JP3281206B2 - Inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly to an on-demand type multi-nozzle ink jet head.

[0002]

2. Description of the Related Art The ink jet recording system has attracted attention because it can record without contacting a head on recording paper, and has a very simple recording process and is suitable for color recording. Conventionally, various methods have been proposed as the ink jet recording method, but at present, the so-called drop-on-demand (DOD) method in which ink is ejected only when a recording signal is input has become mainstream. The DOD method includes a so-called bubble jet method and a piezo actuator method.

In the on-demand type ink jet head, ink in the pressurized liquid chamber is ejected from nozzles by pressurizing the pressurized liquid chamber with energy generating means to change its volume. The presence of air bubbles in the cell is a fatal defect. That is,
Since the bubbles have a low bulk modulus, all the pressure waves generated by the change in the volume of the liquid chamber are consumed by the changes in the volume of the bubbles. Disappears.

[0004] Therefore, it is necessary to discharge air bubbles in the pressurized liquid chamber. However, usually, when the ink is filled for the first time after the product is completed, air bubbles are injected into the pressurized liquid chamber due to some inconvenience in order to maintain the printing function. When bubbles are mixed, it is necessary to discharge bubbles.

Conventionally, as an ink jet head considering the discharge of air bubbles in the pressurized liquid chamber, as described in, for example, JP-A-63-199650, ink is supplied from below each pressurized liquid chamber. Supply and form an air release port communicating with the pressurized liquid chamber above each pressurized liquid chamber, or form a common auxiliary ink chamber that communicates with each pressurized liquid chamber. As described in Japanese Patent Publication No. 60-11542, which has an open air hole,
For example, there is one in which a recovery outlet having the same fluid resistance as an image forming discharge port is connected to an upstream liquid chamber communicating with a plurality of liquid paths provided with energy generating elements.

[0006]

However, in the former ink jet head described above, each of the pressurized liquid chambers is provided with an air opening hole, or a common auxiliary ink chamber communicating with each of the pressurized liquid chambers is provided. Since the open-to-atmosphere holes are provided, pressure waves when pressurizing the pressurized liquid chambers are lost due to propagation to the open-to-atmosphere holes and the auxiliary ink chambers of each pressurized liquid chamber, and the ink droplet ejection energy is reduced. . Further, in the latter ink jet head, since a recovery discharge port having the same fluid resistance as the image forming discharge port is provided in the upstream liquid chamber communicating with the plurality of liquid paths, Ink leakage increases and ink loss increases.

[0007] The present invention has been made in view of the above, first in the multi-nozzle ink jet head
An object of the present invention is to discharge air bubbles at the time of initial ink filling to improve image quality.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a plurality of nozzle rows in which a plurality of nozzles are arranged, and a plurality of pressurizations each of which faces a plurality of nozzles. While having a plurality of pressurized liquid chamber rows composed of liquid chambers,
An ink jet head in which ink was supplied to each of the pressurized liquid chambers from both directions via a fluid resistance portion was configured as follows.

[0009] inkjet head according to claim 1, wherein
On both sides of each pressurized liquid chamber row in the row direction via the fluid resistance part,
A common flow path communicating with the pressurized liquid chamber is provided for each of the pressurized liquid chambers.
A partition is provided between the liquid chamber rows to form a common liquid chamber of the pressurized liquid chamber row.
Independently, each fluid resistance of the common flow path on both sides of the pressurized liquid chamber row
A distribution portion for equalizing the resistance value and distributing the supplied ink to the common flow path on both sides of each of the pressurized liquid chamber rows is formed at the center in a direction orthogonal to the row direction of each of the pressurized liquid chamber rows.

[0010] inkjet head according to claim 2, wherein
Item 1. The ink jet head according to Item 1, wherein each of the common flow paths
Were respectively connected to the dummy nozzles.

[0011] inkjet head according to claim 3, wherein
Item 2. In the ink jet head according to Item 2, the dummy nozzle
The nozzle has a smaller nozzle diameter than the image forming nozzle.
Was.

[0012] inkjet head according to claim 4, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
And the fluid resistance of the fluid resistance portions in both directions.
The resistance value was the same.

[0013] inkjet head according to claim 5, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
It is formed in a position where it is not placed, and the fluid in both directions
The fluid resistance value of the resistance part was varied according to the nozzle position.

[0014] inkjet head according to claim 6, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
The height of the flow path from the fluid resistance section to the nozzle
It was formed by changing the target or gradient.

The ink jet head according to claim 7, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
Between the fluid resistance part and the nozzle in the height direction of the pressurized liquid chamber.
Provided in different directions.

[0016]

According to the first aspect of the present invention, there is provided an ink jet head comprising:
Each of the pressure fluid chamber rows is provided on both sides in the row direction through the fluid resistance section.
And a common flow path communicating with the pressurized liquid chamber is provided.
A common flow path on both sides of the pressurized liquid chamber row by providing a partition between the rows
And a distributing portion for distributing the supplied ink to the common flow path on both sides of each of the pressurized liquid chamber rows at the center in a direction orthogonal to the row direction of each of the pressurized liquid chamber rows. Since each of the common liquid chambers has the same fluid resistance value,
Ink is simultaneously distributed and supplied to each pressurized liquid chamber through each fluid resistance part, and the air in the pressurized liquid chamber is completely discharged at the time of initial ink filling.

The ink jet head according to claim 2, wherein
Item 1. The ink jet head according to Item 1, wherein each of the common flow paths
Are communicated with the dummy nozzles, so that the bubbles in the common liquid chamber can be discharged, and the equivalent fluid resistance value of the common liquid chamber can be maintained.

The ink jet head according to claim 3, wherein
Item 2. In the ink jet head according to Item 2, the dummy nozzle
The nozzle has a smaller nozzle diameter than the image forming nozzle.
Therefore, ink loss when discharging bubbles is reduced.

The ink jet head according to claim 4, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
And the fluid resistance of the fluid resistance portions in both directions.
Since the resistance value is made the same, the ink can simultaneously reach the nozzles and discharge the air in the pressurized liquid chamber.

The ink jet head according to claim 5, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
It is formed in a position where it is not placed, and the fluid in both directions
The fluid resistance value of the resistance part was changed according to the nozzle position
Even if the nozzle is at a position shifted from the center position,
The ink reaches the nozzles at the same time, and the air in the pressurized liquid chamber can be discharged.

The ink jet head according to claim 6, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
The height of the flow path from the fluid resistance section to the nozzle
Since it is formed by changing the angle or gradient, it is possible to prevent the generation of a vortex due to the ink flow and to prevent the adhesion of air bubbles to the corners.

The ink jet head according to claim 7, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
Between the fluid resistance part and the nozzle in the height direction of the pressurized liquid chamber.
Since they are provided in different directions, air bubbles adhering to the bottom surface of the pressurized liquid chamber can be separated and discharged.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an external perspective view of an inkjet head showing one embodiment of the present invention, FIG. 2 is an exploded perspective view of FIG.
1 is a sectional view taken along the line AA of FIG. 1, and FIG. 4 is a sectional view taken along the line BB of FIG.

The ink jet head comprises an actuator unit 1 and a liquid chamber unit 2 joined on the actuator unit 1. The actuator unit 1 includes two rows of piezoelectric element rows 4 and 4 in which a plurality of stacked piezoelectric elements are arranged (arranged) in a row on a substrate 3 and the periphery of the two rows of piezoelectric element rows 4 and 4. The surrounding frame member 5 is joined. The piezoelectric element array 4 is provided with a plurality of piezoelectric elements (hereinafter referred to as “driving unit piezoelectric elements”) to which a drive pulse for causing ink to fly into droplets is applied.
, A plurality of piezoelectric elements (hereinafter referred to as “fixed part piezoelectric elements”) which are located between the drive part piezoelectric elements 7 and 7 and serve merely as a liquid chamber unit fixing member without receiving a drive pulse.
Are alternately arranged in a bi-pitch structure.

The liquid chamber unit 2 is a liquid chamber flow path forming member made of a photosensitive resin film (dry film resist) forming a pressurized liquid chamber, a common flow path, etc. on a diaphragm 12 having a diaphragm 11 formed thereon. Nozzle plate 1 in which nozzles 15 are formed on liquid chamber flow path forming member 13
6 is adhered. The vibrating plate 12, the liquid chamber flow path forming member 13, and the nozzle plate 16 form the piezoelectric element row 4
, A plurality of substantially independent pressurized liquid chambers 17, each having a diaphragm portion 11 facing each of the driving piezoelectric elements 7, 7,.
The pressurized liquid chamber rows 17A, 17B are formed on the nozzle plate 16, and two pressurized liquid chamber rows 17A, 17B are formed on the nozzle plate 16.
There are provided two nozzle rows 15A and 15B in which a plurality of nozzles 15 facing each pressurized liquid chamber 17 of B are arranged.

Here, the liquid chamber flow path forming member 13 of the liquid chamber unit 2 is located between the upper surface of the vibration plate 12 and the nozzle plate 16 to form the flow path of the pressurized liquid chamber 17 as described above. In the manufacturing process, the lower liquid chamber flow path forming member 20 having a liquid chamber pattern formed on the upper surface of the vibration plate 12 using a dry film resist, and the same dry film resist is used on the lower surface of the nozzle plate 16. And the upper liquid chamber flow path forming member 21 having the liquid chamber pattern formed thereon.

The structure of the liquid chamber of the liquid chamber unit 2 will be described with reference to FIGS. Each pressurized liquid chamber row 17
Fluid resistance portions 23, 23 for supplying ink from both sides are provided in the pressurized liquid chambers 17A, 17B (formed by the lower liquid chamber flow path forming member 20), and the fluid resistance portions 23, 23 are further provided. , Ie, both sides in the direction orthogonal to the row direction of the pressurized liquid chamber rows 17A, 17B, are an outer common liquid chamber 24a and an inner common liquid chamber 24b which are common flow paths communicating with the fluid resistance portions 23, 23.
Are provided respectively. In this case, the inner common liquid chambers 24b, 24b of each row can be formed integrally, but here, the partition 25 is provided between the pressurized liquid chamber rows 17A, 17B.
, The inner common liquid chamber 24b,
24b are independent. Also, here, the cross-sectional shapes (width and height) of the outer common liquid chamber 24a and the inner common liquid chamber 24b
Are formed to be equivalent.

The pressurized liquid chamber rows 17A, 1
One end sides of the outer common liquid chamber 24a and the inner common liquid chamber 24b of 7B are provided with distribution portions 27a and 27b of a distribution path 27 that distributes the ink supplied from the ink supply port 26 to the respective pressurized liquid chamber rows 17A and 17B. They are communicating. Here, the distribution path 27
The distribution unit 27a, 27b is pressurized liquid chamber line 17A, 17B
, Ie, the pressurized liquid chamber rows 17A, 17
B is formed at the center in the arrangement direction.

The ink supply port 26 is formed at the center between the pressurized liquid chamber rows 17A and 17B in the direction orthogonal to the row direction. Ink is supplied to the ink supply port 26 through an ink supply hole 3a of the substrate 3 and an ink supply pipe 29 inserted into the ink supply hole 5a of the frame 5 shown in FIG.

On the other hand, the other end sides of the outer common liquid chamber 24a and the inner common liquid chamber 24b of each of the pressurized liquid chamber rows 17A and 17B have a terminal shape as shown in FIG. 28, 28. The dummy nozzle 28 is formed on the nozzle plate 16 (not shown in FIGS. 1 and 2), and has a smaller nozzle diameter than the image forming nozzle 15 described above.

The positional relationship between the pressurized liquid chambers 17 and the nozzles 15 in each of the pressurized liquid chamber rows 17A and 17B is also shown in FIG. 7 (the upper liquid chamber flow path forming member 22 is not shown). The nozzle 15 is formed so that the nozzle 15 is located at the center of the fluid resistance portions 23 on both sides, that is, the center of the pressurized liquid chamber 17 in the longitudinal direction. Accordingly, the fluid resistance values of the fluid resistance portions 23 on both sides of the pressurized liquid chamber 17 are made the same.

In the ink jet head configured as described above, a drive pulse voltage of 20 to 50 V is selectively applied to the drive piezoelectric elements 7, 7... Of the piezoelectric element rows 4, 4 in accordance with a recording signal. The driving piezoelectric element 7 to which the pulse voltage is applied extends in the laminating direction and
Is deformed in the direction of the nozzle 15, whereby the volume of the pressurized liquid chamber 17 is reduced and the ink in the pressurized liquid chamber 17 is pressurized. The droplets are ejected as droplets from the liquid and recording can be performed.

Then, the ink pressure in the pressurized liquid chamber 17 decreases as the ink droplets are ejected, and a slight negative pressure is generated in the pressurized liquid chamber 17 due to the inertia of the ink flow at this time. In this state, by turning off the application of the voltage to the drive unit piezoelectric element 7, the diaphragm portion 11 of the diaphragm 12 returns to the original position, and the pressurized liquid chamber 17 becomes the original shape. , Further negative pressure is generated.

At this time, ink entering from an ink supply pipe 29 leading to an ink tank (not shown) is filled from both sides into the pressurized liquid chamber 17 through the fluid resistance portions 23, 23 from the outer common liquid chambers 24a, 24b. You. Then, after the vibration of the ink meniscus surface of the nozzle 15 is attenuated and stabilized, a pulse voltage is applied to the driving unit piezoelectric element 7 for discharging the next ink droplet. By repeating this operation, a required image can be recorded.

In an ink jet head that ejects ink droplets by the above-described operation, when the pressurized liquid chamber is filled with ink, the meniscus of the nozzle portion vibrates to cause air to enter the pressurized liquid chamber. When this phenomenon is repeated, air accumulates in the pressurized liquid chamber and becomes bubbles, and even if the diaphragm is deformed, the deformation is absorbed by air with a low bulk modulus and no pressure wave is generated Ink droplets cannot be ejected. In addition, since the pressurized liquid chamber and the like contain air when the initial ink is filled, the same disadvantage occurs if the air is not discharged.

Therefore, in the ink jet head of this embodiment, the distribution path for distributing the ink supplied from the ink supply port 26 to the outer common liquid chamber 24a and the inner common liquid chamber 24b of each of the pressurized liquid chamber rows 17A and 17B. 27 distribution units 2
7a and 27b are formed at the center of the direction orthogonal to the row direction of the pressurized liquid chamber rows 17A and 17B, and the ink supply port 26 is also formed in the direction orthogonal to the row direction of the pressurized liquid chamber rows 17A and 17B. Since it is formed at the center, the ink supplied from the ink supply port 26 reaches each pressurized liquid chamber 17 simultaneously from the fluid resistance parts 23 on both sides, and Air is completely exhausted.

Further, by forming a partition 25 between the pressurized liquid chamber rows 17A and 17B, the outer supply liquid chamber 24 is formed.
a and the inner common liquid chamber 24b are connected to the respective pressurized liquid chamber rows 17A, 17A.
Since the inks are independent of each other at B, mutual influence between the pressurized liquid chamber rows 17A and 17B when ink is supplied to each pressurized liquid chamber 17 can be prevented, and generation of bubbles can be suppressed.

Here, as described above, the ink supply port 26 is also formed at the center in the direction orthogonal to the row direction of the pressurized liquid chamber rows 17A and 17B, but as shown in FIG. An ink supply port 26 is provided at an end portion, and each pressurized liquid chamber row 17 is provided through a distribution path 27 communicating with the ink supply port 26.
A, 17B, outer common liquid chamber 24a and inner common liquid chamber 24
The distribution units 27a and 27b for supplying the ink to b may be formed at the center in the direction orthogonal to the row direction of the pressurized liquid chamber rows 17A and 17B.

In this case, the ink is filled from the outer common liquid chamber 24a and the inner common liquid chamber 24b of the pressurized liquid chamber row 17A on the side close to the ink supply port 26. According to the figure, since the distribution portions 27a and 27b are located at the center in the direction orthogonal to the column direction of the pressurized liquid chamber 17, the fluid resistance portion 2 is separated from the outer common liquid chamber 24a and the inner common liquid chamber 24b.
Ink is simultaneously supplied to the pressurized liquid chamber 17 from both sides through 3 and 23, and the air in the pressurized liquid chamber 17 can be completely discharged.

Further, in the above embodiment, each pressurized liquid chamber row 1
Outer common liquid chamber 24a and inner common liquid chamber 24 of 7A and 17B
Since the cross-sectional shapes (width and height) of b are formed to be equivalent, the fluid resistance values of the outer common liquid chamber 24a and the inner common liquid chamber 24b become equal, and the ink is supplied to the respective liquid chambers 24a, 24a.
The time required for b to reach the fluid resistance portions 23, 23 communicating with each other becomes the same, and the air in the pressurized liquid chamber 17 can be completely discharged.

In this case, the outer common liquid chamber 24a and the inner common liquid chamber 24b may be formed so that their cross-sectional shapes are equivalent, and a sufficient distance between the pressurized liquid chamber rows 17A and 17B cannot be obtained. Sometimes, instead of making the width of the inner common liquid chamber 24b narrower than the width of the outer common liquid chamber 24a,
By making the height of 4b higher than the height of the outer common liquid chamber 24a, the fluid resistance values of both common liquid chambers 24a and 24b can be made equal.

For example, assuming that the fluid resistance value of the outer common liquid chamber 24a shown in FIG. 5 is W: 1 mm and H: 0.06 mm, the equivalent radius R is given by the following equation (1) . Since it is obtained, R = 0.057.

[0043]

(Equation 1)

Since the fluid resistance value Rf is obtained by the following equation (2) , Rf = 2.4 × 10 12 (pas · S / m
3)

[0045]

(Equation 2)

Here, the distance between the rows of pressurized liquid chambers is reduced to reduce the size of the head, and the width of the inner common liquid chamber 24b is set to 0.5 mm, which is shorter than the width of the outer common liquid chamber 24a. H
Is H = 0.064 mm from the above equation (1).

Further, since the dummy nozzle 28 is provided at the most downstream position when viewed from the ink supply port 26 of the outer common liquid chamber 24a and the inner common liquid chamber 24b of each of the pressurized liquid chamber rows 17A and 17B, As a result, the bubbles in the common liquid chambers 24a and 24b can be discharged from the dummy nozzle 28 in a form completely separated from the pressurized liquid chamber 17, and the outer common liquid chamber 24a
Also, the equivalence of the fluid resistance value of the inner common liquid chamber 24b can be maintained.

In this case, since the nozzle diameter of the dummy nozzle 28 is formed smaller than the nozzle diameter of the image forming nozzle 15, ink loss can be reduced. That is, when the nozzle diameter of the dummy nozzle 28 is the same as that of the image forming nozzle 15 or the fluid resistance value is equivalent, when performing the bubble discharging operation by the reliability ensuring means, the same amount as that during normal ink ejection is used. Of ink is discharged.

For example, as the image forming nozzle 15,
In a head having nozzles, when four dummy nozzles 28 are provided, 10% of ink is lost. However, only the pressurized liquid chamber needs to actually discharge bubbles, and the dummy nozzle only needs to function at the time of initial ink filling. Leads to. Therefore, by making the nozzle diameter of the dummy nozzle 28 smaller than that of the image forming nozzle 15 as described above,
In addition to reducing ink loss, it is possible to prevent air from being drawn in from the dummy nozzles 28 during normal operation.

Further, ink is caused to flow from both sides of the pressurized liquid chamber 17 through the fluid resistance portions 23, 23,
Since the nozzle 17 is located at the center between the fluid resistance portions 23 and 23 and the fluid resistance values of the fluid resistance portions 23 and 23 are the same, the fluid resistance portions 23 and 23 The flowing ink reaches the nozzle 15 at the same time,
The air in the pressurized liquid chamber 17 can be completely removed.

In this case, the fluid resistance portions 23, 23 on both sides may be formed so that the fluid resistance values thereof are equivalent. If the distance between the pressurized liquid chamber rows 17A, 17B cannot be sufficiently obtained, Instead of making the width of the inner fluid resistance part 23 smaller than the width of the outer fluid resistance part 23, the inner fluid resistance part 23
Is made higher than the height of the outer fluid resistance portion 23, the fluid resistance values of the two fluid resistance portions 23, 23 can be made equivalent.

For example, the fluid resistance value of the fluid resistance portion 23 of the lower liquid chamber flow path forming member 20 is as follows: width W: 0.03 mm, height H: 0.06 mm, and length L: 0.25 mm. At this time, since the equivalent radius R is obtained by the above-described formula 1, R =
0.02, and therefore, the fluid resistance value Rf is calculated from the above-mentioned formula 2 as Rf = 3.98 × 10 12 (pas · S / m
3)

Here, when the distance between the rows of pressurized liquid chambers is reduced to reduce the size of the head, and the width of the inner fluid resistance portion 23 is set to 0.1 mm, which is shorter than the width of the outer fluid resistance portion 23, From the formulas 1 and 2, R '= 1.25R = 0.0
25 mm. From this, when H = 0.06 mm,
W = 0.043 mm.

Here, the nozzle 15 is connected to the pressurized liquid chamber 17.
And the fluid resistance portions 23 on both sides,
23, the nozzles 15 are formed so as to be displaced from the center of the pressurized liquid chamber 17 in the longitudinal direction (between the fluid resistance portions 23 on both sides) as shown in FIG. In this case, the same effect can be obtained even if the fluid resistance values of the fluid resistance portions 23 on both sides (inside and outside) are made different according to the amount of deviation from the center of the nozzle position.

For example, in the example shown in FIG. 9, the nozzle position is shifted from the center toward the inner common liquid chamber 24b, and at this time, the fluid resistance value of the fluid resistance portion 23 communicating with the inner common liquid chamber 24b is changed. Set large, outside common liquid chamber 2
The fluid resistance value of the fluid resistance part 23 communicating with 4a is set small. Thus, when the ink is supplied from the outer common liquid chamber 24a and the inner common liquid chamber 24b to the pressurized liquid chamber 17 via the fluid resistance part 23, the ink simultaneously reaches the nozzle 15 and Bubbles inside are completely removed.

Next, another example of the liquid chamber configuration of the liquid chamber unit 2 will be described with reference to FIGS. First, in the example shown in FIGS. 10 to 12, the liquid chamber flow path forming member 13 is placed between the lower liquid chamber flow path forming member 20 and the upper liquid chamber flow path forming member 21. And a pressurized liquid chamber forming portion of the lower liquid chamber channel forming member 20, the intermediate liquid chamber channel forming member 22, and the upper liquid chamber channel forming member 21 is shortened in the longitudinal direction. Forming step 17a
Is provided so that the height of the flow path from the fluid resistance portion 23 to the nozzle 15 increases stepwise in the direction in which the ink flows.

In the example shown in FIG. 13, the fluid resistance portion 23 is formed in the liquid chamber flow path forming member 33, and the wall surface 33a from the fluid resistance portion 23 to the nozzle plate 16 is formed in a tapered shape. The height of the flow path from the fluid resistance portion 23 to the nozzle 15 in the direction in which the ink flows is formed so as to increase linearly (gradiently).

As in these examples, by making the shape of the fluid resistance portion 23 on the side of the pressurized liquid chamber 17 stepwise or tapered, ink flows from the fluid resistance portion 23 into the pressurized liquid chamber 17. When the flow path does not suddenly expand, the flow path gradually expands, so that the generation of eddies due to the flow can be prevented, the generation of air bubbles can be suppressed, and air bubbles adhere to the corners Is prevented and a smooth flow is obtained.

Also, as shown in FIG. 3, FIG. 10 or FIG. 12, by disposing the position of the fluid resistance portion 23 on the lowermost surface in the height direction of the pressurized liquid chamber 17, for example, as shown in FIG.
As shown in FIG. 2, a peeling force is applied to the bubbles B attached to the surface of the vibration plate 12, and the discharge efficiency is improved. On the other hand, when the fluid resistance portion 23 is arranged at an intermediate position in the height direction of the pressurized liquid chamber 17 as shown in FIG. 13, the peeling force acts only by the ink flowing on the surface of the bubble B. Bubbles remain.

The present invention is not limited to the ink jet head using the displacement of the piezoelectric element in the direction perpendicular to the direction of the electric field (displacement in the direction d33), but the displacement (d31) in the same direction as the direction of the electric field.
Directional displacement). Further, in the above-described embodiment, an example in which the opening direction of the nozzle is applied to a side shooter type ink jet head coaxial with the displacement direction of the piezoelectric element has been described, but the opening direction of the nozzle is orthogonal to the displacement direction of the piezoelectric element. The invention can also be applied to an ink jet head of an edge shooter type which is oriented.

[0061]

As described above, according to the ink jet head of the first aspect, the ink flows to both sides of each pressurized liquid chamber row in the column direction.
Common flow path that communicates with the pressurized liquid chamber via the body resistance part
Is provided, and a partition is provided between each pressurized liquid chamber row,
Separate the common liquid chamber, and set each of the common flow paths on both sides of the
A distribution part for equalizing the fluid resistance value and distributing the supplied ink to the common flow path on both sides of each of the pressurized liquid chamber rows was formed at the center in the direction orthogonal to the row direction of each of the pressurized liquid chamber rows. Therefore, ink is simultaneously distributed and supplied from the distribution unit to each pressurized liquid chamber through each of the common liquid chambers having the same fluid resistance value and each fluid resistance unit, and the air in the pressurized liquid chamber is completely discharged at the time of initial ink filling , and the Quality is improved.

According to the ink jet head of the second aspect, in the ink jet head of the first aspect, each common
Since the channels are respectively connected to the dummy nozzles, the bubbles in the common liquid chamber can be discharged, and the equivalent fluid resistance value of the common liquid chamber can be maintained.

According to the ink jet head of claim 3, in the ink jet head of claim 2, the dummy
Nozzle is smaller than the image forming nozzle
As a result, ink loss when discharging bubbles is reduced.

[0064] inkjet head according to claim 4, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
And the fluid resistance of the fluid resistance portions in both directions.
Since the resistance value is made the same, the ink can simultaneously reach the nozzles and discharge the air in the pressurized liquid chamber.

[0065] inkjet head according to claim 5, wherein
Item 1. The ink jet head according to any one of Items 1 to 3,
The nozzle in a central position between the fluid resistance portions in the two directions.
It is formed in a position where it is not placed, and the fluid in both directions
The fluid resistance value of the resistance part was changed according to the nozzle position
Even if the nozzle is at a position shifted from the center position,
The ink reaches the nozzles at the same time, and the air in the pressurized liquid chamber can be discharged.

[0066] inkjet head according to claim 6, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
The height of the flow path from the fluid resistance section to the nozzle
Since it is formed by changing the angle or gradient, it is possible to prevent the generation of a vortex due to the ink flow and to prevent the adhesion of air bubbles to the corners.

[0067] inkjet head according to claim 7, wherein
Item 1. The ink jet head according to any one of Items 1 to 5,
Between the fluid resistance part and the nozzle in the height direction of the pressurized liquid chamber.
Since they are provided in different directions, air bubbles adhering to the bottom surface of the pressurized liquid chamber can be separated and discharged.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an inkjet head showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG. 1;

FIG. 3 is a sectional view taken along the line AA in FIG. 1;

FIG. 4 is a sectional view taken along the line BB of FIG. 1;

FIG. 5 is a plan view showing a liquid chamber configuration of the liquid chamber unit.

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is a perspective view illustrating a relationship between a pressurized liquid chamber and a nozzle.

FIG. 8 is a plan view showing a liquid chamber configuration of another liquid chamber unit.

FIG. 9 is a perspective view illustrating a relationship between another pressurized liquid chamber and a nozzle.

FIG. 10 is a front sectional view showing a liquid chamber configuration of still another liquid chamber unit.

FIG. 11 is a side sectional view of FIG. 10;

FIG. 12 is a bottom view of FIG. 11;

FIG. 13 is a front sectional view showing a liquid chamber configuration of still another liquid chamber unit.

FIG. 14 is a cross-sectional view for explaining the relationship between the position of the fluid resistance portion and bubbles.

[Explanation of symbols]

1. Actuator unit, 2. Liquid chamber unit, 3.
Substrate, 4 ... piezoelectric element row, 5 ... frame, 7 ... drive section piezoelectric element, 8 ... fixed section piezoelectric element, 11 ... diaphragm section, 1
2: Vibrating plate, 13, 33: Liquid chamber flow path forming member, 15: Nozzle, 16: Nozzle plate, 17: Pressurized liquid chamber, 20:
Lower liquid chamber flow path forming member, 21 ... upper liquid chamber flow path forming member,
22: intermediate liquid chamber flow path forming member, 23: fluid resistance part, 24
a: outer common liquid chamber (common flow path), 24b: inner common liquid chamber (common flow path), 25: partition, 26: ink supply port, 2
7 ... distribution path, 27a, 27b ... distribution section, 28 ... dummy nozzle.

Continuation of the front page (56) References JP-A-4-235057 (JP, A) JP-A-63-252749 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2 / 045 B41J 2/055

Claims (7)

(57) [Claims] A plurality of nozzle rows each including a plurality of nozzles, and a plurality of pressurized liquid chamber rows each including a plurality of pressurized liquid chambers facing the plurality of nozzles of each nozzle row;
In the inkjet head to which ink is supplied via the fluid resistance part from both directions to the respective pressurized liquid chambers, each pressure
Each of the pressure fluid chamber rows is provided on both sides in the row direction through the fluid resistance section.
And a common flow path communicating with the pressurized liquid chamber is provided.
A partition is provided between rows to separate the common liquid chamber of the pressurized liquid chamber row.
And each fluid resistance value of the common flow path on both sides of the pressurized liquid chamber row
And a distributor for distributing the supplied ink to the common flow path on both sides of each of the pressurized liquid chamber rows is formed at the center in a direction orthogonal to the row direction of each of the pressurized liquid chamber rows. Inkjet head. 2. The ink jet head according to claim 1,
In the above, each of the common flow paths is respectively used as a dummy nozzle.
An ink jet head characterized in that it is communicated. 3. The ink jet head according to claim 2,
In the above, the dummy nozzle is more than the image forming nozzle.
The ink jet nozzle is characterized by having a small nozzle diameter
Jet head. 4. The in-line according to claim 1, wherein
In a jet head, the nozzle is moved in both directions.
Formed at a central position between the fluid resistance parts,
The characteristic is that the fluid resistance value of the fluid resistance part of
Inkjet head. 5. The in-line according to claim 1, wherein
In a jet head, the nozzle is moved in both directions.
When formed at a position shifted from the center position between the fluid resistance parts
In both cases, the fluid resistance value of the fluid resistance section in both directions is set at the nozzle position.
Inkjet characterized by different arrangements
head. 6. The in-line device according to claim 1, wherein
In a jet head, a nozzle is provided from the fluid resistance portion.
Formed by changing the height of the flow path up to
An ink jet head, characterized in that: 7. The in-line according to claim 1, wherein
In a jet head, the fluid resistance portion and the nozzle
Are provided differently in the height direction of the pressurized liquid chamber.
Inkjet head.