JP2009090617A - Liquid jetting head and its bubble discharging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head capable of suppressing a liquid consumption caused by a cleaning operation, and also to provide its bubble discharging method. <P>SOLUTION: A recording head introduces ink into a pressure generating chamber through an ink introducing passage 42 with a filter arranged therein, and discharges an ink droplet from a nozzle opening by a pressure variation, and it has a bubble amount adjusting mechanism 50 for increasing an occupancy of bubbles B to a flow passage volume in the ink introducing passage 42. The mechanism 50 improves a bubble discharging efficiency by increasing the volume of the bubbles B up to the limit bubble amount by filling the ink introducing passage 42 with air. <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 ejects liquid droplets from a nozzle opening due to pressure fluctuation, and a method for discharging bubbles.

Examples of the liquid ejecting head that ejects liquid droplets from the nozzle openings by causing pressure fluctuation in the liquid in the pressure generating chamber include, for example, an ink jet type used in an image recording apparatus such as an ink jet recording apparatus (hereinafter simply referred to as a printer). A recording material (hereinafter simply referred to as a recording head), a color material ejection head used for manufacturing a color filter such as a liquid crystal display, an organic EL (Electro
There are electrode material ejecting heads used for forming electrodes such as Luminescence displays and FEDs (surface emitting displays), and bioorganic matter ejecting heads used for manufacturing biochips (biochemical elements).

  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. The ink in the cartridge is introduced into the pressure generation 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 the resin wall forming the ink introduction needle and enter the ink flow path. For this reason, it is difficult to completely prevent the mixing of bubbles. Bubbles that enter the ink flow path gradually grow and become large, and if some of the excessively grown bubbles move to the pressure generation chamber side due to the flow of ink, the bubbles absorb the pressure fluctuation during the discharge operation. May cause problems such as pressure loss due to ink 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, the recording head of any configuration forcibly discharges air bubbles trapped by the filter due to the downward flow of ink by increasing the flow speed during the cleaning operation as compared with that during normal printing. Therefore, depending on the number of cleaning operations, the ink may be consumed excessively.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid jet head capable of suppressing the amount of liquid consumed by a cleaning operation, and a method for discharging bubbles thereof. is there.

In order to achieve the above object, a liquid ejecting head of the present invention is a liquid ejecting head that introduces liquid into a pressure generating chamber through a liquid inflow portion in which a filter is disposed, and ejects liquid droplets from a nozzle opening due to pressure fluctuation. ,
It has a bubble amount adjusting mechanism for increasing the bubble occupancy ratio with respect to the channel volume on the upstream side of the filter of the liquid inflow portion.

  According to the above configuration, since it has the bubble amount adjustment mechanism that increases the occupancy rate of the bubbles with respect to the flow path volume on the upstream side of the filter of the liquid inflow portion, the space in the liquid inflow portion is reduced and narrowed by the enormous amount of bubbles. The flow rate of the liquid flowing down in the flow path is inevitably increased. Therefore, it becomes easy for the bubbles to pass through the filter due to the downward flow of the liquid, and the discharge of the bubbles can be improved. As a result, the flow rate of the liquid during the cleaning operation can be suppressed, and the amount of liquid consumed by the cleaning operation can be suppressed. Furthermore, since the liquid flow-down speed can be suppressed, the meniscus (the liquid level on the liquid nozzle opening side) can be made uniform, whereby the stability of the liquid ejection performance can be maintained.

In the above configuration, it is desirable that the bubble amount adjusting mechanism sets a volume of bubbles upstream of the filter of the liquid inflow portion as a limit bubble amount.
The limit bubble amount indicates the volume of the limit bubble that the bubble can occupy with respect to the volume in the space in an environment where the fluid flows.

  According to the above configuration, since the volume of bubbles upstream of the filter at the liquid inflow portion is set as the limit bubble amount, when a new bubble enters the upstream side of the filter at the liquid inflow portion, the upstream side of the filter It becomes easy to discharge the bubbles from the filter. Therefore, the amount of liquid consumption due to the cleaning operation can be suppressed.

  The said structure WHEREIN: It is desirable for the said bubble quantity adjustment mechanism to fill air upstream from the filter of the said liquid inflow part.

  According to the above configuration, air is filled upstream of the liquid inflow portion filter, so that the filled air becomes bubbles in the liquid inflow portion, and merges with existing bubbles, thereby making the air in the liquid inflow portion more than the filter in the liquid inflow portion. It is possible to easily increase the occupancy rate of bubbles with respect to the flow path volume on the upstream side.

In the above configuration, the filter is disposed in an enlarged diameter part in which an inner diameter of the liquid inflow part is enlarged,
It is desirable to connect the bubble amount adjusting mechanism to the enlarged diameter portion.

  According to the above configuration, since the bubble amount adjusting mechanism is arranged in the enlarged diameter portion, the occupancy rate of the bubbles in the enlarged diameter portion can be increased, and unnecessary bubbles are formed on the wall surface of the flow channel upstream of the enlarged diameter portion. It can prevent adhesion. As a result, it is possible to prevent a shortage of liquid supply to the downstream side of the filter.

Also, the bubble ejection method for a liquid ejecting head according to the present invention introduces a liquid into a pressure generating chamber through a liquid inflow portion in which a filter is disposed, and ejects liquid droplets from a nozzle opening due to pressure fluctuations. Because
The volume of the bubble in the liquid inflow portion is adjusted so as to increase the occupancy ratio of the bubble with respect to the channel volume on the upstream side of the filter of the liquid inflow portion.

  According to the above configuration, the volume of the bubbles in the liquid inflow portion is adjusted so as to increase the occupancy ratio of the bubbles with respect to the channel volume on the upstream side of the filter in the liquid inflow portion. The flow rate of the liquid flowing down the can be increased. For this reason, it is possible to improve the discharge of bubbles, and it is possible to suppress the amount of liquid consumed by the cleaning operation.

  In the above configuration, the volume of bubbles upstream from the filter of the liquid inflow portion is a critical bubble amount.

  According to the above configuration, since the volume of bubbles upstream of the filter at the liquid inflow portion is set as the limit bubble amount, even if new bubbles enter the upstream side of the filter at the liquid inflow portion, the limit bubble amount is reduced. The excess bubbles can be easily discharged from the filter by the downward flow of the liquid.

  In the above configuration, air is filled upstream of the filter of the liquid inflow portion.

  According to the above configuration, air is filled upstream from the filter of the liquid inflow portion, so that the filled air becomes bubbles, so that the occupancy rate of bubbles relative to the channel volume in the liquid inflow portion can be easily increased. .

In the above configuration, the filter is disposed in an enlarged diameter part in which an inner diameter of the liquid inflow part is enlarged,
The amount of bubbles in the enlarged diameter portion is adjusted.

  According to the above configuration, since the amount of bubbles in the enlarged diameter portion is adjusted, it is possible to prevent bubbles from remaining on the upstream side of the enlarged diameter portion.

  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. The printer 1 includes a recording head 3 (corresponding to a kind of liquid ejecting head in the present invention) for ejecting (jetting) ink, a carriage 4 to which the recording head 3 is attached, and a carriage 4 in the main scanning direction (see FIG. 1). 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 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 empty plate 25 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. Then, when the pump unit 13 is operated in close contact with the nozzle plate 25 and negative pressure is generated in the sealed space (sealed space), ink and bubbles in the recording head 3 are sucked from the nozzle openings 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 an exploded perspective view of the recording head 3 attached to the carriage 4, FIG. 3 is a plan view of the recording head 3, and FIG. The illustrated recording head 3 is schematically constituted by 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 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 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 correspond 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 generation chambers 35 are partitioned by partition walls. It is a plate-shaped member formed side by side. The flow path forming substrate 24 is produced, for example, by etching a silicon wafer. Each of the pressure generating chambers 35 is formed as an elongated 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 generating 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 of the piezoelectric vibrator 29 is formed in a portion corresponding to the pressure generating 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 close to or away from the pressure generating chamber 35. As a result, the volume of the pressure chamber 35 changes, and the pressure in the ink in the pressure generating chamber 35 varies. Due to this pressure fluctuation, ink droplets (a type of droplet) are ejected (jetted) from the nozzle opening 26.

  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 skirt portion 45 formed continuously on the downstream side of the straight portion 44 and having an inner diameter larger than that 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 skirt portion 45 (corresponding to the enlarged diameter portion in the present invention) is formed in a tapered shape that gradually increases in diameter from the upstream side (straight portion 44 side) toward the downstream side (needle root side). The filter 18 described above is disposed in the skirt portion 45. The ink introduction needle 19 of the present embodiment is connected to a later-described bubble amount adjusting mechanism 50 that increases the occupancy rate of bubbles relative to the flow path volume in the ink introduction path 42. The details of the bubble amount adjusting mechanism 50 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 provided in the insertion portion 7 ′ (see FIG. 7) of the ink cartridge 7, and the internal space (ink storage area) of the ink cartridge 7. Part) 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, this air may be introduced into the ink introduction path 42 together with the ink as bubbles (indicated by reference sign B in FIG. 9). In addition, for example, air outside the ink introduction needle 19 may permeate through the resin wall forming the ink introduction needle 19 and enter the ink flow path. In the ink introduction path 42, the bubbles B are gradually combined with time and grow into larger bubbles. Largely grown bubbles B 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 the bubble B that has grown greatly.

  In the normal cleaning operation, as described above, the pump unit 13 is operated in a state where the cap member 11 is in close contact with the nozzle plate 25, and the ink flow at a flow rate several times that during normal ink discharge (recording operation) is obtained. (A fluid containing both ink and bubbles) is generated in the recording head 3, and the bubbles in the ink introduction path 42 are put on this ink flow to be 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 discharge characteristics of the bubbles B.

  However, from the viewpoint of reducing the ink consumed in this cleaning operation as much as possible, in the recording head 3 to which the present invention is applied, the bubbles B occupy the flow path volume upstream of the filter 18 in the ink introduction path 42. By increasing the rate, the air bubbles on the upstream side of the filter 18 are discharged in a state where the flow rate of the ink flow is suppressed to a slight speed (for example, 1.2 times) that is slightly higher than the speed during the normal recording operation (ejection operation). Like to do. Hereinafter, this point will be described.

  FIG. 7 is an explanatory view showing the bubble amount adjusting mechanism 50 in the present embodiment. The bubble amount adjustment mechanism 50 of the present embodiment is connected to the straight portion 44 of the ink introduction needle 19. The bubble amount adjusting mechanism 50 includes a pipe 51 and an opening / closing valve 52 attached to the pipe 51.

  One opening of the tube 51 is open to the ink introduction needle 19, that is, the outside (atmosphere) of the recording head 3, and the other opening communicates with the ink introduction path 42 in the ink introduction needle 19. The open / close valve 52 is attached in the middle of the pipe 51, and when closed, blocks communication between one opening of the pipe 51 and the other opening. When opened, the open / close valve 52 is connected to the outside of the ink introduction path 42 and the ink introduction needle 19. To open the atmosphere.

  When the opening / closing valve 52 is changed from the closed state to the open state, the bubble amount adjusting mechanism 50 configured in this way has a negative pressure from the outside of the ink introduction needle 19 because the ink introduction path 42 has a negative pressure from the atmosphere. The ink introduction path 42 is filled with air through the inside 51. When the ink cartridge 7 is of an off-carriage type, as shown in FIG. 13, the flow path from the ink cartridge 7 to the ink introduction needle 19 becomes a liquid inflow portion in the present invention, and the ink introduction needle 19 and the ink cartridge 7 The bubble amount adjusting mechanism 50 can be connected to the flow path therebetween. That is, the bubble amount adjusting mechanism 50 of the present invention may be connected anywhere as long as the ink introduction path 42 can be filled with air.

  When the above-described bubble amount adjusting mechanism 50 fills the ink introduction path 42 with air, the air that has entered the ink introduction path 42 becomes bubbles B, so that the inside of the ink introduction path 42 is smaller than the volume of the ink introduction path 42. As a result, the volume of the bubble B increases. In other words, the bubble amount adjusting mechanism 50 increases the occupation ratio of the bubbles B with respect to the channel volume in the ink introduction channel 42.

FIG. 8 is an explanatory diagram showing the relationship between the bubble volume and the flow velocity. As described above, when the number of bubbles B in the ink introduction path 42 increases, the bubble volume becomes the limit bubble amount (indicated by the symbol V _max ) as shown in FIG. The critical bubble amount V _max indicates the volume of the limit bubble that can be occupied by the bubbles relative to the volume in the space in an environment where the fluid (ink flow) flows. Further, the cleaning flow rate (indicated by symbol a) in FIG. 8 is the flow rate of ink during the cleaning operation in the conventional recording head, and is approximately three times the flow rate of printing (indicated by symbol b). .

Thus, the recording head 3 of the present invention, by making the volume of the bubble B in ink introduction channel 42 and limits the amount of bubbles V _max, the printing velocity slightly faster than b (1.2 times) Flow rate The bubble B can be discharged.

Next, the cleaning operation of this embodiment will be described.
FIG. 9 is an explanatory diagram showing a state in which bubbles have entered the ink introduction needle. FIG. 10 is an explanatory diagram showing a state in which new bubbles have entered from the state of FIG. FIG. 11 is an explanatory diagram showing a state in which bubbles are combined from the state of FIG. FIG. 12 is an explanatory diagram showing a state in which the cleaning operation is performed from the state of FIG.

First, as shown in FIG. 9, when the opening / closing valve 52 of the bubble amount adjusting mechanism 50 is changed from the closed state to the open state from the state where the bubble B1 stays in the ink introduction needle 19, the ink introduction needle 19, that is, the recording head 3. The air is filled into the ink introduction path 42 from the outside (atmosphere) through the tube 51, and the bubbles B2 enter the ink introduction path 42 as shown in FIG. Then, as shown in FIG. 11, the bubble B1 and the bubble B2 are combined to become a grown bubble B3, the space in the ink introduction path 42 is reduced, and the ink flowing down in the narrowed flow path is formed. The flow rate will inevitably increase. At this time, the bubble B3 becomes possible to increase the occupation ratio to the ink introduction path 42, the ink introduction path 42 is the limit bubble amount V _max.

  If a cleaning operation is performed in which the ink flow rate is about 1.2 times the printing flow rate, only some of the bubbles B3 may remain in the ink introduction path 42 as shown in FIG. However, the bubble B3 can pass through the filter 18 and be discharged. The volume of the bubble B4 is smaller than that of the bubble B1.

  As described above, the recording head 3 includes the bubble amount adjusting mechanism 50 that increases the occupancy ratio of the bubbles B with respect to the channel volume in the ink introduction path 42, so that the space in the ink introduction path 42 is reduced by the enormous amount of bubbles B. As a result, the flow rate of the ink flowing down in the narrowed channel is inevitably increased. Therefore, the bubbles B can easily pass through the filter 18 due to the downward flow of ink, and the discharge performance of the bubbles B can be improved. Thereby, the flow rate of ink during the cleaning operation can be suppressed, and the amount of ink consumed by the cleaning operation can be suppressed. Furthermore, since the ink flow-down speed can be suppressed, the meniscus (the liquid level on the liquid nozzle opening side) can be made uniform, whereby the stability of the ink ejection performance can be maintained.

Further, since the volume of the bubble B in ink introduction path 42 and limit the amount of bubbles V _max, when the ink introduction path 42 new bubbles in the B2 to (B) intrudes, bubble on the upstream side of the filter 18 B3 ( B) can be easily discharged from the filter 18. Therefore, it is possible to suppress ink consumption due to the cleaning operation.

  Further, since the ink introduction path 42 is filled with air, the filled air becomes the bubbles B2 (B) in the ink introduction path 42, and is combined with the existing bubbles B1 (B), so that the inside of the ink introduction path 42 is obtained. It is possible to easily increase the occupation rate of the bubbles B with respect to the flow path volume.

  Further, since the bubble amount adjusting mechanism 50 is arranged in the ink introduction needle 19, the occupation ratio of the bubbles B in the ink introduction needle 19 can be increased, and it is not necessary on the wall surface of the flow channel upstream of the ink introduction needle 19. Air bubbles can be prevented from adhering. As a result, it is possible to prevent a shortage of ink supply to the downstream side of the filter 18.

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, display manufacturing equipment for manufacturing color filters such as liquid crystal displays, organic EL (Electro
The present invention can also be applied to an electrode manufacturing apparatus for forming electrodes such as a Luminescence display and FED (surface emitting display), a chip manufacturing apparatus for manufacturing biochips (biochemical elements), and 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 which shows a bubble quantity adjustment mechanism. It is explanatory drawing which showed the relationship between bubble volume and flow velocity. It is explanatory drawing which shows the state which the bubble penetrate | invaded in the ink introduction needle | hook. FIG. 10 is an explanatory diagram showing a state in which new bubbles have entered in the state of FIG. 9. It is explanatory drawing which shows the state which air bubbles couple | bonded in the state of FIG. It is explanatory drawing which shows the state which performed the cleaning operation in the state of FIG. It is explanatory drawing which shows the modification of a bubble quantity adjustment mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Recording head, 18 ... Filter, 26 ... Nozzle opening, 35 ... Pressure generating chamber, 42 ... Ink introduction path, 45 ... Skirt part, 50 ... Bubble quantity adjustment mechanism, B ... Bubble

Claims (8)

A liquid ejecting head that introduces liquid into a pressure generating chamber through a liquid inflow portion in which a filter is disposed and discharges liquid droplets from a nozzle opening due to pressure fluctuation,
A liquid ejecting head, comprising: a bubble amount adjusting mechanism for increasing a bubble occupying ratio with respect to a channel volume upstream of the filter of the liquid inflow portion.   The liquid ejecting head according to claim 1, wherein the bubble amount adjusting mechanism sets a volume of bubbles upstream from the filter of the liquid inflow portion as a limit bubble amount.   The liquid ejecting head according to claim 1, wherein the bubble amount adjusting mechanism fills air upstream of a filter of the liquid inflow portion. The filter is arranged in an enlarged diameter part in which an inner diameter of the liquid inflow part is enlarged,
The liquid jet head according to claim 1, wherein the bubble amount adjusting mechanism is connected to the enlarged diameter portion. A liquid ejection head bubble discharge method for introducing liquid into a pressure generating chamber through a liquid inflow portion where a filter is disposed, and discharging droplets from a nozzle opening due to pressure fluctuation,
A bubble discharge method for a liquid ejecting head, comprising: adjusting a volume of bubbles in the liquid inflow portion so as to increase a bubble occupying ratio with respect to a channel volume upstream of the filter in the liquid inflow portion.   6. The method of discharging bubbles in a liquid jet head according to claim 5, wherein the volume of bubbles upstream from the filter in the liquid inflow portion is defined as a critical bubble amount.   The method of discharging bubbles from a liquid ejecting head according to claim 5, wherein air is filled upstream of the filter of the liquid inflow portion. The filter is arranged in an enlarged diameter part in which an inner diameter of the liquid inflow part is enlarged,
The method of discharging bubbles in a liquid jet head according to claim 5, wherein the amount of bubbles in the enlarged diameter portion is adjusted.

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