JPH09314832A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid ink oozing and inclusion of a bubble without marring the ink filling ability by forming a communication path, one end of which communicates with a common fluid chamber and the other end of which communicates with the atmosphere aperture for bubble discharging into a communication shape which becomes acoustically a comliance component or an inertance component. SOLUTION: The compliance component is proportional to the volume of the fluid in a flow path and indirectly proportional to the bulk modulus of elasticity of the fluid when the flow path is not changed. Alternatively the inertance component is proportional to the flow path length and indirectly proportional to the sectional area. A common fluid chamber 19 connecting the communicating path 42 is formed along a pressurizing fluid chamber 18 group, are here, formed longer than the pressurizing fluid chamber 18 group and 8 communicates with the communication path 42, while continuously narrowing an end part 19a thereof. Thereby, when a bubble is included in the communication path 42, even if the bubble moves to the common fluid chamber 19, the bubble stays at the end part 19a and is prevented from moving to and approaching the pressurizing fluid chamber 18 and an ink discharge extraneous and undischargeness can further reliably be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head, and more particularly to an inkjet head having an atmospheric opening for discharging bubbles.

[0002]

2. Description of the Related Art An ink jet recording apparatus has little vibration and noise at the time of recording and is easy to colorize. Therefore, it is used not only for a printer for outputting data of a digital processing device such as a computer but also for facsimile and copying. It is supposed to be. Such an ink jet recording apparatus is
A nozzle for ejecting ink droplets, an actuator element such as an electromechanical conversion element or an electrothermal conversion element provided corresponding to the nozzle, and an ink flow path (hereinafter referred to as “additional member”) in which ink is pressurized by this actuator element. An ink jet head provided with a "pressure chamber") is used as a recording head, and ink droplets are ejected from a nozzle to a recording medium (the one to which the ink droplets adhere) according to a recording signal, thereby achieving high speed and high resolution. , For high quality recording.

By the way, with the demand for high-speed recording and high image quality for an ink jet recording apparatus, it is necessary to increase the number of nozzles of an ink jet head, increase the density of nozzles, and miniaturize the nozzle diameter. The on-demand type inkjet head ejects the ink in the pressurized liquid chamber from the nozzles by pressurizing the pressurized liquid chamber with an actuator element and changing the volume thereof. Therefore, it is fatal if air bubbles are present in the pressurized liquid chamber during pressurization. Cause a general defect. That is, since the bubbles have a small bulk modulus, the pressure waves generated by the volume change of the liquid chamber are all consumed by the volume changes of the bubbles, and the pressure waves for ejecting the ink are not propagated to the ink, and the ink It will not be jetted.

Therefore, it is necessary to discharge the air bubbles in the pressurized liquid chamber, but normally, when the product is completed, the ink is filled and the air bubbles are not discharged in the pressurized liquid chamber for some reason to maintain the printing function. Since it is necessary to discharge the air bubbles when the ink is mixed, as described in, for example, Japanese Patent Application Laid-Open No. 4-216939, ink is supplied to each pressurized liquid chamber via the ink supply passage. An air opening for discharging bubbles is provided at the end of the common liquid chamber so that the bubbles can be discharged.

[0005]

However, particularly in a multi-nozzle ink jet head having a plurality of nozzles, a large number of channels (channel means a portion constituted by an actuator element, a pressurized liquid chamber and a nozzle) are simultaneously formed. When driven, the pressure wave leaks from the pressurizing liquid chamber propagates into the common liquid chamber, resulting in severe pressure fluctuations in the common liquid chamber. Further, in the case of a serial type recording apparatus in which an inkjet head is mounted on a carriage and recording is performed by moving and scanning the carriage, ink pressure fluctuations occur due to fluctuations in acceleration due to moving and scanning of the carriage, and the same is common. Pressure fluctuations occur in the liquid chamber.

[0006] Usually, the fluid resistance of the communication passage communicating from the common liquid chamber to the atmospheric opening is more than the fluid resistance of the ink supply passage for supplying ink from the common liquid chamber to the pressurized liquid chamber. Because of its small size, when a large pressure fluctuation occurs in the common liquid chamber, ink oozes out from the atmospheric air outlet for bubble discharge and adheres to the nozzle surface, causing disturbance in the ink ejection direction and flying of ink droplets. This causes speed fluctuations and the like, which deteriorates the recording quality. At the same time, air bubbles may be mixed from the air opening, and the air bubbles may remain in the common liquid chamber or may move into the pressurized liquid chamber to adversely affect the ink droplet ejection as described above.

The present invention has been made in view of the above points, and an object thereof is to enable stable high-quality recording.

[0008]

In order to solve the above-mentioned problems, an ink-jet head according to a first aspect of the invention has a plurality of nozzles, a plurality of pressurized liquid chambers communicating with each nozzle, and an ink in each pressurized liquid chamber. In an ink jet head having one or a plurality of common liquid chambers for supplying air, one end communicating with the common liquid chamber, and the other end communicating with an atmosphere opening for discharging bubbles, the communication passages are acoustically connected. The configuration is such that the flow path shape becomes the compliance component or the inertance component.

According to a second aspect of the present invention, in the ink jet head according to the first aspect, the communication passage has a length that is at least twice a linear distance from a communication portion with the common liquid chamber to an atmosphere opening portion. And

According to a third aspect of the present invention, there is provided an ink jet head according to the first or second aspect, wherein the communication passage is formed in a labyrinth.

According to a fourth aspect of the invention, there is provided an ink jet head according to any one of the first to third aspects, wherein a liquid chamber is formed in the middle of the communication passage.

According to a fifth aspect of the present invention, in the ink jet head according to any one of the first to fourth aspects, at least a part of the wall surface of the communication passage is formed of an elastic member having elasticity.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is an external perspective view showing an example of an inkjet head to which the present invention is applied, FIG. 2 is an exploded perspective view of the inkjet head, and FIG. 3 is an AA line in FIG.
FIG. 4 is an enlarged sectional view of a main part along a line BB in FIG. 1. In addition, in FIG. 2, the liquid chamber structure is simplified and shown.

The ink jet head comprises an actuator unit 1 and a liquid chamber unit 2 joined to the actuator unit 1. The actuator unit 1 joins two laminated piezoelectric elements 4 and 4 on an insulating substrate 3 and a frame 5 made of an insulating material surrounding the two rows of piezoelectric elements 4 and 4 with an adhesive 6. ing. The piezoelectric element 4 includes a plurality of actuators 7 to which drive pulses for applying ink to droplets and flying ink droplets are provided.
A plurality of non-driving portions 8, 8... Serving as support portions to which a driving pulse is not applied are alternately arranged.

The liquid chamber unit 2 has a diaphragm 12 having a diaphragm portion 11, and a first photosensitive resin layer 13 serving as a flow path forming portion formed of a photosensitive resin film (dry film resist) and a second photosensitive resin. A layer 14, a third photosensitive resin layer 15, and a nozzle plate 17 which is a nozzle forming member having a nozzle hole 16 are sequentially stacked to form a plurality of pressurized liquid chambers which are ink flow paths corresponding to the respective driving units 7, 7. 18, 18 ...
A plurality of common liquid chambers (common ink flow paths) 19, 19 for supplying ink to the respective pressurized liquid chambers 18, 18 ..., Ink supply also serving as a fluid resistance portion for connecting the common liquid chamber 19 and the pressurized liquid chamber 18 The passages 20 and 20, one end of which communicates with an atmosphere opening provided in a nozzle plate 17 described later, and the other end of which communicates with the common liquid chamber 20 are formed. The liquid chamber unit 2 is firmly bonded to the actuator unit 1 with a bonding agent 21.

Here, the substrate 3 of the actuator unit 1 has a thickness of about 0.5 to 5 mm and is made of a material similar to a piezoelectric element, and can be cut together with the piezoelectric element by, for example, a diamond grindstone. Preferably,
In this embodiment, a ceramic substrate is used. Also,
A groove 25 is formed between the piezoelectric elements 4 and 4 of the substrate 3 along the direction in which the drive units 7 are arranged.

As shown in FIGS. 3 and 4, the piezoelectric element 4 comprises a laminated piezoelectric element, and has a thickness of 20 to 50 μm / 1 layer of PZT (= Pb (Zr.Ti) O ₃ ) 27 and a thickness of Several μm /
Internal electrode 2 consisting of one layer of silver / paradium (AgPd)
8 are alternately laminated. Piezoelectric element with thickness 2
The drive voltage can be reduced by using a stacked type of 0 to 50 μm / 1 layer, and for example, an electric field strength of 1000 V / mm of the piezoelectric element can be obtained with a pulse voltage of 20 to 50 V. The material used as the piezoelectric element is not limited to the above, but is generally used as the piezoelectric element material.
It is also possible to use a ferroelectric substance such as TiO ₃ , PbTiO ₃ , or (NaK) NbO ₃ .

Each inner electrode 28 of the piezoelectric element 4 is connected to the left and right outer electrodes 30 and 31 made of AgPd every other layer. On the other hand, a common electrode pattern 32 for applying a driving waveform to the driving unit 7 is formed on the substrate 3 between the laminated piezoelectric elements 4 and 4, and a selection signal is supplied to the driving unit 7. Are provided.

Then, the external electrodes 30 of each drive unit 7 are connected to the common electrode pattern 32 via a conductive adhesive 34 such as silver paste, and the external electrodes 31 are also connected to the conductive adhesive 34.
Is connected to the individual electrode pattern 33 via the. In addition,
The common electrode pattern 32 is formed on the surface of the groove 25 formed in the center of the substrate 3 so as to conduct with the respective driving units 7. Then, an FPC cable 35 is connected to each of the common electrode pattern 32 and the individual electrode pattern 33.

On the other hand, the vibration plate 12 of the liquid chamber unit 2 has N
It is made of a metal plate of i (nickel) and is manufactured by the electroforming method. As shown in FIG. 3, the diaphragm 12 has a flat surface on the third photosensitive resin layer 15 side, and a diaphragm region 12 having a different thickness on the drive unit 7 side in the direction orthogonal to the channel direction.
a, island-shaped protrusion 12b, escape region 12c, and joining region 12
.. is formed, and diaphragm portions 11, 11 ... Are formed corresponding to the drive portions 7, 7.

The diaphragm area 12a of the diaphragm 12
Is the thinnest region (thin-walled part) and has a thickness of 3
It is a diaphragm region (elastic portion that is deformed according to the displacement of the driving unit 7) of the diaphragm unit 11 having a size of about 10 μm. The island-shaped convex portion 12b is the thickest region (thick-walled rigid portion), is the region where the drive unit 7 is joined, and is formed to a thickness of, for example, about 20 μm or more. The escape region 12c is a region having an intermediate thickness, and the drive unit 7
This is an area for avoiding contact with. Junction area 12d
Is a joint region between the non-driving portion 8 and the frame 5,
Like the island-shaped protrusion 12b, the region is the thickest,
For example, the thickness is about 20 μm or more.

The material forming the vibration plate 12 can form an elastic portion capable of transmitting the pressing force of the driving unit 7 to the pressurized liquid chamber 18, has good liquid resistance to ink, and has low moisture permeability. Good. However, the diaphragm 12 has a Young's modulus of 100 in order to join the non-drive unit 8 with high rigidity.
It is preferable to use an inelastic material of Kg / mm ² or more. Here, a Ni (nickel) metal plate manufactured by the electron forming method (electroforming) as described above is used.
A very thin resin film having low moisture permeability, for example, a resin film of polyphenylene sulfide, polyimide, polyether sulfone, polychlorotrifluoroethylene, aramid, or the like can also be used.

A large number of nozzles 16 are formed in the nozzle plate 17 as fine holes for ejecting ink droplets. The diameter of the nozzles 16 is 35 μm or less on the ink droplet outlet side. I have. This nozzle plate 1
Reference numeral 7 uses a Ni (nickel) metal plate manufactured by an electron forming method (electroforming), but Si or another metal material can also be used.

Actually, one ink jet head is manufactured with a structure of 64 to 128 or more in which two rows of nozzles 16 to 32 to 64 are arranged in two lines. A nozzle plate having a large number of nozzles 16 is manufactured. The quality of 17 determines the droplet shape and the flight characteristics of the ink, and has a great influence on the image quality. Since the surface homogenization treatment is indispensable for obtaining higher quality image quality, the ink ejection is performed. The water-repellent layer 17a is formed on the side surface.

Further, the substrate 3, the frame 5, and the diaphragm 1
2, ink supply holes 37, 38, and 39 for supplying ink supplied from the outside to the common liquid chamber 20 are respectively formed, and the ink supply pipes 40 connected to the ink supply holes 37 of the substrate 3 are provided. Ink is supplied.

In such an ink jet, a drive waveform is applied to the drive unit 7 via the common electrode pattern 32, and a selection signal corresponding to a recorded image is applied to the drive unit 7 via the individual electrode pattern 33. The displacement of the selected drive unit 7 in the stacking direction occurs, the corresponding pressurized liquid chamber 18 is pressurized via the diaphragm 11 of the vibration plate 12, and ink is applied by the pressure increase of the pressurized liquid chamber 18. It is pressurized and ejected as an ink droplet from the nozzle 16.

The ink pressure in the pressurized liquid chamber 18 decreases as the ink droplets are discharged, and a slight negative pressure is generated in the pressurized liquid chamber 18 due to the inertia of the ink flow at this time. In this state, by turning off the application of the drive waveform to the drive unit 7, the diaphragm portion 11 of the diaphragm 12 returns to its original position and the pressurized liquid chamber 18 returns to its original shape. Further, negative pressure is generated, and the ink that has entered from the ink supply pipe 40 that communicates with an ink tank (not shown) is filled into the pressurized liquid chamber 18 from the ink supply passage 20 through the common liquid chamber 19.

On the other hand, the ink meniscus after the ink droplet ejection is drawn inside the nozzle 16 and then returned (refill) to the ejection surface side of the nozzle 16 by the surface tension, and from the ejection surface (nozzle edge portion) of the nozzle 16. Since it stabilizes at a slightly inner position, ink droplets are ejected according to the next drive waveform while the meniscus is stable.

Here, the drastic pressure fluctuation in the common liquid chamber 19 is caused by the driving frequency of ink droplet ejection, the mechanical natural frequency of the carriage driving system, and the structure of the common liquid chamber 19. The fluid natural frequency of the ink in the ink becomes the main factor that determines the frequency component of the vibration. The frequency component of the problematic vibration is that the natural frequency in the common liquid chamber 20 is about 1 to 50 kHz, and the driving frequency is 5 to 5 at the maximum.
Since it is 20 kHz, it is a relatively high frequency component of several to several tens of kHz.

Therefore, a specific embodiment of the present invention will be described with reference to FIG. 5 and subsequent figures. FIG. 5 shows the first of the present invention.
It is a schematic explanatory view showing an example, and a plurality of pressurized liquid chambers 1
8 is shown as a block. In the first embodiment, a communication passage 42 having one end communicating with the end 19a of the common liquid chamber 19 opposite to the ink supply hole 39 and the other end communicating with the atmosphere opening 41 is provided. The passage 42 is formed in a curved flow path shape that acoustically becomes a compliance component or an inertance component.

In this way, the common liquid chamber 19 and the atmospheric opening 41 are formed.
By forming the communication path 42 that communicates with the acoustically shaped flow path that becomes the compliance component or the inertance component, it is possible to prevent the ink from seeping out from the atmosphere opening 41 due to the pressure fluctuation in the common liquid chamber 19. . Therefore, compliance, inertance of flow path elements such as communication passages,
The fluid resistance component will be described.

The compliance is an acoustic element that acts to hinder the applied pressure. Pressure p when compressed
[N / m ² ] is represented by the formula (1).

[Equation 1]

The compression ratio s when the volume V is changed from V to V'is expressed by the equation (2).

[Equation 2]

Since the change [m ³ ] of the volume (V−V ′) is equal to the volume displacement, the volume displacement X [m ³ ] is expressed by the equation 3.

(Equation 3)

Therefore, these equations (1), (2),
From (3), the pressure p [N / m ² ] when compressed is represented by the equation (4).

(Equation 4)

Next, the compliance CA is expressed by the equation (5).
Is defined by

(Equation 5)

This equation (5) indicates that the volume displacement in compliance is proportional to pressure and compliance.

From the above equations (4) and (5), the volume compliance CA is represented by the equation (6).

(Equation 6)

Here, the bulk modulus K = ρc ² [N / m ² ]
Then, the equation (6) can be expressed by the equation (7).

(Equation 7)

Inertance is an acoustic element that acts to prevent changes in volumetric flow. Internace M [kg / m ⁴ ]
Is defined by equation (8).

(Equation 8)

This equation (8) indicates that the driving pressure applied to the inertance is proportional to the change of the inertance and the volume flow.

The inertance M is expressed by the equation (9).

[Equation 9]

The inertance M of the circular tube is expressed by the equation (10).

(Equation 10)

Next, when a fluid is passed through a place having a fluid resistance, acoustic energy is converted into heat. Resistance depends on viscosity. There is a loss of acoustic energy when flowing a fluid with pressure p through the fluid resistance. Fluid resistance rA [NS
/ M ⁵ ] is defined by the equation (11).

[Equation 11]

Equation (11) indicates that the driving pressure applied to the fluid resistance is proportional to the fluid resistance and the volume flow.

When the fluid is a circular tube having a diameter of d (m) and a length of L (m), the fluid resistance rA [N.S / m ⁵ ] is given by the equation (12).
Is represented by

(Equation 12)

At this time, according to the present invention, the communication passage 42 is also referred to as a sufficient compliance component (hereinafter also referred to as “C component”) or an inertance component (hereinafter referred to as “L component”) up to the atmosphere opening 41. Since they are formed in a flow path shape having a), they acoustically form a high frequency filter, so that it is possible to suppress transmission of vibrations at relatively high frequency components. The product of the C component value and the L component value determines the capability of the high frequency filter. Therefore, even if a drastic pressure change occurs in the common liquid chamber 19, it is possible to prevent the ink from seeping out from the atmospheric opening 41 and prevent the bubbles from being mixed.

Here, the C component is proportional to the volume of the liquid in the flow passage and inversely proportional to the bulk modulus of the liquid when the flow passage itself is not deformed (see the above equation (7)). Further, the L component is proportional to the flow path length and inversely proportional to the cross-sectional area (the above equation (1
0)).

Therefore, in order to impart the C component to the communication passage 42, the length of the communication passage 42 is increased or the diameter thereof is increased to increase the ink volume in the communication passage 42. A liquid chamber whose ink volume increases in the middle of the communication passage 42,
That is, the C component can also be provided by forming and installing a chamber having a larger cross-sectional area in the ink flow direction than the communication passage 42. Further, the component C is imparted by forming a wall made of an elastic member having low rigidity elasticity so that the flow path itself can be deformed in the communication passage 42.
The C component can be increased. For example, by forming a part similar to the vibrating plate 12 that changes the volume of the pressurized liquid chamber 18 of the inkjet head on a part of the wall surface of the communication path 42,
The C component can be added and the C component can be increased.

Further, in order to give the L component to the communication passage 42, the length of the communication passage 42 is made longer or the diameter thereof is made smaller. However, reducing the diameter of the communication passage 42 increases the fluid resistance. Therefore, when the resistance value component is the same, increasing the length of the communication passage 42 increases the L component value. You can Further, at least a part of the wall surface of the communication passage 42 may be a wall surface made of an elastic member having elasticity, and by adding a mass component to the wall surface having elasticity, the L component can be imparted and the L component can be increased. For example, the diaphragm 12 that changes the volume of the pressurized liquid chamber 18 of the inkjet head and the island-shaped protrusion 12 of the diaphragm 12.
The L component can be imparted and the L component can be increased by forming the same component as a (mass component) on a part of the wall surface of the communication passage 42.

On the other hand, the fluid resistance component of the communication passage 42 up to the atmospheric opening 41 is set to be smaller than the fluid resistance component of the path from the common liquid chamber 19 to the nozzle 16 via the pressurized liquid chamber 18. There is. This facilitates the outflow of ink from the communication passage during normal ink filling / bubble discharge work, so that the bubbles of the ink supply system up to the common liquid chamber 19 and the head are easily discharged from the atmosphere opening 41. It does not prevent things.

Further, even if air bubbles are mixed from the atmosphere opening 41 due to external vibration, impact, etc. applied to the recording head using this ink jet head, the bubbles will enter the communication passage 42. As a result of being trapped, it is possible to prevent the ink from moving to the common liquid chamber 19 and staying there, and it is possible to prevent a situation in which ink ejection abnormality or ejection failure occurs. In this case, the bubbles mixed in the communication passage 42 can be easily discharged together with the ink by the pump operation (reliability recovery mechanism) performed after the printing is completed.

Further, as shown in FIG. 5, the common liquid chamber 19 connected to the communication passage 42 is formed along the pressurized liquid chamber 18 group. Is formed to be long, and one end portion 19a thereof is continuously squeezed to communicate with the communication passage 42. As a result, when bubbles are mixed in the communication passage 42 as described above, even if the bubbles move to the common liquid chamber 19, they stay at the end portion 19a and remain in the pressurized liquid chamber 18.
It is possible to prevent the ink from moving in and out, and more reliably prevent the abnormal ink ejection or the failure of ejection. At the same time, it becomes possible to easily fill the ink without bubbles remaining in the common liquid chamber 19 even when the ink is filled immediately after the ink tank (ink cartridge) is replaced.

Furthermore, the atmosphere openings 41 are formed on the nozzle rows at the same pitch as the rows of the nozzles 16.
This makes it necessary to increase the contact area of the cap that comes into contact with the nozzle surface when the negative pressure suction is performed by the pump operation via the cap by the reliability recovery mechanism of the head, that is, to increase the size of the cap. Disappears.

Further, by forming the liquid chamber in the middle of the communication passage as described above, or by forming a part of the wall surface of the communication passage with an elastic member, the compliance component and the like can be further increased. The above-mentioned effects can be achieved more effectively.

Next, FIG. 6 is a schematic explanatory view showing a second embodiment of the present invention, and FIG. 7 is an enlarged explanatory view of a main part of FIG. In the second embodiment, similarly to the first embodiment, the end portions 19 of the common liquid chambers 19 opposite to the ink supply holes 39 are formed.
A communication passage 43 having one end communicating with a and the other end communicating with the atmosphere opening 41 is provided, and the communication passage 43 is formed into a curved flow passage shape that acoustically becomes a compliance component or an inertance component. The communication passage 43 is further bent to form a labyrinth, and the length D is 2 when the distance from the communication portion with the common liquid chamber 19 to the atmosphere opening 41 is connected by a straight line distance (shortest path). The flow path is more than twice as long.

As described above, by making the length of the communication passage more than twice the straight line distance from the communicating portion with the common liquid chamber to the atmospheric opening, the compliance component and the inertance component increase, and Compared to the first embodiment, it is possible to prevent ink from seeping out from the air opening for bubble discharge due to pressure fluctuations in the common liquid chamber and to prevent mixing of air bubbles, to prevent air bubbles from mixing into the air opening due to external vibration, and to prevent air bubble mixing. In this case, it is possible to more effectively prevent the influence on the ink droplet ejection characteristics.

Here, the term "maze-like" means that when the total sum of the angles at which the communication passage bends from the common liquid chamber to the atmosphere opening is 360 ° or more, for example, as shown in FIG. When α1 + α2 + α3 + α4 ≧ 360 °, or when a square S having an arbitrary size is hypothesized as shown in FIG. Is greater than.

Next, FIG. 9 is a schematic explanatory view showing a third embodiment of the present invention, and FIG. 10 is an enlarged explanatory view of the main parts of FIG.
In the third embodiment, the common liquid chamber 19 is arranged on both sides of the plurality of pressurized liquid chambers 18 in each of the above-described embodiments, whereas the ink liquid arranged on one side of the plurality of pressurized liquid chambers 18 is used. It has a room structure. Even when such an ink liquid chamber structure is adopted, it is possible to obtain the same effects as those of the above-described respective embodiments.

Depending on the head structure, the pressurized liquid chamber group may have ejection characteristics (ink droplet ejection characteristics) of the pressurized liquid chambers located at both ends different from those of other pressurized liquid chambers. This is because there is a structural difference between both ends, and as a countermeasure against that, a dummy structure (pressurized liquid chamber, diaphragm, etc.) not used for ink ejection may be installed at both ends. In such a head, a dummy pressurized liquid chamber or the like can be used as a part of the communication passage.

That is, the dummy pressurized liquid chamber is installed in the communication passage, the diaphragm facing the dummy pressurized liquid chamber is used as a part of the wall surface of the communication passage, or the diaphragm and The island-shaped convex portion (mass component) that becomes the island-shaped rigid portion can be used as a part of the wall surface of the communication path. By doing so, the dummy structure can be utilized.

In the above embodiment, the ink jet head which pressurizes the pressurizing liquid chamber by using the displacement of the laminated piezoelectric element in the d33 direction has been described.
The present invention can be similarly applied to an ink jet head that pressurizes a pressurized liquid chamber using displacement in 31 directions, another ink jet head using a bimorph type piezoelectric element, a so-called bubble jet type ink head using a heating resistor, and the like. .

In the above embodiment, the pressurized liquid chamber,
The example using the photosensitive resin as the flow path forming member that forms the ink flow paths such as the common liquid chamber, the ink supply path, and the communication path has been described, but the flow path forming member is not limited to this. It is also possible to use a metal, another resin, or the like.

[0064]

As described above, according to the ink jet head of the first aspect, the communication passage, one end of which communicates with the common liquid chamber and the other end of which communicates with the atmospheric opening for discharging bubbles, is acoustically compliant. Since it is configured to have a flow path shape that serves as a component or inertance component, it is possible to prevent the exudation of ink from the atmospheric opening for discharging bubbles and the mixing of bubbles without deteriorating the filling property of the ink, which is stable. High quality recording is possible.

According to a second aspect of the present invention, in the ink jet head of the first aspect, the communication passage has a length that is at least twice the linear distance from the communication portion with the common liquid chamber to the atmospheric opening. Therefore, the compliance component and the inertance component can be increased, the communication passage can be made to act as a bubble trap for bubbles mixed from the atmospheric opening, and more stable and high quality recording can be performed.

According to the ink jet head of the third aspect, in the ink jet head of the first or second aspect, the communication passage is formed in a labyrinth, so that the compliance component and the inertance component can be increased, and The passage can be made to act as a bubble trap for bubbles mixed from the atmosphere opening, and more stable and high quality recording can be performed.

According to the ink jet head of the fourth aspect, in the ink jet head according to any one of the first to third aspects, since the liquid chamber is formed in the middle of the communication passage, the compliance component can be increased. ,
The liquid chamber of the communication passage can be made to act as a bubble trap for bubbles mixed from the atmospheric opening, and more stable high quality recording can be performed.

According to the ink jet head of the fifth aspect, in the ink jet head according to any one of the first to fourth aspects, at least a part of the wall surface of the communication passage is formed of an elastic member having elasticity. The components can be increased, and the communication passage can be made to act as a bubble trap for bubbles mixed from the atmospheric opening, which enables more stable and high quality recording.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an example of an inkjet head to which the present invention is applied.

FIG. 2 is an exploded perspective view of the inkjet head.

FIG. 3 is an enlarged sectional view of a main part along the line AA in FIG. 1;

FIG. 4 is an enlarged sectional view of a main part along the line BB in FIG. 1;

FIG. 5 is a schematic explanatory view showing a first embodiment of the present invention.

FIG. 6 is a schematic explanatory view showing a first embodiment of the present invention.

7 is an enlarged explanatory view of a main part of FIG. 6;

FIG. 8 is an explanatory diagram for explaining a labyrinth-like communication passage.

FIG. 9 is an explanatory diagram for explaining a labyrinth-like communication passage.

FIG. 10 is a schematic explanatory view showing the first embodiment of the present invention.

11 is an enlarged explanatory view of the main part of FIG.

[Explanation of symbols]

1 ... Actuator unit, 2 ... Liquid chamber unit, 3 ...
Frame, 4 ... Multilayer piezoelectric element, 7 ... Driving section, 8 ... Non-driving section, 11 ... Diaphragm section, 12 ... Vibrating plate, 12a ...
Island-shaped projections, 12b ... Thick parts, 13, 14, 15 ... Photosensitive resin layer, 16 ... Nozzle, 17 ... Nozzle plate, 18 ...
Pressurized liquid chamber, 19 ... Common liquid chamber, 20 ... Ink supply passage, 41
... atmosphere opening, 42, 43 ... communication passage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taeko Murai 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Hideyuki Makita 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (5)

[Claims] 1. A plurality of nozzles, a plurality of pressurized liquid chambers that communicate with each nozzle, one or a plurality of common liquid chambers that supply ink to each pressurized liquid chamber, and one end of which communicates with the common liquid chamber. In the inkjet head, the other end of which has a communication path that communicates with an air opening for discharging air bubbles, wherein the communication path has a flow channel shape that acoustically serves as a compliance component or an inertance component. 2. The ink jet head according to claim 1, wherein the communication passage has a length that is at least twice as long as a straight line distance from a communication portion with the common liquid chamber to an atmosphere opening portion. head. 3. The ink jet head according to claim 1 or 2, wherein the communication passage is formed in a labyrinth. 4. The ink jet head according to any one of claims 1 to 3, wherein a liquid chamber is formed in the middle of the communication passage. 5. The inkjet head according to claim 1, wherein at least a part of the wall surface of the communication passage is formed of an elastic member having elasticity.