JP2020168740A - Liquid discharge head and liquid discharge device comprising the same - Google Patents

Abstract

To suppress liquid inside a nozzle from drying.SOLUTION: A liquid discharge head 1 comprises a flow-path forming body 11 which has a plurality of nozzles 21, a nozzle opening surface 1a having opening parts of the nozzles formed thereon, a plurality of individual flow paths 20, a supply flow path 33 for supplying liquid to the plurality of individual flow paths, and a collection flow path 32 for collecting liquid. Each of the individual flow paths has: a communication path 22 connected to the nozzle; an upstream-side pressure chamber 23a arranged between the communication path and the supply flow path; a downstream-side pressure chamber 23b arranged between the communication path and the collection flow path; an upstream-side descender flow path 24a connecting the upstream-side pressure chamber to one end of the communication path; and a downstream-side descender flow path 24b connecting the other end of the communication path to the downstream-side pressure chamber. A downstream-end portion 24a1, which is an end portion at the communication path side in the upstream-side descender flow path extends in a direction in which the path crosses the nozzle opening surface, and the nozzles are connected to a position closer to the upstream-side descender flow path than a center position in the communication path, in the communication path.SELECTED DRAWING: Figure 3

Description

The present invention relates to a liquid discharge head and a liquid discharge device including the liquid discharge head.

Patent Document 1 describes a nozzle opening (nozzle), a communication passage, a first pressure generation chamber (upstream pressure chamber), a second pressure generation chamber (downstream pressure chamber), and a manifold (supply flow path) communicating with a supply path. , And a liquid injection head (liquid discharge head) having a manifold (recovery flow path) communicating with the outflow path is disclosed. In Patent Document 1, ink flows from the manifold communicating with the supply passage to the manifold communicating with the outflow passage through the first pressure generation chamber, the communication passage, and the second pressure generation chamber in this order. Further, the nozzle opening is connected to the end portion on the second pressure generation chamber side in the communication passage. Then, in Patent Document 1, the first piezoelectric element (upstream actuator) that generates pressure in the first pressure generating chamber and the second piezoelectric element (downstream actuator) that generates pressure in the second pressure generating chamber are driven. By doing so, the ink is ejected from the nozzle opening.

JP-A-2018-103418

By the way, in the liquid discharge head, since the nozzle faces the atmosphere, the liquid inside the nozzle tends to be dried and thickened due to evaporation of the water content. If the liquid inside the nozzle is thickened in this way, the discharge characteristics of the liquid are adversely affected.

Therefore, an object of the present invention is to provide a liquid discharge head capable of suppressing drying of the liquid inside the nozzle, and a liquid discharge device including the liquid discharge head.

The liquid discharge head of the present invention is connected to a plurality of nozzles, a nozzle opening surface in which openings of the plurality of nozzles are formed, a plurality of individual flow paths corresponding to the plurality of nozzles, and inlets of the plurality of individual flow paths. A flow path forming body having a supply flow path for supplying liquid to the plurality of individual flow paths and a recovery flow path connected to outlets of the plurality of individual flow paths and recovering liquid from the plurality of individual flow paths. Each of the plurality of individual flow paths is connected to the nozzle and extends in a first direction parallel to the nozzle opening surface, and an upstream arranged between the communication flow path and the supply flow path. A side pressure chamber, a downstream pressure chamber arranged between the communication passage and the recovery flow path, an upstream descender flow path connecting the upstream pressure chamber and one end of the communication passage, and the connection. It has a downstream descender flow path that connects the other end of the passage and the downstream pressure chamber, and has an upstream actuator that applies pressure to the liquid in the upstream pressure chamber and a downstream pressure chamber. A downstream actuator that applies pressure to the liquid is further provided, and a downstream end portion of the upstream descender flow path, which is an end portion on the communication passage side, extends in a second direction intersecting the nozzle opening surface. The nozzle is connected to a position on the descender flow path side on the upstream side of the communication passage in the first direction of the communication passage.

It is a top view of the printer 100 provided with the head 1 which concerns on 1st Embodiment of this invention. It is a top view of the head 1 of FIG. It is sectional drawing of the head 1 along the line III-III of FIG. It is a block diagram which shows the electrical structure of a printer 100. (A) is a cross-sectional view of the head 1 in the vicinity of the nozzle 21, and (b) is the positional relationship between the downstream end portion 24a1 of the upstream descender flow path 24a and the nozzle 21 when viewed from the vertical direction. It is a figure which shows. It is sectional drawing corresponding to FIG. 3 in the head 201 of 2nd Embodiment. It is sectional drawing corresponding to FIG. 3 in the head 301 of 3rd Embodiment. (A) is a cross-sectional view of the head 401 according to the first modified example corresponding to FIG. 5 (a), and (b) is a sectional view of the head 501 according to the second modified example corresponding to FIG. 5 (a).

(First Embodiment)
Hereinafter, a preferred first embodiment of the present invention will be described.

As shown in FIG. 1, the printer 100 according to the first embodiment includes a head unit 1X, a platen 3, a transport mechanism 4, a control device 5, and the like.

The transport mechanism 4 has two transport rollers 4a and 4b arranged side by side in the transport direction. The two transfer rollers 4a and 4b are connected to the transfer motor 4m via a gear or the like (not shown). When the transfer motor 4 m is driven by the control device 5, the transfer rollers 4a and 4b rotate to transfer the paper S, which is a recording medium, in the transfer direction.

The platen 3 is arranged so as to be sandwiched between two transfer rollers 4a and 4b in the transfer direction. The platen 3 supports the paper S transported by the transport mechanism 4 from below. The paper S passes over the platen 3 by being conveyed by the conveying mechanism 4.

The head unit 1X is arranged so as to face the platen 3 in the vertical direction and is long in the paper width direction. The head unit 1X includes four heads 1 (corresponding to "liquid discharge heads") arranged in a staggered pattern in the paper width direction. The head 1 is driven by the driver IC 1d (see FIG. 4) and ejects ink from a plurality of nozzles 21 (see FIGS. 2 and 3). The paper width direction is orthogonal to the transport direction. Both the paper width direction and the transport direction are parallel to the horizontal plane. The head 1 will be described in detail later.

The printer 100 records an image on the paper S by ejecting ink from a plurality of nozzles 21 of the four heads 1 while transporting the paper S in the transport direction by the transport mechanism 4. That is, the printer 100 is a so-called line-type inkjet printer in which ink is ejected from the nozzle 21 of the head 1 to the paper S with the head 1 fixed.

As shown in FIG. 4, the control device 5 is composed of a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 62, a RAM (Random Access Memory) 63, a flash memory 64, an ASIC (Application Specific Integrated Circuit) 65, and the like. The operation of the transfer motor 4m, the driver IC1d, the circulation pump 7p, etc. is controlled. For example, the control device 5 controls the driver IC 1d of each head 1 and the transfer motor 4 m based on a recording command (including image data) input from an external device such as a PC to display an image on paper S. Execute the recording process to record.

Next, the configuration of the head 1 will be described in detail with reference to FIGS. 2 and 3.

The head 1 has a flow path substrate 11 (corresponding to a “flow path forming body”) and an actuator unit 12.

As shown in FIG. 3, the flow path substrate 11 is formed by laminating eight plates 11a to 11h in this order from the top. The lowermost plate 11h (corresponding to the “first plate”) is a nozzle plate on which a plurality of nozzles 21 are formed. The nozzle 21 is a through hole that penetrates the plate 11h in the vertical direction. The lower surface of the plate 11h is a nozzle opening surface 1a in which openings of a plurality of nozzles 21 are formed. The nozzle opening surface 1a is a surface parallel to the horizontal plane. Further, as shown in FIG. 5A, the nozzle 21 is formed in a tapered shape that tapers toward the nozzle opening surface 1a.

A water-repellent material such as a fluororesin is applied to the nozzle opening surface 1a to form a water-repellent film (not shown). The formation of the water-repellent film is performed after the nozzle 21 is formed on the plate 11h. Therefore, when the water-repellent film is formed on the nozzle opening surface 1a, a part of the water-repellent material flows into the nozzle 21, and the water-repellent film is also formed on the inner wall surface 21a of the nozzle 21. As a result, the inner wall surface 21a of the nozzle 21 has water repellency.

A plurality of individual flow paths 20 corresponding to each of the plurality of nozzles 21 are formed on the plates 11a to 11g. Further, the plates 11d to 11f are formed with a common flow path 30 communicating with a plurality of individual flow paths 20. The plurality of nozzles 21, the plurality of individual flow paths 20, and the common flow path 30 are formed by etching or the like on the flow path substrate 11.

As shown in FIG. 2, the common flow path 30 includes recovery flow paths 31 and 32 and supply flow paths 33 arranged in the arrangement direction (direction parallel to the transport direction). The collection flow paths 31 and 32 and the supply flow path 33 extend in the extending direction (direction parallel to the paper width direction), respectively. A supply flow path 33 is arranged between the recovery flow path 31 and the recovery flow path 32 in the arrangement direction.

The supply flow path 33 extends in the vertical direction across the plates 11a to 11f at one end in the extending direction (upper in FIG. 2), and an inflow port 33x is provided at the upper end thereof. The inflow port 33x is connected to the ink tank 7 via a circulation pump 7p. The collection flow paths 31 and 32 extend in the vertical direction across the plates 11a to 11f at the other end (lower part of FIG. 2) in the extending direction, respectively, and the outlets 31y and 32y are located at the upper ends thereof. It is provided. The outlets 31y and 32y are connected to the ink tank 7.

The ink tank 7 is connected to an ink cartridge (not shown) via a tube (not shown) or the like, and ink is supplied from the ink cartridge.

The individual flow path 20 includes a plurality of first individual flow paths 20a connecting the recovery flow path 31 and the supply flow path 33, and a plurality of second individual flow paths 20b connecting the recovery flow path 32 and the supply flow path 33. Including. The first individual flow path 20a straddles the recovery flow path 31 and the supply flow path 33 in the arrangement direction. The second individual flow path 20b straddles the recovery flow path 32 and the supply flow path 33 in the arrangement direction.

Each individual flow path 20 includes a communication passage 22, an upstream pressure chamber 23a, a downstream pressure chamber 23b, an upstream descender flow path 24a, a downstream descender flow path 24b, an upstream throttle flow path 25a, and a downstream throttle flow path. Includes 25b. As shown in FIG. 3, the communication passage 22 is a passage connected to the nozzle 21 and is formed on a plate 11 g (corresponding to a “second plate”). The communication passage 22 extends along the arrangement direction (corresponding to the "first direction").

Further, the lower surface of the communication passage 22 is defined by the upper surface of the plate 11h. In other words, the plate 11h has a wall portion 11ha that defines the lower surface of the communication passage 22. As described above, since the communication passage 22 is a flow path that passes directly above the nozzle 21, the flow of ink inside the passage 22 affects the ejection direction (flying direction) of the ink ejected from the nozzle 21.

The upstream pressure chamber 23a is arranged between the communication passage 22 and the supply passage 33. The downstream pressure chamber 23b is arranged between the communication passage 22 and the recovery passages 31 and 32. Hereinafter, in explaining the upstream side pressure chamber 23a and the downstream side pressure chamber 23b, when they are not distinguished, they are referred to as “pressure chamber 23”.

The pressure chamber 23 is a through hole formed in the plate 11a. Therefore, the pressure chamber 23 is located above the communication passage 22. Further, the pressure chamber 23 has a substantially rectangular planar shape with the arrangement direction as the longitudinal direction. That is, the pressure chamber 23 extends along a plane parallel to the arrangement direction and the extension direction. Further, four rows of pressure chamber rows 23R1 to 23R4 are formed on the plate 11a. The four rows of pressure chambers 23R1 to 23R4 extend in the extending direction and are arranged in the arrangement direction. Of the four pressure chamber rows 23R1 to 23R4, the two pressure chamber rows 23R1, 23R2 on the left side of FIG. 2 are composed of an upstream pressure chamber 23a and a downstream pressure chamber 23b of the first individual flow path 20a. Of the four pressure chamber rows 23R1 to 23R4, the two pressure chamber rows 23R3 and 23R4 on the right side of FIG. 2 are composed of an upstream pressure chamber 23a and a downstream pressure chamber 23b of the second individual flow path 20b. In each of the pressure chamber rows 23R1 to 23R4, the pressure chambers 23 are arranged at the same position in the arrangement direction and at equal intervals in the extending direction. On the other hand, the position of the pressure chamber 23 in the extending direction is deviated between the pressure chamber rows 23R1 to 23R4. As a result, in all the pressure chambers 23, the positions in the extending direction are different from those of the pressure chambers 23 other than the pressure chambers 23. In the present embodiment, the shapes of the pressure chambers 23 are all the same, but the shape is not limited to this.

The upstream side descender flow path 24a is a flow path extending in the vertical direction connecting the upstream side pressure chamber 23a and one end of the communication passage 22. The downstream descender flow path 24b is a flow path extending in the vertical direction that connects the downstream pressure chamber 23b and the other end of the communication passage 22. More specifically, the upstream descender flow path 24a is formed by overlapping through holes 41 to 45 formed in the plates 11b to 11f in the vertical direction. The central positions of these through holes 41 to 45 overlap each other when viewed from the vertical direction.

On the other hand, the downstream descender flow path 24b is formed by overlapping the through holes 51 to 55 formed in the plates 11b to 11f in the vertical direction. The central positions of these through holes 51 to 55 overlap each other when viewed from the vertical direction. The upstream side descender flow path 24a and the downstream side descender flow path 24b have the same length of the flow path.

The through-holes 41 to 45 forming the upstream descender flow path 24a are all in the vertical direction. Similarly, the through-holes 51 to 55 forming the downstream descender flow path 24b are all in the vertical direction.

Further, among the through holes 41 to 45 forming the upstream descender flow path 24a, the diameter of the through holes 45 formed in the plate 11f is smaller than the diameters of the other through holes 41 to 44. As a result, the flow path cross-sectional area of the downstream end portion 24a1 which is the end portion on the communication passage 22 side of the upstream descender flow path 24a is larger than the flow path cross-sectional area of the other flow path portions of the upstream descender flow path 24a. It's getting smaller. Hereinafter, the upstream side descender flow path 24a and the downstream side descender flow path 24b will be described, and when they are not distinguished, they are referred to as "descender flow path 24".

The upstream throttle flow path 25a connects the supply flow path 33 and the upstream pressure chamber 23a. The downstream throttle flow path 25b connects the recovery channels 31 and 32 with the downstream pressure chamber 23b. Hereinafter, in the description of the upstream side throttle flow path 25a and the downstream side throttle flow path 25b, when they are not distinguished, they are referred to as "drawing flow path 25".

The flow path cross-sectional area of the throttle flow path 25 is made smaller than the flow path cross-sectional area of other flow paths such as the pressure chamber 23, so that the pressure wave generated in the pressure chamber 23 is collected in the supply flow path 33 and the flow path 33. It has a function of a diaphragm that makes it difficult to propagate to the flow paths 31 and 32. The throttle flow path 25 is formed across the plates 11b and 11c.

Next, the connection position of the nozzle 21 with respect to the communication passage 22 will be described. As shown in FIG. 5A, the nozzle 21 is connected to a position on the descender flow path 24a on the upstream side of the center position in the arrangement direction in the communication passage 22. In the present embodiment, the nozzle 21 is connected to the central position of the projection region in the vertical direction of the downstream end portion 24a1 of the upstream descender flow path 24a in the communication passage 22. More specifically, as shown in FIG. 5B, the nozzle 21 is arranged inside the edge of the through hole 45 of the plate 11f, which forms the downstream end portion 24a1 when viewed from the vertical direction. There is. When viewed from the vertical direction, the center position of the through hole 45 is arranged so as to overlap the center position of the nozzle 21.

Next, the flow of ink when the circulation pump 7p is driven will be described. The thick arrow in FIG. 2 and the arrow in FIG. 3 indicate the ink flow.

As shown in FIG. 2, when the circulation pump 7p is driven by the control of the control device 5, the ink in the ink tank 7 flows into the supply flow path 33 from the inflow port 33x. Then, ink is supplied from the supply flow path 33 to each of the individual flow paths 20 (first individual flow path 20a and second individual flow path 20b).

The ink supplied to each individual flow path 20 moves substantially horizontally through the upstream side throttle flow path 25a and the upstream side pressure chamber 23a, and further moves downward through the upstream side descender flow path 24a, and continues. It flows into the passage 22. The ink moves horizontally through the communication passage 22, a part of the ink is discharged from the nozzle 21, and the rest moves upward through the downstream descender flow path 24b, and the downstream pressure chamber 23b and the downstream throttle flow. It moves substantially horizontally through the road 25b.

Then, the ink supplied to the first individual flow path 20a is recovered in the recovery flow path 31. The ink flows out of the collection flow path 31 via the outlet 31y and is returned to the ink tank 7. The ink supplied to the second individual flow path 20b is collected in the recovery flow path 32. The ink flows out of the collection flow path 32 via the outlet 32y and is returned to the ink tank 7.

As described above, the ink circulates between the head 1 and the ink tank 7. As a result, thickening of the ink in the nozzle 21 is suppressed. Further, the air in the vicinity of the nozzle 21 of the individual flow path 20 can be discharged to the recovery flow paths 31 and 32. In this embodiment, the ink is constantly circulated between the head 1 and the ink tank 7. That is, the ink is circulated between the head 1 and the ink tank 7 even during the recording process.

The actuator unit 12 is arranged on the upper surface of the flow path substrate 11 and covers a plurality of pressure chambers 23.

As shown in FIG. 3, the actuator unit 12 includes a diaphragm 12a, a common electrode 12b, a plurality of piezoelectric bodies 12c, and a plurality of individual electrodes 12d in this order from the bottom. The diaphragm 12a and the common electrode 12b are arranged on substantially the entire upper surface of the flow path substrate 11 and cover a plurality of pressure chambers 23. On the other hand, the piezoelectric body 12c and the individual electrode 12d are provided for each pressure chamber 23 and face each of the pressure chambers 23. The common electrode 12b is connected to the driver IC1d and is always held at the ground potential.

In the above configuration, one actuator 13 (FIG. 3) is composed of one individual electrode 12d, an electrode portion of the common electrode 12b facing one pressure chamber 23, and a portion of the piezoelectric body 12c facing one pressure chamber 23. See) is configured. In the actuator unit 12, such an actuator 13 is built in each pressure chamber 23.

The driver IC 1d applies a predetermined drive pulse signal to the individual electrodes 12d of each actuator 13 based on the control signal from the control device 5, and sets the potential of the individual electrodes 12d between the drive potential and the ground potential. Switch with. The drive pulse signal is a pulse signal having a predetermined pulse width and pulse height.

Next, a method of driving the actuator 13 to eject ink from the nozzle 21 will be described. In the standby state in which ink is not ejected from the nozzle 21, all the individual electrodes 12d are held at the same ground potential as the common electrode 12b. When ink is ejected from a certain nozzle 21, the potentials of the two individual electrodes 12d corresponding to the two pressure chambers 23 of the individual flow paths 20 corresponding to the nozzle 21 are switched from the ground potential to the drive potential.

Then, a potential difference is generated between each of the above two individual electrodes 12d and the common electrode 12b held at the ground potential, and the two sandwiched between each of the two individual electrodes 12d and the common electrode 12b. The piezoelectric body 12c is piezoelectrically deformed. As a result, the portions of the diaphragm 12a and the piezoelectric body 12c that overlap the two pressure chambers 23 in the vertical direction are bent so as to be convex toward the pressure chamber 23 as a whole. As a result, the volume of the two pressure chambers 23 becomes smaller, so that the pressure of the ink in the two pressure chambers 23 rises, and the ink is ejected from the nozzle 21 communicating with the two pressure chambers 23. Further, after the ink is ejected from the nozzle 21, the potentials of the two individual electrodes 12d are returned to the ground potential. As a result, the diaphragm 12a and the piezoelectric body 12c return to the state before deformation.

By the way, as described above, the nozzle 21 is connected to the position on the descender flow path 24a on the upstream side of the communication passage 22 from the center position in the arrangement direction of the communication passage 22. Therefore, the length of the flow path from the upstream pressure chamber 23a to the nozzle 21 is shorter than the length of the flow path from the downstream pressure chamber 23b to the nozzle 21. As a result, when the control device 5 ejects ink from the nozzle 21, the drive timing of the actuator 13 corresponding to the upstream pressure chamber 23a (hereinafter referred to as the upstream actuator 13a) and the actuator corresponding to the downstream pressure chamber 23b When the driver IC1d is controlled so that the drive timing of 13 (hereinafter, downstream actuator 13b) is the same, the timing at which the pressure wave generated in the upstream pressure chamber 23a reaches the nozzle 21 is the downstream pressure chamber 23b. The generated pressure wave reaches the nozzle 21 earlier than the timing. As a result, the ejection direction of the ink ejected from the nozzle 21 may deviate significantly from the vertical direction instead of the vertical direction (directly below).

Therefore, in the present embodiment, when the control device 5 ejects ink from the nozzle 21, the timing at which the pressure waves generated in each of the upstream pressure chamber 23a and the downstream pressure chamber 23b reach the nozzle 21 is substantially the same. The driver IC1d is controlled so that the drive timing of the upstream actuator 13a is delayed from the drive timing of the downstream actuator 13b. As a result, the ejection direction of the ink ejected from the nozzle 21 can be set to the vertical direction.

Further, by shifting the drive timings of the upstream actuator 13a and the downstream actuator 13b, it is possible to suppress the heat generation of the driver IC1d. The details will be described below.

A current flows through the driver IC 1d when driving the actuator 13. In particular, when the potential of the individual electrode 12d of the actuator 13 is switched between the drive potential and the ground potential, a large current flows through the driver IC 1d. When a current flows through the driver IC1d in this way, the driver IC1d generates heat. Then, when the temperature of the driver IC1d becomes high, it becomes a factor such as a failure of the driver IC1d. Further, in the case of a configuration in which two actuators are driven when ejecting ink from one nozzle as in the present embodiment, a configuration in which only one actuator is driven when ejecting ink from one nozzle is used. In comparison, the amount of current flowing through the driver IC increases, and the problem of heat generation of the driver IC becomes more prominent.

Here, in a configuration in which two actuators 13 are driven when ejecting ink from one nozzle 21 as in the present embodiment, when the drive timings of the upstream actuator 13a and the downstream actuator 13b are the same, Since the timings for switching the potentials of the individual electrodes 12d of the actuator 13 match, an excessive current concentrates and flows in the driver IC1d, while the drive timings of the upstream actuator 13a and the downstream actuator 13b deviate from each other. If so, the timing of switching the potential of the individual electrodes 12d of the actuator 13 is shifted, so that an excessive current does not flow through the driver IC1d. Therefore, as in the present embodiment, by shifting the drive timings of the upstream actuator 13a and the downstream actuator 13b, it is possible to prevent an excessive current from flowing through the driver IC1d, and as a result, the driver IC1d Fever can be suppressed.

By the way, in the head 1, since the nozzle 21 faces the atmosphere, the ink in the nozzle 21 tends to be dried and thickened due to the evaporation of the water content. If the ink inside the nozzle 21 is thickened in this way, the ink ejection characteristics of the head 1 are adversely affected.

Here, as described above, the upstream descender flow path 24a extends in the vertical direction, and the communication passage 22 extends in the arrangement direction parallel to the horizontal plane. Therefore, when the circulation pump 7p is driven to generate the ink flow from the supply flow path 33 to the recovery flow paths 31 and 32, when the ink flows from the upstream descender flow path 24a into the communication passage 22 , The inertial force acts on the ink by changing the traveling direction of the ink. Specifically, since the ink flows downward in the upstream descender flow path 24a, an inertial force acts downward on the ink flowing through the communication passage 22.

Therefore, when the ink flows directly above the nozzle 21 in the communication passage 22, a part of the ink flows into the nozzle 21 due to the inertial force. That is, a flow pressure is applied to the ink in the nozzle 21. As a result, the ink in the nozzle 21 is agitated, so that it is possible to suppress the drying of the ink in the nozzle 21.

However, the downward inertial force acting on the ink increases as the ink flows from one end side to which the upstream descender flow path 24a is connected to the other end side to which the downstream throttle flow path 25b is connected in the communication passage 22. become weak. Therefore, when the nozzle 21 is connected to the center position in the arrangement direction of the communication passage 22 or the position on the downstream side throttle flow path 25b side from the center position, the flow pressure applied to the ink in the nozzle 21 is applied. Is weak, and there is a possibility that the ink in the nozzle 21 cannot be sufficiently agitated.

Therefore, in the present embodiment, the nozzle 21 is connected to a position on the descender flow path 24a on the upstream side of the communication passage 22 in the arrangement direction of the communication passage 22. As a result, the flow pressure applied to the ink in the nozzle 21 becomes stronger, and the ink in the nozzle 21 can be sufficiently agitated. As a result, drying of the ink in the nozzle 21 can be suppressed.

Further, in the present embodiment, the nozzle 21 is connected to the position in the projection region in the vertical direction of the downstream end portion 24a1 of the upstream descender flow path 24a in the communication passage 22. That is, the nozzle 21 is connected to a position directly below the upstream descender flow path 24a. As a result, the flow pressure applied to the ink in the nozzle 21 can be made stronger, and the ink in the nozzle 21 can be agitated more.

Further, in general, the flow velocity of the fluid is highest near the center of the flow path, and becomes slower as it is closer to the wall defining the flow path. Therefore, the inertial force acting on the ink flowing near the center of the downstream end portion 24a1 becomes the largest. Therefore, in the present embodiment, the nozzle 21 is connected to the central position of the projection region in the vertical direction of the downstream end portion 24a1 in the communication passage 22. As a result, the flow pressure applied to the ink in the nozzle 21 can be further increased by utilizing the inertial force of the ink flowing near the center of the downstream end portion 24a1. As a result, the ink in the nozzle 21 can be more agitated.

Further, in the present embodiment, the lower surface of the communication passage 22 is defined by the wall portion 11ha of the plate 11h on which the nozzle 21 is formed. That is, the communication passage 22 passes directly above the nozzle 21. As a result, the influence of the ink flow in the communication passage 22 on the ink in the nozzle 21 can be increased as compared with the configuration in which the lower surface of the communication passage 22 is not defined by the wall portion 11ha of the plate 11h. .. As a result, the flow pressure applied to the ink in the nozzle 21 can be further increased by the downward inertial force acting on the ink flowing in the communication passage 22. As a result, the ink in the nozzle 21 can be more agitated.

Further, in the present embodiment, the nozzle 21 is formed in a tapered shape that tapers toward the nozzle opening surface 1a. As a result, the flow of ink flowing into the nozzle 21 can be dispersed in multiple directions as compared with the case where the inner wall surface 21a of the nozzle 21 is a surface parallel to the vertical direction. As a result, the effect of stirring the ink in the nozzle 21 can be enhanced.

Further, in the present embodiment, the inner wall surface 21a of the nozzle 21 has water repellency. As a result, the inner wall surface 21a of the nozzle 21 repels the ink, so that the effect of stirring the ink in the nozzle 21 can be further enhanced.

Further, in the present embodiment, in the upstream descender flow path 24a, the flow path cross-sectional area of the downstream end portion 24a1 is smaller than the flow path cross-sectional area of the other flow path portions. As a result, it is possible to increase the flow velocity of the ink flowing through the communication passage 22 while suppressing the flow path resistance of the upstream descender flow path 24a from becoming excessively large. As a result, the flow pressure applied to the ink in the nozzle 21 can be increased, and the ink in the nozzle 21 can be agitated more.

(Second Embodiment)
Next, the second embodiment will be described. In the second embodiment, the configuration of the upstream descender flow path in the head is mainly different from that in the first embodiment. Hereinafter, those having the same configuration as that of the first embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

As shown in FIG. 6, in the head 201 according to the second embodiment, the upstream side descender flow path 224a is provided instead of the upstream side descender flow path 24a of the first embodiment. The upstream descender flow path 224a is formed by overlapping through holes 241 to 245 formed in the plates 11b to 11f. Further, the upstream descender flow path 224a is inclined from the lower end to one side (left side in FIG. 6) which is the supply flow path 33 side in the arrangement direction toward the upper end. That is, the upstream descender flow path 224a extends in an inclined direction (corresponding to the "second direction") inclined with respect to the horizontal plane and the vertical direction. More specifically, the through directions of the through holes 241 to 245 are all the above-mentioned inclined directions.

The nozzle 21 is connected to a position in the communication passage 22 within the projection range of the upstream descender flow path 224a in the inclined direction. More specifically, the center position of the connection port of the nozzle 21 connected to the communication passage 22 (the opening on the nozzle 21 opposite to the nozzle opening surface 1a) is arranged at the center position of the projection range. , The nozzle 21 is connected to the communication passage 22. Therefore, as in the first embodiment, the flow pressure applied to the ink in the nozzle 21 can be increased, and the ink in the nozzle 21 can be more agitated.

By the way, in general, the larger the inclination angle between the inflow direction of the ink flowing into the nozzle 21 and the penetrating direction of the nozzle 21, the more the inflowing ink causes a vortex or the like in the nozzle 21. Therefore, the ink in the nozzle 21 is easily agitated.

Here, in the above-described first embodiment, the upstream descender flow path 24a extends in the vertical direction orthogonal to the nozzle opening surface 1a. The penetration direction of the nozzle 21 is the vertical direction. Therefore, the inflow direction of the ink flowing into the nozzle 21 from the upstream descender flow path 24a is mainly in the downward direction parallel to the penetration direction of the nozzle 21. Therefore, in the first embodiment, the inclination angle between the ink inflow direction and the penetration direction of the nozzle 21 is small.

On the other hand, in the second embodiment, the inflow direction of the ink flowing into the nozzle 21 from the upstream descender flow path 224a is mainly the above-mentioned inclination direction inclined with respect to the vertical direction. Therefore, in the second embodiment, the inclination angle between the ink inflow direction and the penetration direction of the nozzle 21 becomes large. As a result, in the second embodiment, the stirring effect of the ink in the nozzle 21 can be enhanced and the drying of the ink in the nozzle 21 can be further suppressed as compared with the first embodiment.

(Third Embodiment)
Next, the third embodiment will be described. The configuration of the upstream descender flow path in the head of the third embodiment is also different from that of the first embodiment. Hereinafter, those having the same configuration as that of the first embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

As shown in FIG. 7, the head 301 according to the third embodiment is provided with the upstream descender flow path 324a instead of the upstream descender flow path 24a of the first embodiment.

The upstream descender flow path 324a is formed by overlapping through holes 341 to 345 formed in the plates 11b to 11f. Further, in the upstream descender flow path 324a, the downstream end portion 324a1, which is the end portion on the communication passage 22 side, becomes one side of the supply flow path 33 side in the arrangement direction from the lower end toward the upper end (FIG. 7). It is inclined to the middle left side). That is, the downstream end portion 324a1 extends in an inclined direction (corresponding to the "second direction") inclined with respect to the horizontal plane and the vertical direction. On the other hand, in the upstream descender flow path 324a, the flow path portions other than the downstream end portion 324a1 extend in the vertical direction.

More specifically, among the through holes 341 to 345 forming the upstream descender flow path 324a, the through direction of the through hole 345 formed in the plate 11f is the above-mentioned inclined direction. On the other hand, the penetration direction of the through holes 341 to 344 is the vertical direction.

The nozzle 21 is connected to a position in the communication passage 22 within the projection range in the inclination direction of the downstream end portion 324a1 of the upstream descender flow path 324a. More specifically, the center position of the connection port of the nozzle 21 connected to the communication passage 22 (the opening on the nozzle 21 opposite to the nozzle opening surface 1a) is arranged at the center position of the projection range. , The nozzle 21 is connected to the communication passage 22. As described above, as in the first embodiment and the second embodiment, the flow pressure applied to the ink in the nozzle 21 can be increased, and the ink in the nozzle 21 can be more agitated.

Further, in the third embodiment, as in the second embodiment, the inflow direction of the ink flowing into the nozzle 21 from the upstream descender flow path 324a is mainly the above-mentioned inclination direction inclined with respect to the vertical direction. .. Therefore, the inclination angle between the inflow direction of the ink and the penetration direction of the nozzle 21 becomes large. As a result, in the third embodiment, as in the second embodiment, the stirring effect of the ink in the nozzle 21 can be enhanced, and the drying of the ink in the nozzle 21 can be further suppressed.

Further, in the third embodiment, in the upstream descender flow path 324a, the flow path portions other than the downstream end portion 324a1 extend in the vertical direction. As a result, the length of the heads 301 in the arrangement direction can be shortened as compared with the second embodiment, so that the heads 301 can be miniaturized.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the connection position of the nozzle with the communication passage is not limited to the above-described embodiment, and the nozzle is connected to a position on the communication passage on the descender flow path side upstream of the center position in the arrangement direction of the communication passage. It suffices if it is done. Specifically, as in the head 401 of the first modification shown in FIG. 8A, the nozzle 21 is located at the center position of the communication passage 22 in the arrangement direction of the communication passage 22 and upstream of the communication passage 22. The side descender flow path 24a may be connected at a position between it and one end to which it is connected. In the head 401 of the first modification, the nozzle 21 is connected to a position outside the projection region in the vertical direction of the downstream end portion 24a1 in the communication passage 22.

Further, in the above-described embodiment, the lower surface of the communication passage 22 is defined by the plate 11h on which the nozzle 21 is formed, but the present invention is not limited to this. The lower surface of the communication passage 22 may not be defined by the plate 11h as in the head 501 of the second modification shown in FIG. 8B. The head 501 of the second modification further has one plate 515 sandwiched between the plate 11g on which the communication passage 22 is formed and the plate 11h on which the nozzle 21 is formed. The lower surface of the communication passage 22 is defined by the plate 515. Further, the plate 515 is formed with a through hole 515a that connects the communication passage 22 and the nozzle 21 and penetrates in the vertical direction. Therefore, in the head 501, the nozzle 21 is connected to the communication passage 22 via the through hole 515a.

Further, in the above-described embodiment, in the upstream descender flow path, the flow path cross-sectional area of the downstream end portion is smaller than that of the other flow path portions, but the present invention is not limited to this, and the upstream side descender is not limited to this. The flow path cross-sectional area of each part in the flow path may be the same.

Further, in the second embodiment described above, the penetration direction of each through hole forming the upstream descender flow path is set to an inclined direction inclined with respect to the orthogonal direction orthogonal to the nozzle opening surface, so that the upstream descender flow. The extending direction of the road was an inclined direction, but the road is not limited to this. For example, by gradually shifting the formation position of the through holes in the arrangement direction while the penetration direction of each through hole forming the upstream descender flow path is set to the orthogonal direction, the extension direction of the upstream descender flow path May be tilted with respect to the orthogonal direction. That is, the extending direction of the upstream descender flow path may be inclined with respect to the orthogonal direction by stacking the through holes forming the upstream descender flow path in a stepped manner.

Further, in the above-described embodiment, the nozzle is formed in a tapered shape that tapers toward the nozzle opening surface, but the present invention is not limited to this. For example, the inner wall surface of the nozzle may be parallel to the orthogonal direction orthogonal to the nozzle opening surface. In this case, in order to enhance the stirring effect of the ink in the nozzle, at least the downstream end portion of the upstream descender flow path extends in the inclined direction inclined with respect to the orthogonal direction as in the second and third embodiments. It is preferable to be present.

Further, in the above-described embodiment, the inner wall surface of the nozzle has water repellency by forming a water-repellent film, but the present invention is not limited to this. For example, water repellency may be provided by forming minute irregularities on the inner wall surface of the nozzle. Further, the inner wall surface of the nozzle does not have to have water repellency.

Further, in the above-described embodiment, the ink is circulated between the head 1 and the ink tank 7, but the ink flows from the supply flow path to the recovery flow path through the plurality of individual flow paths. For example, it does not have to be circulated. In this case, in order to improve the recovery efficiency of the air flowing out from the individual flow paths to the recovery flow path, it is preferable that a tank for collecting air is connected to the recovery flow path.

Further, in the above, an example in which the present invention is applied to a printer provided with a so-called line head has been described, but the present invention is not limited thereto. It is also possible to apply the present invention to a printer provided with a so-called serial head, which is mounted on a carriage that moves in the scanning direction and ejects ink from a nozzle while moving in the scanning direction together with the carriage.

In addition, the above has described an example in which the present invention is applied to a printer that ejects ink from a nozzle to record on paper, but the present invention is not limited to this. It is also possible to apply the present invention to a liquid ejection device that ejects a liquid other than ink, for example, a liquid resin or metal.

1,201,301 Head 20 Individual flow path 21 Nozzle 22 Continuous passage 23a Upstream pressure chamber 23b Downstream pressure chamber 24a, 224a, 324a Upstream descender flow path 24b Downstream side descender flow path 25a Upstream side throttle flow path 25b Downstream side Squeezing flow path 31, 32 Recovery flow path 33 Supply flow path

Claims (10)

Multiple nozzles,
Nozzle opening surface on which openings of the plurality of nozzles are formed,
A plurality of individual flow paths corresponding to the plurality of nozzles,
Connected to the inlets of the plurality of individual flow paths to supply the liquid to the plurality of individual flow paths, and connected to the outlets of the plurality of individual flow paths to collect the liquid from the plurality of individual flow paths. A flow path forming body having a recovery flow path is provided.
Each of the plurality of individual flow paths
A communication passage connected to the nozzle and extending in the first direction parallel to the nozzle opening surface,
An upstream pressure chamber arranged between the communication passage and the supply passage,
A downstream pressure chamber arranged between the communication passage and the recovery passage,
An upstream descender flow path connecting the upstream pressure chamber and one end of the communication passage,
A downstream descender flow path connecting the other end of the communication passage and the downstream pressure chamber,
Have and
An upstream actuator that applies pressure to the liquid in the upstream pressure chamber,
A downstream actuator that applies pressure to the liquid in the downstream pressure chamber,
With more
The downstream end portion of the upstream descender flow path, which is the end portion on the continuous passage side, extends in the second direction intersecting the nozzle opening surface.
A liquid discharge head characterized in that the nozzle is connected to a position on the descender flow path side on the upstream side of the communication passage in the first direction of the communication passage. The liquid discharge head according to claim 1, wherein the nozzle is connected to a position in the projection region in the second direction of the downstream end portion of the upstream descender flow path in the communication passage. .. The liquid discharge head according to claim 2, wherein the nozzle is connected to a central position of the projection region in the communication passage. The flow path forming body is
The first plate forming the nozzle and
The second plate forming the communication passage and
With
The liquid discharge head according to any one of claims 1 to 3, wherein the first plate has a wall portion defining a lower surface of the communication passage. The first to fourth aspects of the upstream descender flow path, wherein the flow path cross-sectional area of the downstream end portion is smaller than the flow path cross-sectional area of the other flow path portions of the upstream descender flow path. The liquid discharge head according to any one item. The second direction is inclined with respect to the orthogonal direction orthogonal to the nozzle opening surface.
The liquid discharge head according to any one of claims 1 to 5, wherein the entire upstream descender flow path extends in the second direction. The second direction is inclined with respect to the orthogonal direction orthogonal to the nozzle opening surface.
The liquid discharge head according to any one of claims 1 to 5, wherein the flow path portion other than the downstream end portion in the upstream descender flow path extends in the orthogonal direction. The liquid discharge head according to any one of claims 1 to 7, wherein each of the plurality of nozzles is formed in a tapered shape that tapers toward the nozzle opening surface. The liquid discharge head according to any one of claims 1 to 8, wherein the inner wall surface of each of the plurality of nozzles has water repellency. The liquid discharge head according to any one of claims 1 to 9,
A pump that transfers a liquid from the supply flow path to the recovery flow path via the plurality of individual flow paths.
A liquid discharge device characterized by being equipped with.

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