JPH0624000A - Ink jet head - Google Patents

Abstract

PURPOSE:To remove deteriorated ink and a bubble in an ink chamber effectively simply outside the ink chamber. CONSTITUTION:An ink chamber 2 having an ink discharge opening has a first and second ink feed openings 11, 13. The first ink feed opening 11 is interconnected to a first reservoir 12, and the second ink feed opening 13 is interconnected to a second reservoir 14. Resistance of a passage from the second ink feed opening 13 to the ink discharge opening 5 is so constructed as to be less than resistance of a passage from the first ink feed opening 11 to the ink discharge opening 5.

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 for ejecting ink droplets according to a print signal to form an ink image on a recording medium such as a recording paper, and particularly for ejecting ink droplets only when necessary. The present invention relates to a demand type inkjet head.

[0002]

2. Description of the Related Art As an on-demand type ink jet head for ejecting ink droplets only when necessary, there is a method of ejecting ink from an ink ejection port by applying electric energy to a piezoelectric element to deform the piezoelectric element to increase the pressure in an ink chamber, and heat generation. A method is generally known in which electric energy is applied to the body and the pressure of the ink chamber is increased by the expansion of the ink vaporized by heat generation to eject the ink from the ejection port.

As means for supplying ink to the ink chamber,
As in Japanese Patent Publication No. 3-57869 shown in FIG. 10, it has a plurality of ink ejection ports 1003 and a common liquid chamber 1002 communicating with the ink chambers formed corresponding to each of them. Two ink flow paths are connected to the common liquid chamber and are independently connected to the ink tanks. A pressure fluctuation means for generating an ink flow is installed in the middle of the first ink flow path 1013, and a backflow prevention valve is arranged between the pressure fluctuation means and the inkjet head, and between the ink tank and the pressure generation means. First ink channel 1013, common liquid chamber 1002, second ink channel 101
4. Ink flow is generated only in the order of the ink tanks,
A method of initially filling or circulating ink in a head is disclosed.

With such a structure, when bubbles or dust are mixed in the ink jet head and the ejection becomes unstable, the ink is circulated between the ink tank and the head to remove the bubbles or dust. It is possible to move the ink from the head to the ink tank and recover the stable ejection state.

Further, in order to obtain the same effect, as in Japanese Patent Publication No. 3-71021 shown in FIG. 11, there are two ink tanks, and the first ink tank 1101 through the first opening / closing means 1150. Inkjet head 1104
And a second ink supply passage 1172 communicating with the inkjet head 1104 from the first ink tank 1101 via the pump 1156 and the second opening / closing means 1154. The second ink tank 1140 communicates with the second ink supply passage 1172 between the above-mentioned pump 1156 and the second opening / closing means 1154 via the backflow prevention means 1158. The first ink tank 1101 is equipped with a third opening / closing means 1152 capable of opening to the atmosphere. The pump 1156 can be operated in forward and reverse directions, and when supplying ink from the second ink tank 1140 to the first ink tank 1101, the first opening / closing means 1150 and the third opening / closing means 1152 are opened, and the second opening / closing means 1152 is opened.
The opening / closing means 1154 is closed, and the pump 1156 is moved from the second ink tank 1140 to the first ink tank 1101.
Rotate forward so that it flows to. Further, in order to remove air bubbles, dust, etc. mixed in the head from the head, the first, second and third opening / closing means 1150. 1152, 115.
4 is opened and the pump 1140 is rotated in the reverse direction opposite to the direction described above. When the ink ejection port is clogged due to drying or the like, the first opening / closing means 1150 is closed, the second and third opening / closing means 1152, 1154 are opened, and the pump is rotated in the reverse direction to rotate the second ink. The head is pressurized from the supply path 1172 and the ink can be pushed out from the ink ejection port and eliminated.

[0006]

However, in the above-mentioned prior art, only one ink supply port is provided to the ink chamber, and when air bubbles, dust or the like is mixed in the ink chamber. The only option was to remove the ink from the ink outlet. Therefore, there are problems that the amount of ink not related to printing is large, the running cost is high, and the mechanism for processing the removed ink is complicated. Furthermore, when a pigment is used as the color material of the ink and an ink of a system dispersed in a solvent is used, the pigment may agglomerate in the ink chamber and the particle size may increase. In such a case, there is a possibility that it will be impossible to remove the increased pigment from the ink ejection port, and there is a possibility that the inkjet head will fail.

Further, in order to switch each mode such as printing, ink supply, circulation, pressurization, etc., a pressure changing means and a plurality of opening / closing means are required, which causes the apparatus to become complicated and large.

[0008]

The ink jet head of the present invention is an ink jet head in which the pressure of an ink chamber is increased to eject an ink droplet from an ink ejection port, wherein the ink chamber has a first ink supply port and a second ink port. 2 of the supply port
A second reservoir having two ink supply ports, a first reservoir communicating with the first ink supply port and a second reservoir communicating with the second ink supply port, and the second ink supply The channel resistance from the mouth to the ink ejection port is smaller than the channel resistance from the first ink supply port to the ink ejection port. In addition, the flow path resistance from the first ink supply port to the ink discharge port is substantially equal to or higher than the flow path resistance of the ink discharge port, and the flow path resistance from the second ink supply port to the ink discharge port is increased. The flow path resistance to reach is smaller than the flow path resistance of the ink ejection port. In addition, pressure fluctuation means for generating a pressure gradient between at least the first reservoir and the second reservoir is provided,
A first circulation mode of flowing ink to the second reservoir via the ink supply port, the ink chamber, and the second ink supply port of
It has a control means for selectively switching a second circulation mode in which ink is supplied from the second reservoir to the first reservoir via the second ink supply port, the ink chamber, and the first ink supply port. To do.

[0009]

1 is a perspective view showing the construction of an embodiment of an ink jet print head of the present invention, FIG. 2 is a sectional view showing the ink ejection portion of this embodiment, and FIG. 3 is a construction of the ink chamber of this embodiment. FIG. 4 is a schematic perspective view showing the upper surface, and FIG. 4 is a schematic view showing an ink supply path to the print head. The print head of this embodiment is a so-called line head having a width substantially the same as the print width of the print medium, and the ink discharge ports are arranged in a line.

In these figures, reference numeral 1 denotes a print head, which increases the pressure of the ink 3 in the ink chamber 2 by driving the piezoelectric element 4 and ejects it as an ink droplet from the ink ejection port 5. The piezoelectric element 4 is the first fixing plate 6
a is fixed by being sandwiched between the second fixing plate 6b and the first fixing plate 6b.
A drive circuit 7 for applying a drive signal as a voltage to the piezoelectric element 4 is provided on the fixed plate 6a. Ink chamber 2
Is formed so as to be surrounded by a vibrating plate 10 and a wall 9 that separates the ink chambers adjacent to the nozzle plate 8 in which the ink ejection ports 5 are formed. The piezoelectric element 4 is fixed to the vibrating plate 10, and the deformation of the piezoelectric element 4 causes the vibrating plate 10 to be displaced, increasing the pressure in the ink chamber 2 and ejecting ink from the ink ejection port. The ink chamber 2 communicates with the first reservoir 12 via the first supply port 11,
The ink 3 is supplied from the reservoir 12 to the ink chamber 2. The first reservoir 12 communicates with the ink tank 16 via the first ink supply passage 15.
Although FIG. 4 shows a state in which the nozzle plate 8 is removed for simplification, the ink ejection port 5 is shown for convenience.

Further, the ink chamber 2 has a first supply port 11
The second supply port 13 is provided at a position opposed to.
The ink chamber 2 and the second reservoir 14 communicate with each other through the second supply port 13, and the ink 3 is also supplied from the second reservoir 14 to the ink chamber 2.
The second reservoir 14 communicates with the ink tank 16 via the second ink supply passage 18.

As shown in FIG. 4, the first ink supply path 1
In the middle of 5, there is arranged a pressure fluctuation means 17 comprising, for example, a gear pump. The pressure fluctuating means 17 is capable of rotating in the forward and reverse directions.
5, pressure is applied to the ink chamber 2 via the first reservoir 12 and the first ink supply port 11. Also, the pressure fluctuation means 1
When 7 is reversed, pressure is applied to the ink chamber via the ink tank, the second ink supply passage, the second reservoir, and the second ink supply port.

The flow path resistance Rp ₁ from the first ink supply port 11 to the ink discharge port 5 shown in FIG. 2 is higher than the flow path resistance Rn of the ink discharge port 5 from the second ink supply port 13. The flow path resistance Rp ₂ reaching the ink ejection port is configured to be lower than the flow path resistance Rn of the ink ejection port 5. Since the pressure fluctuation speed of the pressure fluctuation means 17 is very slow and is considered to be almost static pressure, the flow rate of the ink is substantially determined by the pressing force, the flow path resistance of each part, and the pressurization time.
The flow path resistance Rp from the ink supply port to the ink ejection port is
In the shape of the ink chamber as in this embodiment, the following Equation 1 is used.
It is expressed as.

[0014]

[Equation 1]

Here, η is the viscosity of the ink, Lp is the length from one ink supply port to the ink ejection port, and Wp
Is the width of the ink chamber, and dp is the thickness of the ink chamber. Also,
The flow path resistance Rn of the ink ejection port is generally represented by the following Expression 2.

[0016]

[Equation 2]

Here, Dn is the diameter of the ink ejection port, and tn is the length of the ink ejection port. Dn has a shape that changes depending on the thickness direction x of the ink ejection port. In the present embodiment, the flow path resistance R of the ink ejection port 5
n is about 6 × 10 ¹² N · S / m ⁵ , and the flow path resistance Rp ₁ from the first ink supply port to the ink ejection port is about 1 × 10 ¹³ N.
S / m ⁵ , and the flow path resistance Rp ₂ from the second ink supply port 13 to the ink ejection port is formed to be about 3 × 10 ¹¹ N · S / m ⁵ . In addition, the first and second reservoirs 1
The flow path resistances 2 and 14 are formed in a shape that is smaller than the flow path resistance Rp ₂ from the second ink supply port 13 to the ink discharge port by two digits or more. That is, the flow path resistance Rp ₁ from the first ink supply port 11 to the ink discharge port is 1.7 times the flow path resistance Rn of the ink discharge port 5, and the flow from the second ink supply port 13 to the ink discharge port. The path resistance Rp ₂ is 1/20 times the flow path resistance Rn of the ink ejection port 5.

With such a structure, the pressure fluctuating means 17 is normally rotated to increase the pressure of the first reservoir 12, so that the ink in the ink chamber 2 is supplied to the first ink supply port 11 and the ink chamber 2. Ink can be made to flow to the second reservoir 14 through the second supply port 13, and bubbles in the ink chamber 2 or ink that has deteriorated due to increased viscosity can be removed to the outside of the ink chamber. By increasing the pressure in the ink chamber 2, the ink flows from the second supply port 13 to the second reservoir 14, and the head 1 is also discharged from the ink ejection port 5.
It is discharged outside. However, according to the present invention, the flow path resistance Rn of the ink ejection port 5 is much larger than the flow path resistance Rp ₂ from the second ink supply port 13 to the ink ejection port.
As described above, since the pressure is considered to be almost static pressure, in this embodiment, the amount of ink ejected from the ink ejection port 5 is almost the same as the amount of ink flowing to the second reservoir 14 via the second supply port 13. It can be extremely reduced to 5%.

When the ink ejection port 5 is deteriorated by clogging due to ink drying or the like and is not recovered by the above-described ink circulation, it is necessary to eject the deteriorated ink from the ink ejection port 5 to the outside of the head. In this case, by reversing the pressure changing means 17 in the opposite direction to the above, it is possible to easily discharge the ink from the ink ejection port 5. That is, the flow path resistance Rp ₁ from the first ink supply port 11 to the ink discharge port is larger than the flow path resistance Rn of the ink discharge port 5. The ink pressure in the ink chamber 2 is the second
By being pressurized from the reservoir 14, the ink flows in the direction of the ink ejection port 5 and in the direction of the first reservoir 12 from the first ink supply port 11. At this time, the pressure applied to the ink ejection port 5 is approximately the ratio of the applied pressure to the flow channel resistance Rn of the ink ejection port 5 and the flow channel resistance Rp ₁ from the first ink supply port 11 to the ink ejection port. It is determined. In this embodiment, the amount of ink discharged to the ink ejection port 5 is 1.7 times the amount of ink flowing from the first ink supply port 11 to the first reservoir 12. FIG. 5 shows the pressure fluctuation means 17
Is a calculated value and an actually measured value showing the relationship between the pressing force, the discharge amount from the ink ejection port 5, and the circulation amount of ink flowing from the second ink supply port to the second reservoir when the ink is normally rotated for 1 second. In the figure, the solid line is the regression line obtained by regressing the experimental value by the least squares method, and the broken line is the calculated value. Further, FIG. 6 shows the relationship between the pressing force, the discharge amount from the ink discharge port 5, and the ink circulation amount flowing from the first ink supply port to the first reservoir when the pressure changing means 17 is reversed for 1 second. Calculated and measured values. Similar to FIG. 5, the solid line is the measured value and the broken line is the calculated value. 5 and 6 show the calculation and experimental results in the case where there is one ink ejection port for the sake of simplicity, similar results can be obtained with an inkjet head having a plurality of ink ejection ports.

Next, the printing state, the ink circulation and the ink discharge timing in this embodiment will be described.

During printing, the air release valve 20 installed in the ink tank 16 is opened, and the ink in the ink tank 16 is supplied to the print head while being replaced with air. A filter is inserted in the atmosphere release valve 20 to prevent dust from entering. At this time, the gear portion of the gear pump of the pressure changing means 17 separates from each other so that the ink flow in the ink supply path 15 is not hindered.

For the ink circulation, the pressure fluctuation means 17 should be rotated normally when the power is turned on to the printing apparatus equipped with the print head of this embodiment and when a predetermined time has elapsed from the time when the previous ink circulation was carried out. It is carried out by. For ink circulation when the power is turned on, the ink ejection port 5 is covered with a cap (not shown) to prevent the ink from being discharged to the outside of the print head 1. The pressurizing condition at this time is such that at least all the ink in the ink chamber 2 is removed to the outside of the ink chamber and the pressurizing force is 0.5 kg / c so as to replace the ink in the reservoir.
m ² and pressurizing time are set to 2 seconds. However, even during printing, in the ink chamber corresponding to the ink ejection port that is not printed, the ink in the ink chamber is deteriorated such as sedimentation of the coloring material. Such ink needs to be removed outside the ink chamber. The printing apparatus equipped with the print head of the present embodiment has a timer for measuring the time interval of ink circulation, and when the preset time is reached, the ink circulation operation is carried out. Further, the cap that covers the ink ejection port is automatically applied when a print signal is not input to the present printing device for a set time after the printing on the print medium is completed. If the cap is applied when the set time of the ink circulation interval is reached, the ink circulation condition is set to 0.5 kg / cm ² , which is the same as when the power is turned on, for 2 seconds. There is. If the cap is not applied when the set time of the ink circulation interval is reached, 0.2 kg / c
m ² , 0.5 seconds. In addition,
If printing is in progress when the set time of the ink circulation interval is reached, the ink circulation operation is performed at the stage when the printing of one recording medium is completed.

By setting in this way, it is possible to make the reduction in the printing speed on the print medium due to the ink circulation operation extremely small. That is, when the set time for ink circulation is reached during printing of a plurality of print media, it is not necessary to cover the ink ejection port with the cap means, and the printing is stopped only for 0.5 seconds of the ink circulation operation. Good. At this time, the amount of ink discharged from the ink ejection port is extremely small, the amount of ink not used for printing can be reduced, and a printing device with low running cost can be provided. During ink circulation,
Atmosphere release valve 20 installed in the ink tank 16
Is designed to be closed.

Next, the timing for discharging ink will be described. When the power of the printing apparatus is turned on, the ink around the ink ejection port 5 may be deteriorated and the ink ejection port 5 may be clogged, so that the forced ink ejection is automatically performed. This is carried out by reversing the pressure fluctuation means 17. According to the experiment, at the ink ejection port where the ink ejection operation has not been performed for a long period of time, the pressure in the ink chamber 2 is increased to 0.2 kg / cm ² higher than the atmospheric pressure, and the pressure is applied for 0.5 seconds. By performing the process several times, it is possible to recover the clogging of the ink ejection port.

For example, a pressure of 0.2 kg / cm ² is 0.5
When the pressurizing operation is performed 5 times per second, the amount of ink discharged from the ink discharge port 5 is about 5 mcc per nozzle.
In addition, when the print quality is abnormal, such as missing print, etc., other than when the power of the device is turned on, for example, the operator operates a switch on the device panel to discharge the ink and recover the ink discharge port. Can be carried out. Since the present printing apparatus is equipped with a timer for measuring time, it is possible to set the time interval for ink discharge to be measured and to discharge the ink when a predetermined time has elapsed. At the time of discharging the ink, the atmosphere release valve 20 installed in the ink tank 16 is closed.

FIG. 7 shows a schematic diagram of the ink flow path configuration of the second embodiment of the present invention. An ink chamber 102 communicates with the first reservoir 111 and the second reservoir 114. FIG. 7 illustrates a state in which the nozzle plate is removed for simplicity, but the position of the ink ejection port 105 is illustrated for convenience. In the above-described embodiments, the pressure fluctuation means 17 is normally and reversely rotated to switch the ink circulation and the ink discharge, but as shown in FIG. 7, in the second embodiment, in the first supply path 115. And pressure fluctuation means 117 and 118 are respectively arranged in the second supply path 119.
At this time, the pressure changing means 117 and 118 are composed of, for example, a cylinder pump and a check valve, and can pressurize only in one direction as shown by an arrow in FIG. First
The flow path 123 is formed in parallel with the pressure fluctuation means 117, and the second valve 122 that can be arbitrarily opened and closed is arranged on the way. In addition, a flow path 121 is formed in parallel with the second pressure changing means 118, and a first valve 120 that can be arbitrarily opened and closed is arranged on the way. An air release valve 124 is installed in the ink tank 116. In such a case, during ink circulation, the second pressure changing means 118 in the second ink supply path 119 is operated, the first pressure changing means 117 in the first ink supply path 115 is stopped, and the first pressure changing means 117 is stopped. The ink circulation operation is performed by closing the valve 120 and closing the second valve. When the ink is discharged, the first pressure changing means 117 is operated and the second pressure changing means 1 is operated.
Ink is discharged by stopping 18 and closing the second valve 122. In printing, the first and second pressure fluctuation means 117 and 118 are stopped and the first and second valve 1
By opening 20, 122 and opening the atmosphere release valve 124,
Ink is naturally supplied to the ink chamber 102.

FIG. 8 shows a cross section of the ink ejection portion of the third embodiment of the present invention. In the first embodiment described above, the first ink supply port and the second ink supply port were formed flat, but in the present embodiment, the first ink supply port 211 is parallel to the ink ejection direction. It is located in. Reference numeral 212 denotes a first reservoir, which communicates with the ink chamber 202 via the first ink supply port 211. Reference numeral 214 denotes a second reservoir, which is connected to the ink chamber 2 via the second ink supply port 213.
It is connected to 02. The flow path resistance Rp ₂₁ from the first ink supply port 211 to the ink ejection port 205 is expressed by the following equation 3.

[0028]

[Equation 3]

Here, η is the ink viscosity, Lp is the length of the first ink supply port 211 to the ink ejection port 205, Wp is the width of the ink chamber 202, Dp is the depth of the ink chamber, and Li is the first ink. The length of the supply port 211, Di is the ink supply port 2
11 diameters.

The flow path resistance Rp ₂₂ from the second ink supply port 213 to the ink discharge port 205 and the flow path resistance Rn ₂ of the ink discharge port 205 are expressed by the equations 2 and 3 as in the first embodiment. It

In this embodiment, Rp ₂₁ , Rp _22, and Rn
Are formed so as to be the same as in the first embodiment.

FIG. 9 is a top perspective view showing the ink ejection portion of the fourth embodiment of the present invention. Note that the ink ejection port 305 is illustrated for convenience. The fourth embodiment is an example in which the ink chambers are arranged in a plurality of rows, in this embodiment four rows are arranged. The spacing between the rows of ink ejection ports is formed to be four times the spacing between dots printed on the print medium, and the spacing between the rows of ink ejection ports in the Y direction is the same as the spacing between dots. Is formed. The distance between the ink ejection ports in the X direction between columns is n times the distance between dots (however,
Is a natural number), and in the present embodiment, n = 32. By moving the head configured as described above along the width direction of the print medium, desired characters or graphics are printed on the entire print range of the print medium. In the drawing, 305 is an ink ejection port, and the ink chambers 301, 30
The ink pressures of 2, 303 and 304 are increased by a pressure generating element (not shown), and the ink is ejected as ink droplets. First-row ink chambers 301, 301, 30
, 1 are connected to the first reservoir 314 via the first ink supply port 311. In addition, a second ink supply port 313 is formed at a position facing the first ink supply port 311 and communicates with the second reservoir 312.
The ink chambers 302, 302, 302, ... Of the second row are in communication with the above-mentioned second reservoir 312 via a second ink supply port 313. Further, the first supply port 311 is formed at a position facing the second ink supply port 313,
It is in communication with the third reservoir 315. Similarly, the ink chambers 303 and 304 in the third and fourth rows are similarly provided with the third and fifth reservoirs 315 through the first ink supply port 311 respectively.
A second ink supply port 313 is formed at a position facing the first ink supply port 311 in 317, and communicates with the fourth reservoir 316. The first, third, and fifth reservoirs 314, 315, and 317 communicate with each other at the second connecting portion 322, and the second and fourth reservoirs 312 and 316.
Also communicate with each other at the first connecting portion 321. The first connecting portion 321 communicates with the first ink supply passage 331, and the first ink supply passage 331 is connected to an ink tank (not shown) via a pump (not shown) on the way. The second connecting portion 322 communicates with the second ink supply passage 332, and is connected to the above-mentioned ink tank (not shown).

The flow path resistance Rp ₃₁ from the second ink supply port 313 to the ink ejection port 305 is the first ink supply port 3
11 is smaller than the flow path resistance Rp ₃₂ from the ink discharge port 305 to the ink discharge port 305, and the flow path resistance Rp ₃₁ from the first ink supply port 311 to the ink discharge port 305 is the flow path resistance of the ink discharge port 305. It is formed so as to be almost equal to the resistance Rn. By configuring in this way,
The same effect as that of the first embodiment can be obtained even when a plurality of rows of ink ejection ports are arranged.

In the above description, the laminated piezoelectric element is used as the pressure generating means, but the present invention is not limited to this, and for example, the heating element is arranged at a position corresponding to the ink ejection port, and the ink is ejected. Inkjet head that ejects ink by pressure due to vaporization of the ink, or by stacking a plate-shaped piezoelectric element and a vibrating plate, stretching vibration of the piezoelectric element is converted into flexural vibration, and ink is ejected by pressurizing the ink pressure in the ink chamber. It is apparent from the above description that the same effect can be obtained with the inkjet head.

[0035]

As described above, according to the present invention, it is possible to minimize the discharge of the ink, which is deteriorated in the ink chamber, for example, the sedimentation of the coloring material occurs outside the head, to the inside of the ink chamber. It is possible to replace the ink with the ink in the reservoir. Further, during the replacement operation, no additional operation such as covering the ink ejection port such as the cap is required, so that the print interruption time during the printing can be extremely shortened and the printing apparatus having a high printing speed can be provided.
In addition, ink circulation, discharge,
Since each mode such as printing can be set, simplification of the device and cost reduction can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of an inkjet head of the present invention.

FIG. 2 is a partial cross-sectional view of an ink ejection portion of the above embodiment.

FIG. 3 is a partial perspective view showing the shape of the ink chamber of the above embodiment.

FIG. 4 is a schematic diagram showing an ink supply path of the embodiment.

FIG. 5 is a diagram showing a relationship between a pressurizing force during ink circulation and an ink flow rate in the same embodiment.

FIG. 6 is a diagram showing a relationship between a pressurizing force at the time of discharging ink and an ink flow rate in the same embodiment.

FIG. 7 is a schematic diagram showing an ink supply path of a second embodiment of the present invention.

FIG. 8 is a partial sectional view showing a third embodiment of the present invention.

FIG. 9 is a partial perspective view showing a fourth embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a configuration of a conventional inkjet head.

FIG. 11 is a cross-sectional view showing a configuration of a conventional inkjet head.

[Explanation of symbols]

1 ... Print head 2, 202, 301, 302, 303, 304 ... Ink chamber 3 ... Ink 4 ... Piezoelectric element 5, 205, 305 ... Ink ejection port 10 ... Vibration plate 11, 211, 311 ... First ink supply port 12, 212, 312 ... First reservoir 13, 213, 313 ... Second ink supply port 14, 214, 314 ... Second reservoir 15, 331 ... First ink supply passage 16 ... Ink tank 17, 117, 118 ... Pressure fluctuation means 18, 332 ... Second ink supply passage 315 ... Third reservoir 316 ... Fourth reservoir 317 ... Fifth reservoir 321 ... First connecting part 322 ... Second connecting part

Claims (3)

[Claims] 1. An inkjet head for increasing the pressure of an ink chamber to eject an ink droplet from an ink ejection port,
The pressure chamber has two ink supply ports, a first ink supply port and a second ink supply port, and communicates with a first reservoir and the second ink supply port, which communicate with the first ink supply port. And a flow path resistance from the second ink supply port to the ink ejection port is smaller than a flow path resistance from the first ink supply port to the ink ejection port. Characteristic inkjet head. 2. The flow path resistance from the first ink supply port to the ink discharge port is substantially equal to or higher than the flow path resistance of the ink discharge port, and the ink is discharged from the second ink supply port. The ink jet head according to claim 1, wherein the flow path resistance to the outlet is smaller than the flow path resistance of the ink ejection port. 3. A pressure fluctuation means for generating a pressure gradient between at least a first reservoir and a second reservoir, the first ink supply port, the ink chamber, and the second ink supply from the first reservoir. A first circulation mode of flowing ink to the second reservoir through the mouth and a second circulation mode from the second reservoir.
3. The control means for selectively switching the second circulation mode in which the ink is supplied to the first reservoir via the ink supply port, the ink chamber, and the first ink supply port. Inkjet head.