JP5087971B2 - Inkjet head - Google Patents

Description

  The present invention relates to an inkjet head.

  2. Description of the Related Art Conventionally, ink jet printers that record predetermined images by ejecting ink onto recording media such as paper and plastic thin plates have been proposed and put into practical use. The ink jet printer includes an ink jet head having nozzles, and records a predetermined image on the recording medium by ejecting ink from the nozzles toward the recording medium while moving the ink jet head in a predetermined direction. .

  Incidentally, the ink used in the ink jet printer may be supplied from the ink supply container to the head on the carriage through the ink supply tube.

  In this ink supply mechanism, since the carriage on which the head is mounted is scanned, the ink pressure supplied to the head varies due to acceleration / deceleration and vibration. In that case, there is a problem that the ink meniscus position of the nozzle of the head is shifted, resulting in uneven density, or in the worst case, the meniscus is broken and discharge becomes impossible.

  In addition, as a conventional solution to such a phenomenon, a damper is disposed upstream of the head as shown in Patent Documents 1, 6, and 7, and pressure fluctuation during ink supply is reduced. There is something to absorb. However, if there is a pipe between the damper and the head, there is a problem that the ink supply pressure fluctuates slightly due to mechanical vibration or acceleration / deceleration.

  For this reason, conventionally, there is a head provided with a damper function in order to prevent such a slight pressure fluctuation (see, for example, Patent Documents 2 to 5 and 8).

Japanese Patent Application Laid-Open No. H11-228688 discloses a device having a damper function by providing a sealed air damper chamber in a common ink chamber of a head. Patent Document 3 discloses a laminated head having a damper function using a thin plate. Patent Document 4 discloses that a groove is formed in a common ink chamber of a head and separated from an air damper chamber by a film to have a damper function. Patent Document 5 discloses a gas holding chamber formed adjacent to a common ink chamber of a head, and a bubble function is accumulated by electrolysis to provide a damper function. Patent Document 8 discloses a biochip head that can form a miniaturized pressure chamber when ink in a reservoir of the head is in contact with air.
JP 2000-158668 A JP 2001-130004 A JP 2004-114415 A JP 7-137262 A JP-A-7-323548 Japanese Patent Laid-Open No. 10-193646 JP-A-11-34349 JP 2004-226321 A

  However, in the structure in which air and ink are brought into contact with each other to form a gas-liquid interface as disclosed in Patent Documents 5 and 8, it is not easy to stably keep the air in such a place. There is a problem in that stable discharge is hindered by outflow due to a suction operation or the like to prevent clogging and losing the effect of absorbing pressure fluctuations.

  In particular, when air is introduced into the common ink chamber, since the air is not fixed in the common ink chamber and can move freely, it often enters the pressure chamber and often prevents ink ejection. There is a problem in that the air that has been introduced flows out.

  Further, since air dissolves in ink at the gas-liquid interface where air and ink come into contact with each other, there is a problem that the air disappears after a certain period of time and the effect of absorbing pressure fluctuations is lost.

  None of the patent documents describes the fact that air dissolves in ink, and there is no disclosure about the effect of this on the absorption effect of pressure fluctuations.

  As disclosed in Patent Documents 2, 3, and 4, by interposing a member such as a film at the interface between air and ink, it is possible to reliably prevent outflow and dissolution of air from the air damper chamber. However, such a configuration requires new parts and manufacturing processes, and requires a special design due to the complicated structure, which may increase costs and reduce reliability.

  Further, the structure as disclosed in Patent Document 5 in which a gas holding chamber is formed adjacent to the common ink chamber of the head and air bubbles are accumulated by electrolysis to replenish air is complicated. In addition, complicated control such as timing for generating bubbles by electrolysis is required. Furthermore, there is also a problem that oil-based inks that do not generate gas by electrolysis do not function.

  An object of the present invention is to solve the above problems and provide an ink jet head capable of suppressing outflow and dissolution of air from an air damper chamber with a simple structure.

The problems of the present invention are solved by the following configurations.
1.
An inkjet head chip having a nozzle for discharging ink and a pressure chamber communicating with the nozzle;
An ink supply path for supplying ink from outside to the inkjet head chip;
An air damper chamber having a maze structure branched from the ink supply path ,
The air damper chamber is erected alternately from two opposing inner wall surfaces constituting the air damper chamber toward the inner wall surfaces facing each other, so that the entire inner space is characterized is configured as an elongate channel formed in a zigzag structure, that you have been arranged the gas-liquid interface in the middle of the elongated flow path toward the other end side from the communication position with the ink supply path Inkjet head.
2.
The ink supply path has an ink supply chamber;
The inkjet head according to claim 1, wherein the air damper chamber having the maze structure is branched from the ink supply chamber.
3.
3. The inkjet head according to claim 1, wherein at least a part of an inner wall surface of the air damper chamber having the maze structure is formed by a partition arranged so as to form the maze structure.
4 .
When using the ink jet head, according to claim 1, 2 or 3 plane including the zigzag structure is characterized in that the air damper chamber of the labyrinth structure so that the non-parallel are arranged with respect to the horizontal plane Inkjet head.
5 .
The inkjet head according to any one of claims 1 to 4 , wherein a part of the surface of the inkjet head chip forms a part of an inner wall surface of the air damper chamber having the maze structure.
6 .
Injecting air into different other end side to the communication position with the ink supply path in the air damper chamber of the labyrinth structure, according to any one of claims 1 to 5, characterized in that an air injection mechanism Inkjet head.

  According to the present invention, since the outflow and dissolution of air from the air damper chamber can be suppressed with a simple structure, an ink jet head capable of absorbing fluctuations in ink supply pressure and maintaining ejection stability can do.

  An embodiment of the present invention will be described below with reference to the drawings. However, the following is one embodiment of the present invention and does not limit the present invention.

  First, an overall configuration of an ink jet printer according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram of an ink jet printer according to an embodiment of the present invention.

  The ink jet printer 1 ejects ink onto a recording medium P and records an image on the recording medium P. The ink jet printer 1 is provided with a conveying means (not shown). The conveying means conveys the recording medium P in the sub-scanning direction X perpendicular to the main scanning direction A while passing through the recording area C in FIG. It has become.

  Above the recording area C, a carriage rail 2 extending along the main scanning direction A is arranged. A carriage 3 guided by the carriage rail 2 is movably provided on the carriage rail 2. Yes.

  The carriage 3 is mounted with an inkjet head 4 that ejects ink onto the recording medium P, and moves in the direction of arrow A from the home position area B to the maintenance area D along the carriage rail 2.

  During this main scanning, the inkjet head 4 ejects ink d toward the recording medium P to form an image on the recording medium P. In use, the inkjet head 4 is installed in the vertical direction Y so that the ink ejection direction from the nozzles is downward. At this time, the ink discharge surface 41a is arranged in the horizontal direction.

  In the ink jet printer 1 according to the present embodiment, a total of four ink jet heads 4 are arranged in the carriage 3 so that four colors of ink of black (K), yellow (Y), magenta (M), and cyan (C) can be ejected. Is installed. In FIG. 1, three inkjet heads 4, 4, 4 are arranged in a line in the direction of arrow A, and the back of the inkjet head 4 at the center of the inkjet heads 4, 4, 4 aligned in the direction of arrow A is shown. Another ink jet head 4 (not shown) is arranged on the side (the back side in the direction perpendicular to the paper surface).

  Each of these inkjet heads 4 is connected to an ink tank 5 for storing black, yellow, magenta, and cyan inks via an ink supply pipe 6. That is, the ink in the ink tank 5 is supplied to each inkjet head 4 by the ink supply pipe 6.

  In the maintenance area D, a maintenance unit 7 that performs maintenance on the inkjet head 4 is provided. The maintenance unit 7 includes a plurality of suction caps 8 that cover the ink discharge surface 41a of the inkjet head 4 and suck ink in the nozzles, and a cleaning blade 9 that wipes off ink adhering to the ink discharge surface 41a. An ink receiver 10 that receives ink ejected from the inkjet head 4, a suction pump 11, and a waste ink tank 12 are provided.

  The suction cap 8 communicates with the waste ink tank 12 via the suction pump 11 and is raised during the maintenance operation so as to cover the ink discharge surface 41a of the inkjet head 4. Four suction caps 8, 8,... Are arranged so as to correspond to the respective ink-jet heads 4 so as to cover the ink discharge surfaces 41a of all the ink-jet heads 4 when raised as described above.

  The suction pump 11 includes a cylinder pump and a tube pump, and operates in a state where the suction cap 8 covers the ink discharge surface 41a, so that the ink in the inkjet head 4 from the nozzle 42 (see FIG. 3). A suction force is generated for sucking together with the foreign matter.

  In the home position area B, a moisturizing unit 13 for moisturizing the inkjet head 4 is provided. The moisture retention unit 13 is provided with four moisture retention caps 14 that retain the ink of the inkjet head 4 by covering the ink ejection surface 41a when the inkjet head 4 is in a standby state. These four moisturizing caps 14, 14,... Are arranged corresponding to the arrangement of the inkjet heads 4 so as to simultaneously cover the ink ejection surfaces 41 a of the four inkjet heads 4.

  The control unit is configured to include a CPU (Central Processing Unit) and a memory, and controls each component of the inkjet printer 1. The memory stores image data to be formed on the recording medium P and a program for controlling each component of the inkjet printer 1, and controls each component based on the image data and program in the memory. A signal is transmitted.

  Next, an inkjet head 4 according to an embodiment of the present invention will be described with reference to FIGS.

  2 is an exploded perspective view of the inkjet head 4 of the present embodiment, FIG. 3 is a side view of the inkjet head 4 of the present embodiment, and FIG. 4 is a perspective view of an air damper chamber forming member 58 according to the present embodiment.

  The inkjet head 4 of the present embodiment is provided with an inkjet head chip (hereinafter referred to as “head chip”) 41 that ejects ink. The head chip 41 has a long outer shape in the arrow X direction, and a large number of nozzles 42 are arranged in the arrow X direction on the ink discharge surface 41a. The row of nozzles 42 provided continuously in the arrow X direction is referred to as a nozzle row 42a. The inkjet head 4 of the present embodiment is provided with one nozzle row 42a. The inkjet head 4 is mounted on the carriage 3 so that the arrow X direction (nozzle row direction) and the main scanning direction A shown in FIG.

  As shown in FIG. 3, an ink supply port 43 is provided on one side surface 41 b of the head chip 41, and the ink supply port 43 and the nozzle are connected via an ink flow path 44 formed inside the head chip 41. 42 is continuous. A part of the ink flow path 44 forms a pressure chamber, and has a structure in which an ink droplet is ejected from the nozzle 42 by changing the pressure by the action of a piezoelectric element (not shown) as a pressure generating unit.

  Thus, the head chip 41 is provided with a plurality of nozzles 42 and a plurality of pressure chambers provided corresponding to the plurality of nozzles 42 arranged in the arrow X direction. In the present embodiment, in the head chip 41, a surface extending along the arrangement direction of the pressure chambers is referred to as a side surface.

  One common ink chamber forming member 48 that is connected to the ink supply port 43 and guides the ink from the ink supply path to the head chip 41 is bonded and fixed to one side surface 41 b of the head chip 41. The common ink chamber forming member 48 is made of a material excellent in ink resistance, and has a recess for forming the common ink chamber 480. An ink flow path 481 for allowing ink to flow into the common ink chamber 480 is integrally provided at one end of the common ink chamber forming member 48.

  Further, as shown in FIG. 3, the ink heater 49 is in contact with the common ink chamber forming member 48 between the common ink chamber forming member 48 and the cover 54, as shown in FIG. Is provided. The ink heater 49 is provided to heat the ink introduced into the common ink chamber 480 of the common ink chamber forming member 48 to a predetermined temperature.

  Further, an adhesive is filled between the common ink chamber forming member 48 and the cover 54 so as to include at least the ink heater 49, whereby the housing frame 53, the ink heater 49, and the common ink chamber forming member 48 are filled. Is fixed by bonding.

  In order to stabilize the ink pressure applied to the ink jet head 4 as described above, an air damper chamber forming member 58 is bonded to the side surface 41c of the head chip opposite to the common ink chamber forming member 48 across the head chip (for example, adhesion) ) The air damper chamber forming member 58 is made of a material excellent in ink resistance, and has a maze structure recess 582 for forming the maze structure air damper chamber 580 in which the air 501 exists.

  The air damper chamber 580 includes a box-shaped air damper chamber forming member 58 having a maze structure recess 582 for forming the maze structure air damper chamber 580 therein, and an opening surface 583 thereof being opened, and the air damper. It is formed by the side surface 41c of the head chip that is joined (for example, bonded) to the opening surface 583 of the chamber forming member 58 and closes the recess 582 of the maze structure of the air damper chamber forming member 58.

  An ink flow path 581 for allowing the ink 500 to flow into the air damper chamber 580 is integrally provided at one end of the air damper chamber forming member 58, and the start end 511 of the recess 582 having the maze structure communicates with the ink flow path 581. ing.

  The internal space of the air damper chamber forming member 58 is partitioned by a plurality of partition walls 510 that also function as the inner wall surface constituting part of the air damper chamber 580 having a maze structure, and the internal space communicates with the ink flow path 581. A concave portion 582 having a labyrinth structure is formed.

  The partition wall 510 has one side edge portion integrally coupled to the bottom surface of the air damper chamber forming member 58, and both upper and lower end edge portions integrally coupled to the upper and lower side surfaces of the air damper chamber forming member 58. A start end 511 of a recess 582 having a labyrinth structure that communicates with the ink flow path 581 is provided at a lower portion of the end edge portion of the ink. The other side edge of the partition wall 510 is joined to the side surface 41c of the head chip when the air damper chamber forming member 58 and the head chip are joined.

  The air damper chamber 580 having the maze structure has a start end portion 511 communicating with the ink flow path 581, the other end portion 512 closed, a plurality of partition walls 510 in the vertical direction Y, and one end at the air damper chamber forming member. A zigzag structure in which the direction K of the maze is formed in a zigzag shape from the start end 511 toward the other end 512 by standing apart from 580 alternately.

  An air damper chamber 580 having a maze structure is disposed so that the surface including the zigzag structure is not parallel to the horizontal plane when the inkjet head 4 is used. In the present embodiment, the surface including the zigzag structure is disposed so as to coincide with the XY plane.

  The inkjet head 4 includes an air injection mechanism. The air injection mechanism is a mechanism for injecting air into the other end side 512 different from the start end 511 on the communication side with the ink supply path in the air damper chamber 580. The air injection mechanism is normally closed, and is configured to be opened when the air in the air damper chamber 580 is exhausted. In this embodiment, as shown in FIG. 4, a bypass 513 communicating with the other end side 512 is covered with a sealing means (not shown) such as a valve or a plug, and a syringe can be inserted therein to inject air. It is supposed to be in a state.

  As described above, in this embodiment, since the air damper chamber 580 has a complicated labyrinth structure, the air 501 in the air damper chamber 580 can be freely released with a simple structure in combination with the elongate flow path. Movement can be restricted and the outflow of the air 501 can be suppressed. By elongating the flow path, the cross-sectional area of the flow path can be reduced, so that a predetermined air volume can be maintained in the air damper chamber 580, and the contact area at the gas-liquid interface where the air and ink contact can be reduced. In addition, since the rate of air decrease due to the dissolution of air into the ink is slowed, the dissolution of air can be suppressed with a simple structure.

  Further, by forming at least a part of the inner wall surface of the maze structure air damper chamber 580 by the partition wall 510 arranged so as to form the maze structure, the maze structure air damper chamber 580 can be easily formed. .

  Moreover, since the maze structure of the air damper chamber 580 has a zigzag structure, the outflow and dissolution of air can be more effectively suppressed.

  Further, since the zigzag structure is formed from the communication side 511 to the ink supply path in the air damper chamber 580 having the maze structure toward the other end side 512, the outflow and dissolution of air are more effectively suppressed. can do.

  Further, when the ink jet head is used, the air damper chamber 580 having the maze structure is disposed so that the surface including the zigzag structure is inclined from the horizontal plane, thereby suppressing air outflow and dissolution more effectively. it can.

  In addition, since a part of the surface of the head chip forms a part of the inner wall surface of the air damper chamber, it is possible to reduce the size of the ink jet head and to vibrate the vibration of the piezoelectric element of the head chip during ink ejection. Of the liquid (ink 500) can be absorbed, and vibrations can be prevented from being transmitted to the outside.

  Further, if the maze structure air damper chamber 580 is configured as described above, the partition wall 510 constituting the inner wall surface of the maze structure air damper chamber 580 is formed integrally with the air damper chamber forming member 58, and the maze Since the concave portion of the structure is formed so as to open in one direction, the air damper chamber forming member 58 can be easily formed with a resin material or the like by a mold together with the concave portion of the maze structure.

  Further, when the head chip is joined to the air damper chamber forming member 58, the air damper chamber 580 having a labyrinth structure can be easily formed simply by joining the tip of the partition wall 510 to the side surface 41c of the head chip.

  In addition, by providing an air injection mechanism that injects air into the other end side of the air damper chamber that is different from the side communicating with the ink supply path, air can be injected even when the air in the air damper chamber is exhausted. It becomes easy.

  Returning to FIG. 2, a common ink chamber forming member 48, an air damper chamber forming member 58, and a holding plate 51 for holding the head chip 41 are attached to the lower portion of the head chip 41 so that the ink discharge surface 41a is exposed. ing. At one end of the holding plate 51, the ink flow path 481 of the common ink chamber forming member 48 and the ink flow path 581 of the air damper chamber forming member 58 are held, and ink is supplied to the ink flow path 481 and the ink flow path 581. A flowing ink supply chamber 52 is formed. The ink supply chamber 52 is disposed on one end side of the head chip 41 in the nozzle row direction, and is connected to the ink flow path 481 and the ink flow path 581. A connecting portion between the ink flow path 581 and the air damper chamber 580 is formed at a position closer to the nozzle 42 side than the ink inlet side of the head chip 41 on the wall surface forming the air damper chamber 580.

  A head drive substrate 46 that transmits a control signal from the control unit to each piezoelectric element (not shown) of the head chip 41 is connected via a flexible wiring board 47. A heater circuit for supplying power to the ink heater 49 is formed on the head drive board 46, and a heating wire of the ink heater 49 is electrically connected to the heater circuit via an electric wire 50. Has been. Similarly, the temperature sensor 45 for detecting the temperature is electrically connected to the heater circuit by an electric wire (not shown). The temperature sensor 45 is disposed closer to the head chip 41 than the ink heater 49.

  The head drive board 46 is provided with a connector 461, and an output terminal 62 of a flexible wiring board 60 having an input terminal 61 and an output terminal 62 is connected to the connector 461. A power source and a control unit (not shown) are electrically connected to the input terminal 61 of the flexible wiring board 60, and a control signal and power are supplied to the head drive substrate 46 via the flexible wiring board 60. It is like that.

  As shown in FIG. 2, the inkjet head 4 includes components of the inkjet head 4 such as the head chip 41, the common ink chamber forming member 48, the air damper chamber forming member 58, the head driving substrate 46, and the holding plate 51. Are attached, housed and fixed, and a cover 54 covering the housing frame 53 is provided. The casing frame 53 is provided with a frame ink channel 55 that supplies ink by being connected to the ink supply chamber 52 of the holding plate 51, and the ink supply pipe 6 is connected to the frame ink channel 55. It has come to be. A support beam 56 that supports the head drive substrate 46 is provided inside the housing frame 53.

  In the present embodiment, the ink supply path is configured by the frame ink flow path 55, the ink supply chamber 52, the ink flow path 481 connecting the ink supply chamber 52 and the common ink chamber 480, and the common ink chamber 480. Has been. The common ink chamber 480 and the ink supply chamber 52 serving as an ink reservoir may not be provided. Further, the common ink chamber may be formed integrally with the head chip using a substrate constituting the head chip.

  In the present embodiment, the ink supply path has an ink supply chamber, and the air damper chamber is branched from the ink supply chamber, so that pressure fluctuations can be absorbed more effectively.

  An opening 57 is provided in the upper part of the cover 54, and the input terminal 61 of the flexible wiring board 60 is exposed to the outside from the opening 57 after the ink jet head 4 is assembled.

  Next, the operation of the air damper chamber 580 of this embodiment will be described in detail with reference to FIG. FIG. 5A is a schematic diagram illustrating a state of the gas-liquid interface M1 between the air 501 and the ink 500 in the air damper chamber 580 of the inkjet head 4 according to the present embodiment. FIG. 6B is a schematic diagram illustrating a state of the air-liquid interface M2 between the air 501 in the air damper chamber 580 and the ink 500 when the partition wall 510 of the inkjet head 400 according to the comparative example is not provided. Assume that air 501 of the same volume exists in FIG. 5 (a) and FIG. 5 (b).

  FIG. 5 shows the connection state between the ink damper chamber 580 and the common ink chamber 480 and the ink supply chamber 52 of the inkjet head.

  As shown in FIG. 5A, the ink from the ink supply pipe 6 enters the ink supply chamber 52 through the frame ink flow channel 55, and the ink flow channel 481 connecting the ink supply chamber 52 and the common ink chamber 480 and the ink supply. The chamber 52 branches to an ink flow path 581 that connects the air damper chamber 580. The ink that has passed through the ink flow path 481 is supplied to the head chip 41 from the ink supply port 43 through the common ink chamber 480. The ink that has passed through the ink flow path 581 is supplied to the air damper chamber 580. When the ink 500 is filled from the frame ink flow path 55, the air 501 is sealed in an air damper chamber 580 having a labyrinth structure formed by a plurality of partition walls 510 that communicate with a connection portion with the ink flow path 581. In use, the ink 500 is filled up to a predetermined part of the air damper chamber 580 having a maze structure, and the air 501 is confined in the remaining part to form a gas-liquid interface M1 having a small contact area regulated by the partition wall 510. doing.

  On the other hand, in the case of the comparative example in which the partition 510 is not formed, the ink that has passed through the ink flow path 581 is supplied to the air damper chamber 580 as shown in FIG. When the ink 500 is filled from the frame ink channel 55, the air 501 is contained in the air damper chamber 580 communicating with the connection portion with the ink channel 581. At the time of use, as shown in FIG. 5 (b), when the nozzle 42 is on the lower side, the ink 500 is filled up to a predetermined height of the air damper chamber 580, and the air 501 is confined in the upper part thereof. A gas-liquid interface M2 having a large contact area is formed.

  In the present embodiment, a labyrinth structure that is complicated by the partition wall 510 makes it possible to reduce the cross-sectional area of the channel by elongating the channel, compared to the case where no partition wall is disposed, so that the inside of the air damper chamber 580 While maintaining a predetermined air volume, the contact area at the gas-liquid interface where the air and ink come into contact can be reduced, and the rate of air reduction due to the dissolution of air into the ink is reduced, thereby reducing the air Can be suppressed with a simple structure. Therefore, it is possible to obtain an ink jet head that can absorb fluctuations in ink supply pressure and maintain ejection stability.

  In this embodiment, since the air damper chamber 580 has a complicated labyrinth structure, the air 501 in the air damper chamber 580 can be freely moved with a convenient structure in combination with the elongate flow path. And the outflow of the air 501 can be suppressed.

  For example, in the structure of FIG. 5B, the air 501 from the air damper chamber 580 to the ink flow path 581 when the inkjet head tilts in the direction of arrow R in FIG. 5 or when the gas-liquid interface vibrates due to external vibration. 5 (a), the structure of FIG. 5 (a) is a maze structure having a partition wall 510, so that air can be stably held in the air damper chamber even if tilting or external vibration occurs. Therefore, the outflow of air from the air damper chamber can be suppressed with a simple structure.

  Here, the meniscus holding force at the gas-liquid interface is proportional to the surface tension of the ink and inversely proportional to the diameter (corresponding to the contact area) of the gas-liquid interface. In the present embodiment, since the meniscus holding force can be increased by reducing the contact area, the gas-liquid interface is less likely to move with respect to vibration and inclination, and a strong structure can be obtained.

  The ink pressure change that occurs when the inkjet head 4 moves is transmitted from the ink flow path 581 to the air damper chamber 580 and absorbed by the volume change of the air 501, and the ink pressure in the inkjet head 4 changes the ink ejection characteristics. It is suppressed to a small change that does not affect In order to further improve the pressure absorption performance, the resistance of the ink flow path 581 that connects the ink supply chamber 52 and the air damper chamber 580 is the resistance of the ink flow path 481 that connects the ink supply chamber 52 and the common ink chamber 480. It is preferable to make it smaller than the resistance. In order to reduce the resistance of the channel, the channel cross-sectional area may be increased.

  Next, the operation at the time of image formation by the inkjet printer 1 will be described.

  When the power of the ink jet printer 1 is turned on, power is supplied to each part of the ink jet printer 1.

  Thereafter, when an image recording start instruction is input, the carriage 3 starts reciprocating scanning, and the control unit transmits a control signal based on the image data to the head driving substrate 46 and other driving units. Start image recording. On the recording medium P conveyed to the conveying means, ink is ejected from the inkjet head 4 to form an image.

  When the maintenance timing for recovering the ejection state of the inkjet head 4 is reached, the control unit controls each unit to perform maintenance of the inkjet head 4. More specifically, the control unit controls the scanning motor in accordance with the maintenance timing, and moves the carriage 3 to a position where the inkjet head 4 and the suction cap 8 face each other. When the inkjet head 4 and the suction cap 8 face each other, the control unit controls the lifting motor to raise the maintenance unit 7 until the ink discharge surface 41a of the inkjet head 4 and the suction cap 8 are in close contact with each other.

  After completion of raising the maintenance unit 7, the control unit controls the suction pump 11 so that the inside of the suction cap 8 is sucked for a predetermined time.

  Due to the operation of the suction pump 11, the inside of the inkjet head 4 becomes negative pressure. The ink flow path 581 on the upstream side of the air damper chamber 580 also becomes negative pressure, and the ink stored in the air damper chamber 580 flows out from the ink flow path 581.

  At this time, the air 501 in the air damper chamber 580 shown in FIG. 5 expands, and the gas-liquid interface M between the ink 500 and the air 501 is drawn toward the ink flow path 581 side.

  For example, in the structure of FIG. 5B, when the gas-liquid interface M2 moves downward from this state and reaches the position of the ink flow path 581, the air 501 from the air damper chamber 580 to the ink flow path 581 is obtained. The volume of the air 501 immediately before the outflow is V1.

  On the other hand, in the structure of FIG. 5A, since the partition wall 510 is provided, the gas-liquid interface M1 moves while meandering through the air damper chamber 580 having the maze structure and reaches the position of the ink channel 581 from the air damper chamber 580. The outflow of the air 501 to the ink flow path 581 occurs, and the volume of the air 501 immediately before the outflow occurs is set to V2.

  Here, as apparent from the figure, V1 <V2. Therefore, in the structure of FIG. 5A of the present embodiment, the air 501 does not flow out even when suctioned at the same pressure as the pressure at which the air 501 flows out in FIG. Since air can be more stably held in the air damper chamber, the outflow of air from the air damper chamber can be suppressed with a simple structure.

  As described above, according to the inkjet head 4 of the present embodiment, an inkjet head chip having a nozzle for ejecting ink and a pressure chamber communicating with the nozzle, and an ink for supplying ink from the outside to the inkjet head chip Since a supply path and an air damper chamber having a maze structure branched from the ink supply path are provided, it is possible to suppress the outflow and dissolution of air from the air damper chamber with a simple structure. Ink jet head that can absorb discharge and maintain ejection stability can be obtained.

  The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

  For example, in this embodiment, a serial ink jet printer is used as the ink jet printer, but the present invention is not limited to this, and a line ink jet printer may be used as the ink jet printer.

1 is a plan view illustrating an outline of an inkjet printer according to an embodiment of the present invention. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention. It is a side view of the ink jet head concerning one embodiment of the present invention. It is a perspective view of the air damper chamber formation member concerning one embodiment of the present invention. (A) is a schematic diagram which shows the state of the gas-liquid interface of the air of the air damper chamber of the inkjet head which concerns on one Embodiment of this invention, and an ink. FIG. 6B is a schematic diagram illustrating a state of an air-liquid interface between air and ink in an air damper chamber of an inkjet head according to a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 4,400 Inkjet head 41 Head chip (inkjet head chip)
41a Ink ejection surface (tip surface)
42 Nozzle 42a Nozzle row 48 Common ink chamber forming member 49 Ink heater 53 Housing frame P Recording medium X Nozzle row direction

Claims (6)

An inkjet head chip having a nozzle for discharging ink and a pressure chamber communicating with the nozzle;
An ink supply path for supplying ink from outside to the inkjet head chip;
An air damper chamber having a maze structure branched from the ink supply path ,
The air damper chamber is erected alternately from two opposing inner wall surfaces constituting the air damper chamber toward the inner wall surfaces facing each other, so that the entire inner space is characterized is configured as an elongate channel formed in a zigzag structure, that you have been arranged the gas-liquid interface in the middle of the elongated flow path toward the other end side from the communication position with the ink supply path Inkjet head. The ink supply path has an ink supply chamber;
The inkjet head according to claim 1, wherein the air damper chamber having the maze structure is branched from the ink supply chamber.   3. The inkjet head according to claim 1, wherein at least a part of an inner wall surface of the air damper chamber having the maze structure is formed by a partition arranged so as to form the maze structure. When using the ink jet head, according to claim 1, 2 or 3 plane including the zigzag structure is characterized in that the air damper chamber of the labyrinth structure so that the non-parallel are arranged with respect to the horizontal plane Inkjet head. The inkjet head according to any one of claims 1 to 4 , wherein a part of the surface of the inkjet head chip forms a part of an inner wall surface of the air damper chamber having the maze structure. Injecting air into different other end side to the communication position with the ink supply path in the air damper chamber of the labyrinth structure, according to any one of claims 1 to 5, characterized in that an air injection mechanism Inkjet head.

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