JP2008062454A - Liquid jetting head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head capable of improving venting properties of bubbles during cleaning operation. <P>SOLUTION: An ink introducing needle 19 is constituted into a hollow needle-like shape by an introducing needle part 44 for introducing ink from ink introducing holes 46 and a diameter extended part 45 formed on the downstream side of the introducing needle part and whose inner diameter is gradually extended from the upstream side to the downstream side, and on the lower end part of the diameter extending part, a narrowing part 49 projecting from the inner peripheral face side of the diameter extending part to the diameter center side and narrowing an ink flow path in the ink introducing needle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head such as an ink jet recording head, and in particular, introduces a liquid stored in a liquid storage member into a pressure chamber via a liquid introduction needle, and introduces the liquid introduced into the pressure chamber from a nozzle opening. The present invention relates to a liquid ejecting head that ejects liquid droplets.

  Examples of the liquid ejecting head that ejects liquid droplets from the nozzle opening by causing pressure fluctuation in the liquid in the pressure chamber include, for example, an ink jet recording head (hereinafter, referred to as an ink jet recording head (printer)). Simply called a recording head), a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, FED (surface emitting display), and a biochip There are bio-organic matter ejecting heads used for manufacturing (biochemical elements).

  For example, in the recording head described above, an ink introduction needle, which is a kind of liquid introduction needle, is inserted into an ink cartridge as a liquid storage member in which liquid ink is sealed, so that the ink introduction needle is opened on the tip side. The ink in the ink cartridge is introduced into the pressure chamber side of the recording head through the introduction hole. There has also been proposed a configuration in which an ink cartridge disposed on the printer main body side and an ink introduction needle of a recording head are connected by an ink tube, and ink in the ink cartridge is fed into the recording head by a pump or the like.

  In the recording head configured as described above, it is ideal that the ink flow path (liquid flow path) from the ink introduction needle to the nozzle opening of the recording head is filled with ink. It is difficult to completely prevent bubbles from entering the ink flow path due to (initial filling) or the like. Bubbles that have entered the ink flow path grow and grow over time, and the excessively grown air bubbles pass through a filter arranged in the middle of the ink flow path by the flow of ink to the pressure chamber side. If it moves, there is a risk of incurring problems such as pressure loss due to the absorption of pressure fluctuations during the ejection operation and insufficient supply of ink due to the bubbles blocking the flow path.

  As a method for preventing such a problem caused by bubbles, it is possible to increase bubble discharge efficiency so that bubbles do not remain in the ink flow path as much as possible. As this method, for example, in Patent Document 1, a bubble guide groove is provided on the inner peripheral surface of the ink introduction needle in the vicinity of the filter (filter mounting member), and the bubble in the ink flow path is moved downstream by the bubble guide groove. A configuration for actively guiding is proposed. Similarly, in Patent Document 2, an ink guide path is formed on the inner peripheral surface of the filter chamber formed on the base side of the ink introduction needle to control the flow of ink at the time of initial filling, and bubbles are created by this ink. There has been proposed a configuration in which the bubble discharge performance is improved by pushing it downstream.

  Also, as a method different from the above, a normal recording operation is performed by providing a conical bubble chamber (expanded diameter portion) on the base side of the ink introduction needle and actively containing and holding the bubbles in the bubble chamber. In the ink flow rate in (ink droplet discharge operation), it is possible to prevent bubbles from moving downstream through the filter. As an example of this, Patent Document 3 proposes a configuration in which a bubble interference member is arranged in the bubble chamber of the ink introduction needle so that the bubble interference member prevents the bubbles from moving to the filter side during the recording operation. Has been.

Japanese Patent Application Laid-Open No. 11-078046 JP-A-11-227228 JP 2005-186494 A

  By the way, when bubbles grow and become large inside the ink introduction needle, the cleaning operation for forcibly discharging the ink and bubbles is performed to prevent the bubbles from blocking the ink flow path and the filter. There is a need to do. In general, in this cleaning operation, ink and bubbles are discharged from the nozzle openings by creating a negative pressure inside the cap while the nozzle surface of the recording head is sealed with a cap or the like. However, there is a problem that the bubble that has grown large is difficult to ride the ink flow during cleaning due to the effect of buoyancy, and a lot of ink is wasted before the majority of the bubble is discharged.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting head capable of improving bubble discharge performance during a cleaning operation.

In order to achieve the above object, the liquid ejecting head of the present invention introduces the liquid in the liquid storage member from the liquid introduction needle to the pressure chamber side through the liquid flow path, and opens the liquid in the pressure chamber by the operation of the pressure generating means. A liquid jet head capable of ejecting as droplets from
The liquid introduction needle is continuously formed on the downstream side of the introduction needle portion having a liquid introduction hole for introducing the liquid in the liquid storage member, and the inner diameter thereof is from the upstream side to the downstream side. It is configured in the shape of a hollow needle with a diameter-expanded portion that gradually expands toward
The lower end portion of the enlarged diameter portion is provided with a narrowed portion that projects from the inner peripheral surface side of the enlarged diameter portion toward the center of the diameter and narrows the liquid flow path in the liquid introduction needle.

  According to the above configuration, since the narrowed portion that projects from the inner peripheral surface side of the enlarged diameter portion toward the radial center side and narrows the liquid flow path in the liquid introduction needle is provided at the lower end portion of the enlarged diameter portion, During the cleaning operation for forcibly discharging the liquid and bubbles in the passage from the nozzle opening, the bubbles in the liquid introduction needle temporarily close the liquid flow path at a position corresponding to the narrowed portion. Thereby, a pressure difference can be generated between the upstream side and the downstream side with the stenosis portion as a boundary. That is, the pressure on the downstream side of the narrowed portion can be temporarily made lower than the pressure on the upstream side. Then, this pressure difference allows the bubbles to flow vigorously downstream. Thereby, it becomes possible to discharge | emit a bubble efficiently in a short time compared with the past. As a result, the amount of liquid consumed during one cleaning operation can be reduced.

  In the above configuration, it is desirable that the lower surface of the narrowed portion is formed by an inclined surface that rises from the inner peripheral surface side toward the radial center side.

  According to this configuration, when the filter for filtering the liquid in the liquid flow path is disposed downstream of the liquid introduction needle, a space can be provided between the filter and the constriction, and the constriction can be Liquids and bubbles can be made to flow smoothly without hindering the effective filtration area (area where the liquid can actually pass through the filter).

  Moreover, the said structure WHEREIN: The structure formed in the inclined surface which descend | falls from the inner peripheral surface side toward a radial center side can also be employ | adopted for the upper surface of the said constriction part.

  According to this configuration, it is possible to prevent liquid and bubbles from staying at the corner portion where the inner peripheral surface of the enlarged diameter portion and the narrowed portion intersect, and to flow the liquid and bubbles more smoothly downstream.

  In the above-described configuration, it is desirable that an elongated groove portion is formed on the inner peripheral surface of the enlarged diameter portion along the liquid flow direction from the introduction needle portion side to the narrowed portion side.

  According to this configuration, the liquid can flow down the groove even when the bubbles grow to such an extent that they contact the inner peripheral surface of the enlarged diameter portion. This makes it possible to smoothly flow the liquid to the downstream side regardless of the size of the bubbles. Further, it is possible to prevent bubbles from being pushed away by the flow of the liquid at the flow rate of the liquid during a normal discharge operation other than the cleaning operation.

  Further, in the above configuration, a filter for filtering the liquid in the liquid flow path is disposed in the middle of the liquid flow path and downstream of the liquid introduction needle, and the lower end opening of the narrowed portion is opposed to the filter. It is desirable to employ a configuration in which the liquid introduction needle is disposed in a state.

  In each of the above configurations, the narrowed portion can be formed integrally with the liquid introduction needle. Or you may employ | adopt the structure which comprises the said constriction part by the ring-shaped member whose inner diameter is smaller than the said enlarged diameter part, and attaches to the downstream opening part of an enlarged diameter part.

  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 a recording head) will be described as an example of a liquid ejecting head.

  First, a schematic configuration of an ink jet recording apparatus (a type of liquid ejecting apparatus, hereinafter referred to as a printer) equipped with a recording head will be described with reference to FIG. The illustrated printer 1 is a device that records an image or the like by ejecting liquid ink onto the surface of a recording medium (ejection target) 2 such as recording paper. The printer 1 includes a recording head 3, a carriage 4 to which the recording head 3 is attached, a carriage moving mechanism 5 that reciprocates the carriage 4 in the main scanning direction, and a recording medium 2 in the sub-scanning direction (in the main scanning direction). A paper feed mechanism 6 and the like for feeding in a direction orthogonal to each other are provided. Here, the ink is a kind of liquid in the present invention, and is stored in the ink cartridge 7 (a kind of liquid storage member). 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. Accordingly, 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 (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 12 ′ that can come into contact with the nozzle forming surface of the recording head 3. In this capping mechanism 12, the space in the cap member 12 ′ functions as a sealing void, and the nozzle opening 26 (see FIG. 2) of the recording head 3 faces the nozzle forming surface in the sealing void. It is configured to be in close contact. 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. It is adapted to be discharged into the 12 'sealing space. That is, the capping mechanism 12 is configured to perform a cleaning operation for forcibly sucking and discharging ink and bubbles in the recording head 3 (in the ink flow path).

  Next, the configuration of the recording head 3 will be described. 2 is a schematic exploded perspective view of the recording head 3, FIG. 3 is a plan view of the recording head 3, and FIG. The illustrated recording head 3 is generally composed of an introduction needle unit 15, a head case 16, a flow path unit 17, a vibrator unit 22, and the like.

  The introduction needle unit 15 is made of, for example, a synthetic resin, and as shown in FIG. 3, a plurality of cartridge mounting portions 15 ′ are provided on the upper surface thereof. An ink introduction needle 19 (corresponding to a liquid introduction needle in the present invention) with a filter 18 interposed is attached to each cartridge mounting portion 15 'with the tip protruding upward. In addition, an ink cartridge 7 storing various inks is mounted on these cartridge mounting portions 15 '. When the ink cartridge 7 is attached to the cartridge attachment portion 15 ′, the ink introduction needle 19 is inserted into the ink cartridge 7. As a result, the ink storage space inside the cartridge and the ink flow path inside the recording head 3 communicate with each other through the ink introduction hole 46 (see FIG. 6) formed in the pointed end portion 43 of the ink introduction needle 19 to be stored inside the cartridge. The ink thus introduced is introduced into the recording head 3 through the ink introduction hole 46. The ink cartridge is not limited to the type that is mounted on the carriage 4 as in the present embodiment, but is a type that is mounted on the housing side of the printer 1 and supplies ink to the recording head side through the ink supply tube. Is also possible.

  As shown in FIG. 2, a circuit board 20 is attached between the lower surface of the introduction needle unit 15 and the upper surface of the head case 16 on the side opposite to the cartridge mounting portion 15 ′. The circuit board 20 includes, for example, a circuit pattern for supplying a drive signal to the piezoelectric vibrator 30 (see FIG. 5), a connector for connection with the printer main body, and the like. And this circuit board 20 is attached to the introduction needle unit 15 via the sheet | seat member 21 which functions as packing.

  The head case 16 is a hollow box-shaped member for housing the vibrator unit 22 having the piezoelectric vibrator 30. Inside the head case 16, a housing empty portion 32 (see FIG. 5) capable of housing the transducer unit 22 is formed. The vibrator unit 22 is housed in the housing space 32 and is fixed to the inner wall surface of the housing space 32 by bonding or the like. A flow path unit 17 is fixed to the front end surface of the head case 16 opposite to the mounting surface of the introduction needle unit 15 with an adhesive or the like. This flow path unit 17 is manufactured by joining and integrating with an adhesive etc. in the state which laminated | stacked the diaphragm 23, the flow path formation board | substrate 24, and the nozzle plate 25. As shown in FIG.

  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. The head cover 27 is made of, for example, a metal thin plate member, and is attached to the distal end portion of the head case 16 so as to surround the peripheral edge portion from the outside of the nozzle plate 25. 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 includes a piezoelectric vibrator group 29 functioning as pressure generating means, a fixed plate 31 to which the piezoelectric vibrator group 29 is joined, and a drive signal from the circuit board 20 to the piezoelectric vibrator group 29. It consists of a flexible cable (not shown) for supply. The piezoelectric vibrator group 29 of the present embodiment includes a plurality of piezoelectric vibrators 30 arranged in a comb shape. Each piezoelectric vibrator 30 has a fixed end joined to the fixed plate 31 and a free end protruding outward from the tip surface of the fixed plate 31. That is, each piezoelectric vibrator 30 is mounted on the fixed plate 31 in a so-called cantilever state. The fixing plate 31 that supports each piezoelectric vibrator 30 is made of stainless steel having a thickness of about 1 mm, for example. 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.

  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). Further, the common ink chamber 33 is connected to the ink introduction path 42 (ink introduction needle side) of the ink introduction needle 19 through a head flow path 37 (head side ink flow path) formed penetrating the height direction of the head case 16. An ink flow path (see FIG. 6) is a chamber into which ink stored in the ink 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 diaphragm 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 of the piezoelectric vibrator 30 is formed in a portion corresponding to the pressure chamber 35 of the diaphragm 23, and this portion functions as a diaphragm portion. The diaphragm 23 also functions as a compliance unit by sealing one of the open surfaces of the empty portion that becomes the common ink chamber 33. Only the elastic film is used for the portion functioning as the compliance portion.

  In the recording head 3, when the piezoelectric vibrator 30 is expanded and contracted in the longitudinal direction of the element, the island portion 36 moves in a direction close to 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. An ink droplet (a type of droplet) is ejected from the nozzle opening 26 due to the pressure fluctuation.

Next, the configuration of the ink introduction needle 19 will be described.
6A and 6B are diagrams showing the configuration of the ink introduction needle 19 in the present embodiment. FIG. 6A is a cross-sectional view in the longitudinal direction of the needle, and FIG. 6B is a cross-sectional view along AA in FIG. The ink introduction needle 19 is a hollow needle-like member having an internal space as an ink introduction path 42, and is roughly configured by an introduction needle portion 44 and a diameter-expanded portion 45. The ink introduction needle 19 is made of, for example, a synthetic resin.

  The introduction needle portion 44 is a hollow cylindrical member inserted into the ink cartridge 7, and a conical pointed portion 43 formed in a tapered shape is formed at a tip portion thereof. A plurality of ink introduction holes 46 (corresponding to the liquid introduction holes in the present invention) for communicating the outside of the ink introduction needle 19 and the ink introduction path 42 are formed in the tip end portion 43. That is, as described above, when the introduction needle portion 44 is inserted into the ink cartridge 7, the ink in the cartridge can be introduced into the ink introduction path 42 through the ink introduction hole 46. In the present embodiment, the configuration in which the ink introduction hole 46 is opened in the tip end portion 43 is exemplified. However, for example, the configuration in which the ink introduction hole 46 is opened in the side surface of the introduction needle portion 44 on the downstream side of the tip end portion 43. Can also be adopted.

  The enlarged diameter portion 45 is formed continuously in the downstream side of the introduction needle portion 44 and has a substantially conical shape that gradually increases in diameter from the upstream side toward the downstream side. The inner space of the enlarged diameter portion 45 functions as a part of the ink introduction path 46 and also functions as a bubble chamber that can accommodate the bubbles B in the ink introduction path 46 as shown in FIG. . Further, an elongated groove 48 having a rectangular cross section extending in the ink flow direction (including a direction oblique to the vertical direction) is provided on the inner peripheral surface of the enlarged diameter portion 45. In this embodiment, as shown in FIG. 6B, a total of four groove portions 48 are formed on the inner peripheral surface of the enlarged diameter portion 45 in a state where the circumferential phases of adjacent groove portions 48 are different from each other by 90 °. is doing. The groove portion 48 is provided as a relief passage through which ink can flow even when the bubble B grows to the extent that it contacts the inner peripheral surface of the enlarged diameter portion 45. As a result, regardless of the size of the bubble B, the ink can smoothly flow to the downstream side (pressure chamber side) without being obstructed by the bubble B, and at the ink flow rate during the normal recording operation. Can prevent the bubbles B from being pushed to the filter 18 side by the flow of ink. The shape of the groove 48 is not limited to a rectangular cross section, and may be any shape as long as ink can flow, such as a semicircular cross section. In addition, the number of grooves 48 may be at least one.

  Further, as shown in FIGS. 6A and 6B, the lower end portion of the enlarged diameter portion 45, that is, the lower end opening portion of the ink introduction hole 46, from the inner peripheral surface side of the enlarged diameter portion 45 to the central axis side. A narrowed portion 49 is projected toward the end. In other words, a disc-shaped (flat washer-shaped) constricted portion 49 having a circular through hole 50 formed in the central portion is formed integrally with the ink introduction needle 19 so that a part of the lower end opening of the enlarged diameter portion 45 is formed. Closed (squeezed). The inner diameter of the opening portion (that is, the through hole 50) of the narrowed portion 49 is set to be smaller than the maximum inner diameter of the enlarged diameter portion 45 and larger than the inner diameter of the introduction needle portion 44. Accordingly, the ink flow path (ink introduction path 42) of the ink introduction needle 19 is narrowed by the narrowed portion 49. When the narrowed portion 49 is provided at the lower end portion of the enlarged diameter portion 45 in this way, when the bubbles in the enlarged diameter portion 45 reach a position corresponding to the narrowed portion 49, the ink flow path is blocked by the bubbles ( The state of the bubble B ′ in FIG. This closed state of the ink flow path is intentionally generated in order to facilitate the discharge of bubbles during the cleaning operation for forcibly discharging the ink and bubbles in the ink flow path of the recording head 3. Details of this point will be described later.

  The ink introduction needle 19 is attached to the introduction needle unit 15 by, for example, ultrasonic welding in a state where the lower end opening (through hole 50) of the narrowed portion 49 is opposed to the filter 18. Accordingly, the ink introduction path 42 of the ink introduction needle 19 and the head passage 37 on the head case 16 side communicate with each other in a liquid-tight state. The ink introduction path 42 and the head flow path 37 function as a liquid flow path in the present invention.

  Incidentally, when the ink introduction needle 19 is inserted into or removed from the ink cartridge 7, air may enter the ink introduction path 42. In the ink introduction path 42, fine bubbles are combined and gradually grow into a large bubble B (see FIG. 6A). In the present embodiment, when the lower portion of the bubble B reaches a position corresponding to the constricted portion 49, the pressure passes through the filter 18 at the flow velocity during the normal recording operation (ink droplet ejection operation). Without moving to the chamber side, the bubbles can be accommodated and held in the enlarged diameter portion 45 in a state of being floated above the filter 18 by buoyancy acting on the bubbles. Further, in the printer 1, the bubbles B accommodated in the enlarged diameter portion 45 are discharged by periodically performing a cleaning operation using the capping mechanism 12.

  In this cleaning operation, the pump unit 13 is operated in a state where the cap member 12 ′ is in close contact with the nozzle formation surface, and an ink flow having a flow rate several times that in a normal recording operation is generated in the ink flow path. The bubbles B in the part 45 are discharged from the nozzle openings 26 to the outside of the head by being put on this ink flow. 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 executing this cleaning operation as much as possible, the timing at which this cleaning operation is executed is such that the bubbles B are in contact with the inner peripheral surface of the enlarged diameter portion 45. It is desirable to set it until it grows to a size before reaching the filter 18 beyond the lower end of the enlarged diameter portion 45.

  Here, since the ink introduction needle 19 has a narrowed portion 49 projecting from the lower end portion of the enlarged diameter portion 45, the bubble B ′ is positioned at a position corresponding to the narrowed portion 49 when the bubbles are discharged by the cleaning operation. Temporarily closes the ink flow path. Thereby, a pressure difference can be generated between the upstream side and the downstream side with the narrowed portion 49 as a boundary. That is, the pressure on the downstream side of the narrowed portion 49 can be temporarily lower than the pressure on the upstream side. When the pressure difference exceeds a certain level, the bubble B 'can be vigorously flowed downstream using this pressure difference. As a result, the bubbles B ′ can easily pass through the filter 18, so that the bubbles B ′ can be efficiently discharged in a shorter time than in the past. As a result, the amount of ink consumed during one cleaning operation can be reduced.

  As described above, in the printer to which the present invention is applied, since the air discharging property of the ink introduction needle 19 is high, the suction force and the suction time of the cleaning operation can be suppressed, and thus the ink is wasted. Can be prevented.

Next, another embodiment of the present invention will be described.
FIG. 7 is a diagram illustrating the configuration of the ink introduction needle 19 in the second embodiment.
The present embodiment is different from the first embodiment in that the narrowed portion 49 ′ is separate from the ink introduction needle 19. Specifically, a ring-shaped member having an inner diameter smaller than that of the enlarged diameter portion 45 is attached as a narrowed portion 49 ′ to the lower end portion of the enlarged diameter portion 45 by adhesion or welding. The constricted portion 49 'can be made of, for example, a synthetic resin or metal. Thus, by making the constricted portion 49 ′ separate from the ink introduction needle 19, it can be easily applied to the existing ink introduction needle 19.

  Further, in the second embodiment, the lower surface 49d of the narrowed portion 49 'is configured by an inclined surface that rises from the inner peripheral surface side of the enlarged diameter portion 45 toward the radial center side. This is different from the embodiment. That is, the narrowed portion 49 ′ has a configuration in which the inner diameter of the opening (through hole 50) is increased from the upstream side toward the downstream side. The opening area on the lower end side is aligned with the effective filtration area of the filter 18. In this way, a space can be provided between the filter 18 and the constricted portion 49 ′, and ink and bubbles can be smoothly flowed to the downstream side (filter 18 side) while ensuring an effective filtration area of the filter 18. Can do.

  In the second embodiment, only the lower surface 49d of the narrowed portion 49 ′ is inclined, but for example, both the upper surface 49u and the lower surface 49d, as in the narrowed portion 49 ″ in the third embodiment shown in FIG. In other words, the constricted portion 49 ″ in the present embodiment is configured such that the lower surface 49d is an inclined surface that rises from the inner peripheral surface side toward the radial center side, and the upper surface 49u is the inner peripheral surface. It is composed of an inclined surface that descends from the side toward the radial center. This prevents ink and bubbles from staying at the corners where the inner peripheral surface of the enlarged diameter portion 45 and the constricted portion 49 "intersect, and allows these ink and bubbles to flow more smoothly downstream. Can do.

  In the above, the recording head 3 which is a kind of liquid ejecting head has been described as an example. However, the present invention can also be applied to other liquid ejecting heads having a liquid introduction needle. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, an FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to bioorganic matter ejecting heads and the like used in the production of

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 explaining the structure of an ink introduction needle | hook, (a) is sectional drawing of a needle | hook longitudinal direction, (b) is AA sectional drawing in (a). It is sectional drawing explaining the structure of the ink introduction needle | hook in 2nd Embodiment. It is sectional drawing explaining the structure of the ink introduction needle | hook in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer, 3 ... Recording head, 12 ... Capping mechanism, 13 ... Pump unit, 15 ... Introduction needle unit, 16 ... Head case, 17 ... Flow path unit, 18 ... Filter, 19 ... Ink introduction needle, 26 ... Nozzle opening , 29 ... Piezoelectric vibrator group, 30 ... Piezoelectric vibrator, 32 ... Storage empty part, 33 ... Common ink chamber, 34 ... Ink supply port, 35 ... Pressure chamber, 37 ... Head flow path, 41 ... Skirt part, 42 ... Ink introduction path, 43 ... pointed end, 44 ... introduction needle, 45 ... enlarged diameter part, 46 ... ink introduction hole, 48 ... groove part, 49 ... narrowing part, 50 ... through hole

Claims (7)

A liquid ejecting head capable of introducing the liquid in the liquid storage member from the liquid introduction needle to the pressure chamber through the liquid flow path, and discharging the liquid in the pressure chamber as a droplet from the nozzle opening by the operation of the pressure generating unit;
The liquid introduction needle is continuously formed on the downstream side of the introduction needle portion having a liquid introduction hole for introducing the liquid in the liquid storage member, and the inner diameter thereof is from the upstream side to the downstream side. It is configured in the shape of a hollow needle with a diameter-expanded portion that gradually expands toward
A liquid jet characterized in that a narrowed portion is provided at a lower end portion of the expanded diameter portion so as to protrude from the inner peripheral surface side of the expanded diameter portion toward the center of the diameter to narrow the liquid flow path in the liquid introduction needle. head.   The liquid ejecting head according to claim 1, wherein a lower surface of the narrowed portion is formed as an inclined surface that rises from the inner peripheral surface side toward the radial center side.   3. The liquid jet head according to claim 1, wherein an upper surface of the narrowed portion is formed as an inclined surface that descends from an inner peripheral surface side toward a radial center side.   The elongate groove part which followed the liquid flow down direction was formed in the inner peripheral surface of the said enlarged diameter part from the said introduction needle part side to the said constriction part side, The Claim 1 characterized by the above-mentioned. Liquid jet head. A filter that filters the liquid in the liquid flow path is disposed in the middle of the liquid flow path and downstream of the liquid introduction needle,
5. The liquid ejecting head according to claim 1, wherein a liquid introduction needle is disposed in a state where a lower end opening of the narrowed portion is opposed to the filter.   The liquid ejecting head according to claim 1, wherein the narrowed portion is formed integrally with the liquid introduction needle. 6. The narrowed portion is constituted by a ring-shaped member having an inner diameter smaller than that of the enlarged diameter portion, and is attached to an opening on the downstream side of the enlarged diameter portion. The liquid jet head described.

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