JP2008246676A - Liquid ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection head which can suppress consumption of liquid by decreasing the number of execution times of cleaning operation. <P>SOLUTION: In the halfway of an ink introduction path 42, a portion 45 having an inside diameter enlarged as compared with other portion of the ink introduction path 42 is provided, a filter 18 is arranged in the enlarged diameter portion 45, and a bubble trap member 47 having open upstream side and downstream side is arranged in the enlarged diameter portion 45 on the upstream side of the filter 18. The bubble trap member 47 has a bubble trap chamber 48 which can accommodate bubbles internally, and the bubble trap member 47 is arranged to form a sub-channel 52 for passing the liquid between the inner circumferential surface of the enlarged diameter portion 45 and the bubble trap member 47. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head such as an ink jet recording head, and more particularly to a liquid ejecting head that introduces liquid into a pressure chamber through a liquid inflow portion and ejects liquid from a nozzle opening by pressure fluctuation.

  A liquid ejecting head that ejects (ejects) liquid droplets from a nozzle opening by causing pressure fluctuations in a pressure chamber is used, for example, in an image recording apparatus such as an ink jet recording apparatus (hereinafter simply referred to as a printer). Used for forming electrodes such as inkjet recording heads (hereinafter simply referred to as recording heads), color material ejection heads used in the production of color filters such as liquid crystal displays, organic EL (Electro Luminescence) displays, FEDs (surface emitting displays), etc. There are an electrode material ejection head, a bioorganic matter ejection head used for manufacturing a biochip (biochemical element), and the like.

  For example, in the recording head described above, an ink introduction needle opened at the tip of the ink introduction needle is inserted into an ink cartridge (hereinafter simply referred to as a cartridge) in which liquid ink is sealed. Ink in the cartridge is introduced into the pressure chamber of the recording head through the hole.

  In the recording head having the above-described configuration, it is ideal that the ink flow path from the ink introduction needle to the nozzle opening of the recording head is filled with ink. However, ink filling (initial filling) in the recording head or Bubbles may enter the ink flow path when the ink cartridge is replaced. Further, for example, external air may pass through a resin wall forming the ink introduction needle and enter the ink flow path (gas exchange). For this reason, it is difficult to completely prevent the mixing of bubbles. Bubbles that have entered the ink flow path gradually grow and become large, and when some of the excessively grown bubbles move to the pressure chamber side due to the flow of ink, the bubbles absorb the pressure fluctuation during the discharge operation. There is a risk of causing problems such as pressure loss and insufficient supply of ink due to air bubbles blocking the flow path.

  In order to prevent such problems due to air bubbles, the width of the ink supply passage is increased, and an elastic body is provided on the side wall of the filter chamber in which the filter is disposed, and the ink and air bubbles are forcibly discharged from the nozzle openings. When the pressure in the filter chamber is reduced during operation, a recording head has been proposed in which the elastic body is deformed inward to reduce the flow path, thereby facilitating the discharge of bubbles (see, for example, Patent Document 1). In addition, a recording head has been proposed that includes a pushing member that moves in the downflow direction by ink flow down and pushes out bubbles (for example, see Patent Document 2).

JP 2000-296622 A JP 2006-142816 A

  However, since there is no configuration in which any of the recording heads temporarily captures excessively grown bubbles while securing the flow path at the flow rate of ink for performing normal printing, the bubbles are flow paths. There was a risk of blocking. In addition, it is difficult to suppress the growth of bubbles due to the above gas exchange. This necessitates frequent cleaning operations.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting head capable of suppressing the consumption of liquid by reducing the number of executions of a cleaning operation.

In order to achieve the above object, a liquid jet head of the present invention is a liquid jet head that introduces liquid into a pressure chamber through a liquid inflow portion, and jets liquid from a nozzle opening due to pressure fluctuation,
On the downstream side of the liquid inflow portion, an enlarged diameter portion that is larger than the inner diameter of the liquid inflow portion is provided,
Place a filter in the enlarged diameter part,
A bubble trap member having an opening on the upstream side and the downstream side is disposed in the enlarged diameter portion on the upstream side of the filter.

  According to the above configuration, since the bubble trap member opened on the upstream side and the downstream side is arranged in the enlarged diameter portion on the upstream side of the filter, even when bubbles grow in the enlarged diameter portion, the bubbles are trapped in the bubble trap member. By accommodating in the inside, it is possible to prevent bubbles from covering and closing the entire surface of the filter. Thereby, it becomes possible to prevent the supply of the liquid to the downstream side of the filter from being insufficient. Further, by accommodating the bubbles in the bubble trap member and separating them from the wall surface of the liquid inflow portion, it is possible to suppress the bubbles from growing due to gas exchange through the wall surface of the liquid inflow portion. As a result, it is possible to reduce the number of executions of the cleaning operation, and thereby it is possible to suppress liquid consumption.

  The said structure WHEREIN: It is desirable to arrange | position the said bubble trap member in the state which formed the subflow path which a liquid can pass between the internal peripheral surfaces of the said enlarged diameter part.

  According to the above configuration, the bubble trap member is disposed in a state in which a sub-flow path through which the liquid can pass is formed between the bubble trap member and the inner peripheral surface of the enlarged diameter portion. Even when the bubble trap member is blocked by bubbles at the flow velocity, the sub-flow channel can be secured as a flow channel through which the liquid can pass. Thereby, it becomes possible to prevent liquid supply shortage more reliably.

  The said structure WHEREIN: It is desirable for the opening area of the upstream opening of the said bubble trap member to be smaller than the opening area of the upstream end opening of the said enlarged diameter part.

  According to the above configuration, the flow area of the fluid flowing into the upstream opening of the bubble trap member is increased by making the opening area of the upstream opening of the bubble trap member smaller than the opening area of the upstream end opening of the enlarged diameter portion. be able to. The flow downward force makes it easy to introduce bubbles into the bubble trap member, and allows the bubbles in the bubble trap member to easily pass through the filter and be discharged downstream during the cleaning operation. . Furthermore, by reducing the opening area of the upstream opening, it is possible to make it difficult for the bubbles once introduced into the bubble trap member to rise from the upstream opening to the upstream side.

  The said structure WHEREIN: It is desirable for the said bubble trap member to be arrange | positioned in the state in which the said upstream opening is located on the central axis of the upstream end opening of the said enlarged diameter part.

  According to the above configuration, the bubble trap member is disposed in a state where the upstream opening is positioned on the central axis of the upstream end opening of the enlarged diameter portion, that is, the bubble trap member is positioned at a position where the fluid flow rate is faster. Since the upstream side opening is arranged, it is possible to easily introduce the fluid into the bubble trap member.

  The said structure WHEREIN: It is desirable for the said bubble trap member to have a bubble trap chamber diameter-expanded toward the downstream opening side from the upstream opening side.

  According to the above configuration, since the bubble trap chamber expands from the upstream opening side toward the downstream opening side, the upstream opening has a higher flow velocity than the downstream opening, and the upstream opening has the upstream opening. Since the flow rate is slower than that, the bubbles can be easily introduced into the bubble trap chamber, and the bubbles once accommodated in the bubble trap chamber can be easily held.

  The said structure WHEREIN: It is desirable for the said bubble trap member to adhere to the upstream surface of the said filter.

  According to the above configuration, since the bubble trap member is fixed to the upstream surface of the filter, it is possible to prevent the bubble trap member from being separated from the filter. For this reason, by disposing the bubble trap member at an appropriate position, it is possible to ensure a state in which bubbles are easily introduced into the inside from the upstream opening of the bubble trap member.

  The said structure WHEREIN: It is desirable for the said bubble trap member to have larger specific gravity than the said liquid, and to be mounted on the upstream surface of the said filter.

  According to the above configuration, since the bubble trap member has a specific gravity greater than that of the liquid and is placed on the upstream surface of the filter, the bubble trap member is prevented from floating from the filter. Fixing the member to the filter, such as adhesion or welding, is unnecessary and simple.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In this embodiment, an ink jet recording head (hereinafter referred to as “recording head”) will be described as an example of the liquid ejecting head.

  FIG. 1 is a perspective view of an ink jet recording apparatus. First, a schematic configuration of an ink jet recording apparatus (hereinafter referred to as a printer) equipped with a recording head will be described with reference to FIG. The illustrated printer 1 is an apparatus that records an image or the like by discharging liquid ink onto the surface of a recording medium (landing target) 2 such as recording paper. This printer 1 includes a recording head 3 (corresponding to one type of liquid ejecting head in the present invention) for ejecting (ejecting) ink, a carriage 4 to which the recording head 3 is attached, and a carriage 4 in the main scanning direction (FIG. A carriage moving mechanism 5 for moving the recording medium 2 in the sub-scanning direction (in the direction orthogonal to the main scanning direction, indicated by Y in FIG. 1) and the like are provided. Here, the ink is a kind of liquid of the present invention, and is stored in the ink cartridge 7. The ink cartridge 7 is detachably attached to the recording head 3.

  The carriage moving mechanism 5 includes a timing belt 8. The timing belt 8 is driven by a pulse motor 9 such as a DC motor. Therefore, when the pulse motor 9 is operated, the carriage 4 is guided by the guide rod 10 installed on the printer 1 and reciprocates in the main scanning direction X (width direction of the recording paper 2).

  A capping mechanism 12 is disposed at a home position that is a non-recording area of the printer 1. The capping mechanism 12 has a tray-like cap member 11 that can come into contact with a later-described nozzle forming surface (nozzle plate 25) of the recording head 3. In the capping mechanism 12, the space in the cap member 11 functions as a sealing empty portion, and the nozzle opening 26 (see FIG. 2) of the recording head 3 faces the nozzle forming surface in the sealing empty portion. It is configured to be possible. Further, a pump unit 13 is connected to the capping mechanism 12, and the inside of the sealed empty space can be made negative pressure by the operation of the pump unit 13. When the pump unit 13 is operated in close contact with the nozzle forming surface and the inside of the sealing empty portion (sealed space) is made negative pressure, the ink and bubbles in the recording head 3 are sucked from the nozzle opening 26 and the cap member. 11 is discharged into the sealed space. That is, the capping mechanism 12 is configured to perform an operation for forcibly sucking and discharging ink and bubbles in the recording head 3 (hereinafter referred to as a cleaning operation). Details of this cleaning operation will be described later.

  Next, the configuration of the recording head 3 will be described. 2 is a schematic perspective view of the recording head 3 attached to the carriage 4. FIG. 3 is a plan view of the recording head 3. FIG. The illustrated recording head 3 is schematically configured from a cartridge base 15 (hereinafter referred to as “base”), a head case 16, a flow path unit 17, a vibrator unit 22, and the like.

  The base 15 is molded from, for example, a synthetic resin, and as shown in FIG. 3, a plurality of compartments 14 (liquid storage member mounting portions) are provided on the upper surface thereof. An ink introduction needle 19 is attached to each compartment 14 with a mesh-like filter 18 interposed. The ink cartridges 7 are mounted in these compartments 14. That is, the ink cartridge 7 is mounted in a state of being positioned on the base 15. The details of the ink cartridge 7 and the ink introduction needle 19 will be described later.

  As shown in FIG. 2, a circuit board 20 is attached to the other surface of the base 15 opposite to the section 14. The circuit board 20 includes, for example, a drive circuit for controlling supply of a drive signal to a piezoelectric vibrator 29 (see FIG. 5) to be described later, a connector for connection to the printer body side, and a through hole for supplying ink. Etc. And this circuit board 20 is attached to the base 15 via the sheet | seat member 21 which functions as packing.

  The head case 16 is fixed to the base 15 and is a casing for housing a vibrator unit 22 having a piezoelectric vibrator 29 described later. For this reason, the housing case 32 (see FIG. 5) capable of housing the transducer unit 22 is formed in the head case 16. The vibrator unit 22 is inserted into the housing space 32 and fixed by bonding or the like. And the flow path unit 17 is being fixed to the front end surface on the opposite side to the attachment surface of the base 15 of the head case 16 with the adhesive agent.

  The flow path unit 17 is manufactured by joining and integrating with an adhesive or the like in a state where the elastic plate (vibration plate) 23, the flow path forming substrate 24, and the nozzle plate 25 are laminated.

  The nozzle plate 25 is a member made of, for example, a thin plate made of stainless steel, and fine nozzle openings 26 are formed in a row in the nozzle plate 25 at a pitch corresponding to the dot formation density of the printer 1.

  A head cover 27 is attached to the front end portion of the head case 16 so as to surround the periphery of the nozzle plate 25 from the outside. The head cover 27 is made of, for example, a metal thin plate member. The head cover 27 has a function of protecting the front end portions of the flow path unit 17 and the head case 16 and preventing the nozzle plate 25 from being charged.

  FIG. 5 is a cross-sectional view of the main part of the recording head 3. The vibrator unit 22 supplies a drive signal from the circuit board 20 to the piezoelectric vibrator group 30 as pressure generating means, a fixing plate 31 to which the piezoelectric vibrator group 30 is joined, and the piezoelectric vibrator group 30. For example, a flexible cable (not shown). The piezoelectric vibrator group 30 of the present embodiment includes a plurality of piezoelectric vibrators 29 arranged in a comb shape. Each piezoelectric vibrator 29 has a fixed end joined on the fixed plate 31, and a free end protruding outside the front end surface of the fixed plate 31. That is, each piezoelectric vibrator 29 is mounted on the fixed plate 31 in a so-called cantilever state. The fixing plate 31 that supports each piezoelectric vibrator 29 is made of, for example, stainless steel having a thickness of about 1 mm. In addition to the piezoelectric vibrator, an electrostatic actuator, a magnetostrictive element, a heating element, or the like can be used as the pressure generating means.

  Inside the head case 16, an accommodation empty portion 32 that can accommodate the vibrator unit 22 is formed in a state where the height direction of the head case 16 is penetrated. The vibrator unit 22 is housed and fixed in the housing space 32 by bonding the back surface of the fixing plate 31 to the inner wall surface of the case that defines the housing space 32.

  A plurality of flow path forming substrates 24 are formed corresponding to the respective nozzle openings 26 in a state in which empty portions that become common ink chambers 33, groove portions that become ink supply ports 34, and empty portions that become pressure chambers 35 are partitioned by partition walls. It is a plate-shaped member. The flow path forming substrate 24 is produced, for example, by etching a silicon wafer. The pressure chamber 35 is formed as a long and narrow chamber in a direction perpendicular to the direction in which the nozzle openings 26 are arranged (nozzle row direction). The common ink chamber 33 communicates with an ink introduction path 42 (see FIG. 6), which will be described later, of the ink introduction needle 19 via an ink communication path 37 formed so as to penetrate the height direction of the head case 16. This is a chamber into which ink stored in the cartridge 7 is introduced. The ink introduced into the common ink chamber 33 is supplied to each pressure chamber 35 through the ink supply port 34.

  The elastic plate 23 is a composite plate material having a double structure in which an elastic film is laminated on a metal support plate such as stainless steel. An island portion 36 for joining the tip of the free end portion of the piezoelectric vibrator 29 is formed at a portion corresponding to the pressure chamber 35 of the elastic plate 23, and this portion functions as a diaphragm portion. Further, the elastic plate 23 seals one opening surface of the empty portion that becomes the common ink chamber 33, and also functions as a compliance portion. Only the elastic film is used for the portion functioning as the compliance portion.

  In the recording head 3, when the piezoelectric vibrator 29 is expanded and contracted in the element longitudinal direction, the island portion 36 moves in a direction toward or away from the pressure chamber 35. As a result, the volume of the pressure chamber 35 changes, and the pressure in the ink in the pressure chamber 35 varies. Due to this pressure fluctuation, ink droplets (a type of droplet) are ejected (jetted) from the nozzle opening 26.

  Next, the ink cartridge 7 will be described. The ink cartridge 7 is a member that stores ink to be supplied to the recording head 3. The printer 1 of the present embodiment is configured to be able to eject eight types of inks, specifically, a total of eight colors of yellow, magenta, cyan, and the like, and each ink is individually supplied to the recording head 3. A total of eight ink cartridges 7 are mounted. A needle insertion opening (not shown) is provided on the bottom surface of each ink cartridge 7. This needle insertion opening is a portion into which the ink introduction needle 19 is inserted. At the time of shipment from the factory, the needle insertion port is sealed with a film (not shown) to prevent air from entering the cartridge. This is because the ink in the ink cartridge 7 is stored in a deaerated (negative pressure) state, so that this deaerated state is maintained until just before use.

  Next, the configuration of the ink introduction needle 19 inserted into the ink cartridge 7 will be described. FIG. 6 is a cross-sectional view of the ink introduction needle 19 in the needle longitudinal direction. The ink introduction needle 19 is a hollow needle having an internal space as an ink introduction path 42 (corresponding to a liquid inflow portion in the present invention), and a conical pointed portion 43 formed in a tapered shape, A cylindrical straight portion 44 continuously formed on the downstream side, and a diameter-increased portion 45 formed continuously on the downstream side of the straight portion 44 and having an inner diameter larger than the inner diameter of the straight portion 44. It is comprised by. In the present embodiment, an ink introduction hole 46 that communicates the outside (external space) of the introduction needle and the ink introduction path 42 is formed in the tip portion 43. The enlarged diameter portion 45 is formed in a tapered shape that gradually increases in diameter from the upstream side (straight portion 44 side) to the downstream side (needle root side). Further, the above-described filter 18 is disposed in the enlarged diameter portion 45, and a bubble trap member 47 that retains bubbles is disposed on the upstream side of the filter 18. The details of the bubble trap member 47 will be described later.

  The ink introduction needle 19 is attached to the base 15 by ultrasonic welding, for example, with the filter 18 interposed. As a result, the ink introduction path 42 of the ink introduction needle 19 and the ink communication path 37 on the head case 16 side communicate with each other.

  When the ink cartridge 7 is mounted on the base 15, the ink introduction needle 19 is inserted into the needle insertion port of the ink cartridge 7, and the internal space (ink storage portion) of the ink cartridge 7 and the ink introduction path 42 in the ink introduction needle 19. Communicate with each other through the ink introduction hole 46. The ink stored in the ink cartridge 7 is introduced into the ink introduction path 42 through the ink introduction hole 46 and supplied to the common ink chamber 33 on the recording head 3 side through the ink communication path 37.

  By the way, as described above, since the internal space of the ink cartridge 7 is in a deaerated state, when the tip of the ink introduction needle 19 pushes up a valve (not shown) provided in the needle insertion port, the ink Air enters the boundary between the cartridge 7 and the ink introduction needle 19. When the ink is filled into the recording head 3, the air may be introduced into the ink introduction path 42 together with the ink as bubbles. For example, air outside the ink introduction needle 19 may permeate through the resin wall forming the ink introduction needle and enter the ink flow path (gas exchange). Then, in the ink introduction path 42, the bubbles gradually combine with time and grow into larger bubbles. Largely grown bubbles may block the ink introduction path 42 and the filter 18, which may cause problems such as ink droplets not being ejected. For this reason, the printer 1 performs a cleaning operation using the capping mechanism 12 every elapse of a certain period of time so as to discharge bubbles that have grown greatly.

  In this cleaning operation, as described above, the pump unit 13 is operated while the cap member 11 is in close contact with the nozzle formation surface (nozzle plate 25), and is several times that during normal ink ejection (recording operation). A flow of ink having a flow velocity (a fluid including both ink and bubbles, which corresponds to a kind of fluid in the present invention) is generated in the recording head 3, and the bubbles in the ink introduction path 42 are placed on the ink flow. Then, it is discharged out of the recording head 3. The suction conditions (suction force, suction time) of the pump unit 13 at this time are set to conditions that take into account the bubble discharge properties. From the viewpoint of reducing the ink consumed by the cleaning operation as much as possible, in the recording head 3 to which the present invention is applied, the bubble trap member 47 is provided on the upstream side of the filter 18 in the enlarged diameter portion 45 of the ink introduction needle 19. By disposing, bubbles are temporarily trapped in the bubble trap member 47 while ensuring a flow path through which ink can pass during normal recording operation (ejection operation), and captured bubbles are captured during the cleaning operation. The filter 18 is discharged and discharged. Hereinafter, this point will be described.

  7A and 7B are explanatory views of the bubble trap member 47, where FIG. 7A is a front view and FIG. 7B is a plan view. In the present embodiment, as shown in FIGS. 6 and 7, the bubble trap member 47 is formed in a trapezoidal shape having a trapezoidal shape when viewed from the front by notching the tip of the cone. In other words, the bubble trap member 47 has an outer shape that is obtained by reducing the shape of the internal space of the enlarged diameter portion 45 as it is. The inside of the bubble trap member 47 is hollow. The internal space is a portion that functions as a bubble trap chamber 48 that can store bubbles, and the upper and lower portions thereof are opened as an upstream opening 49 and a downstream opening 50, respectively. That is, the bubble trap member 47 has a cylindrical shape with the upstream side and the downstream side opened. The bubble trap chamber 48 has a diameter that increases from the upstream opening 49 side toward the downstream opening 50 side. In other words, the upstream opening 49 is formed to have a smaller opening area than the downstream opening 50. The bubble trap member 47 is made of, for example, plastic or metal.

  The bubble trap member 47 configured as described above forms a sub-flow channel 52 through which ink can pass between the inner peripheral surface of the enlarged diameter portion 25 on the upstream surface of the filter 18 by adhesion or welding. It is fixed in the state. That is, the sub-flow channel 52 is a space defined by the outer surface of the bubble trap member 47 and the inner peripheral surface of the enlarged diameter portion 45. The sub-flow path 52 extends from the upstream end opening 53 of the enlarged diameter portion 45 over the surface of the filter 18. The upstream end opening 53 is an opening at a boundary portion between the enlarged diameter portion 45 and the straight portion 44.

  The upstream opening 49 is formed so that the opening area is smaller than the opening area of the upstream end opening 53 of the enlarged diameter portion 45. In other words, the diameter of the upstream opening 49 (indicated by reference numeral L in FIG. 6) is formed to be smaller than the diameter of the upstream end opening 53 of the enlarged diameter portion 45 (indicated by reference numeral M in FIG. 6). Therefore, the upstream side opening 49 is in a state where the flow path width is narrower than that of the upstream end opening 53. The upstream opening 49 is set to have a much smaller opening area than the downstream opening 50. Therefore, the flow velocity of the fluid flowing into the bubble trap chamber 48 from the upstream opening 49 is faster than the flow velocity of the fluid flowing down the upstream ink introduction path 42 from the bubble trap member 47.

  Further, the upstream opening 49 is disposed on the central axis (hereinafter, indicated by the symbol O) of the upstream end opening 53 of the enlarged diameter portion 45. By arranging the upstream opening 49 in this way, the fluid flowing down on the central axis O of the upstream end opening 53 rather than the fluid flowing down near the edge (circumference) of the upstream end opening 53 of the enlarged diameter portion 45. However, it is possible to facilitate the flow of fluid, in particular, bubbles, into the bubble trap chamber 48 through the upstream opening 49. The fluid flowing into the bubble trap chamber 48 from the upstream opening 49 has a higher flow velocity than the fluid flowing into the sub flow channel 52. It should be noted that the center axis O of the upstream opening 40 and the center axis O of the upstream end opening 53 are allowed to slightly deviate, and the upstream opening 49 is disposed so that the center axis O enters the opening of the upstream opening 49. It ’s fine.

Next, the movement of bubbles in the ink introduction needle 19 provided with the bubble trap member 47 during the cleaning operation will be described with reference to FIGS.
FIG. 8 is a schematic diagram for explaining a state in which bubbles are generated in the ink introduction path 42 of the ink introduction needle 19, and FIG. 9 is a schematic diagram for explaining a state in which the bubbles in FIG. FIG. 10 is a schematic diagram for explaining a state in which the bubbles in FIG. 9 have entered the bubble trap member, and FIG. 11 is a schematic diagram for explaining a state in which the bubbles in FIG. 10 pass through the filter. FIG. 12 is a schematic diagram for explaining a state in which the bubbles in FIG. 11 float as residual bubbles.

  In the ink introduction needle 19 in the present embodiment, as shown in FIG. 8, bubbles (indicated by symbol A in FIG. 8) mixed in the ink introduction path 42 of the ink introduction needle 19 are upstream of the ink introduction path 42. When the cleaning operation is performed from the stayed state to generate a flow rate faster than usual, as shown in FIG. 9, the bubbles A flow down toward the filter 18 due to the downward flow. At this time, since the flow rate on the center side is faster than the outer periphery side of the ink introduction path 42, the bubble A moves toward the downstream side near the center axis O. As described above, since the bubble trap chamber 27 is arranged so that the upstream opening 49 is positioned on the central axis O, the bubbles A flow down toward the upstream opening 49.

  Then, when the bubble A comes into contact with the upstream opening 49 of the bubble trap member 46, as shown in FIG. 10, the fluid A flowing down on the central axis O causes the fluid A to flow into the bubble trap chamber 27 from the upstream opening 49. invade. The bubble A that has entered the bubble trap chamber 27 is pressed against the surface of the filter 18 by the downward flow of the ink flow. Then, the downstream side opening 50 is choked (closed) while the bubbles A are pressed against the surface of the filter 18, so that the suction force (fluid flow force) of the cleaning operation acts on the bubbles A to the maximum extent. Thereby, as shown in FIG. 11, the bubbles A pass through the filter 18.

  After the cleaning operation is completed, as shown in FIG. 12, some of the bubbles (bubbles A ′) may remain in the bubble trap chamber 48, but the bubbles A ′ larger than the upstream opening 48 Since the flow from the upstream opening 48 to the outside of the bubble trap member 46 is blocked, it can be trapped in the bubble trap chamber 58. The bubble A ′ trapped in the bubble trap chamber 58 is in a state of being separated from the wall surface of the ink introduction needle 19 (the ink introduction path 42 and the enlarged diameter portion 45).

  FIG. 13 is a schematic diagram for explaining how normal printing is performed in a state where the bubble A ′ is trapped in the bubble trap chamber 58. As shown in the figure, when normal printing is performed in a state where the bubble A ′ is trapped in the bubble trap chamber 58, the flow rate of the fluid is slower than that at the time of cleaning. 18 cannot pass through 18 and remains in the bubble trap chamber 58. Further, since the sub-flow path 52 is provided between the bubble trap member 46 and the inner peripheral surface of the enlarged diameter portion 45, the ink from the ink introduction path 42 can flow down in the sub-flow path 52 ( (Indicated by an arrow in FIG. 16).

  As described above, in the recording head 3 of the present embodiment, the bubble trap member 47 opened on the upstream side and the downstream side is disposed in the enlarged diameter portion 45 on the upstream side of the filter 18. Even when the bubbles grow, by accommodating the bubbles in the bubble trap member 47, it is possible to prevent the bubbles from covering and closing the entire filter surface. Thereby, it is possible to prevent the supply of ink to the downstream side of the filter 18 from being insufficient. Further, by accommodating the bubbles in the bubble trap member 47 and separating them from the wall surface of the ink introduction needle 19, it is possible to prevent the bubbles from directly growing due to gas exchange through the wall surface of the ink introduction needle 19. . As a result, it is possible to reduce the number of times that the cleaning operation is performed, thereby suppressing ink consumption.

  In addition, since the bubble trap member 47 is disposed in a state in which the sub-flow path 52 through which ink can pass is formed, the bubble trap member 47 is blocked by bubbles when the ink has a flow velocity for normal printing. Even in such a case, it is possible to ensure the sub-flow channel 52 as a flow channel through which at least ink can pass. As a result, it is possible to more reliably prevent ink supply shortage.

  Further, since the opening area of the upstream opening 49 of the bubble trap member 47 is smaller than the opening area of the upstream end opening 53 of the enlarged diameter portion 45, the flow velocity of the fluid flowing into the upstream opening 49 of the bubble trap member 47 is increased. be able to. The flow downward force makes it easy to introduce bubbles into the bubble trap member 47, and also makes it easier for the bubbles in the bubble trap member 47 to pass through the filter 18 and to be discharged downstream during the cleaning operation. be able to. Furthermore, by reducing the opening area of the upstream opening 49, it is possible to make it difficult for the bubbles once introduced into the bubble trap member 47 to rise from the upstream opening 49 to the upstream side. That is, it becomes possible to easily trap the bubbles in the bubble trap member 47.

  Further, since the bubble trap member 47 is disposed in a state where the upstream opening 49 is positioned on the central axis O of the upstream end opening 53 of the enlarged diameter portion 45, that is, the bubble is positioned at a position where the fluid flow velocity is faster. Since the upstream opening 49 of the trap member 47 is disposed, the fluid can be easily introduced into the bubble trap member 47.

  Further, since the bubble trap chamber 48 expands from the upstream opening 49 side toward the downstream opening 50 side, the upstream opening 49 has a higher flow velocity than the downstream opening 50 and the downstream opening 50 has an upstream flow rate. Since the flow velocity is slower than that of the side opening 49, it is possible to easily introduce bubbles into the bubble trap chamber 47 and to more easily hold the bubbles once accommodated in the bubble trap chamber 47.

  Further, since the bubble trap member 47 is fixed to the upstream surface of the filter 18, it is possible to prevent the bubble trap member 47 from being separated from the filter 18. For this reason, by arranging the bubble trap member 47 at an appropriate position, it is possible to always ensure a state in which bubbles are easily introduced into the inside from the upstream opening 49 of the bubble trap member 47.

By the way, the present invention is not limited to the above embodiment, and various modifications can be made based on the description of the scope of claims.
In each of the above embodiments, the bubble trap member 47 is fixed to the filter 18. However, the present invention is not limited to this. For example, the bubble trap member 47 has a specific gravity larger than that of the ink, You may arrange | position so that it may be mounted on an upstream surface. Thereby, while preventing the bubble trap member 47 from floating from the filter 18, it is not necessary to fix the bubble trap member 47 to the filter 18 such as adhesion or welding. Even if the bubble trap member 47 is separated from the filter 18 and floats in the enlarged diameter portion 45, it is placed on the filter 18 again by the weight of the bubble trap member 47. In addition, when the bubble trap member 47 floats toward the filter 18, the bubble trap member 47 can push out the bubble from the filter 18 by pressing the bubble downward.

  In the above, the printer 1 which is a kind of liquid ejecting apparatus has been described as an example, but the present invention can also be applied to other liquid ejecting apparatuses. For example, a display manufacturing apparatus that manufactures color filters such as liquid crystal displays, an electrode manufacturing apparatus that forms electrodes such as organic EL (Electro Luminescence) displays and FEDs (surface-emitting displays), and chips that manufacture biochips (biochemical elements) The present invention can also be applied to a manufacturing apparatus or the like.

FIG. 2 is a perspective view illustrating a configuration of a printer. FIG. 2 is an exploded perspective view illustrating a configuration of a recording head. FIG. 3 is a plan view illustrating a configuration of a recording head. 2 is a cross-sectional view illustrating an internal structure of a recording head. FIG. 2 is a partial cross-sectional view illustrating an internal structure of a recording head. FIG. It is sectional drawing of the needle longitudinal direction of an ink introduction needle. It is explanatory drawing of a bubble trap member, (a) is a front view, (b) is a top view. FIG. 6 is a schematic diagram for explaining the movement of bubbles in an ink introduction needle during a cleaning operation. It is a schematic diagram explaining the state which the bubble of FIG. 8 flowed downstream. It is a schematic diagram explaining the state which the bubble of FIG. 9 penetrate | invaded in the bubble trap member. It is a schematic diagram explaining the state in which the bubble of FIG. 10 passes a filter. It is a schematic diagram explaining the state which the bubble of FIG. 11 floated as a remaining bubble. It is. It is a schematic diagram explaining the flow of the fluid in the ink introduction needle at the time of normal printing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording medium, 3 ... Recording head, 4 ... Carriage, 5 ... Carriage moving mechanism, 6 ... Platen roller, 7 ... Ink cartridge, 8 ... Timing belt, 9 ... Pulse motor, 10 ... Guide rod, 11 DESCRIPTION OF SYMBOLS ... Wiping mechanism, 12 ... Capping mechanism, 13 ... Pump unit, 15 ... Base, 16 ... Head case, 17 ... Flow path unit, 18 ... Filter, 19 ... Ink introduction needle, 20 ... Circuit board, 21 ... Sheet member, 22 ... vibrator unit, 23 ... elastic plate, 24 ... flow path forming substrate, 25 ... nozzle plate, 26 ... nozzle opening, 27 ... head cover, 29 ... piezoelectric vibrator, 30 ... piezoelectric vibrator group, 31 ... fixing plate, 32 ... Storage empty part, 33 ... Common ink chamber, 34 ... Ink supply port, 35 ... Pressure chamber, 36 ... Island part, 37 ... Ink communication path, 42 ... Ink introduction path 43: Pointed portion, 44: Straight portion, 45: Expanded diameter portion, 46: Ink introduction hole, 47 ... Bubble trap member, 48 ... Bubble trap chamber, 49 ... Upstream opening, 50 ... Downstream opening, 52 ... Side flow Road, 53 ... Upstream end opening, O ... Center axis

Claims (7)

A liquid ejecting head for introducing liquid into a pressure chamber through a liquid inflow portion and ejecting liquid from a nozzle opening by pressure fluctuation,
On the downstream side of the liquid inflow portion, an enlarged diameter portion that is larger than the inner diameter of the liquid inflow portion is provided,
Place a filter in the enlarged diameter part,
A liquid ejecting head, wherein a bubble trap member having an opening on the upstream side and the downstream side is disposed in the enlarged diameter portion on the upstream side of the filter.   2. The liquid jet head according to claim 1, wherein the bubble trap member is disposed in a state where a sub-flow path through which liquid can pass is formed between the bubble trap member and an inner peripheral surface of the enlarged diameter portion.   The liquid ejecting head according to claim 2, wherein an opening area of an upstream opening of the bubble trap member is smaller than an opening area of an upstream end opening of the enlarged diameter portion.   4. The liquid jet head according to claim 2, wherein the bubble trap member is disposed in a state in which the upstream side opening is positioned on a central axis of the upstream end opening of the enlarged diameter portion. .   5. The liquid jet head according to claim 1, wherein the bubble trap member has a bubble trap chamber whose diameter is increased from the upstream opening side toward the downstream opening side.   The liquid jet head according to claim 1, wherein the bubble trap member is fixed to an upstream surface of the filter.   6. The liquid jet according to claim 1, wherein the bubble trap member has a specific gravity greater than that of the liquid, and is placed on an upstream surface of the filter. head.

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