JP2002079664A - Ink jet head and ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pressure chamber 4 from being adversely effected by a propagating pressure wave propagating in an ink supply channel 11 and its reflecting wave which are generated in association with the action of a piezoelectric actuator 21 for discharging ink drops. SOLUTION: A branching channel 16 is set to a diaphragm of the ink supply channel 11 between a supply port 3a and an end part 11a of the ink supply channel 11. A depth D of the branching channel 16 is set to satisfy D=(2n-1)λ/4 (n is a natural number) when a wavelength of the propagating pressure wave is λ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet head and an ink jet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, ink jet heads include:
Although an ink supply flow path for supplying ink to a pressure chamber in which a nozzle for ejecting ink droplets is formed is provided,
For example, Japanese Patent Application Laid-Open No. 9-314836 discloses a configuration in which a part of the partition wall of the ink supply flow path is configured to have flexibility. In this apparatus, a partition wall near a supply port that connects the ink supply flow path and the pressure chamber is formed of a flexible wall having flexibility, so that when the actuator is driven to eject ink droplets, It is attempted to prevent the pressure in the vicinity of the supply port in the ink supply flow path from rising due to the pressure fluctuation in the pressure chamber caused by the pressure fluctuation.

[0003]

By the way, the pressure fluctuation in the pressure chamber is transmitted to the ink supply channel, and the pressure wave propagates in the ink supply channel. This pressure wave is reflected at the end face of the ink supply flow path, and the reflected wave returns to the supply port of the ink supply flow path. When the reflected wave returns to the vicinity of the supply port, the reflected wave (pressure wave) is transmitted to the pressure chamber,
For example, the meniscus in the nozzle may be vibrated, or the supply of the ink to the pressure chamber may be adversely affected, thereby deteriorating the recording quality. In particular, when the actuator is driven at a high frequency, the adverse effect on the pressure chamber due to the reflected wave may be further remarkable.

However, in the conventional ink jet head having the above-described flexible wall, only the pressure near the supply port in the ink supply flow path is reduced, and the pressure wave propagating through the ink supply flow path and its reflected wave cause the pressure wave to propagate. There is a problem that the adverse effect on the pressure chamber cannot be avoided.

The present invention has been made in view of such circumstances, and has as its object to prevent a pressure wave propagating in an ink supply flow path and its reflected wave from affecting a pressure chamber. Is to avoid.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a pressure wave propagating in an ink supply channel is extinguished before reaching the end face of the ink supply channel. I decided that.

More specifically, the present invention provides a pressure chamber filled with ink, and an ink supply passage communicating with the pressure chamber through a supply port and supplying ink to the pressure chamber. The present invention is directed to an inkjet head including a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink in the pressure chamber from the nozzle.

[0008] Propagation generated by the operation of the pressure applying means and propagated in the ink supply flow path between the supply port in the ink supply flow path and at least one of both end faces of the ink supply flow path. Pressure wave annihilation means for annihilating the pressure wave is provided, and the pressure wave annihilation means generates an anti-phase pressure wave having an opposite phase to the propagating pressure wave from the propagating pressure wave, and It is a specific matter that a configuration is adopted in which the propagating pressure wave is eliminated by superimposing the propagating pressure wave.

According to the first aspect of the present invention, the pressure wave eliminating means has a phase opposite to that of the propagating pressure wave generated by the operation of the pressure applying means and propagating through the ink supply flow path. Generate an antiphase pressure wave. Then, the propagating pressure wave disappears by superimposing the antiphase pressure wave and the propagating pressure wave. At this time, since the pressure wave eliminating means is provided between the supply port and the end face of the ink supply flow path, the propagating pressure wave does not reach the end face of the ink supply flow path. No reflected wave of the pressure wave is generated. As a result, the pressure wave (reflected wave) does not return to the vicinity of the supply port in the ink supply channel, and as a result, the pressure wave propagating in the ink supply channel and the reflected wave adversely affect the pressure chamber. Is avoided.

The pressure wave eliminating means is constituted by, for example, a branch flow path formed concavely in a partition wall for partitioning the ink supply flow path, and the depth D of the branch flow path is defined as follows. When the wavelength of the propagating pressure wave is λ, D = (2
n-1) It may be configured by setting so as to satisfy λ / 4 (n is a natural number).

According to the second aspect of the invention, a part of the propagation pressure wave propagating in the ink supply flow path also propagates in the branch flow path formed in the partition wall in a concave shape, and the end face of the branch flow path is formed. Reflected by The depth D of the branch flow path is 1 / of the propagating pressure wave.
Since the pressure wave is set to an odd multiple of four wavelengths, when the pressure wave propagating in the branch flow path is reflected at its end face and returns to the opening position of the branch flow path, it is a half wavelength with respect to the propagating pressure wave. The pressure wave is shifted by only That is, it becomes an anti-phase pressure wave whose phase is opposite to that of the propagating pressure wave. For this reason, the propagating pressure wave disappears because the antiphase pressure wave and the propagating pressure wave overlap near the opening of the branch channel.

According to a third aspect of the present invention, a pressure chamber filled with ink communicates with the pressure chamber via a supply port.
An ink supply passage for supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink in the pressure chamber from the nozzle. A branch flow formed in a concave shape on a partition wall defining the ink supply flow path between the supply port in the ink supply flow path and at least one of both end faces of the ink supply flow path for an inkjet head. Make a road.

When the depth D of the branch flow path is λ, the wavelength of the propagating pressure wave is λ, D = (2n−1) λ / 4
(N is a natural number) is set as a specific matter.

Thus, the same operations and effects as those of the first and second aspects of the invention can be obtained.

According to the first to third aspects of the present invention, the propagating pressure wave is eliminated before reaching the end face of the ink supply flow path. The reflection wave generated by the reflection of the propagating pressure wave on the end face of the ink supply channel disappears.

More specifically, the invention according to claim 4 is characterized in that a pressure chamber filled with ink and an ink supply flow path which communicates with the pressure chamber via a supply port and supplies ink to the pressure chamber. The present invention is directed to an inkjet head including a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink in the pressure chamber from the nozzle.

[0017] At least one of the two ends of the ink supply channel, a propagating pressure wave generated by the operation of the pressure applying means and propagating in the ink supply channel is reflected at an end face of the ink supply channel. A reflected wave quenching means for quenching the reflected wave generated by the reflected wave, and generating the two reflected waves, which are reflected waves of the propagating pressure wave and have opposite phases to each other, by the reflected wave quenching means. It is a specific matter that the configuration is such that two reflected waves of the propagation pressure wave are annihilated together by superimposing two reflected waves.

According to the fourth aspect of the present invention, the reflected wave quenching means converts the two reflected waves having phases opposite to each other with respect to the propagating pressure wave generated by the operation of the pressure applying means and propagating in the ink supply flow path. generate. Then, by superimposing the two reflected waves having phases opposite to each other, the reflected wave of the propagation pressure wave disappears near the end of the ink supply flow path. Therefore, the reflected wave does not return to the vicinity of the supply port in the ink supply channel, and as a result, the pressure wave propagating in the ink supply channel and the reflected wave adversely affect the pressure chamber. Is avoided.

The reflected wave quenching means is constituted by a first branch flow path and a second branch flow path which branch off and extend at the end of the ink supply flow path. When the wavelength of the propagating pressure wave is λ, the length L1 of the channel and the length L2 of the second branch channel are (L1-L1).
L2) = (2n-1) λ / 4 (n is a natural number).

According to the fifth aspect of the invention, a part of the propagation pressure wave propagating in the ink supply flow path propagates in the first branch flow path that branches off at the end of the ink supply flow path. . This pressure wave is reflected at the end face of the first branch flow path to generate a reflected wave (first reflected wave). On the other hand, part of the propagating pressure wave propagates in the second branch flow path, is reflected at the end face of the second branch flow path, and another reflected wave (second reflected wave) is generated. At this time, since the difference between the channel lengths of the first and second branch channels is set to an odd multiple of １ ／ wavelength of the propagating pressure wave, the difference between the end surfaces of the first and second branch channels is obtained. The first reflected wave and the second reflected wave that have been reflected and returned to the branch point are shifted in phase from each other by a half wavelength. Therefore, when the first reflected wave and the second reflected wave overlap near the branch point, both the first and second reflected waves disappear.

Further, in contrast to this, the reflected wave quenching means is opened at a part of the end face of the ink supply flow path and is provided so as to extend from the position of the end face. And the flow path length L of the extension flow path
3 assuming that the wavelength of the propagating pressure wave is λ, L3 = (2
n-1) It may be configured by setting so as to satisfy λ / 4 (n is a natural number).

According to the sixth aspect of the present invention, a part of the propagation pressure wave propagating in the ink supply flow path is opened at a part of the end face of the ink supply flow path and provided so as to extend from the end face position. In the extended flow path. This pressure wave is reflected at the end face of the extension flow path to generate a reflected wave (first reflected wave). On the other hand, a part of the propagating pressure wave is reflected on the end face of the ink supply flow path (the end face where the extension flow path is not provided), and another reflected wave (second reflected wave) is generated.
At this time, the flow path length of the extension flow path is １ ／ of the propagating pressure wave.
Since the wavelength is set to an odd multiple of the wavelength, the first reflected wave that has propagated in the extended flow path, reflected at the end face, and returned to the end position of the ink supply flow path is different from the second reflected wave. The pressure wave is shifted by a half wavelength and the phase is reversed. For this reason, the first and second reflected waves overlap each other near the end of the ink supply flow path, so that both the first and second reflected waves disappear.

According to a seventh aspect of the present invention, there is provided a pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber through a supply port, and supplying ink to the pressure chamber.
An ink jet head including a nozzle communicating with the pressure chamber and pressure applying means for applying pressure to the pressure chamber to discharge ink in the pressure chamber from the nozzle, and both ends of the ink supply flow path At least one of
A first branch flow path and a second branch flow path that branch and extend are provided.

Then, the channel length L1 of the first branch channel and the channel length L2 of the second branch channel are determined by changing the wavelength of the propagating pressure wave to λ.
Where (L1−L2) = (2n−1) λ / 4
(N is a natural number) is set as a specific matter.

Thus, the same functions and effects as those of the fourth and fifth aspects can be obtained.

Further, according to the present invention, there is provided a pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port, and supplying ink to the pressure chamber. A nozzle communicating with a pressure chamber, and an inkjet head including a pressure application unit that applies pressure to the pressure chamber and ejects ink in the pressure chamber from the nozzle, is used as an object of the inkjet head. At least one of the ink supply passages is provided with an extended flow passage that is open at a part of the end face of the ink supply flow path and extends from the end face position.

If the length L3 of the above-mentioned extended flow path is defined as λ, the wavelength of the propagating pressure wave is L3 = (2n−1)
It is a specific matter that the setting is made so as to satisfy λ / 4 (n is a natural number).

Thus, the same operations and effects as those of the fourth and sixth aspects are obtained.

As described above, even when the pressure wave eliminating means and the reflected wave eliminating means are provided, the partition wall near the supply port in the ink supply flow path is configured to have flexibility. Is good.

This makes it possible to prevent an increase in the pressure near the supply port in the ink supply flow path when the pressure applying means operates and a pressure fluctuation occurs in the pressure chamber.

[0031] The invention according to claim 10 relates to an ink jet recording apparatus.
It is a specific matter that the ink jet head according to any one of the first to ninth aspects is further provided with a relative moving unit that relatively moves the ink jet head and a recording medium.

Thus, it is possible to prevent the pressure wave propagating in the ink supply flow path and its reflected wave from affecting the pressure chamber, thereby preventing the recording quality from deteriorating due to the pressure wave or the like. An expression recording device is configured.

[0033]

As described above, according to the ink jet head and the ink jet recording apparatus of the present invention, by providing the ink supply channel with the pressure wave eliminating means or the reflected wave eliminating means, the inside of the ink supply channel can be controlled. It is possible to prevent the pressure chamber and the reflected wave from adversely affecting the pressure chamber.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 shows a schematic configuration of an ink jet recording apparatus according to a first embodiment. As shown in FIG. And an inkjet head 1 for discharging ink. The ink jet head 1 is supported and fixed on a carriage 31, and the carriage 3
1 is guided by a carriage shaft 32 extending in the main scanning direction (X direction shown in FIGS. 1 and 2), and reciprocates in the main scanning direction by a carriage motor (not shown).

The recording paper 41 is sandwiched between two transport rollers 42 that are driven to rotate by a transport motor (not shown).
Under the inkjet head 1, the paper is transported in a sub-scanning direction (Y direction shown in FIGS. 1 and 2) orthogonal to the main scanning direction.

The carriage 31, the carriage shaft 32, the carriage motor, the transport motor and the transport roller 42 constitute a relative moving means for relatively moving the ink jet head 1 and the recording paper 41.

As shown in FIGS. 2 to 6, the ink jet head 1 has a plurality of pressure chamber recesses 3 having a supply port 3a for supplying ink and a discharge port 3b for discharging ink. Head body 2.
The recesses 3 of the head main body 2 are opened on the upper surface of the head main body 2 so as to extend in the main scanning direction, and are arranged side by side at substantially equal intervals in the sub scanning direction. . In addition, both ends of the opening edge of each of the concave portions 3 have a substantially semicircular shape.

The side wall of each recess 3 of the head body 2
It is composed of a first substrate 61 made of photosensitive glass having a thickness of about 200 μm, and the bottom wall of each recess 3 is composed of a second substrate 62 bonded and fixed to the lower surface of the first substrate 61. The second substrate 62 is made of stainless steel having a thickness of about 30 μm, and the supply port 3a and the discharge port 3b are formed in the second substrate 62.

The lower surface of the second substrate 62 has a thickness of about 300 μm.
A third substrate 63 made of stainless steel having a thickness of m is adhered and fixed,
In the third substrate 63, one ink supply channel 11 connected to the supply port 3a of each of the concave portions 3 and extending in the sub-scanning direction, and a plurality of ink discharge channels respectively connected to the discharge port 3b. 12 are formed. The ink supply channel 11 is provided to extend in the sub-scanning direction from a region where the concave portion 3 (a pressure chamber 4 described later) is formed.
It is connected to an ink tank (not shown) via an ink supply port 15 provided at the end 11a. Thus, the ink is supplied from the ink tank into the ink supply channel 11.

On the lower surface of the third substrate 63, a fourth substrate 64 constituting the lower surface of the ink jet head 1 is adhered and fixed. The fourth substrate 64 is made of stainless steel having a thickness of about 70 μm, and has a plurality of nozzles 1 having a diameter of about 20 μm for discharging ink droplets toward the recording paper 41.
Four. Each of the nozzles 14 is connected to the ink discharge channel 12 and communicates with the discharge port 3 b of each of the recesses 3 via the ink discharge channel 12. They are provided so as to be arranged in a row in the sub-scanning direction.

Above each concave portion 3 of the head body 2,
Each of the piezoelectric actuators 21 is provided. Each of the piezoelectric actuators 21 has a vibrating plate 22 made of Cr forming a pressure chamber 4 together with the concave portion 3 by covering each concave portion 3 of the head main body 2 while being bonded and fixed to the upper surface of the head main body 2. ing. This vibration plate 22 is made of one common to all the piezoelectric actuators 21, and
It also serves as a common electrode common to all the piezoelectric elements 23 described later.

Each of the piezoelectric actuators 21
On the side surface (upper surface) of the vibration plate 22 opposite to the pressure chamber 4, a portion corresponding to the pressure chamber 4 (a portion facing the opening of the concave portion 3) is joined and lead zirconate titanate (P
ZT) (piezoelectric constant 8 × 10 ⁻¹¹ m)
/ V) and a voltage (drive signal) for applying a voltage (drive signal) to each piezoelectric element 23 together with the vibration plate 22. And a Pt individual electrode 24 having a thickness of 1 μm. The piezoelectric elements 23 and the individual electrodes 24 are provided so as to extend in the same direction (main scanning direction) as the opening of the recess 3 at a substantially central portion in the width direction of the opening of the recess 3 of the head body 2 in a state where they overlap each other. The length thereof is slightly shorter than the opening of the concave portion 3, and both end portions have a substantially semicircular shape like the opening of the concave portion 3. The vibration plate 22, the piezoelectric element 23 and the individual electrodes 24 are formed by a thin film by a sputtering method.

Each piezoelectric actuator 21 applies a driving voltage to each piezoelectric element 23 via the vibration plate 22 and each individual electrode 24 to thereby control the pressure chamber 4 of the vibration plate 22.
Is deformed so that the ink in the pressure chamber 4 is discharged from the ejection port 3b or the nozzle 1
4 is ejected. That is, when a pulse-like voltage is applied between the vibration plate 22 and the individual electrode 24, the rising of the pulse voltage causes the piezoelectric element 23 to contract in the width direction perpendicular to the thickness direction due to the piezoelectric effect. Since the plate 22 and the individual electrodes 24 do not shrink, the portion of the vibration plate 22 corresponding to the pressure chamber 4 is bent and deformed toward the pressure chamber 4 due to the so-called bimetal effect. Due to this bending deformation, a pressure is generated in the pressure chamber 4, and the ink in the pressure chamber 4 is discharged as ink droplets from the nozzle 14 to the recording paper 41 via the discharge port 3 b and the ink discharge flow path 12 by this pressure, The recording paper 41 adheres to the surface of the recording paper 41 in the form of dots. This allows each piezoelectric actuator 2
Reference numeral 1 denotes a pressure application unit that applies pressure to the pressure chamber 4 and discharges the ink in the pressure chamber 4 from the nozzle 14. Then, the piezoelectric element 23 expands due to the fall of the pulse voltage, and the portion corresponding to the pressure chamber 4 of the vibration plate 22 returns to the original state. At this time, ink is supplied from the ink tank into the pressure chamber 4. The ink is filled through the flow channel 11 and the supply port 3a. Each piezoelectric element 2
The pulse voltage to be applied to 3 is not limited to the push-pull type as described above, and the first voltage after falling from the first voltage to the second voltage lower than the first voltage.
It may be of a push-pull type that rises to a voltage of.

As shown in FIGS. 5 and 6, the partition wall (side wall) facing the main scanning direction on the side where the nozzle 14 is formed is a partition wall for partitioning the ink supply flow path 11. A branch flow path 16 is provided as a pressure wave eliminating means. The branch flow path 16 is connected to the ink supply flow path 11.
And the supply port 3a closest to the end 11a among the plurality of supply ports 3a provided side by side in the sub-scanning direction.
At a substantially intermediate position with respect to the side wall, the side wall is provided in a concave shape in the main scanning direction. The depth D of the branch flow path 16 is set by Expression (1), where λ is the wavelength of a propagation pressure wave described later.

D = (2n−1) λ / 4 (n is a natural number) (1) Here, the above-described propagated pressure wave and the wavelength λ of the propagated pressure wave will be described. Since the waveform includes a high-order frequency component such as a wave or a triangular wave, it serves as an excitation source for exciting Helmholtz resonance. Therefore, a vibration is generated in the pressure chamber 4 by Helmholtz resonance. The wavelength λ ₁ and the frequency f of the vibration represent the path length from the nozzle 14 to the supply port 3 a through the ink discharge flow path 12 and the pressure chamber 4 in the longitudinal section of the ink jet head 1 (see FIG. 4). Equation (2),
It is represented by (3).

Λ ₁ = 2 × L / m (m is a natural number) (2) f = c / λ ₁ (3) where c is the speed of sound.

The vibration (pressure fluctuation) of the frequency f in the pressure chamber 4 is changed from the supply port 3 a to the ink supply flow path 1.
1 and becomes a pressure wave (propagating pressure wave) having a frequency f that propagates in the longitudinal direction (sub-scanning direction) in the ink supply flow path 11. The wavelength λ of the propagating pressure wave is represented by Expression (4).

Λ = c / f (4) From the equations (3) and (4), the wavelength λ of the pressure wave propagating through the ink supply flow path 11 is determined by the Helmholtz resonance.
Becomes the same as the wavelength λ ₁ . Therefore, the depth D of the branch passage 16 is determined based on the path length L of the pressure chamber 4. The sectional area of the branch passage 16 is not particularly limited, and may be set as appropriate.

The partition wall near the supply port 3a in the ink supply flow path 11, specifically, the partition wall facing the supply port 3a in the region where the plurality of supply ports 3a are formed, is flexible. It is constituted by flexible walls 13 having properties. The flexible wall 13 is connected to the ink supply channel 11.
The opening of the recess 13a formed in the fourth substrate 64 serving as the partition wall is closed so that a space is formed inside. The flexible wall 13 bends when the pressure fluctuation generated in the pressure chamber 4 is transmitted to the ink supply channel 11, whereby the pressure near the supply port 3 a in the ink supply channel 11 increases. To prevent them from getting lost.

The flexible wall 13 is not limited to the partition wall facing the supply port 3a, but may be provided on another partition wall in the area where the supply port 3a is formed.

Next, the recording operation of the ink jet recording apparatus having the ink jet head 1 will be described. The ink jet head 1 and the carriage 31 are moved from one end to the other end of the recording paper 41 at a substantially constant speed in the main scanning direction. When a predetermined time (for example, 50 μs
About: each piezoelectric element 23 for every 20 kHz of driving frequency)
The driving voltage is applied to the recording paper 41 (however, when the ink jet head 1 reaches a position where the ink droplets do not land on the recording paper 41, no voltage is applied). Let it land. When printing for one scan is completed, the recording paper 41 is conveyed by a predetermined amount in the sub-scanning direction by the conveying motor and the respective conveying rollers 42, and the ink droplets are again moved while the inkjet head 1 and the carriage 31 are moved in the main scanning direction. Is ejected to perform printing for one new scan. By repeating this operation, a desired image is formed on the entire recording paper 41.

When the recording is performed on the recording paper 41 by discharging the ink droplets in this manner, the driving of the piezoelectric actuator 21 causes a pressure fluctuation in the pressure chamber 4,
This pressure fluctuation is transmitted to the ink supply channel 11. Thus, as described above, a pressure wave that propagates in the sub-scanning direction in the ink supply channel 11 is generated. The ink supply channel 1
A part of the propagating pressure wave on the way to the first end 11a propagates in the branch flow path 16 in the main scanning direction. This branch channel 1
The pressure wave propagating in the inside 6 is reflected at its end face (bottom face) 16a to become a reflected wave.
Is set to an odd multiple of 1/4 wavelength of the propagating pressure wave, so that when the reflected wave returns to the opening position of the branch flow path 16, the propagating pressure wave propagating through the ink supply flow path 11 Is shifted by a half wavelength with respect to the pressure wave and the phase is reversed (opposite phase pressure wave). The antiphase pressure wave and the propagating pressure wave overlap each other near the opening of the branch passage 16, whereby the propagating pressure wave disappears.

As described above, the pressure wave propagating in the ink supply channel 11 disappears near the branch channel 16 and the ink supply channel 1
Since it does not reach the end 11a, the reflected wave of the propagation pressure wave does not return to the vicinity of the supply port 3a.

Therefore, the pressure wave (reflected wave) propagating in the ink supply channel 11 causes, for example, the ink supply channel 11
It is possible to reliably prevent ink supply to the pressure chamber 4 from being affected by the ink jetting or to affect the ejection of ink droplets, thereby preventing a reduction in recording quality. In particular, even when the piezoelectric actuator 21 is driven at a high frequency, the pressure chamber 4 is not adversely affected.

It is preferable that the flexible wall 13 is provided only near the supply port 13a and not provided near the branch flow path 16. This is because the propagating pressure wave and the reflected wave of the propagating pressure wave are not attenuated, so that the propagating pressure wave can be effectively eliminated by superimposing the antiphase pressure wave and the propagating pressure wave. This is because it is preferable that the partition wall near the branch flow path 16 be rigid so as not to attenuate the flow path.

In the first embodiment, the branch flow path 16 is provided on the partition wall (side wall) facing the main scanning direction on the side where the nozzle 14 is formed.
May be provided on another partition as long as it is between the end 11a and the supply port 3a.

The branch flow path 16 is formed at an end 11 a of the ink supply flow path 11 where the ink supply port 15 is provided.
May be provided on the partition wall of the ink supply channel 11 between the end opposite to the end and the supply port 3a closest to the end. However, when the branch flow path 16 is provided between the end portion 11a where the ink supply port 15 is provided and the supply port 3a, the pressure wave does not propagate near the ink supply port 15, so that the ink from the ink tank is There is no risk of adversely affecting the supply of ink to the supply channel 11.

Further, the branch flow path 16 is connected to the ink supply port 15 in the ink supply flow path 11 with the supply port 3a interposed therebetween.
May be provided both on the side of the end 11a where the is provided and on the side of the end opposite to the end 11a.

<Second Embodiment> FIG. 7 shows an ink supply flow path 1 of an ink jet head 1 according to a second embodiment of the present invention.
1, which is not a branch flow path 16 as a pressure wave eliminating means in the first embodiment, but a propagating pressure wave generated by reflection at the end face 11b of the ink supply flow path 11. A reflected wave extinguishing means for extinguishing the reflected wave is provided in the ink supply channel 11.

The structures of the pressure chamber 4, the piezoelectric actuator 21, and the other components of the ink jet head 1 are the same as those in the first embodiment. Therefore, the same members are denoted by the same reference numerals, and the description thereof will be omitted. Only the configuration of the ink supply channel 11 different from that of the first embodiment will be described.

The reflected wave eliminating means provided in the ink supply flow path 11 generates two reflected waves which are reflected waves of the propagating pressure wave and which have phases opposite to each other, and superimposes the two reflected waves. In this case, the reflected wave is extinguished, and specifically, the end 11b of the ink supply flow path 11 (the end opposite to the end 11a provided with the ink supply port 15). The first branch flow path 17 and the second branch flow path 18 branch in the sub-scanning direction and extend in directions inclined by angles θ1 and θ2 with respect to the sub-scanning direction, respectively. Channel length L1 of the first branch channel 17
(The length from the branch point 11c in the ink supply flow path 11 to the end face 17a of the first branch flow path 17) and the flow path length L2 of the second branch flow path 18 (the length from the branch point 11c in the ink supply flow path 11 to the second (Length to the end face 18a of the branch flow path 18)
Is set by Expression (5), where λ is the wavelength of the propagating pressure wave propagating in the ink supply channel 11.

(L1−L2) = (2n−1) λ / 4 (n is a natural number) (5) The sectional area of the first branch flow path 17 and the second branch flow path 18
Is preferably substantially the same as the cross-sectional area, but the size of the cross-sectional area itself is not particularly limited. The angles θ1 and θ2 formed by the first branch flow path 17 and the second branch flow path 18 with respect to the sub-scanning direction are also not particularly limited, and the flow path lengths L1 and L2 May be set appropriately so as to secure.

In the case of the second embodiment, a part of the propagating pressure wave propagating in the ink supply flow path 11 toward the end 11b propagates in the first branch flow path 17, and the first branch flow The light is reflected by the end face 17a of the road 17 and becomes a reflected wave (first reflected wave). On the other hand, a part of the propagating pressure wave propagates into the second branch flow path 18 and is reflected on the end face 18a of the second branch flow path 18 to become another reflected wave (second reflected wave). At this time, since the difference (L1−L2) between the channel lengths of the first and second branch channels 17 and 18 is set to an odd multiple of 波長 wavelength of the propagating pressure wave, the first and second branch channels 17 and 18 are set. 2-branch flow path 1
The first and second reflected waves that have returned to the branch points 11c at 7 and 18 respectively become two reflected waves that are shifted from each other by a half wavelength and have opposite phases. Therefore, when the first reflected wave and the second reflected wave overlap near the branch point 11c, both the first and second reflected waves disappear.

As a result, the reflected wave of the propagating pressure wave does not return to the vicinity of the supply port 3a in the ink supply channel 11, and as a result, the pressure wave propagating in the ink supply channel 11 and its The pressure wave is prevented from being adversely affected by the reflected wave.

The first and second branch flow paths 17, 18
Is provided at the end 11b of the ink supply channel 11 opposite to the end 11a at which the ink supply port 15 is provided, but may be provided at the end 11a at the side at which the ink supply port 15 is provided. Good.

The first and second branch flow paths 17, 1
8 are both ends 11 a, 11 in the ink supply flow path 11.
b.

-Modifications- In the second embodiment,
The first branch flow path 17 and the second branch flow path 18 that branch off and extend at the end 11b of the ink supply flow path 11 constitute a reflected wave eliminating means.
For example, it may be configured as shown in FIG.

That is, the reflected wave eliminating means according to the modified example is provided so as to open toward the nozzle 14 formation side from the center of the end face 11d of the ink supply flow path 11 in the main scanning direction, and to extend from this end face position in the sub-scanning direction. It is constituted by the extended flow path 19 provided. Therefore, the cross-sectional area of the end face 19a of the extension flow path 19 is equal to the cross-sectional area of the end face 11d of the ink supply flow path 11 where the extension flow path 19 is not provided.

The flow path length L3 of the extension flow path 19
(Length from the opening position of the extension flow path 19 to the end face 19a of the extension flow path 19) is set by Expression (6), where λ is the wavelength of the propagation pressure wave propagating in the ink supply flow path 11. Have been.

L3 = (2n−1) λ / 4 (n is a natural number) (6) In this modified example, part of the propagation pressure wave propagating in the ink supply flow path 11 is the extension flow path 19, and is reflected by the end face 19a of the extension flow path 19 to be reflected (first wave 19).
(Reflected wave). On the other hand, a part of the propagating pressure wave is reflected by the end face 11d of the ink supply channel 11 to be another reflected wave (second reflected wave). At this time, since the flow path length L3 of the extension flow path 19 is set to an odd multiple of １ ／ wavelength of the propagation pressure wave, the first reflected wave returning to the opening position of the extension flow path 19 is , The pressure wave is shifted by a half wavelength with respect to the second reflected wave and has a phase opposite to that of the second reflected wave. Therefore, when the first and second reflected waves overlap near the end 11b of the ink supply channel 11, both the first and second reflected waves disappear.

The sectional area of the end face 19a of the extension flow path 19 and the ink supply flow path 1 not provided with the extension flow path 19
The cross-sectional area of the one end face 11d is preferably the same, but does not necessarily have to be the same.

The extension channel 19 may be provided so as to extend in a direction inclined at a predetermined angle with respect to the sub-scanning direction.

Further, the extension flow path 19 is provided at the end 1 of the ink supply flow path 11 where the ink supply port 15 is provided.
Although it is provided at the end 11b on the opposite side to 1a, it may be provided at the end 11a on the side where the ink supply port 15 is provided.

In addition, the extension flow path 19 may be provided at both ends 11 a and 11 b of the ink supply flow path 11.

<Other Embodiments> The present invention is not limited to the above-described embodiments, but includes various other embodiments. That is, in the above embodiment, a plurality of nozzles 14 are provided in the inkjet head 1, and a plurality of pressure chambers 4 and piezoelectric actuators 21 are correspondingly provided.
However, the present invention can be applied to a single nozzle 14, the pressure chamber 4, the piezoelectric actuator 21, and the like.

In the above embodiment, the piezoelectric actuator 21 is used as the pressure applying means for applying the pressure to the pressure chamber 4 and ejecting the ink in the pressure chamber 4 from the nozzle 14. However, the present invention is not limited to this. Any of the above may be used.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a partial bottom view of the inkjet head.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 2;

FIG. 5 is a sectional view taken along line VV of FIG. 6;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 2;

FIG. 7 shows an ink supply flow path according to a second embodiment.
FIG.

FIG. 8 is a view corresponding to FIG. 5, illustrating an ink supply flow path according to a modification of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet head 4 Pressure chamber 11 Ink supply channel 13 Flexible wall 14 Nozzle 15 Branch channel (pressure wave eliminating means) 17 First branch channel (reflected wave eliminating means) 18 First branch channel (reflected wave eliminating means) 19) Extended flow path (reflection wave eliminating means) 21 Piezoelectric actuator (pressure applying means) 31 Carriage (relative moving means) 32 Carriage shaft (relative moving means) 41 Recording paper (recording medium) 42 Transport roller (recording medium) 3a Supply mouth

Claims (10)

[Claims] A pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port and supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, An ink jet head comprising: pressure application means for applying pressure to the pressure chamber to discharge ink in the pressure chamber from the nozzle, wherein the supply port in the ink supply flow path and both ends of the ink supply flow path Between at least one of the surfaces, there is provided pressure wave eliminating means for eliminating propagation pressure waves generated by the operation of the pressure applying means and propagating in the ink supply flow path. From the propagating pressure wave, an opposite-phase pressure wave having a phase opposite to that of the propagating pressure wave is generated, and the propagating pressure wave disappears by superimposing the anti-phase pressure wave and the propagating pressure wave. Ink jet head, characterized by being made. 2. The pressure wave eliminating means according to claim 1, wherein the pressure wave eliminating means is constituted by a branch flow path formed in a concave shape on a partition wall that defines the ink supply flow path. An ink jet head characterized in that, when the wavelength of the pressure wave is λ, D = (2n−1) λ / 4 (n is a natural number). 3. A pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port and supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, An ink jet head comprising: pressure application means for applying pressure to the pressure chamber to discharge ink in the pressure chamber from the nozzle, wherein the supply port in the ink supply flow path and both ends of the ink supply flow path Between at least one of the surfaces, there is provided a branch flow path formed in a concave shape on a partition wall for partitioning the ink supply flow path, and the depth D of the branch flow path is such that the wavelength of the propagating pressure wave is λ. An ink jet head is set so as to satisfy D = (2n-1) λ / 4 (n is a natural number). 4. A pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port and supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, Pressure applying means for applying pressure to the pressure chamber to eject ink in the pressure chamber from the nozzle, wherein at least one of both ends of the ink supply flow path applies the pressure A reflected wave quenching means for quenching a reflected wave generated by the reflection of the propagating pressure wave generated by the operation of the means and propagating in the ink supply flow path at the end face of the ink supply flow path; The means generates two reflected waves which are reflected waves of the propagating pressure wave and which are opposite in phase to each other, and superimposes the two reflected waves to form two reflected waves of the propagated pressure wave. Ink jet head, characterized in that it is configured to both extinguish. 5. The first branch flow according to claim 4, wherein the reflected wave quenching means includes a first branch flow path and a second branch flow path that branch off and extend at an end of the ink supply flow path. The flow path length L1 of the road and the flow path length L2 of the second branch flow path are: (L1−L2) = (2n−1) λ / 4 (n is a natural number), where λ is the wavelength of the propagating pressure wave. An ink jet head characterized by being set so as to satisfy the following. 6. The extended wave passage according to claim 4, wherein the reflected wave extinguishing means is opened at a part of an end face of the ink supply flow path, and is provided so as to extend from a position of the end face. Ink-jet printing, wherein the flow path length L3 of the flow path is set so as to satisfy L3 = (2n-1) λ / 4 (n is a natural number), where λ is the wavelength of the propagating pressure wave. head. 7. A pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port and supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, A pressure application unit for applying pressure to the pressure chamber to discharge ink in the pressure chamber from the nozzle, wherein at least one of both ends of the ink supply flow path is branched. A first branch flow path and a second branch flow path that extend are provided. The flow path length L1 of the first branch flow path and the flow path length L2 of the second branch flow path are defined assuming that the wavelength of the propagating pressure wave is λ. (L1-L2) = (2n-1) λ / 4 (n is a natural number). 8. A pressure chamber filled with ink, an ink supply passage communicating with the pressure chamber via a supply port and supplying ink to the pressure chamber, a nozzle communicating with the pressure chamber, Pressure applying means for applying pressure to the pressure chamber to discharge ink in the pressure chamber from the nozzle, wherein at least one of both ends of the ink supply flow path is provided with the ink supply. An extended flow path is provided at a part of the end face of the flow path and extends from the end face position. The flow path length L3 of the extended flow path is L3 = (2n -1) An inkjet head characterized in that it is set so as to satisfy λ / 4 (n is a natural number). 9. The ink jet head according to claim 1, wherein a partition wall near the supply port in the ink supply flow path has flexibility. 10. An ink jet type comprising: the ink jet head according to claim 1; and a relative moving means for relatively moving the ink jet head and a recording medium. Recording device.