JP2004255862A - Ink-jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact ink-jet printer wherein bubbles stored in air buffer chambers mounted together with a recording head on a carriage are efficiently removed. <P>SOLUTION: The recording head 34 in the ink-jet printer has a plurality of ink supply channels. A plurality of the air buffer chambers 40 for storing both ink and bubbles are formed in a buffer tank 36 correspondingly to the ink supply channels. A plurality of bubble discharge passages 47 are formed at the carriage 17, each having one end connected to the air buffer chamber 40 and the other end made openable to the outside. A discharging means 68 is set for discharging the bubbles in each air buffer chamber 40 to the outside through the other end of each bubble discharge passage 47. The bubble discharge passages 47 are formed to have an almost equal channel resistance value each other for discharging the bubbles. A discharge amount from each air buffer chamber for discharging the bubbles is made mutually equal, and the bubbles are removed efficiently. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an ink jet printer, and more particularly, to an ink jet printer capable of storing air bubbles generated in an ink flow path to maintain good recording quality and efficiently removing the stored air bubbles. It is about structure.

  Conventionally, a tube supply type ink jet printer that supplies ink to a recording head mounted on a moving carriage via a flexible tube from an ink tank fixed in the ink jet printer main body is disclosed in Patent Document 1 or the like. Known. On the other hand, in an ink jet printer, if bubbles (air) are contained in the ink in the recording head, ink ejection failure and deterioration of recording quality are caused.

  In the tube supply type ink jet printer, it is inevitable that air passes through the tube and dissolves in the ink due to the characteristics of the material constituting the tube, and an air buffer chamber is provided upstream of the recording head to remove air bubbles. Work was needed.

The configuration of Patent Document 1 describes a configuration in which a manifold (corresponding to an air buffer chamber) is provided above a recording head, an ink tank and a circulation pump are provided on a stationary position side, and the circulation pump is driven to remove bubbles. Have been. Specifically, the ink is circulated from the ink tank in the order of the first ink flow path, the manifold, the second ink flow path, and the ink tank, and the air bubbles in the circulation path are returned to the ink tank and removed. Further, at the maintenance position, the ink is suctioned from the nozzle (ink ejection) side of the recording head by the suction purge means.
JP 2000-103084 A (see FIG. 1 and the like)

  However, according to the configuration of Patent Literature 1, the ink tank is open to the atmosphere, and air (bubbles) tends to enter the ink when the ink is circulated. In addition, a tube for returning from the circulation pump to the ink tank is required for circulation, and there has been a problem that the apparatus becomes large and complicated.

  Further, when a plurality of ink tanks are provided according to the colorization of the ink jet printer, a plurality of air buffer chambers are provided for each ink tank. Then, at the time of maintenance, the operation of removing air bubbles from each air buffer chamber is performed simultaneously. For this reason, there has been a demand that the time required for removing the air bubbles be completed almost simultaneously in all the air buffer chambers so as to improve the efficiency of the operation.

  SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and provides a compact inkjet printer that can efficiently remove bubbles stored in an air buffer chamber mounted on a carriage together with a recording head. It is the purpose.

  In order to achieve the above object, an ink jet printer according to the first aspect of the present invention includes an ink jet recording head mounted on a carriage that moves with respect to a recording medium, and supplies ink from an ink tank mounted on a main body of the printer. In an ink jet printer configured to supply ink to the recording head via a buffer tank mounted on the carriage via a pipe, the recording head has a plurality of ink supply channels, and the buffer tank has A plurality of air buffer chambers for storing ink and air bubbles are formed corresponding to each ink supply channel, and the carriage has a plurality of air buffer chambers each having one end connected to each air buffer chamber and the other end openable to the outside. A bubble discharging passage is formed, and the air bubbles in each of the air buffer chambers are separated from the respective bubble discharging passages. Provided discharge means for discharging to the outside through the said respective bubble discharge passage, the flow path resistance for the bubble discharge is characterized in that is formed to be almost equal to each other.

  According to a second aspect of the present invention, in the inkjet printer according to the first aspect, at least a part of each of the plurality of air buffer chambers is arranged substantially along a moving direction of the carriage, and the plurality of air bubble discharge passages are provided. Each of the other ends is arranged substantially along a direction orthogonal to the moving direction of the carriage, and the plurality of bubble discharge passages are formed by connecting one end and the other end thereof with substantially the same length. It is characterized by the following.

  According to a third aspect of the present invention, in the inkjet printer according to the second aspect, at least a part of the plurality of bubble discharge passages is formed to be bent along a wall surface of the buffer tank. It is assumed that.

  According to a fourth aspect of the present invention, in the ink jet printer according to the first aspect, at least a part of each of the plurality of air buffer chambers is arranged substantially along a moving direction of the carriage, and the plurality of air bubble discharge passages are provided. The other ends are arranged substantially along a direction perpendicular to the direction of movement of the carriage, and the cross-sectional area of each of the bubble discharge passages increases as the length of the passage connecting one end to the other end increases. Are shorter and smaller.

  According to a fifth aspect of the present invention, in the ink jet printer according to the fourth aspect, the shorter the linear distance connecting one end and the other end of each of the bubble discharge paths, the shorter the path length, and the longer the linear distance, the longer the path length. Are formed long.

  According to a sixth aspect of the present invention, in the inkjet printer according to the fourth or fifth aspect, each of the air bubble discharge passages is formed along a wall surface of the buffer tank.

  According to a seventh aspect of the present invention, in the inkjet printer according to the third or sixth aspect, the plurality of air buffer chambers are formed in the buffer tank so as to be separated from each other by a partition wall, and each of the air bubble discharge passages is provided. One end of the buffer tank is connected to the air buffer chamber through each ventilation hole formed through the upper wall of the buffer tank, and at least a part of each of the bubble discharge passages is connected to each of the ventilation holes. It is characterized in that it is formed in a concave groove shape on the upper wall of the tank.

  According to an eighth aspect of the present invention, in the inkjet printer according to any one of the first to seventh aspects, exhaust valve means for opening and closing the bubble discharge passage is provided at the other end of each of the bubble discharge passages. When discharging ink from the recording head, the exhaust valve means is closed, and when the discharge means is driven, the exhaust valve means is opened.

  According to a ninth aspect of the present invention, in the inkjet printer according to any one of the first to eighth aspects, the discharge unit is a suction pump detachably connected to the other end of each of the bubble discharge passages. It is characterized by the following.

  According to the first aspect of the present invention, the air bubbles stored in the plurality of air buffer chambers are removed by the discharging means by forming the air bubble discharge passages such that the flow path resistance values thereof are substantially equal to each other. In this case, the exhaust amount per unit time (hereinafter, simply referred to as the exhaust amount) can be made equal to each other. As a result, the evacuation work from all the air buffer chambers can be started at the same time and finished almost simultaneously, so that the evacuation work can be made more efficient.

  According to the second aspect of the present invention, at least a part of each of the plurality of air buffer chambers is arranged substantially along a moving direction of the carriage, and each of the other ends of the plurality of bubble discharge passages is connected to the carriage. Are arranged substantially along the direction perpendicular to the direction of movement of the bubble discharge passage, so that the linear distance connecting one end of the bubble discharge passage on the air buffer chamber side and the other end of the bubble discharge passage on the discharge means side is determined by the bubble discharge passage. Different. Therefore, as for the bubble discharge passage having the short linear distance, by arranging the path in a circuitous manner, the length of the passage from one end to the other end in each bubble discharge passage is made substantially the same, and in the bubble discharge passage, The flow path resistance values are made substantially equal. This makes it possible to equalize the amount of air bubbles exhausted from each air buffer chamber, thereby realizing more efficient exhausting work in all the air bubble discharge passages at the same time.

  According to the third aspect of the invention, by forming the bubble discharge passage along the wall surface of the buffer tank, the arrangement of the bubble discharge passage can be saved. In addition, the length of the bubble discharge passage can be easily adjusted by bending the passage.

  According to the invention as set forth in claim 4, at least a part of each of the plurality of air buffer chambers is arranged substantially along the moving direction of the carriage, and the other ends of the plurality of bubble discharge passages are moved by the carriage. Since they are arranged substantially along the direction perpendicular to the direction, one end of the bubble discharge passage on the air buffer chamber side and the other end of the bubble discharge passage on the discharge means side are connected to each other so that the passage length of each bubble discharge passage is mutually different. There are restrictions on the placement to make them the same length. Therefore, by increasing the cross-sectional area of the passage as the straight line distance between the one end and the other end is longer, the cross-sectional area of the passage is smaller as the straight line distance is shorter. The flow path resistance values are substantially equal to each other. This makes it possible to equalize the amount of air bubbles exhausted from each air buffer chamber, thereby realizing more efficient exhausting work in all the air bubble discharge passages at the same time.

  According to the fifth aspect of the present invention, the length of the bubble discharge passage can be freely determined according to the length of the linear distance connecting one end and the other end of each bubble discharge passage. There is no need to bother and arrange the short bubble discharge passage around the circuit. Therefore, it is possible to freely arrange the bubble discharge passage and save the space, and it is also possible to realize the miniaturization as a whole.

  According to the sixth aspect of the invention, by forming the bubble discharge passage along the wall surface of the buffer tank, the space of the bubble discharge passage can be reduced.

  According to the seventh aspect of the present invention, in the air buffer chamber which is partitioned in the buffer tank and stores the bubbles and the ink, the bubbles are stored above the ink and stored in the buffer tank. By being formed on the upper wall, air bubbles are discharged from above as it is. Therefore, the amount of ink discharged along with the removal of air bubbles can be reduced, and the effect of not wasting ink can be obtained.

  According to the eighth aspect of the present invention, the presence or absence of air bubbles in the air buffer chamber through the air bubble discharge passage by the discharge means can be easily realized by opening and closing the other end of the air bubble discharge passage by the exhaust valve means. Can be.

  According to the ninth aspect of the present invention, the use of the suction pump as the discharging means makes it possible to easily discharge the air bubbles in the air buffer chamber through the air bubble discharging passage. Further, by allowing the suction pump to be detachably connected, it is possible to easily switch the presence / absence of bubble discharge by the discharge means.

  Next, an embodiment embodying the present invention will be described. First, in the first embodiment, the present invention is applied to a multi-function device (MFC) 1 having a printer function, a copy function, a scanner function, and a facsimile function. As shown in FIG. A paper feeder 3 is provided at the rear end of the paper feeder 2, and a document reading device 4 for a copy function and a facsimile function is provided above the front side of the paper feeder 3. An ink jet printer 5 (to be described later) for realizing a printer function is provided on the entire lower side of the document reading device 4, and a front side thereof is for receiving a recording medium such as a sheet P which is recorded and discharged. A paper ejection tray 6 is provided.

  Although not shown, the document reading device 4 is configured to be swingable up and down by a horizontal axis at a rear end portion. When the cover body 4a is opened upward, a loading glass plate on which a document is placed is provided. An image scanner for reading an original is provided below the original.

  When the entire document reading device 4 is opened upward, an ink tank 7 (individual colors, that is, black, cyan, magenta, and yellow ink tanks) is used for the ink jet printer 5 for full-color recording. 7a to 7d, see FIG. 2) can be exchanged.

  Next, a schematic configuration of the inkjet printer 5 will be described with reference to FIGS. The inkjet printer 5 includes a recording mechanism unit 9 that is included in a main body frame 14 and discharges ink onto a sheet P as a recording medium to perform recording, and a maintenance unit 11 that performs maintenance processing of a recording head unit 10 in the recording mechanism unit 9. An ink supply unit 12 for supplying ink from the ink tanks 7a to 7d to the recording head unit 10, and an air supply unit 13 for supplying pressurized (positive pressure) air to the ink tanks 7a to 7d. Have been.

  As shown in FIGS. 2, 3 and 5, the recording mechanism 9 and the maintenance unit 11 are housed in a box-shaped main body frame 14 whose upper part is opened in a substantially elliptical shape. A carriage 17 is slidably mounted on a left and right longitudinal rear guide shaft 15 and a front guide shaft 16 provided in parallel in the main body frame 14, and the recording head unit 10 is integrally mounted on the carriage 17. Has been.

  The carriage 17 is configured to be able to reciprocate in the left and right direction along the front and rear guide shafts 16 and 15 by a carriage drive motor 18 disposed on the right rear side of the main body frame 14 and a timing belt 19 as an endless belt. (See FIG. 2). On the other hand, the main conveyance below the rear guide shaft 15 is performed via a sheet feeding motor 20 disposed on the left rear side of the main body frame 14 and a transmission mechanism 21 such as a belt and a gear disposed on the left side of the main body frame 14. The sheet P is conveyed horizontally on the lower surface side of the recording head unit 10 by a roller 22 and a conveying roller (not shown) positioned below the front guide shaft 16, and the recorded sheet P is used for discharging. The sheet is conveyed and discharged in the direction of the tray 6.

  An ink receiver 8 is provided at one end (in the embodiment, the left end in FIGS. 2 and 3) outside the width of the paper P to be conveyed, and a maintenance unit 11 is provided at the other end. Are located. As a result, the recording head unit 10 periodically discharges ink to prevent nozzle clogging at the flushing position where the ink receiving unit 8 is provided during the recording operation, and receives ink at the ink receiving unit 8. . At the head standby position on the other end side, the maintenance unit 11 is disposed to clean the nozzle surface 29, and to perform a recovery process for selectively sucking ink for each color and air bubbles in the buffer tank 36 described later. A removal process for removing (air) is performed.

  Next, the configuration of the ink supply unit 12 will be described. As shown in FIGS. 2, 4 and 5, the nozzle surface 29 of the lower surface of the recording head unit 10 is provided below the transport path of the paper P and in front of the upper surface of the lower partition plate 2 a of the main body case 2. At a lower position, there is provided an ink tank mounting portion 23 into which the ink tanks 7 for the individual colors can be inserted and mounted from the front, respectively. In FIG. 2, the ink tanks 7a for black (BK) are arranged in order from the left side. , Cyan (C) ink tank 7b, magenta (M) ink tank 7c, and yellow (Y) ink tank 7d are arranged horizontally and in parallel.

  In each of the ink tanks 7, a flexible film material 24a (corresponding to a deformable wall surface) is adhered to substantially the entire area thereof, and the film material 24a causes the lower ink storage chamber 24b and the upper ink storage chamber 24b to adhere to each other. It is partitioned into an air chamber 24c.

  An air hole (not shown) communicating with the air chamber 24c and the atmosphere is formed in the rear side wall surface of each ink tank 7, while a silicone or the like partitioning the ink storage chamber 24b from the outside is provided. The seal member 25 is mounted.

  On the rear side of the ink tank mounting portion 23, an ink supply hollow needle 26 is horizontally projected so as to face the insertion direction (rear side wall surface) of the ink tank 7 of each color. The base end of the hollow needle 26 corresponding to each color of ink is connected to the recording head unit 10 via a corresponding flexible ink supply tube (corresponding to an ink supply tube in the claims) 27a to 27d. . In this case, the middle portions of the black and cyan ink supply tubes 27a and 27b and the middle portions of the magenta and yellow ink supply tubes 27c and 27d are tied up and down to be stacked.

  The air supply unit 13 includes four pressure-bonding pads 31 protruding forward in parallel with the hollow needles 26, a diaphragm-type air pump 28 driven by a drive motor 30, and an air connecting them. The pressure pad 31 is configured to be brought into close contact with an air hole on the rear surface of each ink tank 7 inserted and fixed in the ink tank mounting portion 23 by the urging force of an urging spring. By driving the air pump 28, pressurized (positive pressure) air is supplied to the air chamber 24c of each of the ink tanks 7a to 7d, and a positive pressure can be applied to the ink in each of the ink storage chambers 24b.

  Here, as shown in FIG. 5, the nozzle surface 29 of the recording head unit 10 where the nozzle 33 is opened is disposed at a position higher than the position of the hollow needle 26 by the head H1. A negative pressure (back pressure) corresponding to the water head H1 acts on the nozzle 33 of the unit 10. At the time of the initial introduction of the ink, as is well known, a suction cap member to be described later is brought into close contact with the nozzle and suctioned by a suction pump to introduce the ink from the ink tanks 7a to 7d into the recording head 34. By driving, a positive pressure may be applied to each of the ink tanks 7a to 7d.

  Next, the configuration of the recording head unit 10 mounted on the carriage 17, the exhaust valve means 41, and the like will be described with reference to FIGS. In the first embodiment, the recording head unit 10 includes a recording head 34 having a row of nozzles 33 for each color and an upper surface of the recording head 34 for full-color recording, as shown in FIGS. It comprises a flat plate-shaped actuator 35 such as a piezoelectric element, a buffer tank 36 having an air buffer chamber 40 and the like, a case 37 having exhaust valve means 41 adjacent to a side surface of the buffer tank 36, and the like. .

  On the lower surface of the recording head 34, from the left side in FIG. 3, a row of nozzles 33a for black (BK), a row of nozzles 33b for cyan (C), a row of nozzles 33c for magenta (M), and yellow And a row of nozzles 33d are formed long in a direction orthogonal to the moving direction of the carriage 17. Each nozzle 33 is exposed downward so as to face the upper surface of the paper P. The recording head 34 distributes the ink supplied from the buffer tank 36 to a pressure chamber for each nozzle in the same manner as a known one, and discharges the ink from the nozzle by an actuator 35 such as a piezoelectric element corresponding to the pressure chamber. It is.

  A buffer tank 36 in which an air buffer chamber 40 (individually designated by reference numerals 40a, 40b, 40c, and 40d, see FIG. 10 and the like) is partitioned for each color ink, is made of a synthetic resin material into a substantially rectangular shape in plan view. An ink inflow port 39 (4 in this embodiment) is formed on one side surface of the buffer tank 36 for connection to a joint member 38 (details are omitted) to which the tips of the ink supply tubes 27a to 27d for the respective colors are connected. Location) is protruded sideways. The respective inks supplied from the respective ink tanks 7 are stored in the respective air buffer chambers 40, and after the bubbles in the ink are separated, the ink flows from the ink flow chamber 42 on the bottom side of the buffer tank 36 to the downward outflow portion 43. The recording head 34 is supplied to the recording head 34 via the recording head 34. The filter 44, which partitions most of the lower surface side of the air buffer chamber 40 and the ink flow chamber 42 into a substantially horizontal shape, is formed of a mesh formed by meshing stainless steel metal wires in a mesh shape. The ink flow from the air buffer chamber 40 to the ink flow chamber 42 is allowed for the ink flow at a low speed during the recording operation, while bubbles and dust contained in the ink are filtered by the ink flow. It is prevented from flowing to the recording head 34 side through 44. The filter 44 has an opening 44 a at an end far from the ink inlet 39, the passage resistance of which is sufficiently smaller than the mesh of the filter 44. A sufficient flow of ink to the ink flow chamber 42 through 44a is ensured.

  As shown in FIGS. 6A, 6B and 7, a cylindrical ventilation hole 46 as one end of a bubble discharge passage 47 is formed in a ceiling wall 45 of each air buffer chamber 40. ) Is formed to project downward so as to suck air bubbles, and a bubble discharge passage 47 (individual members are denoted by reference numerals 47a to 47d) is formed on the upper surface side of the ceiling wall 45. An outlet 54 as the other end of the bubble discharge passage 47 is provided so as to communicate with an inlet of a case 37 described later.

  As in the prior art, when ink is sucked from the nozzle side and air (bubbles) accumulated in the air buffer chamber 40 is to be sucked during the recovery purge operation, the recording head 34 becomes thin unless the suction force is increased. There is a problem that air bubbles are clogged in the ink flow path, and the air bubbles (air) on the upper side cannot be sucked unless the amount corresponding to almost all of the ink in the buffer tank 36 is discharged. There is a problem that the ink is wasted and the running cost of the ink jet printer is increased.

  According to the configuration of the first embodiment, the air accumulated in the air buffer chamber 40 above the buffer tank 36 is evacuated from the upper part of the buffer tank 36, particularly from the location of the ceiling wall 45, so that the recording in which the air bubbles are at the lower position is performed. The ink does not flow into the head 34, so that the ink flow path in the recording head 34 is not clogged with bubbles. Further, with the operation of removing air bubbles (air) from the buffer tank 36, it is not necessary to discharge a large amount of ink stored in the buffer tank 36, so that the running cost can be reduced and the effect of being economical can be obtained. Play.

  In the first embodiment, the air bubble discharge passages 47a to 47d are formed between a groove formed in the upper surface (upper wall) of the ceiling wall 45 and a film body such as a synthetic resin film 48 adhered over the groove. You. Reference numeral 45a shown in FIG. 7 is a partition for separating the air bubble discharge passages 47a to 47d, and a film 48 is adhered to the upper surface thereof.

  Each of the bubble discharge passages 47a to 47d shown in FIGS. 6A and 7 has the same cross-sectional area (cross-sectional area in a direction orthogonal to the longitudinal direction of the passage). The passage area of the ink inlet 39 or the ink supply tube 27 connected thereto is formed to be equal to or smaller than the sectional area of the passage.

  Also, by appropriately setting the height H2 at which the cylindrical portion having the ventilation hole 46 therein protrudes downward from the lower surface of the ceiling wall 45, an air reservoir portion having an appropriate volume that cannot be discharged from the ventilation hole 46 is formed by each air. It is formed in the upper part of the buffer chamber 40, and absorbs the pressure fluctuation of the ink in each air buffer chamber 40 due to the left and right movement of the carriage 17 in the air reservoir.

  Further, in the first embodiment, the vent holes 46 (46a to 46d) as one ends of the bubble discharge passages 47a to 47d are arranged substantially along the moving direction of the carriage 9, and the outlet 54 as the other end. (54a to 54d) are arranged substantially along a direction orthogonal to the moving direction of the carriage 9. As a result, the linear distance connecting the ventilation hole 46 and the outlet portion 54 is different depending on each bubble discharge passage 47, but the path of each bubble discharge passage 47 from the ventilation hole 46 to the outlet portion 54 is It is formed to bend along the upper wall and its length is set equal to each other. That is, the length of the bubble discharge passage 47a from the vent 46a to the outlet 54a, the length of the bubble discharge passage 47b from the vent 46b to the outlet 54b, and the bubble discharge passage from the vent 46c to the outlet 54c. The length of the passage 47c is made equal to the length of the bubble discharge passage 47d from the ventilation hole 46d to the outlet 54d. Thereby, the flow path resistance values in the bubble discharge paths 47a to 47d are made equal to each other.

  Further, when the air in each of the air buffer chambers 40 is exhausted by the exhaust valve means 41, the flow path resistance value on the upstream side of each of the ventilation holes 46a to 46d in the ink flow path also has an effect. As shown in the schematic diagram of FIG. 26, ink supply tubes 27a to 27d, ink inlets 39a to 39d, and air buffers are provided on the upstream side of the air holes 46a to 46d in the ink flow path. A path is formed to each of the ventilation holes 46a to 46d via the chambers 40a to 40d, and the flow path resistance value (R0) in this path is determined by making the length of the ink supply tube 27 the same for each color. They are set equal to each other in advance.

  As a result, the flow path resistance values of the respective paths from the ink tanks 5a to 5d to the exhaust valve means 41 become equal to each other. As a result, the exhaust amount when exhausting the air in each air buffer chamber 40 by the exhaust valve means 41 is equalized, and the exhaust valves for the air stored in the plurality of (four colors) air buffer chambers 40 are exhausted. When the exhaust operation is started simultaneously by the means 41, the exhaust operation can be completed almost simultaneously. Therefore, the phenomenon that a large amount of ink is continuously discharged from the air buffer chamber 40, which has been quickly exhausted, to the air does not occur.

  Further, due to the cross-sectional area and the length of each of the bubble discharge passages 47a to 47d, the flow passage resistance of each bubble discharge passage to ink becomes larger than that of air (bubble). When the amount of air stored in the plurality of (four colors) air buffer chambers 40 varies, even if the exhaust operation is simultaneously performed on all the air buffer chambers 40, one air hole is required. When the ink level reaches 46, the resistance of the ink flow is large. Therefore, the air discharge in the other air buffer chambers 40 is performed preferentially, and even if the air amount in the air buffer chambers 40 is different, the air amount is small (in other words, the ink amount). That is, the phenomenon that only the amount of ink discharged from the buffer tank 36 at the (larger) portion increases does not occur.

  The case 37 of the exhaust valve means 41 is provided adjacent to one side of the buffer tank 36 (the right side in FIGS. 6A, 7 and 10). As shown in FIGS. 9, 11 (a) and 11 (b), the synthetic resin case 37 has a cylinder block 50 made of the same synthetic resin and having a passage hole 51 which is long in the vertical direction and has a vertically open passage. Is mounted so as to be airtight. In the embodiment, four passage holes 51 are provided so as to correspond to each of the bubble discharge passages 47a to 47d. Four passage cylinders 52 communicating with the upper ends of the passage holes 51 protrude upward from the upper end of the case 37, and each of the passage cylinders 52 and each of the bubble discharge passages 47a via a cap body 53 made of soft rubber or the like. 47d is connected to the lateral outlet 54 which is the other end. The eaves 60 projecting laterally from the upper part of the buffer tank 36 regulate the cap body 53 from being easily removed.

  Each of the passage holes 51 includes an upper half large diameter portion 51a and a lower half small diameter passage 51b. A small-diameter valve rod 56 is integrally formed at the lower end of the large-diameter valve body 55. A packing 57 such as an O-ring for sealing is disposed on the lower end side of the valve body 55 so as to be fitted on the valve rod 56. A packing 57 and a valve body 55 are inserted into the large diameter portion 51a so as to be able to move up and down, and a valve rod 56 is inserted into the small diameter passage 51b. The lower end of the valve rod 56 extends to near the lower end opening of the small diameter passage 51b. The valve body 55 is constantly pressed downward by a spring means 58 such as a coil spring provided in the large diameter portion 51a. In this state, the packing 57 is pressed against the bottom surface of the large diameter portion 51a of the passage hole 51 to close the valve (see FIG. 11A). On the other hand, when a release rod 62 as a valve operating means in a bubble removing means 61 to be described later rises and presses the valve rod 56 upward against the urging force of the spring means 58, the packing 57 becomes large-diameter portion 51a. , And is configured to communicate with the atmosphere (see FIG. 11 (b)).

  Next, the configuration of the maintenance unit 11 will be described with reference to FIGS. In the maintenance unit 11, while the carriage 17 is at rest at the standby position (the right end side in FIGS. 2 and 3 in the embodiment), the nozzle surface 29 of the recording head unit 10 mounted on the carriage 17 is capped. A recovery means 63 for sucking ink from the nozzles and sucking clogged solidified ink, fine dust, and air bubbles in the recording head 34 in a state covered with the member 64, and the air buffer chambers 40. A bubble removing unit 61 is provided for discharging and removing the air accumulated in the nozzle through the bubble discharging passage 47 and the exhaust valve unit 41, and suctioning and removing the ink leaking at that time. The recovery unit 63 is disposed adjacent to the bubble removing unit 61, and the bubble removing unit 61 is disposed on the outermost end side in the moving direction of the carriage 17. The wiper 65 for wiping and cleaning the nozzle surface 29 is disposed on the opposite side of the lifting / lowering body 66 having the release rod 62 in the bubble removing means 61 with the cap member 64 of the recovery means 63 interposed therebetween in a plan view (FIG. 12). And FIG. 13).

  12 is a plan view of the maintenance unit 11, FIG. 13 is a perspective view, FIG. 14 is a plan view of the elevating mechanism 70, and FIG. 8 is a view of the carriage 17 and the maintenance unit 11 shown by arrows VIII-VIII in FIG. It is a side view of a part.

  The maintenance unit 11 is provided with a mechanism 67 as one operation converting means, and this mechanism 67 operates an elevating mechanism 70 for selectively elevating and lowering the recovery means 63 and the bubble removing means 61. Selectively operating a suction pump 68 as suction means for sucking ink, and a switching valve unit 69 for selectively connecting the suction force of the suction pump 68 to the recovery means 63 and the bubble removing means 61. Is performed. In this embodiment, the suction pump 68 is used as a discharge means in the claims, and is detachably connected to the other end of the bubble discharge passage 47 by the mechanism 67.

  The mechanism 67 has a gear train pivotally attached to the unit base 73, and one forward / reverse rotatable motor 71 disposed at one end of the unit base 73 transmits power to the gear train. When the motor 71 rotates in the reverse direction (counterclockwise in FIG. 12), the driving force is used to rotate the suction pump 68 clockwise through a plurality of gears 72a to 72i to apply a negative pressure to the switching valve unit 69 side. To suck ink as described below. In this case, among the gears 72a to 72i, the gear 72e and the sun gear 72f rotate counterclockwise. With this, the planetary gear 72g meshing with the gear sun gear 72f rotates clockwise while revolving counterclockwise about the axis of the sun gear 72f, meshes with the intermediate gear 72h, and through this, a tube-type suction pump. The power is transmitted to a gear 72i of 68.

  When the motor 71 rotates forward (clockwise in FIG. 12), the driving force rotates the gear 72e and the sun gear 72f clockwise via the gears 72a to 72d. With this, the planetary gear 72g meshing with the sun gear 72f rotates counterclockwise while revolving clockwise around the axis of the sun gear 72f, meshes with the gear 72j at the subsequent stage, and rotates through the gears 72k to 72o. The power is transmitted to the gear 72r so as to change the angle of the switching member 110 in the switching valve unit 69 via the gears 72p and 72q while rotating the moving cam body 74 counterclockwise.

  Next, the recovery means 63, the bubble removing means 61, the elevating mechanism 70 for selectively elevating and lowering them, and the rotating cam body 74 for driving them will be described with reference to FIGS. I will explain it.

  The recovery means 63 includes two rows of cap members 64a and 64b that abut against the nozzle surface 29 to cover the four rows of nozzles 33 exposed on the lower surface side of the carriage 17 two by two. And a support block 75 having a substantially rectangular shape in plan view arranged in parallel. The cap members 64a and 64b are separated to avoid mixing of ink colors. Each cap member 64a, 64b is provided with ink suction holes (not shown), and these suction holes are provided through two passages (not shown) inside the support block 75 through two discharge ports on the side surface. From the tubes 76a and 76b. In this case, the cap members 64a for the black ink and the cyan ink are connected to the port A of the switching valve unit 69 via the tube 76a. On the other hand, the cap members 64b for the magenta ink and the yellow ink are connected to the port B of the switching valve unit 69 via the tube 76b (see FIGS. 21 and 22).

  As shown in FIGS. 10 and 15, a guide tube 77 is provided at the center on the lower surface of a support block 75 made of synthetic resin or the like, and a pair of sliding contact pins 78 as cam followers are provided on the outer surface of the guide tube 77. , 78 (only one is shown in the figure) project horizontally. Also, four spring seats 79 are provided to project downward so as to surround the guide cylinder 77. On the other hand, the guide cylinder 77 and the sliding pins 78, 78 are vertically guided substantially in the center of the guide groove 80 formed on the upper surface of the unit base 73 made of synthetic resin or the like, and the support block 75 is raised and lowered. A pair of guide pieces 81, 81 having an arcuate cross section for restricting rotation around a plane perpendicular to the direction of the protrusion is provided (see FIGS. 14 and 15). Further, a projection 83 for positioning the lower end of the upward biasing spring 82 is provided between the respective spring seats 79 and the outside of the guide groove 80 so as to project therefrom.

  As shown in FIGS. 14 to 17, four dish-shaped suction portions 90 that can be in close contact with the respective passage holes 51 of the cylinder block 50 are formed on the upper surface of the elevating body 66 in the bubble removing means 61. Each suction portion 90 has a suction port 91 that can communicate with each small-diameter passage 51b that opens on the lower surface of the cylinder block 50, and an upwardly projecting release rod 62 that can come into contact with the valve rod 56. The opening 91 communicates with a side discharge cylinder 93 through a passage 92 in the elevating body 66 (see FIG. 17A). A pair of positioning rectangular bodies 94a and 94b project upward from the upper surface of the elevating body 66 (see FIGS. 15 to 17C). When approaching to the cylinder block 50, the lifting and lowering body 66 can be positioned in two horizontal directions by slidingly contacting a pair of positioning guide grooves 95a and 95b provided in the cylinder block 50, and each release rod 62 is connected to each small-diameter passage 51b. It is configured to fit smoothly (see FIG. 8).

  The elevating body 66 is provided with a downwardly projecting leg 98 that can be fitted between a pair of vertical guide pieces 97, 97 of a parallel moving cam body 96 described later. At the lower end of the leg body 98, a pair of sliding contact pins 99, 99 as cam followers are provided to protrude outward in the horizontal direction along the longitudinal direction of the elevating body 66. On the lower surface of the elevating body 66, two spring seats 66a for supporting an upper end of an urging spring 100 (only one of which is shown in FIG. 15) disposed between the elevating body 66 and the unit table 73 are provided. , 66a (see FIGS. 15 to 17C).

  One operation conversion for selectively performing the operation of the cap members 64a and 64b in the recovery means moving toward and away from the nozzle surface 29 and the operation of moving the bubble removing means up and down by the release rod 62 to open and close the valve. The means comprises a parallel moving cam body 96 and a rotating cam body 74.

  As shown in FIGS. 10, 14, 15, 19, 20 and the like, the parallel moving cam body 96 has a bifurcated horizontal guide piece 101 that is horizontally guided along the guide groove 80 in the unit base 73. , And a pair of vertical guide pieces 97, 97 erected from the horizontal guide piece 101. A pin 104 projecting upward from the horizontal guide piece 101 is fitted into an endless cam groove 74a (see FIG. 18) of the rotating cam body 74, and as described later, the rotation cam body 74 is fixed. With the rotation in the direction, the parallel moving cam body moves in a direction perpendicular to the direction in which the lifting / lowering body 66 comes into contact with or separates from the lower surface of the cylinder block 50 (X1-X2 directions shown in FIGS. 10, 15, 19, and 20). ).

  Sliding contact pins 78, 78 and 99, 99, which are cam followers protruding laterally from the recovery means 63 and the bubble removing means 61, respectively, are urged by the urging springs 82, 100 on the respective vertical guide pieces 97. A cam portion having a pair of cam surfaces 102 and 103 for abutting in the direction (upward) and restricting the elevating operation of the recovery means 63 and the bubble removing means 61 as the parallel moving cam body 96 reciprocates. Have.

  More specifically, the pair of cam surfaces 102 and 103 are formed so that the lifting and lowering directions of the recovery unit 63 and the bubble removing unit 61 are opposite to each other. That is, the cam surfaces 102 and 103 are formed by connecting the horizontal lowermost cam surfaces 102a and 103a, the intermediate cam surfaces 102b and 103b, and the uppermost cam surfaces 102c and 103c in an inclined plane. The lowermost cam surfaces 102a, 103a are formed at positions approaching each other, and the uppermost cam surfaces 102c, 103c are formed at a position farthest from each other (see FIGS. 10, 15 and the like). Then, when the recording head 34 performs recording on the sheet, as shown in FIG. 10, the upper surfaces of the sliding members 78, 99 of the cap members 64a, 64b and the elevating body 66 are provided on the intermediate cam surfaces 102b, 103b. Is in contact.

  At the time of the recovery processing operation shown in FIG. 19 and in the storage state, the translation cam body 96 moves in the X2 direction by the cam groove 74a of the rotation cam body 74. As a result, the sliding contact pin 78 is disengaged from the intermediate cam surface 102b and moves toward the uppermost cam surface 102c, the upward movement of the sliding contact pin 78 is released, and the support block 7 is raised by the urging spring 82. . As a result, the upper surfaces of the cap members 64a and 64b are brought into close contact with the nozzle surface 29 of the recording head 34 so as to press them. On the other hand, the upper surface of the sliding contact pin 99 abuts on the lowermost cam surface 103a, the elevating body 66 descends to the lowest position, and the upper end of the release rod 62 in the elevating body 66 and the lower surface of the cylinder block 51 in the bubble removing means 61 The elevating body 66 is held at such a height as to have an appropriate gap between them.

  During the process of removing (bleeding) air bubbles from all the air buffer chambers 40a to 40d shown in FIG. 20, the parallel moving cam body 96 moves in the X1 direction by the cam grooves 74a of the rotating cam body 74. As a result, the upper surface of the sliding contact pin 78 comes into contact with the lowermost cam surface 102a, and the support block 75 is held at the lowest position where the upper surfaces of the cap members 64a and 64b are farthest from the nozzle surface 29 of the recording head 34. At this time, the sliding contact pin 99 is disengaged from the intermediate cam surface 103b and moves to the uppermost cam surface 103c side, the upward movement of the sliding contact pin 99 is released, and the lifting body 66 is raised by the urging spring 100. . As a result, each suction portion 90 of the elevating body 66 comes into close contact with the lower end opening of each small-diameter passage 51b, and the release rod 62 pushes up the valve rod 56.

  As described above, when the support block 75 is located at the lowest position by the one cam surface 102, the urging spring 82 has the largest urging force. The urging force of the urging spring 100 at that time is weak. The pair of cam surfaces 102 and 103 are formed so that the lifting and lowering directions of the recovery unit 63 and the bubble removing unit 61 are opposite to each other. , 103 at the same time, there is no need to increase the strength of the cam portion more than necessary, and the parallel moving cam body 96 can be formed compactly.

  Next, a description will be given of a suction unit connected in parallel with the bubble removing unit 61 and the recovery unit 63 to suction ink. The suction means includes a suction pump 68 and a switching valve unit 69 as a suction switching valve. The suction means selectively executes an operation of sucking ink leaked together with bubbles from the air buffer chambers 40a to 40d and an operation of sucking ink from the nozzles via the recovery means 63.

  The suction pump 68 is a tube-type pump that generates a negative pressure using a volume change in the flexible tube 105. One end (ejection side) of the flexible tube 105 is connected to a waste ink storage section containing a waste liquid form 111 described later, and the other end (suction side) of the flexible tube 105 is switched via a connector 106 and a tube 107. It is connected to the discharge port 108 of the valve unit 69.

  As shown in FIGS. 21A, 21B and 22, the switching valve unit 69 includes a cylindrical main body 109, a switching member 110 rotatably fitted in the main body 109, and a unit base. A gear 72r that rotates about a rotation shaft provided upright at 73 and rotates the switching member 110 with respect to the main body 109. The discharge port 108 is provided on the top surface of the main body 109 made of synthetic resin, and ports A, B, W, and F are provided on the side surface of the main body at a predetermined phase angle. Port A is connected to cap member 64a via tube 76a, and port B is connected to cap member 64b via tube 76b. Further, the port W is connected to a discharge cylinder 93 in the bubble removing means 61 via a tube 76c. The port F is connected to a tube 76d opened to the atmosphere. In this case, as shown in FIGS. 12 and 13, the tube 76d is arranged to be sufficiently long and to have the middle part bent 180 degrees or more so that the ink is always stored inside. The opening end (tip opening) of the tube 76d is pierced upward by the thick waste liquid foam 111 in the main body case 2, and the entire multifunctional device 1 is inclined and dropped, and the ink tank 7 is dropped. Even if the ink inside is shocked and ink leaks from the open end of the tube 76d due to the pressure of the ink at that time, the ink is captured by the waste liquid form 111. As shown in FIGS. 4 and 5, the waste liquid foam 111 is provided on the bottom plate 2 c of the main body case 2 and in the ink tanks 7 a to 7 d arranged in parallel in the left-right direction of the main body case 2 of the ink supply unit 12. The waste ink tube 76d is disposed long in the side-by-side direction, and the opening end of the waste ink tube 76d is located at a substantially central portion in the longitudinal direction, in other words, even when the main body case is tilted in any of the left and right directions, the portion where the head difference is minimized. This arrangement reduces the amount of ink leakage.

  The cylindrical switching member 110 is formed of an elastic body such as rubber, and has top circular grooves 112a to 112d extending in four radially outward directions on its circular top. The discharge port 108 is connected to the central portion, and the four ends are connected to the outer peripheral grooves 113a to 113d of the switching member 110. The outer peripheral groove 113c is long downward and corresponds to the port W. The outer peripheral grooves 113a, 113b, 113d are short downward and correspond to the ports A, B, F. The outer peripheral groove 113c also corresponds to the ports A, B, and F. Further, three ribs 114 are formed on the outer peripheral surface of the switching member 110 along the circumferential direction so as to surround the outer peripheral grooves 113a to 113d. By forming the ribs 114, when the switching member 110 is rotated in order to accumulate the negative pressure and to apply the negative pressure, a gap is formed between the switching member 110 and the main body 109 so that the negative pressure is reduced. Can be prevented from leaking.

  As shown in FIGS. 10, 19, and 20, a cam groove 74a in which the pin 104 of the parallel moving cam 96 fits is formed endlessly on the bottom surface of the rotating cam body 74, as described above. . FIG. 18 is a view of the rotating cam body 74 as viewed from above. A cam (not shown) for moving the wiper 65 up and down and a leaf switch 116 for detecting the rotational position (phase) of the rotary cam 74 are provided on the outer periphery of the rotary cam 74. The ridge cams 117a to 117e are in contact with each other. The maintenance motor 71, the air pump 28, the carriage, the drive motor 18, and the like are controlled by a control device including a CPU, a ROM storing programs for respective operations described below, and the like.

  Next, the operation of the maintenance unit will be described with reference to FIGS. 12, when the maintenance motor 71 is rotated in the reverse direction (counterclockwise), the suction pump 68 is rotated clockwise in FIG. 12 to apply a negative pressure to the discharge port 108 at the center of the top surface of the switching valve unit 69. And ink can be sucked. At this time, the switching member 110 and the rotating cam body 74 of the switching valve unit 69 are non-rotating and stationary.

  When the maintenance motor 71 is rotated forward (clockwise), the suction pump 68 is not rotated. Instead, the switching member 110 of the switching valve unit 69 rotates forward (clockwise), and the rotating cam body 74 is rotated. Rotates counterclockwise. In the following description, operations that can be performed in accordance with the rotation of the rotating cam body 74 will be described in order. However, it is not necessary that all the operations be continuously performed in accordance with the rotation of the rotating cam body 74, and maintenance can be performed. Only predetermined operations are selectively performed each time they are needed.

  FIG. 23 is an explanatory view showing the rotational phase position of the switching member 110 and the communication and non-communication states with the ports A, B, W, and F during each operation. FIG. 24 shows an air bleeding operation (an elevating operation of the elevating / lowering body 66 as a valve operating means) accompanying a rotation of the rotary cam body 74 and a cap operation (an elevating operation of the support block 75 of the cap members 64a and 64b in the recovery means). 5 is a timing chart showing the lifting operation of the wiper 65. In FIG. 24, the high (ON) position of the cam number 1 is set to ON1, the subsequent low (OFF) position is set to OFF1, and other cam numbers are similarly described and described.

  When there is no recording command to the recording head 34 and no operation command to the maintenance unit 11, the control device moves the carriage 17 to the standby position at the right end in FIG. Before this, the leaf switch 116 descends from the ridge cam 117e (cam number 5), and rotates the rotation cam body 74 to a position immediately after being placed on the ridge cam 117a (cam number 1) (FIG. 24, ON1), the parallel moving cam body 96 is moved and set to the position shown in FIG. 10, and the upper surfaces of the sliding contact pins 78 and 99 are brought into contact with the intermediate cam surfaces 102b and 103b. In this state, the carriage 17 is moved to the standby position at the right end in FIG. 2 so that the nozzle surface 29 of the recording head 34 and the cap members 64a and 64b face each other. Accordingly, an appropriate gap is maintained between the upper surfaces of the cap members 64 a and 64 b and the nozzle surface 29 of the recording head 34, and the release rod 62 and the suction unit 90 in the elevating body 66 and the cylinder block in the air bubble removing unit 61. An appropriate narrow gap is maintained between the lower surface of the first and the lower surface 51. In this state, the rotation position of the switching member 110 of the switching valve unit 69 is in the phase of the cappable position in FIG. 23, and the ports A, B, F and the discharge port 108 are in communication.

  From the above state, the cap members 64a and 64b are brought into close contact with the nozzle surface 29 of the recording head 34, and the recording head 34 is brought into the storage state. For this purpose, the rotating cam 74 is rotated forward, and the leaf switch 116 is moved from the position (ON1) where the leaf cam 117a (cam number 1) is placed on the protruding cam 117a to a position further rotated by 60 °. . In this state, the parallel moving cam body 96 moves in the X2 direction and is set at the position shown in FIG. 19, the sliding contact pin 78 is disengaged from the intermediate cam surface 102b and moves to the uppermost cam surface 102c side, and the urging spring 82 is moved. , The support block 75 is raised. As a result, the upper surfaces of the cap members 64a and 64b come into close contact with the nozzle surface 29 of the recording head. On the other hand, the upper surface of the sliding contact pin 99 is in contact with the lowermost cam surface 103a, and the elevating body 66 is lowered to the lowest position (see FIG. 19).

  In this storage state, the cap members 64a and 64b communicate with the discharge port 108 via the ports A and B (see the standby position, ON1 state in FIG. 23), and the tube 76d connected to the port F of the switching valve unit 69. Since some ink always remains in the tube 105 on the discharge side of the suction pump 68, the nozzle surface 29 can be sealed with the cap members 64a and 64b to prevent the nozzle from drying. Further, since the port F communicates with the atmospheric pressure, the insides of the cap members 64a and 64b are also substantially at the atmospheric pressure.

  The position rotated by 60 ° from (ON1) can be arranged, for example, by rotating the maintenance motor 71 composed of a stepping motor from (ON1) by a predetermined number of steps (887 steps).

  When the control device instructs the recording head 34 to perform a recording operation, the maintenance motor 71 is continuously rotated forward to rotate the rotary cam body 74 to the ON4 position in FIG. The carriage is moved from the standby position to the left in FIG. 2 from the state where gaps are again formed between the cap members 64a and 64b and the nozzle surface 29 and between the elevating body 66 and the cylinder block 51. That is, it is moved to the recording position.

  When the control device outputs a recovery processing command to the recording head 34, when the recording head 34 is not at the standby position, the maintenance motor 71 is first rotated forward as described above to switch the rotating cam body 74. 116 is rotated to the position immediately after the ON position, and the recording head 34 is further moved to the standby position. In this state, the maintenance motor 71 is rotated forward to bring the cap members 64a and 64b into close contact with the recording head 34 in the same manner as in the storage state. Further, the rotary cam body 74 is moved to a position (OFF1) where the leaf switch 116 has been lowered from the ridge cam 117a (cam number 1). At the same time, the switching member 110 of the switching valve unit 69 is rotated to a position where none of the ports A, B, W, and F communicates with the atmosphere (external) (see BC negative pressure storage, OFF1 in FIG. 23). In this state, by rotating the maintenance motor 71 in the reverse direction and operating the suction pump 68 (see FIG. 25), a negative pressure is once applied to the tube 107 to suck the ink from the nozzles of the black ink and the cyan ink. Earn. Next, when the maintenance motor 71 is rotated forward and the leaf switch 116 reaches the position (ON2) on the ridge cam 117b (cam number 2), the port A communicates with the groove 112a, and the stored negative pressure To suck the ink from the nozzles of the black ink and the cyan ink through the cap member 64a (see BC suction, ON2 in FIG. 23). The air pump (positive pressure pump) 28 is operated slightly after the start of the operation of the suction pump 68 to apply a positive pressure to the ink in the buffer tank 36 through the ink tank 7.

  Next, when the rotary cam body 74 is rotated to the position (OFF2) where the leaf switch 116 is lowered from the ridge cam 117b (cam number 2), the switching member 110 of the switching valve unit 69 causes any of the ports A and B to switch. , W, and F also rotate to positions not communicating with the atmosphere (external) (see OFF2 in FIGS. 24 and 23). Then, as described above, the motor 71 is rotated in the reverse direction to operate the suction pump 68, thereby storing negative pressure for sucking magenta ink and yellow ink. Next, when the maintenance motor 71 is rotated forward and the leaf switch 116 reaches the position (ON3) on the ridged cam 117c (cam number 3) (see FIG. 24), the port B and the groove 112b communicate with each other to store. The ink is sucked from the nozzles of the magenta ink and the yellow ink through the cap member 64b by the negative pressure (YM suction in FIG. 23, see ON3). At this time, a positive pressure is applied to the ink in the buffer tank 36 by operating the air pump 28 as described above.

  When performing the suction recovery operation on only one of the set of black ink and cyan ink or the set of magenta ink and yellow ink, the motor 71 is reversed at the position of the cam number corresponding to the other set. By driving the suction pump 68 forward without rotating it, the driving of the suction pump 68 is omitted.

  After the ink suction operation is completed, the translation cam body 96 is moved in the X1 direction by the counterclockwise rotation of the rotation cam body 74 and returned to the position shown in FIG. 10, and the cap members 64a and 64b are moved. The support block 75 is lowered so as to separate from the nozzle surface 29.

  The operation of the air pump 28 is continued until the cap members 64a and 64b are separated from the nozzle surface 29. This is because, at the end of the ink suction operation, the ink in the cap member is foaming, and the foam may enter the nozzle due to the back pressure acting on the ink in the nozzle 33. The operation of 28 applies a positive pressure to the ink in the nozzle 33 to prevent bubbles from entering. The operation of the air pump 28 and the operation of the suction pump 68 need not be performed in parallel, and the operation of the air pump 28 is performed from immediately before the cap members 64 a and 64 b are separated from the nozzle surface 29 after the suction pump 68 is stopped. You may do so. The positive pressure applied to the ink in the nozzle 33 by the air pump 28 is large enough to prevent the ink from leaking from the nozzle.

  At the time when the carriage 17 starts moving for the wiping operation by the next wiper, as shown in FIG. 10, the sliding members 78 and 99 of the cap members 64a and 64b and the elevating body 66 are moved to the intermediate cam surface 102b. , 103b, the rotary cam body 74 is rotating.

  When the rotary cam 74 rotates 35 degrees (OFF3) from the position where the leaf switch 116 descends from the ridge cam 117b (cam number 3), the switching member 110 of the switching valve unit 69 switches any of the ports A, B, and W. , F also rotate to positions where they do not communicate with the atmosphere (external) (wipe position in FIG. 23). On the other hand, the wiper 65 has already risen from the OFF1 position and protrudes into the movement locus of the nozzle surface 29. In this state, by moving the carriage 7 to the left in FIG. 2, the nozzle surface 29 is brought into sliding contact with the wiper 65, and the ink attached to the nozzle surface 29 is wiped.

  Thereafter, the carriage 17 is moved to a position where the recording head does not oppose the cap member 64a, for example, to a position opposing the ink receiving section 8 at the left end, while continuously rotating the maintenance motor 71 forward to rotate. The cam 74 is continuously rotated counterclockwise and stopped again at the ON2 position. In this state, the motor 71 is rotated in the reverse direction to operate the suction pump 68. As a result, so-called empty cap suction (refer to the empty cap suction section in FIG. 25) can be performed to remove ink remaining in the cap member 64a. Subsequently, the operation is stopped at ON3, and idle suction is similarly performed on the cap member 64b.

  Further, after the empty suction of the cap, the rotating cam 74 is stopped at the OFF4 position, and the groove 113c of the switching valve unit 69 is communicated with the port F (atmospheric communication suction in FIG. 23). That is, while the tube 76d open to the atmosphere is in communication with the suction pump 68, the motor 71 is rotated in the reverse direction to rotate the suction pump 68, thereby sucking the ink remaining in the switching valve unit 69 and the like. .

  Then, the carriage 17 at the left end position in FIG. 2 is directed to the recording operation.

  When the control device outputs a command for removing air bubbles (air) from the air buffer chambers 40a to 40d, when the carriage 17 is not at the standby position at the right end, the rotary cam 74 is first put on the ON1 as described above. The carriage 17 is moved to the position immediately after, and the carriage 17 is moved to the standby position at the right end. Then, the motor 71 is continuously rotated forward to rotate the rotary cam 74 continuously to the ON5 position. Before reaching the position, the parallel moving cam body 96 is moved in the X1 direction at the position from ON4 to OFF4, and the sliding contact pin 78 is moved from the intermediate cam surface 102b to the lowermost cam surface 102a side, so that the support block 7 is moved. Is lowered to the lowermost position, the sliding contact pin 99 is moved from the intermediate cam surface 103b to the uppermost cam surface 103c, and the lifting body 66 is raised by the biasing spring 100. As a result, all the release rods 62 on the elevating body 66 push up all the valve rods 56, the valve bodies 55, and the packing 57 in the exhaust valve means 41 to open the valves. Further, the suction portions 90 are in close contact with the lower end openings of the small diameter passages 51b, and all the air buffer chambers 40a to 40d are connected to the bubble discharge passages 47a to 47d, the outlet portion 54, the passage cylinder 52, the passage hole 51, the suction portion 90 The port W of the switching valve unit 69 is communicated through the passage 92, the discharge cylinder 93, and the tube 76c (see FIGS. 20 and 9). The air pump 28 starts operating from the position of ON4 at which the elevating body 66 starts to ascend, applies a positive pressure to the ink in the ink tanks 7a to 7d, and passes through the hollow needle 26 and the ink supply tubes 27a to 27d. Although the pressure in the air buffer chambers 40a to 40d is increased, no air bubbles are discharged because the port W of the switching valve unit 69 is closed (OFF4 in FIG. 24).

  Then, when the port W and the groove 112c communicate with the switching member 110 of the switching valve unit 69 at the ON5 position of the rotary cam body 74 (buffer suction in FIG. 23), the pressure of the air pump 28 causes the air to flow. The ink liquid level in the buffer chambers 40a to 40d is pushed up, and the air (bubbles) stored above the buffer chambers 40a to 40d is discharged through the communicating bubble discharge passage 47 described above. In this case, the rotation speed of the drive motor 30 is increased and the positive pressure of the air pump 28 is increased as compared with the case where the air pump 28 is operated during the suction operation. However, also in this case, the positive pressure is large enough that the ink does not leak from the nozzles.

  Since a small amount of ink leaks together with the air bubbles (air) when the air bubbles are discharged, the maintenance motor 71 is rotated in reverse and intermittently several times to suck the ink, and the suction pump 68 is intermittently rotated. (See the exhaust empty suction part in FIG. 25). As a result, a small amount of ink leaked together with the air bubbles (air) flows from the dish-shaped suction unit 90 to the suction port 91 around the base end of the release rod 62, the passage 92, the discharge cylinder 93, the tube 76c, the port W, and the suction port. The liquid is discharged to a waste liquid form 111 via a pump 68. The reason for the intermittent drive is that, unlike the empty suction of the cap, the amount of ink leaking together with the air bubbles (air) is small, so that it is not necessary to continuously suction. In this case, the operation time (t4) of the air pump 28 may be changed according to the environmental temperature, and the number of intermittent operations of the suction pump 68 may be changed accordingly, or they may be set to be constant.

  Thereafter, similarly to the above-described recovery operation by suction, the rotary cam body 74 is rotated from the OFF1 position to the ON3 position to continue the recovery operation by suction, the carriage is moved to perform the wiping operation by the wiper, and further thereafter. Then, the rotary cam 74 is rotated to the ON2 position to perform empty suction of the cap and suction of the residual ink in the switching valve unit 68. Note that the suction recovery operation after the bubble (air) removal operation may be omitted.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the above-described first embodiment, the length and the cross-sectional area of the bubble discharge passage are set to be equal in order to substantially equalize the flow path resistance value of each bubble discharge passage when discharging the air in the air buffer chamber. Alternatively, in the second embodiment, the cross-sectional area of the bubble discharge passage is changed in accordance with the difference in the length of the bubble discharge passage in order to make the flow resistance substantially equal. It is.

  As shown in FIG. 27, the ink jet printer 200 includes a recording mechanism unit 202 that is included in a main body frame 201 and discharges ink onto a sheet P as a recording medium to perform recording, and a recording head unit 203 in the recording mechanism unit 202. The printing apparatus includes a maintenance unit 204 for performing a maintenance process, an ink tank 205 for storing ink to be supplied to the recording head unit 203 fixedly disposed in the main body frame 201, and the like.

  A plurality of ink tanks 205 for full-color printing (indicated by reference numerals 205a to 205d for ink tanks for individual colors, that is, black, cyan, magenta, and yellow, see FIG. 27) are used for ink consumption. Can be exchanged accordingly.

  In the recording mechanism 202, a carriage 209 is slidably mounted on a left and right longitudinal rear guide shaft 206 and a front guide shaft 207 provided in parallel in the main body frame 201, and a recording head unit is mounted on the carriage 209. 203 is integrally attached.

  The carriage 209 is configured to be able to reciprocate left and right along the front and rear guide shafts 206 and 207 by a carriage driving motor 210 disposed on the right rear side of the main body frame 201 and a timing belt 211 as an endless belt. I have. On the other hand, although not shown, the paper P is transported horizontally (in the direction of arrow A in FIG. 27) in a direction perpendicular to the moving direction of the carriage 209 on the lower surface side of the recording head unit 203 by a known paper transport mechanism. .

  An ink receiver 212 is provided at one end (the left end in FIG. 27 in the second embodiment) outside the width of the paper P to be conveyed, and a maintenance unit 204 is provided at the other end. Have been. Accordingly, during the recording operation, the recording head unit 203 periodically discharges ink to prevent nozzle clogging at the flushing position where the ink receiving section 212 is provided, and receives ink at the ink receiving section 212. . At the head standby position on the other end side, the maintenance unit 204 is disposed to clean the nozzle surface, to perform a recovery process for selectively sucking ink for each color, and to perform air bubbles (to be described later) in the buffer tank 213. (Air) is removed.

  As shown in FIG. 27, the ink tank 205 for each color can be inserted from the front and mounted below the nozzle surface on the lower surface of the recording head unit 203. In FIG. 27, in order from the left, an ink tank 205a for black ink (BK), an ink tank 205b for cyan ink (C), an ink tank 205c for magenta ink (M), and an ink tank for yellow ink (Y) 205d are arranged horizontally and side by side.

  A hollow needle (not shown) for supplying ink is horizontally protruded from the rear side of each of the ink tank mounting portions so as to face the insertion direction (rear side wall surface) of the ink tank 205 of each color. The base end of the hollow needle corresponding to each color ink is connected to the recording head unit 203 via a corresponding flexible ink supply tube (corresponding to an ink supply tube in the claims) 214a to 214d. In this case, the middle portions of the ink supply tubes 214a and 214b for black and cyan and the middle portions of the ink supply tubes 214c and 214d for magenta and yellow are tied up and down.

  Next, the recording head unit 203 mounted on the carriage 209 will be described with reference to FIGS. In the second embodiment, the recording head unit 203 for full-color recording includes a box-shaped head holder 220, an ink jet recording head 221 fixed to the lower surface side of the bottom plate 220 a of the head holder 220, A buffer tank 213 and exhaust valve means 226 fixed above the bottom plate 220a are provided.

  On the lower surface of the recording head 221, a row of nozzles 222a for black ink (BK), a row of nozzles 222b for cyan ink (C), and a row of yellow ink are shown from the left side in FIG. 28 (a view of the recording head 221 from the bottom). A row of nozzles 222c for ink (Y) and a row of nozzles 222d for magenta ink (M) are formed to be long in a direction orthogonal to the moving direction (main scanning direction) of the carriage 209. Each nozzle 222 is exposed downward so as to face the upper surface of the paper P.

  The recording head 221 has an ink supply port for each ink color (for example, four colors) on one side of the upper surface, similarly to those known in JP-A-2002-67312 and JP-A-2001-219560. Ink is distributed to a number of pressure chambers via ink supply channels extending from the supply ports, and ink is ejected from nozzles 222 by driving an actuator 223 such as a piezoelectric element corresponding to each pressure chamber. . A flexible flat cable 224 for applying a voltage to the actuator 223 is fixed to the upper surface of the actuator 223. Ink is supplied to each ink supply port from each ink tank 205 via a buffer tank 213.

  Next, the configurations of the buffer tank 213 and the exhaust valve means 226 will be described in detail with reference to FIGS. The buffer tank 213 includes a plurality of independent air buffer chambers 227 for each ink color, with the main partition wall 235 interposed therebetween and divided by sub-partition walls 235a and 230 intersecting with the main partition wall. In the embodiment, a part of the air buffer chamber 227a for black ink (BK) is disposed below the main partition wall 235, and the air buffer chamber 227b for cyan ink (C) and yellow ink are disposed above the main partition wall 235. An air buffer chamber 227c for (Y) and an air buffer chamber 227d for magenta ink (M) are partitioned and arranged by the sub-partition walls 235a and 230, and are configured as two layers vertically.

  Specifically, the main body case 225 of the buffer tank 213 has a rectangular cylindrical side wall as an outer periphery, and is fixed so as to cover a box-shaped lower case 232 having open upper and lower surfaces and an upper surface of the lower case 232. And an upper case 231. The upper case 231 and the lower case 232 are both injection-molded with a synthetic resin material, and are liquid-tightly connected by ultrasonic welding or the like.

  The lower case 232 is provided on its lower surface with an opening that opens most of the area of the lower surface, and main partition walls 235 are formed at positions parallel to and spaced from the opening and the upper open surface, respectively. ing. The opening is sealed with a flexible film (236 made of synthetic resin and impermeable to air and liquid) for a damper. Specifically, the outer peripheral edge of the flexible film 236 is bonded to the lower end surface of the outer peripheral wall 237 defining the outer periphery of the opening by bonding or ultrasonic welding. A first chamber 227a-1 of an air buffer chamber for black ink (BK) is formed between the flexible film 236 and the main partition wall 235. A gap for deforming the flexible film 236 is secured between the flexible film 236 and the bottom plate 220a of the head holder 220, and the buffer tank 213 is fixed to the head holder 220.

  On the upper surface of the main partition wall 235, a sub-partition wall 235a that intersects with the main partition wall 235 and rises integrally is formed, and a portion above the main partition wall 235 in the lower case 232 will be described later. A plurality of air buffer chambers are formed in cooperation with the upper case 231. In the embodiment, two sub-partition walls 235a are arranged at intervals from each other, and cooperate with the side wall of the lower case 232 to form three sub-partition walls for cyan ink (C), yellow ink (Y), and magenta ink (M). Air buffer chambers 227b to 227d (specifically, second chambers 239b to 239d of the air buffer chamber) are formed. As shown in FIG. 32, each sub-partition wall 235a is formed to extend over the entire length in the lower case 232, and at a position off the upper surface of the main partition wall 235, the air buffer chambers 227b to 227d (specifically, the second chamber 239b To 239d) are communicated with ink outlets 241b to 241d for each ink color.

  Further, an additional sub-partition wall 235b is formed extending to a position off the upper surface of the main partition wall 235 near the ink outlets 241b to 241d, and a black portion is provided between the sub-partition wall 235b and the side wall of the lower case 232. A second chamber 239a of an air buffer chamber for ink (BK) is formed. The lower end of the second chamber 239a communicates with the ink outlet 241a (see FIGS. 29 and 32).

  The first chamber 227a-1 of the air buffer chamber for black ink (BK) is connected to the second chamber 239a via a passage 242 as a throttle section that vertically passes through a cylindrical portion formed along the sub-partition wall 235b. (See FIG. 32). The passage 242 is formed to have a smaller cross-sectional area than the first chamber 227a-1, and the passage resistance is set to be larger than the inside of the first chamber 227a-1.

  The upper case 231 is formed in a flat shape having a plurality of concave portions on the upper surface. The upper case 231 has a cyan ink (C) and a yellow ink separated by two sub-partition walls 230 at an upper position substantially corresponding to the first chamber 227a-1 of the air buffer chamber for black ink (BK). First chambers 227b-1 to 227d-1 of three air buffer chambers 227b to 227d for (Y) and magenta ink (M) are formed to open upward (see FIG. 30). The sub-partition wall 230 is located on the extension surface of the sub-partition wall 235a of the lower case 232, and the bottom wall 229 of the first chamber 227b-1 to 227d-1 has a number of passage holes 244 as a throttle unit. The first chambers 227b-1 to 227d-1 are formed to penetrate vertically, and the first chambers 227b-1 to 227d-1 are individually communicated with the lower chamber (the chamber partitioned by the sub-partition wall 235a in the lower case 232), that is, the second chambers 239b to 239d. are doing.

  The passage hole 244 is formed to have a smaller cross-sectional area than each of the first chambers 227b-1 to 227d-1, and is set to have a larger flow path resistance than each of the first chambers 227b-1 to 227d-1.

  The upper open surfaces of the first chambers 227b-1 to 227d-1 are commonly sealed with a single damper flexible film (film made of synthetic resin and impermeable to air and liquid) 243. Specifically, a flexible film 243 is bonded to the outer peripheral wall defining the outer periphery of each first chamber and the upper end surface of the sub-partition wall 230 by bonding or ultrasonic welding.

  As shown in FIG. 31, the ink outlets 241a to 241d are arranged side by side on the lower surface of the lower case 232, and open downward at positions extending below the flexible film 236. On the other hand, the recording head 221 has a plurality of ink supply ports (not shown) communicating with the ends of the ink supply channels (manifolds) for each ink color on the upper surface at positions facing the ink outlets 241a to 241d. ing. Each of the ink outlets 241a to 241d penetrates an opening provided in the bottom plate 220a of the head holder 220, and communicates with each ink supply port of the recording head 221 via a sealing material such as rubber packing.

  As shown in FIGS. 29 and 30, the ink inlets 247 (four in the embodiment) for each ink color are provided in a portion 232a protruding in a flange shape from the side surface of the lower case 232 opposite to the ink outlets 241a to 241d. 247a, 247b, 247c, and 247d respectively indicate ink inlets for black ink (BK), cyan ink (C), yellow ink (Y), and magenta ink (M). ing.

  A joint member 245 having an ink flow path for each ink color is connected to these ink inflow ports via a seal 246 such as a packing so that the lower ends of the ink flow paths correspond to each other. To the upper end of each ink flow path of the joint member 245, the tip of the ink supply tube 214a to 214d of each ink color is connected.

  Further, the ink inlet 247a for the black ink (BK) is connected to a corresponding first chamber of the air buffer chamber 227a via a concave passage 248 formed horizontally on the lower surface of the lower case 232 so as to open downward. Have been. The other ink inflow ports 247b to 247d are formed in a concave passage 248 formed in the lower surface of the lower case 232 so as to be open downward and horizontally, and along one side wall of the lower case 232 in the vertical direction (the plane formed by the main partition wall 235). The communication passage 249 is formed so as to extend in a direction substantially orthogonal to the first case, and is connected to the corresponding first air buffer chambers 227b to 227d via a communication passage 250 vertically penetrating the upper case 231 (see FIG. 1). FIGS. 30, 31, 33 (a), 33 (b) and 34 (b)). In this case, since the opening surface of the communication passage 250 is located at a height close to the lower surface of the flexible film 243, the ink flowing into the air buffer chambers 227b to 227d faces the opening surface of the communication passage 250. Since it can directly collide with the flexible film 243 approaching, the dynamic pressure fluctuation of the ink in the ink supply tubes 214b to 214d can be efficiently absorbed and reduced (damped).

  The open lower surface of each of the ink inlets 247a to 247d and the concave passage 248 is sealed with a portion where the flexible film 236 is extended.

  On the ceiling surface of the first chamber 227a-1 of the air buffer chamber for black ink, that is, on the lower surface of the main partition wall 235, a U-shaped rib 235c having both ends connected to the side wall on the side of the concave passage 248 has a flexible film. It is formed at a height that does not reach 236. For this reason, a space where the ink does not enter is secured in a portion surrounded by the U-shaped rib 235c, and the air and the flexible film 236 cooperate with the flexible film 236 to absorb the pressure fluctuation of the ink described later. I have.

  Further, on the upper surface of the upper case 231, third chambers 255a to 255d of the respective air buffer chambers are independently recessed at positions corresponding to the respective second chambers 239a to 239d near the ink outlets 241a to 241d. Is formed. The third chambers 255a to 255d communicate with the corresponding second chambers 239a to 239d by air holes 254 formed through the upper case 231. In other words, the air buffer chambers 227a to 227d for each ink color are respectively composed of three chambers from a first chamber to a third chamber.

  Further, a plurality of bubble discharge passages 251 are formed in the upper surface of the upper case 231 independently of each other, and the bubble discharge passages 251 are formed in the longitudinal direction of the main body case (ink inlets 247a to 247d and ink outlets 241a to 241d). (The connecting direction). In the upper case 231, a ventilation hole 253 communicating with an upper portion of each of the second chambers 239 a to 239 d is formed between the first chamber and the third chamber, and the ventilation hole 253 is connected to one end of the bubble discharge passage 251. It has become. The other end of the bubble discharge passage 251 is connected to an exhaust valve unit 226 described later.

  Each ventilation hole 253 is formed in a cylindrical wall that hangs from the upper case 231 into each of the second chambers 239a to 239d, and opens into each of the second chambers 239a to 239d at a position spaced a predetermined distance from the upper case 231. ing. That is, as described later, even in a state where the air bubbles in the second chambers 239a to 239d are exhausted from the ventilation holes 253, air only at the hanging height of the cylindrical wall is secured above the second chambers 239a to 239d. I have.

  The third chambers 255a to 255d of each of the air buffer chambers and the bubble discharge passage 251 are covered on their open upper surfaces with a portion extending from the flexible film 243, and the respective chambers and the passages are defined.

  The buffer tank 213 is fixed on the carriage 209 such that the main partition wall 235 and the flexible films 236 and 243 extend in the moving direction of the carriage 209, that is, in parallel with the opening surface of the nozzle of the recording head 221. .

  Next, the exhaust valve means 226 will be described. The storage section 234 provided integrally on one side of the lower case 232 (the right end in FIG. 30 and FIG. 34A) is provided for each ink color (four). A passage hole 256 that is long in the up-down direction and that opens up and down is formed. Each of the passage holes 256 includes an upper half large diameter portion 256a and a lower half small diameter passage 256b. A small diameter valve rod 258 is integrally formed at the lower end of the large diameter valve body 257. A packing 259 such as an O-ring for sealing is disposed on the lower end side of the valve body 257 so as to be fitted on the valve rod 258. A packing 259 and a valve body 257 are inserted into the large diameter portion 256a so as to be able to move up and down, and a valve rod 258 is inserted into the small diameter passage 256b. The lower end of the valve rod 258 extends to near the lower end opening of the small diameter passage 256b. The valve body 257 is constantly pressed downward by spring means 260 such as a coil spring provided in the large diameter portion 256a. In this state, the packing 259 is pressed against the bottom surface of the large-diameter portion 256a of the passage hole 256, and the valve is closed (see FIG. 34A).

  A side edge of the upper case 231 is extended to a position covering an upper end of the storage portion 234, and the other end of each of the bubble discharge passages 251 is an upper end of each of the passage holes 256, as shown in FIG. The connection ports 252 are individually communicated with each other. That is, the exhaust valve means 226 and each of the third chambers 255 of the air buffer chamber 227 are connected by a bubble discharge passage 251. In this embodiment, the bubble discharge passage 251 corresponds to four ink colors. Are formed. Then, as described above, the air bubble discharge passage 251 and the air buffer chamber 227 are connected by the vent hole 253 (253a to 253d) which is one end of the air bubble discharge passage 251 (individually denoted by reference numerals 251a to 251d). The connection port 252 (252a to 252d) which is the other end of the bubble discharge passage 251 connects the bubble discharge passage 251 and the exhaust valve means 226.

  In the second embodiment, as in the first embodiment, the ventilation holes 253 are arranged substantially along the moving direction of the carriage 209, whereas the connection ports 252a to 252d are orthogonal to the moving direction of the carriage 209. It is arranged substantially along the direction. As a result, in the four bubble discharge passages 251, as shown in FIG. 35, the linear distance W connecting the passage hole 253 and the connection port 252 is the linear distance from the black passage hole 253a to the connection port 252a. Wa, the linear distance from the passage hole 253b for cyan to the connection port 252b is Wb, the linear distance from the passage hole 253c for yellow to the connection port 252c is Wc, and the linear distance from the passage hole 253d for magenta to the connection port 252d. Is Wd, these have a relationship of Wa <Wb <Wc <Wd.

  However, in the second embodiment, unlike the first embodiment, the four bubble discharge passages 251 are arranged such that the path length L of the path from the ventilation hole 253 to the connection port 252 is in the order of the length of the linear distance W. The length of the passage from the ventilation hole 253a for black to the connection port 252a is La, the length of the passage from the ventilation hole 253b for cyan to the connection port 252b is Lb, and the length for yellow is Assuming that the path length from the ventilation hole 253c to the connection port 252c is Lc and the path length from the magenta ventilation hole 253d to the connection port 252d is Ld, these are formed such that La <Lb <Lc <Ld. I have.

  As shown in the schematic diagram of FIG. 36, each of the bubble discharge passages 251a to 251d is a part of a path from the corresponding ink tank 205a to 205d to the connection port 252a to 252d. When discharging the air bubbles in the air buffer chamber 227, the flow path resistance from the ink tanks 205a to 205d to the connection ports 252a to 252d affects.

  Based on the Hagen-Poiseuille equation, a flow path resistance value R for discharging air bubbles in a path from the ink tank 205 to the connection port 252 is represented by (Equation 1).

  Here, μ: viscosity of ink, L: length of the bubble discharge passage 251, r: equivalent radius of the bubble discharge passage 251 (the radius of a circle having an area equal to the cross-sectional area of the bubble discharge passage 251), R0: ink tank 205 Is the flow path resistance from the air passage to the vent hole 253. In the second embodiment, the ink supply tubes 214a to 214d, the ink inlets 247a to 247d, and the air buffer chambers 227a to 227d are provided from the ink tanks 205a to 205d on the upstream side of the air holes 253 in the ink flow path. The flow path resistance value (R0) of the path leading to each of the vent holes 253a to 253d through the ink supply tube 214 is previously set to be equal to each other by making the length of the ink supply tube 214 the same for each color.

  Then, based on (Equation 1), (Equation 2) is set in order to set all of the flow path resistance values R of the respective paths from the ink tank 205 including the bubble discharge passage 251 to the connection port 252 to be equal to each other. Thus, the equivalent radii ra to rd of each bubble discharge passage 251 can be obtained.

  ra, rb, rc, rd: equivalent radii of the respective bubble discharge passages 251a, 251b, 251c, 251d.

  In other words, since the passage lengths La to Ld of the bubble discharge passages 251a to 251d are different from each other as described above, by changing the equivalent radii ra to rd of each of the bubble discharge passages 251a to 251d, the flow passage resistance values can be changed. Can be equal to each other. Then, the respective sectional areas of the bubble discharge passages 251a to 251d can be determined from the equivalent radii ra to rd.

  Therefore, in the second embodiment, in order to make the flow path resistance values of the bubble discharge paths equal to each other, the cross-sectional area (passage) is set such that the bubble resistance path 251 having a longer path length L has a smaller flow path resistance value. The cross-sectional area in the direction perpendicular to the longitudinal direction of the bubble discharge passage 251 is increased, and the cross-sectional area of the bubble discharge passage 251 having a shorter passage length L is reduced so that the resistance value of the passage increases. In the second embodiment, the cross-sectional area is changed by equalizing the width of each bubble discharge passage 251 (see FIG. 33B), while changing the depth of the passage (not shown). Let me.

  Next, the maintenance unit 204 in which the exhaust by the exhaust valve means 226 is performed will be described.

  The maintenance unit 204 includes a cap member 271 for opening and closing the opening surface of the nozzle 222 of the recording head 221 and a plurality of small caps for individually opening and closing the lower end surface of the exhaust valve means 226, that is, the opening surface of each small diameter portion 256b. And a member 272. When the carriage 209 is moved to the standby position (the right end position in FIG. 27) by the vertical movement mechanism 273 similar to a known maintenance unit, the cap members 271 and 272 form the opening surface of the nozzle 222 and the exhaust valve means 226. It rises so as to be in close contact with the lower end faces, and falls away from those faces at other positions. Further, the cap member 271 is detachably connected to the suction pump 274 as a discharge unit (similar to the maintenance unit of the first embodiment), and the suction pump 274 drives the suction nozzle 222 to remove the ink and foreign substances thickened from the nozzle 222 by suction. Is done.

  Each small cap member 272 has a protruding portion 272a (corresponding to the release rod 62 of the first embodiment) protruding from the cap member. When the small cap member 272 comes into close contact with the lower end surface of the exhaust valve means 226, the protruding portion 272a Then, the bubble rod 258 is pushed up against the urging force of the spring means 260, and the packing 259 is separated from the inner bottom of the large diameter portion 256a to open the valve. Further, each small cap member 272 is connected to the suction pump 274 through a common flow path, and the bubbles accumulated in the second chambers 239a to 239d of the air buffer chambers are collectively sucked by driving the suction pump 274. Is discharged. This is because the ink supplied from the ink tank 205 through the ink supply tube 214 is temporarily stored in the second chambers 239a to 239d to separate and float air bubbles from the ink and accumulate in the upper portions of the second chambers 239a to 239d. The generated air bubbles are discharged by the suction pump 274 as described above.

  The cap member 271 and the small cap member 272 are alternatively connected to a suction pump 274 by a switching valve 275. The cap member 271 and the small cap member 272 are simultaneously brought into close contact with the opening surface of the nozzle 222 and the lower end surface of the exhaust valve means 226 by the up and down movement mechanism 273. Preferably, the second chamber is first passed through the small cap member 272. The bubbles accumulated in the upper portions of 239 a to 239 d are discharged, and then the ink is discharged from the nozzle 222 through the cap member 271. If an attempt is made to discharge bubbles in the second chambers 239a to 239d only by the cap member 271, a large amount of ink must be discharged. Head recovery processing can be performed.

  Further, only the suction of the ink from the nozzle 222 or only the discharge of the air bubbles from the second chambers 239a to 239d can be performed independently.

  Note that, instead of the suction operation of the suction pump 274 as described above, a positive pressure is applied to the ink from the ink tank 205 side to suck and remove the thickened ink and foreign matter from the nozzle 222, and to remove the second chamber 239a to 239a to 239a. The air bubbles of 239d can also be discharged. Alternatively, the suction operation and the application of the positive pressure to the ink can be used in combination.

  Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, as in the second embodiment, in order to make the resistance of the flow path when the air in the air buffer chamber is discharged substantially equal, the bubble discharge is performed according to the difference in the length of the bubble discharge passage. It is configured to change the cross-sectional area of the passage.

  In the third embodiment, the colors of the ink are four colors of black, cyan, magenta, and yellow, and two recording heads 221 having a row of nozzles 222 for each color similar to the second embodiment are arranged in parallel in the main scanning direction. And fixed to the head holder 220.

  The buffer tank 213 of the third embodiment supplies ink of a corresponding color to the two recording heads 221. That is, there is one ink inlet 247 for each color, but two ink outlets 241 are formed. Since the third embodiment is a modified example of the second embodiment, the same parts and configurations as those of the second embodiment will be described below by assigning the same reference numerals.

  In this embodiment, the colors of the ink are four colors of black, cyan, magenta, and yellow. However, in FIG. 37 (a diagram of the recording head 221 viewed from below), nozzles 222a and 222b for cyan ink (C) are viewed from the left side. , Two rows of nozzles 222c for yellow ink (Y), four rows of nozzles 222d, 222e, 222f, 222g for black ink (Bk), four rows of nozzles 222h for yellow ink (Y), and magenta ink ( The two rows of M) nozzles 222i and 222j are formed to be long in a direction orthogonal to the moving direction (main scanning direction) of the carriage 209. Each nozzle 222 is exposed downward so as to face the upper surface of the paper P.

  The recording head 221 has an ink supply port for each ink color on one side of the upper surface, similarly to those known in JP-A-2002-67312 and JP-A-2001-219560. The ink is distributed to a large number of pressure chambers 261 via respective ink supply channels 260 (FIG. 37) extending from the nozzles 222. The ink is distributed from the nozzles 222 by driving an actuator (not shown) such as a piezoelectric element corresponding to each pressure chamber 261. Is discharged. A flexible flat cable (not shown) for applying a voltage to the actuator is fixed to the upper surface of the actuator. Ink is supplied to each ink supply port from each ink tank 205 via a buffer tank 213.

  The main body case 225 of the buffer tank 313 of the third embodiment includes an upper case 231 and a lower case 232, and the upper case 231 is liquid-tightly fixed to the upper end of the lower case 232 by ultrasonic welding or the like. .

  In the lower case 232, similarly to the second embodiment, a first chamber 227a-1 of an air buffer chamber for black ink (BK) is formed below the main partition wall 235, and the first chamber 227a-1 is formed. Is open downward in most of the area of the lower surface of the lower case 232, and a flexible film 236 is bonded to cover the open surface. Further, a plurality of ink outlets 241a to 241d are arranged on the lower surface of the lower case 232 adjacent to the open surface of the first chamber 227a-1. In this embodiment, two ink outlets at the center are ink outlets 241a for black ink (BK), two ink outlets on both sides thereof are ink outlets 241c for yellow ink (Y), and two ink outlets at one end. These are ink outlets 241b for cyan ink (C), and the other two are ink outlets 241d for magenta ink (M).

  The second chamber 239a of the air buffer chamber for black ink (BK) is defined by a partition wall 235b formed so as to surround the central two ink outlets 241a in plan view, and penetrates the main partition wall 235. The passage 242 communicates with the first chamber 227a-1. The third chamber 255a formed on the upper surface of the upper case 231 by being surrounded by the wall 230b located on the extension surface of the partition wall 235b is formed by the air hole 254 formed through the upper case 231 to form the second chamber 239a. Is in communication with

  Each of the air buffer chambers 227b to 227d for the cyan ink (C), the yellow ink (C), and the magenta ink (M) has a sub-partition wall formed on the upper surface of the main partition wall 235, similarly to the second embodiment. 235 a and a sub-partition wall 230 formed on the upper surface of the upper case 231 on the extension surface thereof. In each of the air buffer chambers 227b to 227d, the upper side of the bottom wall 229 of the upper case 231 is formed as first chambers 227b-1 to 227d-1, and the lower side is formed as second chambers 239b to 239d. The second chambers 239b to 239d extend over the entire length of the lower case 232 in the longitudinal direction, and communicate with the ink outlets 241b to 241d, respectively. In this embodiment, a second chamber 239c for yellow ink (C) is formed in a Y shape in plan view, and a second chamber 239b for cyan ink (C) and a magenta ink are sandwiched between the second chambers 239c. A second chamber 239d for (M) is formed.

  Although each of the first chambers 227b-1 to 227d-1 on the upper surface of the upper case 231 is located above the corresponding second chamber, in the third embodiment, the cyan ink (C) of the second embodiment, There is no third chamber for yellow ink (C) and magenta ink (M). In the bottom wall 229 of each first chamber, a plurality of passage holes 244 are formed on a side near a communication passage 250 described later, and a passage hole 244 is also formed on a side near ink outlets 241b to 241d. The chamber communicates with the second chamber.

  The plurality of bubble discharge passages 251 are formed in the upper case 231 in a recessed manner on the upper surface, communicate with the second chambers 239a to 239d through the vent holes 253 as one end thereof, and have the other end having the same structure as the second embodiment. 226. The ventilation holes 253 for the cyan ink (C), the yellow ink (C), and the magenta ink (M) are opened below the ceiling surfaces of the second chambers 239b to 239d as in the second embodiment. There is a space above the two rooms to store air.

  The upper open surfaces of the first chambers 227 b-1 to 227 d-1, the third chamber 255 a for black ink, and the bubble discharge passage 251 are covered with a single flexible film 243.

  In the lower case 232, ink inlets 247a to 247d are formed in substantially the same manner as in the second embodiment. The ink inlet 247a for black ink is connected to the air buffer chamber 227a for black ink via the concave passage 248. The ink inlets 247b to 247d for the cyan ink (C), the yellow ink (C), and the magenta ink (M) are respectively connected to the corresponding air buffer chambers 227b to 227d via the communication paths 249 and 250. Connected. The open lower surfaces of the ink inlets 247a to 247d and the concave passage 248 are sealed by extending the flexible film 236.

  In the third embodiment, as in the second embodiment, the ventilation holes 253 (253a to 253d) as one ends of the bubble discharge passages 251 (251a to 251d) are arranged substantially along the moving direction of the carriage 209. On the other hand, a connection port 252 (252a to 252d) as the other end of the bubble discharge passage 251 (251a to 251d) is arranged substantially along a direction orthogonal to the moving direction of the carriage 209. Therefore, as shown in FIG. 46, the linear distance W connecting the air hole 251 and the connection port 252 in each bubble discharge passage 251 is Wa, the linear distance from the black path hole 253a to the connection port 252a is Wa, and the cyan distance is If the linear distance from the passage hole 253b to the connection port 252b is Wb, the linear distance from the passage hole 253c for yellow to the connection port 252c is Wc, and the linear distance from the passage hole 253d for magenta to the connection port 252d is Wd, Wb <Wc <Wa <Wd.

  The path length from the black vent 253a to the connection port 252a is La, the path length from the cyan vent 253b to the connection port 252b is Lb, and the path length from the yellow vent 253c to the connection port 252c. Let Lc be the path length from the magenta vent 253d to the connection port 252d, and Lb <Lc <La <Ld according to the order of the length of the linear distance W. .

  Therefore, in each of the bubble discharge passages 251 of the third embodiment, similarly to the second embodiment, the same flow path resistance value R from each corresponding ink tank 205 to the connection port 252 is required. The equivalent radius of each bubble discharge passage 251 is determined based on (Equation 1) and (Equation 2), and the sectional area of each bubble discharge passage 251 is determined from this equivalent radius. In the third embodiment, the cross-sectional area is changed by changing the depth dimension of the passage (not shown) and also changing the width dimension of the passage (see FIG. 44A).

  As described in the first to third embodiments, in the present invention, by setting the flow path resistance values R when discharging bubbles from the air buffer chambers (40, 227) to be equal to each other, The amount of exhaust air from each air buffer chamber is made substantially equal. As a result, the time required for removing the air bubbles from each air buffer chamber becomes substantially equal, and the removing operation can be completed in all the air buffer chambers at the same time, thereby improving the efficiency of the operation. If the exhaust amount is different depending on the bubble discharge passage, ink is discharged following the bubble from the air buffer chamber where the discharge of the bubble has been completed early, and the ink is wasted. Since the amount of discharged ink can be reduced as much as possible, the ink in the air buffer chamber can be effectively used.

  Further, in the first embodiment, the flow path resistance value of each bubble discharge passage is made equal by making the length of each bubble discharge passage equal, whereas in the second and third embodiments, By changing the cross-sectional area of each bubble discharge passage according to the difference in the length of each bubble discharge passage, the flow path resistance value of each bubble discharge passage is made equal. Therefore, particularly in the second and third embodiments, the flow path resistance values of all the bubble discharge paths 251 can be made equal to each other without arranging the bubble discharge path 251 having a short path length to be detoured. Can be easily arranged, and the bubble discharge passage can be freely arranged according to the arrangement of another configuration. Therefore, the size of the entire apparatus can be easily reduced.

  Needless to say, the present invention can be applied to various types of ink jet printers.

FIG. 2 is a perspective view of the inkjet printer according to the first embodiment. FIG. 3 is a plan view of a recording mechanism unit according to the first embodiment. It is a top view of a main part frame of a 1st embodiment. FIG. 2 is a schematic plan view of an ink tank mounting section and an ink supply section according to the first embodiment. FIG. 5 is a side sectional view taken along line VV of FIG. 2. FIG. 7A is a plan view of a carriage on which the buffer tank and the like of the first embodiment are mounted, and FIG. 6B is a cross-sectional view taken along line VIb-VIb in FIG. FIG. 3 is a plan view showing a bubble discharge passage on the upper surface of a buffer tank according to the first embodiment. FIG. 13 is a side view of the carriage and the maintenance unit taken along line VIII-VIII in FIG. 12. It is a schematic cross section of a means for removing air from the air buffer chamber of the first embodiment. It is a side view which shows the position of a carriage, a parallel movement cam body, a recovery means, and a bubble removal means in a standby state. (A) is an enlarged sectional view of a main part of the on-off valve means in a closed state, and (b) is an enlarged sectional view of a main part of the on-off valve means in an open state. It is a top view of the maintenance unit of 1st Embodiment. FIG. 3 is a perspective view of a maintenance unit according to the first embodiment. It is a principal part enlarged plan view which shows the arrangement | positioning part of the translation cam body of 1st Embodiment. FIG. 4 is a perspective view showing a unit base, a parallel-moving cam body support block, and an elevating body in the maintenance unit of the first embodiment. (A) is a front view of the elevating body of the first embodiment, (b) is a plan view, and (c) is a left side view. 17A is a cross-sectional view of the elevating body of the first embodiment, and FIG. 17B is a cross-sectional view taken along line XVIIb-XVIIb in FIG. It is a figure showing the shape of the cam groove and the projected cam seen from the upper surface of the rotation cam body of a 1st embodiment. It is a side view which shows the position of the carriage in a holding | maintenance state, a parallel movement cam body, a recovery means, and a bubble removal means. It is a side view which shows the position of the carriage, a parallel movement cam body, a recovery means, and an air bubble removal means in the state of the air removal from the buffer tank of 1st Embodiment. (A) is a perspective view of a switching valve unit of the first embodiment, and (b) is a perspective view of a switching member. It is a schematic diagram which shows the tube connection relationship of the switching valve unit of 1st Embodiment, a recovery means, and a bubble removal means. It is explanatory drawing which shows the rotation phase relationship of the switching member in each operation position in the switching valve unit of 1st Embodiment. 6 is a time chart of each operation according to the rotation angle of the rotating cam body of the first embodiment. It is a time chart which shows operation of an air pump of a 1st embodiment, a suction pump, a release rod, and a cap member. FIG. 4 is a schematic diagram illustrating a path for discharging bubbles in the first embodiment. It is a top view of a recording mechanism part of an ink jet printer of a second embodiment. It is a bottom view of a head holder of a 2nd embodiment. FIG. 29 is a sectional view taken along the line XXIX-XXIX in FIG. 28. It is a top view of a buffer tank in the state where flexible film 243 of a 2nd embodiment was removed. It is a bottom view of the buffer tank of the 2nd embodiment in the state where flexible membrane 236 was removed. It is a top view of the lower case of 2nd Embodiment. (A) is a plan view of only the upper case of the second embodiment, and (b) is a bottom view of only the upper case of the second embodiment. 30A is a sectional view taken along line XXXIVa-XXXIVa of FIG. 30, FIG. 30B is a sectional view taken along line XXXIVb-XXXIVb of FIG. 30, and FIG. 31C is a sectional view taken along line XXXIVc-XXXIVc of FIG. It is explanatory drawing which shows the dimension of each bubble discharge path in 2nd Embodiment. It is a mimetic diagram showing a course for air bubbles discharge of a 2nd embodiment. It is a bottom view of a head holder of a 3rd embodiment. It is an upper perspective view of the buffer tank of 3rd Embodiment, and its flexible membrane. It is a lower perspective view of a buffer tank and its flexible membrane of a third embodiment. (A) is an upper perspective view of a main body case (in a state where a lower case and an upper case are combined) of a third embodiment, and (b) is a lower perspective view. (A) is an upper perspective view of the lower case of the third embodiment, and (b) is a lower perspective view. (A) is an upper perspective view of the upper case of the third embodiment, and (b) is a lower perspective view. It is a top view of a lower case of a 3rd embodiment. (A) is a front view of the upper case of the third embodiment, and (b) is a cross-sectional view taken along line XLIVb-XLIVb in FIG. 43 (a). (A) is a sectional view taken along line XLVa-XLVa in FIG. 43 (a), and (b) is a sectional view taken along line XLVb-XLVb in FIG. 43 (a). It is explanatory drawing which shows the dimension of each bubble discharge passage in 3rd Embodiment.

Explanation of reference numerals

17,209 carriage 34,221 printhead 36,213,313 buffer tank 40,227 air buffer chamber 41,226 exhaust valve means 47,251 air bubble discharge passage

Claims (9)

An ink jet recording head is mounted on a carriage that moves with respect to the recording medium, and an ink tank mounted on the main body of the printer is connected to the recording head via a buffer tank mounted on the carriage via an ink supply pipe. In an inkjet printer configured to supply ink,
The recording head has a plurality of ink supply channels,
In the buffer tank, a plurality of air buffer chambers for storing ink and air bubbles are formed corresponding to each ink supply channel,
In the carriage, a plurality of bubble discharge passages are formed, one end of which is connected to each of the air buffer chambers and the other end of which is openable to the outside.
Discharging means for discharging the air bubbles in each air buffer chamber to the outside via the other end of each air bubble discharging passage is provided,
An ink jet printer, wherein each of the bubble discharge passages has substantially the same flow path resistance value for discharging the bubbles. At least a part of each of the plurality of air buffer chambers is arranged substantially along the moving direction of the carriage, and the other ends of the plurality of bubble discharge passages are arranged substantially along a direction orthogonal to the moving direction of the carriage. And
2. The ink jet printer according to claim 1, wherein the plurality of bubble discharge passages are formed by connecting one end and the other end of the passages at substantially the same length.   The ink jet printer according to claim 2, wherein at least a part of the plurality of bubble discharge passages is formed to bend along a wall surface of the buffer tank. At least a part of each of the plurality of air buffer chambers is arranged substantially along the moving direction of the carriage, and the other ends of the plurality of bubble discharge passages are arranged substantially along a direction orthogonal to the moving direction of the carriage. And
2. The ink-jet printer according to claim 1, wherein the cross-sectional area of each of the bubble discharge passages is larger as a passage length connecting one end and the other end is longer, and is smaller as the passage length is shorter.   The ink jet printer according to claim 4, wherein the shorter the linear distance connecting one end and the other end of each of the bubble discharge passages, the shorter the passage length, and the longer the longer, the longer the passage length. .   The ink jet printer according to claim 4, wherein each of the bubble discharge passages is formed along a wall surface of the buffer tank.   The plurality of air buffer chambers are formed in the buffer tank so as to be separated from each other by a partition wall, and one end of each of the bubble discharge passages is formed through each of the ventilation holes formed through the upper wall of the buffer tank. 4. The air buffer chamber, wherein at least a part of each of the air bubble discharge passages is formed in a concave groove shape on an upper wall of the buffer tank connected to each of the air holes. 5. Or the inkjet printer according to 6.   Exhaust valve means for opening and closing the bubble discharge path is provided on the other end side of each of the bubble discharge paths, and when discharging ink from the recording head, the exhaust valve means is closed and the discharge means is driven. The ink jet printer according to any one of claims 1 to 7, wherein the exhaust valve means is opened when the printer is turned off.   9. The ink jet printer according to claim 1, wherein the discharge unit is a suction pump detachably connected to the other end of each of the bubble discharge passages.