator unit 42.

  In FIG. 3, a heat sink 28 bent in a U shape is disposed on the side wall of the holder 3 facing the driver IC 51. The driver IC 51 is pressed against the heat sink 28 by the elastic member 27 with the FPC 50 interposed therebetween. The heat sink 28 can efficiently dissipate heat generated by the driver IC 51.

  FIG. 5 is an exploded perspective view of the inkjet head 5 shown in FIG. As can be seen from FIG. 5, the head body 40 includes a flow path unit 41 and an actuator unit 42. Among these, the flow path unit 41 has a total of eight sheets including a cavity plate 81, a supply plate 82, an aperture plate 83, two manifold plates 84 and 85, a damper plate 86, a cover plate 87, and a nozzle plate 88 from the top. It is a laminated structure in which materials are laminated. In the present embodiment, except for the nozzle plate 88 made of synthetic resin, each of the plates 81 to 87 is made of stainless steel.

  As shown in FIG. 5, the nozzle plate 88 has a large number of minute diameter nozzles 60 formed at minute intervals. These nozzles 60 are arranged in five rows in a staggered arrangement along the longitudinal direction of the nozzle plate 88.

  As shown in FIG. 5, in the center of the cavity plate 81, a plurality of pressure chambers 46 are formed in five rows in a staggered arrangement along the longitudinal direction of the cavity plate 81. Further, four holes 65 serving as the ink supply ports 41 a are formed on one end side in the longitudinal direction of the cavity plate 81 so as to be separated along the short direction of the cavity plate 81. Each pressure chamber 46 is formed in a substantially rectangular shape with a narrow width and rounded corners. The longitudinal directions of the pressure chambers 46 are orthogonal to the longitudinal direction of the cavity plate 81. As shown in FIG. 5, one end of each pressure chamber 46 is formed in a staggered arrangement in the supply plate 82, the aperture plate 83, the two manifold plates 84 and 85, the damper plate 86 and the cover plate 87. The nozzle plate 88 communicates with the nozzle 60 through the through hole 61 having a small diameter.

  As shown in FIG. 5, among the two manifold plates 84 and 85, the manifold plate 84 on the side close to the aperture plate 83 has five ink chamber half portions 70a formed in a penetrating manner. The five ink chamber halves 70 a extend along the longitudinal direction of the manifold plate 84 and are separated from each other in the short direction of the manifold plate 84.

  On the other hand, the manifold plate 85 on the damper plate 86 side is also formed with five ink chamber half portions 70b penetrating the same as the five ink chamber half portions 70a. By laminating a total of four manifold plates 84 and 85, an aperture plate 83, and a damper plate 86 with this configuration, the two opposing ink chamber halves 70a and 70b are joined to each other and formed at this time. The upper and lower openings to be formed are covered with an aperture plate 83 from above and a damper plate 86 from below. As a result, a total of five common ink chambers 70 are formed between and outside the row of through holes 61. Note that one end of each common ink chamber 70 faces the ink supply port 41a.

  In addition to the plurality of through holes 61, a plurality of communication holes 62 are formed through the supply plate 82. These communication holes 62 communicate with the pressure chamber 46 at one opening and communicate with an aperture 63 described later at the other opening. Further, the plurality of communication holes 62 are arranged in five rows in a staggered manner along the longitudinal direction of the supply plate 82 corresponding to each pressure chamber 46. The supply plate 82 has four holes 66 on one end side in the longitudinal direction. These holes 66 are formed so as to face the four holes 35 of the cavity plate 81, respectively.

  In addition to the plurality of through holes 61, the aperture plate 83 has substantially rectangular planar apertures 63 extending in the short direction of the aperture plate 83 in a staggered arrangement along the longitudinal direction of the aperture plate 83. It is arranged in 5 columns. The aperture 63 communicates with the communication hole 62 at one end, and communicates with the common ink chamber 70 at the other end. The aperture 63 has a slightly smaller cross-sectional area in the direction orthogonal to the ink flow direction, and restricts the flow of ink that attempts to flow backward from the pressure chamber 46 toward the common ink chamber 70 when ink is ejected. The aperture plate 83 is formed with holes 67 at positions facing the four holes 65 or 66, respectively. Each hole 67 communicates with the hole 66 at one opening, and communicates with one end of the corresponding common ink chamber 70 at the other opening.

  Of the four holes 67, one hole 67 located at the back in FIG. 5 communicates with the two common ink chambers 70 at the back in FIG. 5, and the other three holes 67 are in FIG. The three common ink chambers 70 in front of the middle communicate with each other. That is, out of the five common ink chambers 70, two common ink chambers 70 located in the back of FIG. 5 are supplied with ink from one ink supply port 41a, respectively, and the other three common ink chambers 70 are supplied. Are supplied with ink from one corresponding ink supply port 41a. In the present embodiment, black ink is supplied to the two common ink chambers 70 at the back in FIG. 5, and magenta and yellow are supplied to the three common ink chambers 70 arranged from the front to the back in FIG. Ink is supplied in the order of cyan.

  As shown in FIG. 5, the damper plate 86 is provided with five rows of damper grooves 68. These damper grooves 68 are formed so as to open only toward the cover plate 87, and the positions and shapes thereof are the same as those of the common ink chamber 70. Therefore, when the manifold plates 84 and 85 and the damper plate 86 are joined, the damper portion 69 is located at a portion of the damper plate 86 facing the common ink chamber 70. Here, the damper portion 69 is configured as a bottom surface of a recess formed in stainless steel that can be appropriately elastically deformed, and therefore can freely vibrate toward the common ink chamber 70 side and the damper groove 68 side. With such a configuration, even if the pressure fluctuation generated in the pressure chamber 46 during ink ejection propagates to the common ink chamber 70, the damper 69 can be absorbed and attenuated by elastically deforming correspondingly.

  With such a configuration of the flow path unit 41, the flow path unit 41 has a nose 60 that passes through the common ink chamber 70, the aperture 63, the communication hole 62, the pressure chamber 46, and the through hole 61 in order from the ink supply port 41 a. The ink flow path leading to is configured. The ink that has flowed into the flow path unit 41 from the ink supply port 41 a is temporarily stored in the common ink chamber 70. Then, it is supplied to each pressure chamber 46 via the aperture 63. Ink applied with pressure by the actuator unit 42 in each pressure chamber 46 is ejected from the corresponding nozzle 60 via each through hole 61.

  Although not shown, the actuator unit 42 has a structure in which three sheets of two piezoelectric sheets and an insulating top sheet are laminated, and one sheet of each sheet has a thickness of about 30 μm. . On the upper surface of the piezoelectric sheet located below the two piezoelectric sheets, narrow individual electrodes are arranged in a row along the longitudinal direction (sub-scanning direction) of the actuator unit 42 for each region facing each pressure chamber 46. Is formed. Each individual electrode has a longitudinal direction orthogonal to the longitudinal direction of the actuator unit 42. On the other hand, a common electrode formed across the plurality of pressure chambers 46 is formed on the upper surface of the piezoelectric sheet positioned above the two piezoelectric sheets. On the upper surface of the top sheet located at the uppermost stage, a surface electrode 71 electrically connected to each of the plurality of individual electrodes and a surface electrode 72 electrically connected to the common electrode are provided. ing.

  An adhesive sheet is attached in advance to the entire lower surface of such a plate-type actuator unit 42, and the actuator unit 42 corresponds to each of the pressure chambers 46 in the channel unit 41 with respect to the channel unit 41. The head main body 40 is configured by bonding and fixing. Then, while the FPC 50 is overlapped with the actuator unit 42, a plurality of wiring patterns (not shown) of the FPC 50 are joined to the surface electrodes 71 and 72 of the actuator unit 42 by soldering, and the inkjet head 5 is created.

  FIG. 6 is an enlarged view of a region surrounded by a dashed line drawn in FIG. FIG. 7 shows a valve member of the communication valve 26 shown in FIG. 6, (a) is a side view of the valve member, and (b) is a bottom view of the valve member. 8 shows a slide member of the communication valve 26 shown in FIG. 6, wherein (a) is a sectional view of the slide member, and (b) is a top view of the slide member. As shown in FIG. 6, the communication valve 26 includes a substantially cylindrical case 91, a lid 92 fixed to the upper end portion of the case 91, and a slide that is slidably arranged at the lower end portion in the case 91. Member 93. The lid body 92 is formed with a through hole 94 penetrating in the thickness direction, and a groove 95 extending from the through hole 94 to the ink chamber 6 side along the upper surface of the lid body 92. By fixing the upper lid 4a to the upper surface of the lid 92, the above-described passage 8 through which the communication valve 26 and the ink chamber 6 communicate is formed. The passage 8 can communicate with the outside through a through hole 91 b formed in the inside of the communication valve 26 and the lower end of the case 91.

  As shown in FIG. 6, a spring 96, a valve member 97, and an O-ring 98 are disposed in the case 91 between the lid 92 and the slide member 93. The lid 92 has a lower end outer periphery cut out by a notch 92 a, and one end of a spring 96 is fitted and fixed to the lower end of the lid 92.

  As shown in FIG. 7A, the valve member 97 is formed with a recess 99 that opens upward. A projecting portion 100 projecting downward is formed in a substantially central region of the bottom 99 a of the recess 99. The protrusion 100 has a cylindrical body 101 and a tip 102 that tapers toward the tip. Three protrusions 103 are formed on the outer peripheral surface of the distal end portion 102 and project outward and extend from the body portion 101 to the vicinity of the distal end. These protrusions 103 are spaced apart from each other at an interval of about 120 ° as shown in FIG. In addition, inclined surfaces 104 having the same inclination angle are formed at the tips of the three protrusions 103, respectively. Further, the other end of the spring 96 is fitted in the recess 99, and the spring 96 always presses the valve member 97 in a direction (downward) approaching the slide member 93.

  The O-ring 98 is disposed between the outer end of the bottom 99 a of the valve member 97 and a step 91 a formed in the case 91. With this configuration, the spring 96 presses the valve member 97, and the valve member 97 sandwiches and deforms the O-ring 98 with the stepped portion 91a, whereby the communication valve 26 is closed. On the other hand, when the valve member 97 is not sandwiching and deforming the O-ring 98 with the stepped portion 91a, that is, when the valve member 97 and the O-ring 98 are separated from each other, the communication valve 26 is opened. Since the inside of the communication valve 26 communicates with the outside through a through hole 91 b formed at the lower end of the case 91, the ink chamber 6 also passes through the passage 8 when the communication valve 26 is opened or closed. Can communicate with the outside or cannot communicate. That is, the inside of the communication valve 26 and the passage 8 form an air inlet / outlet path for the ink chamber 6.

  As shown in FIG. 8A, the slide member 93 is formed with a recess 105 that opens upward. On the outer peripheral surface of the slide member 93, there are formed six protrusions 106 protruding outward and extending in the vertical direction in FIG. As shown in FIG. 8B, these protrusions 106 are separated from each other with an interval of about 60 °. Further, the protrusion 106 has a protruding amount that overlaps with the outer peripheral edge of the through hole 91 b of the case 91 in the vertical direction. Thus, the slide member 93 is prevented from falling downward from the through hole 91b. The opening end of the slide member 93 has a zigzag shape in the vertical direction so that the crests 107 and the troughs 108 are alternately formed. As shown in FIG. 6, the open end of the slide member 93 overlaps the protrusion 103 of the valve member 97 in the vertical direction. When the slide member 93 moves upward from the state shown in FIG. It comes to touch.

  FIG. 9 is a developed view of the lower end portion of the communication valve 26 shown in FIG. 6, (a) is an explanatory view showing a plurality of grooves formed on the lower end inner wall of the communication valve 26, and (b) is a diagram of FIG. It is sectional drawing of the IXA-IXA line in 9 (a), (c) is sectional drawing of the IXB-IXB line in FIG. 9 (a). As shown in FIGS. 9A and 9B, a projecting portion 109 projecting inward is formed on the inner wall at the lower end of the case 91. The protrusion 109 is formed with a plurality of two types of grooves 110a and 110b extending in the vertical direction. As shown in FIG. 9B, the groove 110 a has a depth (depth in the thickness direction of the case 91) corresponding to the protruding amount of the protrusion 106 of the slide member 93. The groove 110b has a depth corresponding to the protrusion amount of the protrusion 103 of the valve member 97, as shown in FIG. That is, since the groove 110a is formed to be shallower than the groove 110b, the protrusion 103 of the valve member 97 cannot be disposed in the groove 110a. Only the projection 106 of the slide member 93 can slide in the vertical direction. On the other hand, since the groove 110b is formed deeper than the groove 110a, the protrusion 103 of the valve member 97 and the protrusion 106 of the slide member 93 can be disposed in the groove 110b. That is, both the protrusion 103 of the valve member 97 and the protrusion 106 of the slide member 93 can slide in the vertical direction.

  Further, as shown in FIGS. 9A and 9B, at the end of the projecting portion 109 on the valve member 97 side, the bottom region of the groove 110a in the region sandwiched between the grooves 110b has the same inclination angle. An inclined surface 111a having the tip thereof positioned at the same height level is formed. On the other hand, at the end of the projecting portion 109 on the valve member 97 side, the region sandwiched between the groove 110a and the groove 110a bottom region and the groove 110b has the same inclination angle and the tip has the same height level. Inclined surfaces 111b and 111c are formed. The inclined surface 111a is formed such that its apex overlaps with the low point of the inclined surface 111b. That is, as shown to Fig.9 (a), it is the continuous inclined surface 113 with which the inclined surface 111a and the inclined surface 111b adjacent to the right side of the inclined surface 111a continue. On the other hand, the inclined surface 111a and the inclined surface 111c adjacent to the left side thereof are not continuous with each other.

  Subsequently, the operation of the open and closed states of the communication valve 26 will be described below. FIG. 10 shows operations related to the open and closed states of the communication valve 26 shown in FIG. 6, and (a) shows the operations of the slide member and the valve member when the closed state of the communication valve 26 is opened. It is explanatory drawing, (b) is explanatory drawing which shows a state when the communication valve 26 will be in an open state, (c) is a slide member and valve member when making the open state of the communication valve 26 into a closed state It is explanatory drawing which shows operation | movement. FIG. 10 is an expanded view of the lower end portion of the communication valve 26.

  As shown in FIG. 6, when the valve member 97 of the communication valve 26 sandwiches the O-ring 98 with the stepped portion 91a, that is, when the communication valve 26 is closed, as shown in FIG. The protrusion 103 of the valve member 97 falls into the groove 110b. When the communication valve 26 is opened, as shown in FIG. 10A, the valve member together with the slide member 93 is brought into contact with the inclined surface 104 of the projection 103 while the apex of the peak portion 107 of the slide member 93 is brought into contact with the inclined surface 104 of the projection 103. Slide 97 up. When the tip of the inclined surface 104 of the protrusion 103 reaches a position exceeding the apex of the inclined surface 111b, as shown in FIG. 10A, the slide member 93 moves toward the trough 108 while sliding on the upper end surface. When the slide member 93 is slid downward from this state as shown in FIG. 10B, the protrusion 103 continuously inclines to a position where the low point of the inclined surface 111a and the tip of the inclined surface 114 of the protrusion 103 overlap. It moves obliquely downward along the surface 113. At this time, since the inclined surface 104 of the protrusion 103 is in contact with the inclined surface 111a, the valve member 97 is held at that position even if the valve member 97 and the slide member 93 are not in contact with each other. That is, since the valve member 97 is held at a position separated from the O-ring 98, the sealing performance between the outer end of the bottom 99a of the valve member 97 and the stepped portion 91a is lost, and the communication valve 26 is opened. Become.

  Next, when the communication valve 26 is changed from the open state to the closed state, as shown in FIG. 10C, the apex of the peak portion 107 of the slide member 93 is brought into contact with the inclined surface 104 of the protrusion 103. The valve member 97 is further slid upward together with the slide member 93. When the tip of the inclined surface 104 of the protrusion 103 reaches a position exceeding the apex of the inclined surface 111c, as shown in FIG. 10C, the slide member 93 moves toward the valley portion 108 while sliding on the upper end surface. When the slide member 93 is slid downward from this state as shown in FIG. 9A, the protrusion 103 moves obliquely downward along the inclined surface 111c. There is a groove 110b at the destination. As described above, since the depth of the groove 110b is determined corresponding to the protrusion amount of the protrusion 103, the protrusion 103 falls along the groove 110b. At this time, the outer end of the bottom 99a of the valve member 97 is in contact with the O-ring 98, and the O-ring 98 is deformed between the outer end of the bottom 99a and the stepped portion 91a by the restoring force of the spring 96. Thus, the sealing performance by the O-ring 98 is exhibited between the outer end of the bottom 99a of the valve member 97 and the stepped portion 91a, and the communication valve 26 is closed. In the present embodiment, the slide member 93 is moved in the vertical direction by the slide bar 35.

  Next, the configuration of the purge mechanism 20 and the valve opening / closing mechanism 34 will be described in detail below. FIG. 11 is a schematic configuration diagram of the purge mechanism 20 and the valve opening / closing mechanism 34 shown in FIG. 11 shows a cross section in the same positional relationship as the IV-IV line shown in FIG. 2 when the head unit 2 is disposed at a position facing the purge mechanism 20 and the valve opening / closing mechanism 34.

  As shown in FIG. 11, the purge cap 21 of the purge mechanism 20 has an annular projection 54 that protrudes from the bottom 53 facing the ink discharge surface 40a toward the ink discharge surface 40a. That is, the purge cap 21 is formed with a recess 55 that opens toward the ink ejection surface 40 a by the bottom 53 and the annular protrusion 54. In the present embodiment, a tube 57 is connected to the annular protrusion 54. The tube 57 has a passage 56 communicating with the inside of the recess 55. A shutoff valve 58 that allows the passage 56 to be opened and closed is disposed in the middle of the tube 57. With this configuration, the interior of the recess 55 can communicate with the atmosphere via the passage 56 when the shutoff valve 58 is open, and cannot communicate with the atmosphere when the shutoff valve 58 is closed. A passage 47 communicating with the inside of the recess 55 is connected to the bottom 53 of the purge cap 21. The passage 47 extends from the bottom 53 to the switching valve 48. In addition to the passage 47, a passage 77, which will be described later, and a passage 49 that connects the switching valve 48 and the pump 23 are connected to the switching valve 48. Thus, the purge cap 21 is connected to the pump 23 through a series of communication paths including the passage 47, the switching valve 48 and the passage 49. Note that the tube 57 may be connected to the bottom 53 from the viewpoint of reliably discharging the ink sucked into the purge cap 21.

  The valve opening / closing mechanism 34 includes a slide bar 35, a cap 73, and a cam 22b (see FIG. 1) that slides the slide bar 35 and the cap 73 up and down independently of each other. The cap 73 has an annular protrusion 75 that protrudes from the bottom 74 toward the communication valve 26. That is, the cap 73 is formed with a recess 76 that opens toward the communication valve 26 by the bottom 74 and the annular protrusion 75. A passage 77 communicating with the inside of the recess 76 is connected to the annular protrusion 75. The passage 77 extends from the annular protrusion 75 to the switching valve 48. Thereby, the cap 73 is connected to the pump 23 through a series of communication paths including the passage 77, the switching valve 48, and the passage 49. Further, a through hole 74a having substantially the same planar shape as the slide bar 35 is formed in the bottom 74 of the cap 73 so that the slide bar 35 can slide in the vertical direction.

  The slide bar 35 has a substantially cylindrical shape, and its diameter is slightly smaller than the diameter of the through hole 91 b of the communication valve 26. Thereby, even if the slide bar 35 slides in the up-down direction in the through hole 74a and the recess 76 by the rotation of the cam 22b, the slide bar 35 can enter the through hole 91b at a position facing the through hole 91b. .

  Next, the control system of the inkjet printer 1 will be described with reference to FIG. FIG. 12 is a schematic block diagram showing a control configuration of the ink jet printer according to the embodiment of the present invention. The control unit 120 included in the inkjet printer 1 includes a CPU (Central Processing Unit) that is an arithmetic processing device, a ROM (Read Only Memory) in which a control program executed by the CPU and data used for the control program are stored. A RAM (Random Access Memory) for temporarily storing data during program execution.

  The control unit 120 includes a print control unit 121 and a maintenance control unit 123, as shown in FIG. In the inkjet printer 1, a cam drive control circuit 131 that drives the cams 22 a and 22 b, a pump drive circuit 132 that drives the pump 23, and a counter 133 that measures an elapsed time from when the drive of the pump 23 stops. The elapsed time measured by the counter 133 (hereinafter simply referred to as “elapsed time”) is input, and the selector 134 for determining whether or not the predetermined time has been reached and the opening / closing operation of the shutoff valve 58 are performed. A shutoff valve driving circuit 135 to be performed, a wiper driving circuit 136 for driving the elevating part 36b, a carriage driving circuit 137 for driving the motor 17, an ink jet head driving circuit 138 for driving the ink jet head 5, and a communication path of the switching valve 48 Switch valve drive circuit 139 for switching between and a transport motor for rotating the platen roller 18 And a feeding motor driving circuit 140 for driving the 41.

  The print control unit 121 receives the print data transmitted from the PC (personal computer) 115 via the communication processing unit 118 after the control unit 120 receives the print data, and then prints on the paper. And the transport motor drive circuit 140 is controlled.

  The maintenance control unit 123 includes a purge cap control unit 145, a pump control unit 146, a communication valve control unit 147, a shutoff valve control unit 148, a wiping control unit 149, and a flushing control unit 150. The purge cap control unit 145 controls the carriage drive circuit 137 and the cam drive control circuit 131 after the control unit 120 receives the purge signal transmitted from the PC 115 via the communication processing unit 118. At this time, the carriage drive circuit 137 drives the motor 17 so that the head unit 2 is moved to a position where the ink discharge surface 40 a faces the purge cap 21. On the other hand, the cam drive control circuit 131 moves the purge cap 21 toward and away from the ink ejection surface 40a. When the purge cap 21 abuts on the ink discharge surface 40a, a closed space 180 is formed between the purge cap 21 and the ink discharge surface 40a. Further, when the purge cap 21 is separated from the ink discharge surface 40a, the above-described closed space 180 is eliminated.

  The pump control unit 146 controls the switching valve drive circuit 139 and the pump drive circuit 132 after the control unit 120 receives the purge signal transmitted from the PC 115 via the communication processing unit 118. At this time, the switching valve drive circuit 139 switches the switching valve 48 to a position where the passage 47 and the passage 49 are communicated or a position where the passage 77 and the passage 49 are communicated. On the other hand, the pump drive circuit 132 drives the pump 23 so as to reduce the pressure in the closed space 180 and the pressure in the ink chamber 6 formed between the purge cap 21 and the ink discharge surface 40a.

  The communication valve control unit 147 controls the cam drive control circuit 131 based on the result of the selector 134 determining that the elapsed time measured by the counter 133 has reached a predetermined time. The cam drive control circuit 131 drives the cam 22b to slide the slide bar 35 so that the communication valve 26 is opened. Further, the cam drive control circuit 131 drives the cam 22b to slide the slide bar 35 so that the communication valve 26 is closed after the purge cap 21 is disposed at a position where the closed space 180 is eliminated. . In the present embodiment, since the communication valve 26 having the above-described structure is used, the slide bar 35 is inserted and removed once every time the open / close state is switched.

  In addition, the communication valve control unit 147 controls the cam drive control circuit 131 so as to form a closed space between the lower end surface of the communication valve 26 and the cap 73 when the communication valve 26 is closed. At this time, the cam drive control circuit 131 drives the cam 22b to slide the cap 73, and slides the slide bar 35 as described above to open the communication valve 26. After the pressure in the ink chamber 6 is reduced, the cam 22b is rotationally driven to slide the slide rod 35 as described above to close the communication valve 26, and the cap 73 is removed from the lower end surface of the communication valve 26. Move away from the closed space.

  The shutoff valve controller 148 controls the shutoff valve drive circuit 135 to open the shutoff valve 58 immediately before the purge cap 21 forms the closed space 180 with the ink ejection surface 40a, so that the closed space 180 is opened. Allow communication with the atmosphere. Immediately after the purge cap 21 forms a closed space with the ink ejection surface 40a, the shut-off valve drive circuit 135 is controlled to close the shut-off valve 58 so that the closed space 180 cannot communicate with the atmosphere. .

  The wiping control unit 149 controls the wiper driving circuit 136 and the carriage driving circuit 137 after the purge cap 21 is separated from the ink ejection surface 40a. At this time, the wiper drive circuit 136 drives the elevating unit 36b to move the wiper 36a to a position where it contacts the ink discharge surface 40a and a position away from the ink discharge surface 40a. On the other hand, the carriage drive circuit 137 moves the head unit 2 so that the ink discharge surface 40a is wiped by the wiper 36a.

  The flushing control unit 150 controls the carriage driving circuit 137 and the inkjet head driving circuit 138 after the control unit 120 receives the flushing signal transmitted from the PC 115 via the communication processing unit 118. At this time, the carriage drive circuit 137 drives the motor 17 to move the head unit 2 to a position where the ink discharge surface 40 a faces the ink receiving portion 25. On the other hand, the inkjet head driving circuit 138 drives the inkjet head 5 so that ink is preliminarily ejected from the nozzle 60.

  Next, an operation flow at the time of purging of the ink jet printer 1 and an operation flow after the purging will be described below with reference to FIGS. FIG. 13 is a flowchart showing an operation flow at the time of purging and after the purging of the inkjet printer 1 according to the embodiment of the present invention. FIG. 14 shows a series of operation states of the inkjet head 5 and the purge mechanism 20 during the purge of the inkjet printer 1 according to the embodiment of the present invention. FIG. 14A shows the purge cap 21 in contact with the ink ejection surface 40a. 4B is a cross-sectional view showing a state when the valve opening / closing mechanism 34 opens the communication valve 26, and FIG. 4C is a cross-sectional view showing that the purge cap 21 is separated from the ink discharge surface 40a. It is sectional drawing which shows the state made. FIG. 15 shows a series of operation states of the inkjet head 5 and the purge mechanism 20 when a part of the air in the ink chamber 6 is discharged after the purge of the inkjet printer 1 according to the embodiment of the present invention. ) Is a cross-sectional view showing a state in which the purge cap 21 is in contact with the ink ejection surface 40a, and (b) shows a state when a part of the air in the ink chamber 6 is sucked through the communication valve. It is sectional drawing, (c) is sectional drawing which shows a state when the communicating valve 26 is made into a closed state after a part of air in the ink chamber 6 is attracted | sucked.

  In the inkjet printer 1, in the purge operation performed when bubbles or the like are mixed in the ink in the inkjet head 5, first, in step 1 (S1), as shown in FIG. Move to a position facing the purge cap 21. At this time, the slide member 93 of each communication valve 26 is disposed at a position facing each of the slide rods 35.

  Next, in step 2 (S2), the shutoff valve 58 is opened. In step 3 (S3), as shown in FIG. 14A, the purge cap 21 is moved so that the tip of the annular protrusion 54 comes into contact with the ink discharge surface 40a (capping operation). Thus, the inside of the recess 55 of the purge cap 21 becomes a closed space 180 surrounded by the ink discharge surface 40 a and the purge cap 21. At this time, since the inside of the recess 55 of the purge cap 21 communicates with the atmosphere via the tube 57 and the shutoff valve 58, the purge cap 21 may be pressed against the ink ejection surface 40a in order to form the closed space 180. At that time, the air compressed in the closed space 180 does not enter the nozzle 60.

  Next, in step 4 (S4), the shut-off valve 58 is closed and the closed space 180 is sealed so as not to communicate with the atmosphere. Here, prior to step 5 (S5) in which the pump 23 is driven, the communication state of the switching valve 48 interposed between the purge cap 21 and the pump 23 is confirmed. If the purge cap 21 and the pump 23 are in communication, the process proceeds to the next step 5. On the other hand, if the communication valve 26 and the pump 23 are in communication, the switching valve 48 is connected to the passage 47 side. In step 5, the pump 23 is driven to depressurize the closed space 180. As a result, the ink in the inkjet head 5 is sucked from the nozzle 60. In the present embodiment, as shown in FIG. 14B, the ink liquid level in the ink chamber 6 is lower than the ink liquid level in the ink chamber 6 shown in FIG. If the amount of ink flowing from the ink cartridge into the ink chamber 6 and the amount of ink sucked from the nozzle 60 are almost the same, the ink level in the ink chamber 6 hardly fluctuates.

  Next, in step 6 (S6), it is determined whether or not the pump 23 has rotated a predetermined number of revolutions. If the pump 23 does not rotate at the predetermined number of rotations, the process waits until the predetermined number of rotations is repeated. That is, step 6 is repeatedly performed. When the pump 23 rotates a predetermined number of revolutions, the process proceeds to step 7 (S7), and the pump 23 is stopped. Here, the pump 23 can generate a predetermined pressure (a negative pressure larger than the negative pressure by the ink cartridge) in the closed space 180 when the pump 23 rotates by a predetermined number of rotations. Is being aspirated.

  Next, in step 8 (S8), the selector 134 determines whether or not the elapsed time after the pump stop measured by the counter 133 has reached a predetermined time. At this time, if the elapsed time does not reach the predetermined time, it waits in that state until the elapsed time reaches the predetermined time. That is, step 8 is repeatedly performed. This predetermined time is the time from when the closed space 180 is depressurized to a predetermined negative pressure by the pump 23 and the pump 23 is stopped until the pressure in the closed space 180 naturally returns to almost atmospheric pressure. The ink in the inkjet head 5 is sucked from the nozzle 60 while the pump 23 is stopped from when the closed space 180 is depressurized and the closed space 180 rises to almost atmospheric pressure. In step 8, when the elapsed time reaches a predetermined time, the process proceeds to step 9 (S9). At this time, the suction of ink from the nozzle 60 has been completed.

  In step 9, as shown in FIG. 14 (b), the slide rod 35 is slid and its tip abuts against the slide member 93, and the valve member 97 is moved upward to open the communication valve 26. Next, in step 10 (S10), as shown in FIG. 14C, the purge cap 21 is separated from the ink ejection surface 40a (uncapping operation). Thus, the closed space 180 surrounded by the ink ejection surface 40a and the purge cap 21 is eliminated. At this time, the ink in the inkjet head 5 is subjected to atmospheric pressure because the ink chamber 6 communicates with the atmosphere. Therefore, the ink tends to leak from the nozzle 60 to the outside due to its own weight, and the bubble mixed ink adhering to the ink ejection surface 40 a is not drawn into the nozzle 60.

  Next, in step 11 (S11), the ink adhering to the ink ejection surface 40a is wiped off by a wiping operation. This wiping operation is performed by moving the head unit 2 slowly in such a state where the tip of the wiper 36a is moved to a position where the tip of the wiper 36a can come into contact with the ink discharge surface 40a by the elevating part 36b.

  Next, in step 12 (S12), the communication valve 26 is closed. In this case, the slide bar 35 is slid upward, the tip thereof abuts against the slide member 93, and the valve member 97 is also moved upward. Then, by sliding the slide bar 35 downward, the valve member 97 is also moved downward, and the communication valve 26 is closed. Thereby, the purge operation of the inkjet head 5 is completed.

  Next, after the purge is completed, as shown in FIG. 15A, the ink level in the ink chamber 6 is at a position considerably lower than the ink level in the ink chamber 6 shown in FIG. If yes, go to Step 13 (S13). That is, an operation for sucking a part of the air in the ink chamber 6 is started.

  In step 13, as shown in FIG. 15A, the purge cap 21 is brought into contact with the ink discharge surface 40a to form the closed space 180 as described above (capping operation). In step 14, the communication valve 26 is opened. At this time, as shown in FIG. 15 (b), the tip end of the cap 73 is brought into contact with the lower end surface of the communication valve 26, and then the slide bar 35 is slid and the tip is brought into contact with the slide member 93. Further, the valve member 97 is moved upward by the slide rod 35 to open the communication valve 26. By doing so, the communication valve 26 communicates with the passage 77 through the cap 73. Here, prior to step 15 (S15) in which the pump 23 is driven, the communication state of the switching valve 48 interposed between the communication valve 26 and the pump 23 is confirmed. If the communication valve 26 and the pump 23 are in communication, the process proceeds to the next step 15. On the other hand, if the purge cap 21 and the pump 23 are in communication, the switching valve 48 is connected to the passage 77 side.

  Next, in step 15, the pump 23 is driven to decompress the ink chamber 6 through the communication valve 26. As a result, the air in the ink chamber 6 is sucked and discharged from the passage 8. In step 16 (S16), it is determined whether or not the pump 23 has rotated by a predetermined number of rotations. If the pump 23 does not rotate at the predetermined number of rotations, the process waits until the predetermined number of rotations is repeated. That is, step 16 is repeatedly performed. When the pump 23 rotates a predetermined number of revolutions, the process proceeds to step 17 (S17) and the pump 23 is stopped. Here, when the pump 23 rotates by a predetermined number of revolutions, a part of the air in the ink chamber 6 (excess air) is sucked, and the ink liquid level in the ink chamber 6 is indicated by a two-dot chain line shown in FIG. Return to the position drawn in. At this time, since all the nozzles 60 on the ink ejection surface 40a are covered by the purge cap 21 (that is, the closed space 180 is formed), the ink in the ink cartridge is supplied to the ink chamber 6 and described above. As described above, the ink level in the ink chamber 6 rises. This makes it difficult for the ink meniscus of the nozzle 60 to be destroyed when the excess air is sucked and discharged from the ink chamber 6. Thus, by discharging the excess air in the ink chamber 6, it is possible to prevent the air from increasing in the ink chamber 6 as the air enters the ink jet head 5. That is, the ink liquid level in the ink chamber 6 is further lowered from the state shown in FIG. 15A due to air entering the ink chamber 6 from the outside and bubbles in the ink, so that the air flows into the flow path unit 4. It is possible to prevent intrusion. In addition, since an appropriate amount of air is left in the ink chamber 6, the dynamic pressure in the ink generated by the movement of the carriage 11 can be suppressed by the damper effect.

  Next, in step 18 (S18), as shown in FIG. 15 (c), the communication valve 26 is closed. In step 19 (S19), the cap 73 is separated from the lower end surface of the communication valve 26, and the purge cap 21 is separated from the ink ejection surface 40a (uncapping operation). Thus, the closed space 180 surrounded by the ink ejection surface 40a and the purge cap 21 is eliminated. At this time, almost no bubble mixed ink or the like adheres to the ink discharge surface 40a. Since the communication valve 26 is closed in step 18, the ink is not drawn into the nozzle 60 even if the purge cap 21 is separated and the ink discharge surface 40a is opened to the atmosphere. There is no leakage outside. At this time, the negative pressure from the ink cartridge and the weight of the ink from the ink chamber 6 to the nozzle 60 are substantially balanced.

  Next, in step 20 (S20), a small amount of ink adhering to the ink ejection surface 40a is wiped off by a wiping operation. As described above, the wiping operation is performed when the tip of the wiper 36a comes into contact with the ink discharge surface 40a by the elevating part 36b and the head unit 2 moves slowly in this state. In step 21 (S21), ink is preliminarily ejected from the nozzle 60 toward the ink receiving portion 25 in a state where the head ejection unit 40 has moved to a position where the ink ejection surface 40a faces the ink receiving portion 25 (flushing operation). ). Thereby, when the ink adhering to the ink discharge surface 40a is removed by the wiper 36a, the mixed color ink that has entered the nozzle 60 can be discharged. Thus, after a series of purging operations in the ink jet printer 1 is completed, in preparation for printing, the head unit 2 is moved to a position where the ink ejection surface 40a faces the purge cap 21 in step 22 (S22), and the nozzle In order to prevent the ink 60 from drying, the ink ejection surface 40 a is capped by the purge cap 21.

  As described above, according to the ink jet printer 1 of the present embodiment, the communication valve 26 is opened while the pressure in the closed space 180 is the pressure at which ink is not drawn into the nozzle 60 due to the pressure reduction during the purge. As a result, the pressure in the ink chamber 6 disposed above the inkjet head 5 becomes atmospheric pressure. Therefore, even if the air pressure on the ink discharge surface 40a subsequently rises to atmospheric pressure, the pressure that causes the ink to be discharged from the nozzle 60 is applied to the ink due to the water head difference between the ink chamber 6 and the nozzle 60 ( That is, ink is about to leak from the nozzle 60). Therefore, it is difficult for the bubble-mixed ink adhering to the ink ejection surface 60 during the purge to be drawn into the inkjet head 5 from the nozzle 60. Further, at the time of purging, since the communication valve 26 is opened after the elapsed time measured by the counter 133 reaches a predetermined time, a sensor or the like is unnecessary and the apparatus configuration is simplified.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in the present embodiment described above, the excess air in the ink chamber 6 is discharged after purging. However, the excess air may not be discharged, and the passage 77 and the cap 73 for discharging the excess air. The switching valve 48 may not be provided in the ink jet printer. Further, the counter 133 and the selector 134 may not be provided in the inkjet printer 1 described above. Further, the flushing control unit 150 may not be provided in the control unit 120. That is, it is not necessary to perform the flushing operation. The inkjet printer 1 described above is a serial printer in which the head reciprocates, but may be a line printer with a fixed head.

  In the present embodiment described above, in the purge operation, when the purge cap 21 is brought into contact with the ink discharge surface 40a to create a closed space, the shut-off valve 56 is opened before the purge cap 21 comes into contact, and the shut-off valve is contacted after the contact. 56 was closed. This has the effect of preventing the outside air from entering the nozzle 60 due to the positive pressure generated in the closed space by the contact of the purge cap 21. Therefore, when the air amount in the ink chamber 6 is adjusted, or when a series of purge operations is completed and the purge cap 21 is brought into contact with the ink discharge surface 40a to prepare for the next printing, the shut-off valve as described above is used. 56 opening / closing operations may be added. Thereby, it is possible to reliably prevent outside air from entering the nozzle 60 when the closed space is formed by the purge cap 21.

1 is a schematic perspective view illustrating an internal configuration of a color inkjet printer according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the head unit shown in FIG. 1. It is sectional drawing in the III-III line of FIG. It is sectional drawing in the IV-IV line of FIG. FIG. 3 is an exploded perspective view of the ink jet head shown in FIG. 2. It is an enlarged view of the area | region enclosed with the dashed-dotted line drawn by FIG. The valve member of the communicating valve shown by FIG. 6 is shown, (a) is a side view of a valve member, (b) is a bottom view of a valve member. FIG. 7 shows a slide member of the communication valve shown in FIG. 6, (a) is a sectional view of the slide member, and (b) is a top view of the slide member. It is the figure which expanded the lower end part of the communicating valve shown in FIG. 6, (a) is explanatory drawing which shows the some groove | channel formed in the lower end inner wall of a communicating valve, (b) is IXA in FIG. 9 (a). It is sectional drawing of the -IXA line, (c) is sectional drawing of the IXB-IXB line in Fig.9 (a). 6A and 6B show operations related to the open and closed states of the communication valve shown in FIG. 6, and FIG. 7A is an explanatory diagram illustrating the operations of the slide member and the valve member when the closed state of the communication valve is set to the open state. (b) is explanatory drawing which shows a state when a communicating valve will be in an open state, (c) is explanatory drawing which shows operation | movement of a slide member and a valve member when making the open state of a communicating valve into a closed state. . FIG. 2 is a schematic configuration diagram of a purge mechanism and a valve opening / closing mechanism shown in FIG. 1. It is a schematic block diagram which shows the control structure of the inkjet printer of one Embodiment by this invention. 5 is a flowchart showing an operation flow at the time of purging and after purging of the inkjet printer according to the embodiment of the present invention. FIG. 2 shows a series of operation states of an inkjet head and a purge mechanism during purging of an inkjet printer according to an embodiment of the present invention, (a) is a cross-sectional view showing a state in which a purge cap is in contact with an ink ejection surface; (B) is a sectional view showing a state when the valve opening / closing mechanism opens the communication valve, and (c) is a sectional view showing a state where the purge cap is separated from the ink ejection surface. FIG. 2A shows a series of operating states of an inkjet head and a purge mechanism when a part of air in an ink chamber is discharged after purging of an inkjet printer according to an embodiment of the present invention, and FIG. FIG. 4B is a cross-sectional view showing a contact state, FIG. 4B is a cross-sectional view showing a state when a part of the air in the ink chamber is sucked through the communication valve, and FIG. It is sectional drawing which shows a state when a communicating valve is made into a closed state after a part is attracted | sucked.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 4 Buffer tank 5 Inkjet head 6 Ink chamber 8 Passage 11 Carriage 20 Purge mechanism 21 Purge cap 22a, 22b Cam 23 Pump 26 Communication valve 36a Wiper 36b Drive part 37 Wiping mechanism 54 Annular protrusion 55 Recessed part 60 Nozzle 120 Control part 131 Cam drive control circuit 132 Pump drive circuit 133 Counter 134 Selector 135 Shut-off valve drive circuit 136 Wiper drive circuit 137 Carriage drive circuit 145 Purge cap control unit 146 Pump control unit 147 Communication valve control unit 148 Shut-off valve control unit 149 Wiping control unit 150 Flushing Control unit

Claims (6)

An inkjet head having an ink ejection surface on which a plurality of nozzles for ejecting ink are formed;
An ink chamber that is disposed above the inkjet head and temporarily stores ink to be supplied to the inkjet head, an air inlet / outlet passage that communicates air stored in the ink chamber with the outside, and the air inlet / outlet passage A buffer tank including a communication valve capable of opening and closing;
A first cap recesses defined by the first annular protrusion is formed,
A position in which said first annular projection first closed space between the first cap and the ink discharge surface by contact with the ink discharge surface is formed, said first annular projection is the A first capping drive mechanism for displacing the first cap to any position where the first closed space is removed away from the ink ejection surface;
A second cap formed with a recess defined by a second annular projection;
A second closed space is formed between the lower end surface and the second cap by the second annular projection coming into contact with the lower end surface of the communication valve of the buffer tank in which the opening of the air inlet / outlet passage is formed. A second capping for displacing the second cap between the position where the second cap is formed and the position where the second annular protrusion is separated from the lower end surface to eliminate the second closed space A drive mechanism;
A valve opening / closing portion that is disposed through the second cap in the vertical direction and is movable independently of the second cap along the vertical direction;
First decompression means for decompressing the first closed space;
A wiper for wiping the ink ejection surface;
A wiping drive mechanism that moves at least one of the wiper and the inkjet head so that ink attached to the ink ejection surface is removed by the wiper;
A first capping control means for said first cap to control said first capping drive mechanism to abut the ink ejection surface,
When the first cap by the first capping control means is brought into contact with the ink discharge surface, by reducing the pressure of the first closed space by said first pressure reducing means to the ink from at least the nozzle starts to be discharged Closed space decompression control means for stopping the decompression operation by the first decompression means,
First valve opening control means for moving the valve opening / closing part to open the communication valve while the pressure in the first closed space is an atmospheric pressure at which ink is not drawn into the nozzle;
When the first valve opening control means opens the communication valve, and a first uncapping control means for controlling said first capping drive mechanism such that the first cap is spaced apart from the ink ejection surface ,
When the first cap is separated from the ink ejection surface by the first uncapping control means, either the wiper or the inkjet head is moved to remove the ink adhering to the ink ejection surface First wiping control means for controlling the wiping drive mechanism to
A first valve closing control means for moving the valve opening / closing portion to close the communication valve when the ink attached to the ink discharge surface is removed by the wiper ;
Second decompression means for decompressing the ink chamber through the air inlet / outlet path by decompressing the second closed space;
Second capping control means for controlling the second capping drive mechanism so that the second cap contacts the lower end surface;
When the second cap is brought into contact with the lower end surface by the second capping control means, second valve opening control means for moving the valve opening / closing portion to open the communication valve;
When the second valve opening control means opens the communication valve, the second pressure reduction is performed until at least part of the air in the ink chamber is discharged to the outside through the second closed space and the air inlet / outlet passage. An ink chamber decompression control means for depressurizing the ink chamber by means and then stopping the decompression operation by the second decompression means;
And second valve closing control means for moving the valve opening / closing portion to close the communication valve when the air in the ink chamber is exhausted to the outside while leaving a predetermined amount of air by the second pressure reducing means. An ink jet recording apparatus. The inkjet according to claim 1, wherein the first valve opening control means opens the communication valve by moving the valve opening / closing portion in a state where the second cap is separated from the lower end surface. Recording device. Time measuring means for measuring an elapsed time from the time when the pressure reducing operation by the first pressure reducing means is stopped;
Elapsed time determining means for determining whether or not the elapsed time measured by the time measuring means has reached a predetermined time during which the pressure in the first closed space has not increased to the pressure at which ink is drawn into the nozzle; Further comprising
The first valve opening control means, when the elapsed time said counting means has measured said to have reached the predetermined time the elapsed time determining means for determining, according to claim 1 or 2, characterized in that opening the communication valve 2. An ink jet recording apparatus according to 1. When the front Symbol first valve closing control means closes the communication valve, further a third capping control means for said first cap to control said first capping drive mechanism to abut the ink ejecting surface Has
It said second valve opening control means, when the first cap by the third capping control means is brought into contact with the ink ejection surface, any claim 1-3, characterized in that opening the communication valve 2. An ink jet recording apparatus according to item 1 . When the second valve closing control means closes the communication valve, and a second uncapping control means for controlling said first capping drive mechanism such that the first cap is spaced apart from the ink ejection surface ,
When the first cap is separated from the ink ejection surface by the second uncapping control means, one of the wiper and the inkjet head is moved to remove ink adhering to the ink ejection surface Second wiping control means for controlling the wiping drive mechanism to
Preliminary ejection control means for controlling the inkjet head so that ink is preliminarily ejected from the plurality of nozzles when ink attached to the ink ejection surface is removed by the wiper;
When ink is ejected preliminary from the plurality of nozzles by the preliminary discharge control means, the fourth capping control means for said first cap to control said first capping drive mechanism to abut the ink ejecting surface the ink-jet recording apparatus according to claim 1, characterized by further comprising and. The first cap includes an atmosphere release passage that allows the inside and the outside of the recess of the first cap to communicate with each other, and a shut-off valve that can open and close the atmosphere release passage.
Shut-off valve opening control means for opening the shut-off valve before the first cap comes into contact with the ink ejection surface by the first capping control means;
When the first cap by the first capping control means is brought into contact with the ink ejection surface, according to claim 1 to 5, characterized by further comprising a shut-off valve closing control means closing said shut-off valve The ink jet recording apparatus according to any one of the above.

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