Liquid spraying device

Abstract

To shorten a distance at which self-liquid is formed into liquid droplets, in jetting liquid at a high speed.SOLUTION: A liquid jet device 1 is equipped with a nozzle 27 that jets liquid 3, a liquid carriage pipe 7 through which the liquid 3 is carried to the nozzle 27, and a vibration generating part 40 that generates vibrations. The vibration generating part 40 contacts at least one of the liquid 3, the nozzle 27 and the liquid carriage pipe 7, where when the liquid 3 jetted from the nozzle 27 is formed into a plurality of liquid droplets 3b and then the liquid droplets scatter in a state where the vibration generating part 40 is not generating vibrations, and the number of the liquid droplets 3b passing through a predetermined position in a unit time is defined as frequencies at which self-liquid is formed into liquid droplets, frequencies of vibrations that are generated by the vibration generating part 40 are larger than the frequencies at which self-liquid is formed into liquid droplets.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus. [Background technology]

[0002] Conventionally, various liquid ejection devices have been used to eject liquid onto an object. Among these liquid ejection devices, there is a liquid ejection device that continuously ejects liquid, turns it into droplets, and causes the droplets to collide with the object. For example, Patent Document 1 describes a method in which gas is mixed into a pressurized liquid and the liquid is ejected from a nozzle, causing the droplets to collide with the object in a droplet state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-257997 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional liquid injection devices configured to collide droplets onto a target object as described in Patent Document 1, when the liquid is injected at high speed, the distance over which the droplets are generated becomes long. When the droplet generation distance becomes long, the distance from the injection part to the target object must be increased, which requires a larger working space, thereby reducing workability. [Means for solving the problem]

[0005] In order to solve the above problem, the liquid injection device of the present invention comprises a nozzle that injects liquid, a liquid transport pipe that transports the liquid to the nozzle, and a vibration generating unit that generates vibrations, wherein the vibration generating unit is in contact with at least one of the liquid, the nozzle, and the liquid transport pipe, and when the liquid injected from the nozzle when the vibration generating unit is not generating vibrations becomes multiple droplets and flies, and the number of droplets that pass a predetermined position in a unit time is defined as the self-dropletization frequency, the frequency of the vibration generated by the vibration generating unit is greater than the self-dropletization frequency. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating a liquid ejecting apparatus according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view illustrating an ejection portion of the liquid ejection device according to the first embodiment. [Figure 3] 10 is a photograph showing a state in which a fluid is ejected from a nozzle when no flow rate pulsation is applied. [Figure 4] Photographs showing the state of fluid ejection from a nozzle when flow rate pulsation is applied at a vibration frequency of 252 kHz at 10 V peak-to-peak. [Figure 5] A photograph showing the state in which the fluid from the nozzle is broken into droplets when a flow rate pulsation is applied at a vibration frequency of 130 kHz at 10 V peak-to-peak. [Figure 6] This photograph shows the state in which the fluid from the nozzle did not break into droplets when a flow rate pulsation was applied at a vibration frequency of 134 kHz at 10 V peak-to-peak. [Figure 7] Graph showing droplet formation distance when vibration frequency is changed at 10V peak-to-peak. [Figure 8] Graph showing droplet formation distance when vibration frequency is changed at 20V peak-to-peak. [Figure 9] This graph shows normalized values ​​of the self-condensation frequency and the self-condensation distance for droplets generated at a flow rate of 3 ml / min and an amplitude of 20 V peak-to-peak, and for droplets generated at a flow rate of 4 ml / min and an amplitude of 20 V peak-to-peak. DETAILED DESCRIPTION OF THE INVENTION

[0007] First, the present invention will be briefly described. In order to solve the above problem, a first aspect of the present invention provides a liquid injection device comprising a nozzle for injecting liquid, a liquid transport pipe for transporting the liquid to the nozzle, and a vibration generating unit for generating vibrations, wherein the vibration generating unit is in contact with at least one of the liquid, the nozzle, and the liquid transport pipe, and when the liquid injected from the nozzle forms multiple droplets and flies in a state where the vibration generating unit is not generating vibrations, and the number of droplets that pass a predetermined position in a unit time is defined as the self-dropletization frequency, the frequency of the vibration generated by the vibration generating unit is greater than the self-dropletization frequency.

[0008] According to this aspect, the frequency of the vibration generated by the vibration generating unit is greater than the self-dropletizing frequency. As a result of extensive research, the inventors have found that the droplet-forming distance can be shortened by making the frequency of the vibration generated by the vibration generating unit greater than the self-dropletizing frequency. Therefore, the self-dropletizing distance can be shortened even when the liquid is sprayed at high speed.

[0009] A second aspect of the present invention is the liquid ejecting device of the first aspect, characterized in that the frequency of the vibration generated by the vibration generating section is 1.5 times or less the self-dropletizing frequency.

[0010] According to this aspect, the frequency of the vibrations generated by the vibration generating unit is 1.5 times or less the self-dropletizing frequency. If the frequency of the vibrations generated by the vibration generating unit is too high, droplets may not be formed properly, but by setting the frequency of the vibrations generated by the vibration generating unit to 1.5 times or less the self-dropletizing frequency, it is possible to prevent droplets from not being formed properly.

[0011] A third aspect of the present invention is the liquid ejecting device of the first or second aspect, characterized in that the frequency of the vibration generated by the vibration generating section is 90 kHz or higher.

[0012] According to this aspect, the frequency of the vibration generated by the vibration generating unit is 90 kHz or more. By setting the frequency of the vibration generated by the vibration generating unit to 90 kHz or more, the droplet formation distance can be particularly suitably shortened.

[0013] A fourth aspect of the liquid injection device of the present invention is characterized in that, in any one of the first to third aspects, the vibration generating unit generates vibrations that pulsate the liquid in the transport direction of the liquid.

[0014] According to this aspect, the vibration generating unit generates vibrations that pulsate the liquid in the liquid transport direction. Pulsating the liquid in the liquid transport direction can particularly suitably shorten the droplet formation distance.

[0015] A fifth aspect of the present invention is the liquid ejecting apparatus of the fourth aspect, characterized in that the vibration generating section vibrates the liquid transport pipe in the transport direction of the liquid.

[0016] According to this aspect, the vibration generating unit vibrates the liquid transport pipe in the liquid transport direction. By vibrating the liquid transport pipe in the liquid transport direction, the liquid can be suitably pulsated in the liquid transport direction.

[0017] A sixth aspect of the present invention is the liquid ejecting apparatus of the fourth aspect, characterized in that the vibration generating section vibrates the liquid transport pipe in a direction perpendicular to the transport direction of the liquid.

[0018] According to this aspect, the vibration generating section vibrates the liquid transport pipe in the liquid transport direction, which makes it possible to easily form a configuration for vibrating the liquid transport pipe in the liquid transport direction.

[0019] A seventh aspect of the present invention is the liquid ejecting device of any one of the first to sixth aspects, characterized in that the vibration generating section includes a piezoelectric element.

[0020] According to this aspect, the vibration generating unit includes a piezoelectric element, and therefore, the piezoelectric element can form a vibration generating unit capable of generating high frequency vibrations.

[0021] In an eighth aspect of the present invention, in the liquid ejecting device of any one of the first to sixth aspects, the vibration generating section includes an electrostatic actuator.

[0022] According to this aspect, the vibration generating unit includes an electrostatic actuator, which can generate high frequency vibrations.

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, an overview of a liquid ejection device 1 according to one embodiment of the present invention will be described with reference to Fig. 1. The liquid ejection device 1 shown in Fig. 1 includes a head unit 2, a tank 8 that stores the liquid 3 to be ejected, a liquid transport pipe 7 that is composed of a tube connecting the head unit 2 and the tank 8 and a flow path for the liquid 3 within the head unit 2, a liquid delivery pump 6, and a control device 5 that has a drive signal line 51 to the head unit 2 and a control signal line 52 to the liquid delivery pump 6.

[0024] A user uses the liquid ejection device 1 configured as described above to perform various tasks by holding the grip portion 21, ejecting the liquid 3 from the head portion 2, and causing the liquid 3 to collide with a desired object. Examples of various tasks include dental treatment, but other tasks include cleaning, deburring, peeling, chipping, excising, cutting, and crushing the object. The liquid ejection device 1 of this embodiment is a liquid ejection device in which the liquid 3a continuously ejected from the nozzle 27 provided on the head portion 2 in direction b becomes droplets 3b, and the droplets 3b collide with the object in the droplet-formed state.

[0025] Next, the head unit 2, which is a main part of the liquid ejection device 1, will be described in detail with reference to Fig. 2. As shown in Fig. 2, the head unit 2 has an introduction channel 23 and an inflow channel opening 24 that constitute the liquid transport pipe 7 within the gripping part 21. Liquid 3 that flows into the head unit 2 from the tank 8 in direction a passes through the introduction channel 23 and the inflow channel opening 24, is guided to a fluid chamber 25, and is sprayed from the nozzle 27 in direction b as a high-speed continuous flow of liquid 3a, as shown in Fig. 1.

[0026] The fluid chamber 25 is sealed by an intermediate member 33 and a diaphragm 41 made of a thin metal film and fixed to the intermediate member 33. A single-plate piezoelectric element 42 made of PZT with electrodes formed on both sides and 17.7 mm in diameter and 1 mm thick is fixed to the surface of the diaphragm 41 opposite the fluid chamber 25 with a conductive adhesive to establish electrical continuity with the diaphragm 41. Two drive signal lines 51 are provided: one is fixed in electrical continuity with the diaphragm 41 through one of the holes 31 in the restricting portion 34, and the other is fixed in direct electrical continuity with the electrode of the PZT single-plate piezoelectric element 42 through the other hole 31 in the restricting portion 34. The single-plate piezoelectric element 42 of this embodiment, configured as described above, constitutes the vibration generating unit 40 that generates vibrations in the liquid 3 flowing through the liquid transport pipe 7 in the head unit 2. Because it is durable, inexpensive, and can be miniaturized, it is suitable for achieving high-frequency thickness-wise displacement.

[0027] As described above, it is preferable that the vibration generating unit 40 includes a piezoelectric element such as the single-plate piezoelectric element 42. This is because such a piezoelectric element can form a vibration generating unit capable of generating high vibration frequencies. Among these, particularly preferable piezoelectric elements include, for example, PZT piezoelectric elements as in this embodiment, as well as ceramic piezoelectric elements such as BaTiO3 and PbTiO3.

[0028] On the other hand, the vibration generating unit 40 may be configured to include an electrostatic actuator in which a dielectric is sandwiched between electrodes. This is because, when the vibration generating unit 40 is configured to include an electrostatic actuator, the electrostatic actuator can generate a high frequency vibration. In particular, by forming the dielectric from a soft material such as resin, the degree of freedom in design can be increased.

[0029] Next, a specific operation of the liquid ejection device 1 of this embodiment will be described. For example, first, a pump drive signal is sent to the liquid feed pump 6 via the control signal line 52 from the control device 5 shown in FIG. 1. This causes the liquid feed pump 6 to suck the liquid 3 from the tank 8 through the tube that constitutes the liquid transport pipe 7, and feed the liquid 3 at high pressure through the tube to the head unit 2. The liquid 3 flows in the direction a in FIG. 2, passing through the inflow channel opening 24 and flowing into the fluid chamber 25.

[0030] The liquid ejection device 1 of this embodiment can perform droplet promotion by driving the vibration generating unit 40 to vibrate the liquid 3 in the head unit 2, or it can not perform droplet promotion by not driving the vibration generating unit 40 and not vibrating the liquid 3 in the head unit 2. In the liquid ejection device 1 of this embodiment, when droplet promotion is not performed, the liquid 3 ejected from the nozzle 27 is sprayed as a continuous stream as shown by liquid 3a in FIG. 1, and is eventually broken up by the surface tension of the liquid 3 itself and flies as droplets as shown by droplet 3b in FIG. 1. Hereinafter, the process of generating droplets 3b by breaking up the liquid 3 due to the surface tension of the liquid 3 itself without performing droplet promotion will be referred to as self-dropletization.

[0031] When the liquid 3 collides with an object, the impact pressure that the object receives from the liquid 3 is calculated as follows when the liquid 3a is in a continuous flow state: 1 / 2 × ρ × V, where V is the injection speed of the liquid 3 and ρ is the working fluid density. 2The stagnation point pressure is ρ×C×V. On the other hand, the impact pressure when liquid 3 is broken down into droplets 3b is an impact pressure expressed as ρ×C×V, where C is the speed of sound in liquid 3. For example, the speed of sound in water is approximately 1500 m / s, so when liquid 3 is jetted at a speed of 100 m / s, the force exerted on the target when liquid 3 is in a dropletized state is 30 times that of when liquid 3 is in a continuous flow state. In other words, by breaking liquid 3 into droplets and causing them to collide with the target, operations such as crushing and cutting the target can be performed extremely effectively when compared to when liquid 3 is not broken down into droplets at the same flow rate.

[0032] Here, Figure 3 is a photograph showing the state of liquid 3 when water is sprayed at 4 ml / min from a nozzle with a nozzle diameter of 42 μm without pulsation. The left edge of Figure 3 corresponds to a position 19 mm away from nozzle 27, and the scale lines at the top of the photograph correspond to 1 mm intervals, with the numbers above the scale lines corresponding to the distance from nozzle 27. As can be seen from Figure 3, at a position 26 mm away from nozzle 27, the continuous water stream is interrupted by surface tension and breaks into droplets. In this example, this 26 mm corresponds to the self-condensation distance.

[0033] For example, when dental treatment is performed by causing droplets 3b to collide with a target inside the oral cavity, it is difficult to spray liquid 3 onto the affected area from a position more than 26 mm away from nozzle 27. The number of droplets 3b generated per second in this case is 247,000, and the self-dropletization frequency is called 247 kHz. In other words, when vibration generating unit 40 is not generating vibrations, liquid 3 sprayed from nozzle 27 forms multiple droplets, and the number of droplets 3b that fly and pass a specified position per unit time is called the self-dropletization frequency.

[0034] In the present invention, the fluid chamber 25, the diaphragm 41, and the single-plate piezoelectric element 42, which is the drive element, form a vibration generating unit 40 as a pulsation generating unit. When an AC voltage is applied to the single-plate piezoelectric element 42 via the drive signal line 51 while the liquid 3 is pressure-fed by the liquid feed pump 6 and ejected from the nozzle 27, the single-plate piezoelectric element 42 vibrates in its thickness direction at the frequency of the applied voltage. The vibration of the single-plate piezoelectric element 42 is transmitted to the liquid 3 in the fluid chamber 25 via the diaphragm 41, and the vibration of the liquid 3 in the fluid chamber 25 is transmitted to the liquid 3 ejected from the nozzle 27, promoting the formation of droplets.

[0035] Figure 4 shows the case where droplet formation was promoted by a flow rate pulsation of 252 kHz, which is close to the self-dropletization frequency of 247 kHz but slightly higher than the self-dropletization frequency. In addition, when applying a 252 kHz flow rate pulsation to the liquid 3, a voltage of 10 V peak-to-peak with an offset of 5 V was applied to the single-plate piezoelectric element 42. The left edge of Figure 4 corresponds to a position 8 mm away from the nozzle 27, and the scale lines at the top of the photograph correspond to 1 mm intervals, with the numbers above the scale lines corresponding to the distance from the nozzle 27. Comparing the photograph in Figure 4 with the photograph in Figure 3, where no pulsation was applied, clearly shows that droplet formation occurred at a distance of approximately 13 mm from the nozzle 27, approximately half the self-dropletization distance, and that the droplet shape and droplet spacing were consistent. In other words, because droplet formation began near the nozzle 27, this device can be used in intraoral or other confined spaces where short-distance treatment is required. Furthermore, because the droplet shape and spacing are consistent, the impact pressure is consistent and it is less susceptible to the influence of the water film from the previous bullet, allowing for efficient fragmentation and cutting.

[0036] As described above, in the liquid ejection device 1 of this embodiment, the vibration generating unit 40 is in contact with the liquid 3. The frequency of the vibrations generated by the vibration generating unit 40 is greater than the self-dropletizing frequency. As can be seen from a comparison of FIGS. 3 and 4, it was found that the dropletizing distance can be shortened by increasing the frequency of the vibrations generated by the vibration generating unit 40 above the self-dropletizing frequency. Therefore, the liquid ejection device 1 of this embodiment can shorten the dropletizing distance even when ejecting the liquid 3 at high speed. Note that, although the vibration generating unit 40 of this embodiment is in contact with the liquid 3, it is sufficient that the vibration generating unit 40 be in contact with at least one of the liquid 3, the nozzle 27, and the liquid transport pipe 7.

[0037] As described above, the self-forming frequency without flow pulsation is approximately 247 kHz, but flow pulsation can be used to promote droplet formation. Changing the frequency of the flow pulsation also changes the diameter of droplets 3b, making it possible to change the droplet diameter to suit the conditions of crushing, cutting, or cleaning the target object.

[0038] To determine a particularly suitable frequency, sine waves of 10 V peak-to-peak with an offset of 5 V and 20 V peak-to-peak with an offset of 10 V were applied to the single-plate piezoelectric element 42 and examined. The static characteristics of the single-plate piezoelectric element 42 at these voltages showed a small displacement of 0.005 nm at 10 V and 0.01 nm at 20 V. The frequency range was from 89 kHz, at which flow rate pulsation begins to promote droplet formation, to 374 kHz, at which promotion of droplet formation ceases, and was examined in 1 kHz steps up to 100 kHz and in 2 kHz steps above that.

[0039] The definition of droplet formation is that droplets 3b become approximately spherical after the continuous flow is broken up. This is because there are frequencies at which effective droplet formation is not possible, such as when droplets 3b break up but satellite droplets are generated. Therefore, Figures 5 and 6 show specific examples of when effective droplet formation is possible and when effective droplet formation is not possible. Figure 5 is a photograph of an example where an oscillation frequency of 130 kHz at 10 V peak-to-peak was used, in which effective spherical droplet formation was achieved. On the other hand, Figure 6 is a photograph of an example where an oscillation frequency of 134 kHz at 10 V peak-to-peak was used, in which satellite droplets were generated and droplets 3b did not become a desirable sphere.

[0040] FIG. 7 shows test results for a flow rate of 4 ml / min, with a voltage applied to the single-plate piezoelectric element 42 of 10 V peak-to-peak, representing cases where effective droplet formation was achieved and cases where effective droplet formation was not achieved. FIG. 8 shows test results for a flow rate of 4 ml / min, with a voltage applied to the single-plate piezoelectric element 42 of 20 V peak-to-peak, representing cases where effective droplet formation was achieved and cases where effective droplet formation was not achieved. In both FIGS. 7 and 8, the horizontal axis represents the pulsation frequency, which is the frequency of the sine wave applied to the single-plate piezoelectric element 42, and the vertical axis represents the droplet formation distance. In FIGS. 7 and 8, frequencies displayed at a droplet formation distance of 0 mm represent cases where effective droplet formation was not achieved, such as when droplets 3b did not form into spheres, as shown in FIG. 6.

[0041] As shown in Figure 7, for the 10V peak-to-peak voltage in Figure 7, stable droplet formation was possible from 242 kHz, just below the self-dropletization frequency of 247 kHz, and continued up to 334 kHz. Stable droplet formation was indicated by the droplet formation distance being 26 mm or less from 242 kHz to 334 kHz, not 0 mm. Furthermore, from 338 kHz to 366 kHz, the droplet formation distance was also 26 mm or less, not 0 mm, indicating stable droplet formation. Meanwhile, as shown in Figure 8, for the 20V peak-to-peak voltage in Figure 8, which increased the amplitude compared to the 10V peak-to-peak voltage in Figure 7, stable droplet formation was possible from 228 kHz to 374 kHz.

[0042] Here, stable droplet formation begins at 228 kHz, which is approximately 0.9 times the self-droplet formation frequency of 247 kHz, for the 20 V peak-to-peak voltage of FIG. 8. Also, at 10 V peak-to-peak voltage of FIG. 7, it is 242 kHz, which is approximately 1 time the self-droplet formation frequency of 247 kHz. The preferred upper frequency limit for the 20 V peak-to-peak voltage of FIG. 8 is 374 kHz / 228 kHz, or approximately 1.6 times the self-droplet formation frequency. Also, at 10 V peak-to-peak voltage of FIG. 7, the preferred upper frequency limit is 334 kHz / 242 kHz, taking into account the 336 kHz portion that did not form single droplets, or approximately 1.3 times the self-droplet formation frequency. If this portion is not taken into account, the preferred upper frequency limit is 366 kHz / 242 kHz, or approximately 1.5 times the self-droplet formation frequency.

[0043] From the above results, it is preferable that the frequency of the vibrations generated by vibration generating unit 40 is 1.5 times or less the self-liquidization frequency. If the frequency of the vibrations generated by vibration generating unit 40 is too high, droplet formation may not be performed properly, but by setting the frequency of the vibrations generated by vibration generating unit 40 to 1.5 times or less the self-liquidization frequency, it is possible to prevent the self-liquidization from not being performed properly.

[0044] Furthermore, as a result of thorough investigations conducted by the inventors under various conditions, it was found that the frequency of the vibration generated by the vibration generating unit 40 is preferably 90 kHz or higher. By setting the frequency of the vibration generated by the vibration generating unit to 90 kHz or higher, the droplet formation distance can be particularly suitably shortened.

[0045] 8, it is preferable that the frequency of the vibration generated by the vibration generating unit 40 is 370 kHz or less. By setting the frequency of the vibration generated by the vibration generating unit to 370 kHz or less, the droplet formation distance can be particularly suitably shortened.

[0046] FIG. 9 is a graph normalized by the self-liquidization frequency and the self-liquidization distance for droplet formation at a flow rate of 3 ml / min and a 20 V peak-to-peak amplitude, respectively, and for droplet formation at a flow rate of 4 ml / min and a 20 V peak-to-peak amplitude. Here, normalization refers to a preferred range of the vibration frequency, i.e., pulsation frequency, generated by the vibration generating unit 40. Specifically, it refers to the range of pulsation frequency / self-liquidization frequency where the droplet formation distance / self-liquidization distance in FIG. 9 is not 0 but is less than or equal to 1.0. At a flow rate of 3 ml / min, the self-liquidization frequency is 180 kHz and the self-liquidization distance is 17 mm. At a flow rate of 4 ml / min, the self-liquidization frequency is 247 kHz and the self-liquidization distance is 26 mm, based on the above results.

[0047] As shown in Figure 9, even if the self-liquidization frequency changes, the frequency of the flow rate pulsation is stable in a range that exceeds the self-liquidization frequency, that is, in a range where the pulsation frequency / self-liquidization frequency exceeds 1. The region in Figure 9 where the frequency of the flow rate pulsation is stable is a region where the ratio of the droplet formation distance / self-liquidization distance is not 0 but is 1.0 or less. Furthermore, as described above, the preferred upper limit of the frequency (the frequency of the vibrations generated by the vibration generating unit 40) is 1.5 times or less the self-liquidization frequency, and more preferably 1.3 times or less.

[0048] 2 can generate vibrations that pulsate the liquid 3 in direction a, which is the transport direction of the liquid 3. Pulsating the liquid 3 in the transport direction of the liquid 3 can particularly suitably shorten the droplet formation distance.

[0049] In detail, the vibration generating unit 40 uses the single-plate piezoelectric element 42 to vibrate the liquid transport pipe 7 in a direction perpendicular to direction a, which is the transport direction of the liquid 3. By configuring the vibration generating unit 40 in this way, it is possible to easily form a configuration that vibrates the liquid transport pipe 7 in the transport direction of the liquid 3.

[0050] However, the present invention is not limited to this configuration. For example, the vibration generating unit 40 may be configured to vibrate the liquid transport pipe 7 in the transport direction of the liquid 3 by changing the shape of the liquid transport pipe 7 and the arrangement of the single-plate piezoelectric element 42 relative to the liquid transport pipe 7. Vibrating the liquid transport pipe 7 in the transport direction of the liquid 3 can also suitably pulsate the liquid 3 in the transport direction of the liquid 3, similar to the vibration generating unit 40 of this embodiment.

[0051] The present invention is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit of the present invention. The technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0052] 1...liquid ejection device, 2...head portion, 3...liquid, 3a...liquid in continuous flow state, 3b...droplets, 5...control device, 6...liquid feed pump, 7...liquid transport pipe, 8...tank, 21...gripping portion, 23...inlet flow path, 24...inlet flow path opening, 25...fluid chamber, 27...nozzle, 31...hole portion, 33...intermediate member, 34...regulating portion, 40...vibration generating portion, 41...diaphragm, 42...single-plate piezoelectric element, 51...drive signal line, 52...control signal line

Claims

1. A nozzle for spraying a liquid; a liquid transport pipe that transports the liquid to the nozzle; a vibration generating unit that generates vibrations; Equipped with the vibration generating unit is in contact with at least one of the liquid, the nozzle, and the liquid transport pipe; When the liquid ejected from the nozzle becomes a plurality of droplets in a state in which the vibration generating unit does not generate vibration, the number of droplets that fly and pass a predetermined position per unit time is defined as a self-dropletization frequency, The liquid ejecting apparatus is characterized in that the frequency of the vibration generated by the vibration generating unit is higher than the self-dropletizing frequency.

2. The liquid ejection apparatus according to claim 1 , The liquid ejecting apparatus is characterized in that the frequency of the vibration generated by the vibration generating unit is 1.5 times or less the self-dropletizing frequency.

3. 3. The liquid ejection apparatus according to claim 1, The liquid ejecting device, wherein the frequency of the vibration generated by the vibration generating unit is 90 kHz or higher.

4. The liquid ejection apparatus according to claim 1 , The liquid ejecting apparatus is characterized in that the vibration generating unit generates vibrations that pulsate the liquid in a transport direction of the liquid.

5. The liquid ejection apparatus according to claim 4, The liquid ejecting apparatus is characterized in that the vibration generating section vibrates the liquid transport pipe in the liquid transport direction.

6. The liquid ejection apparatus according to claim 4, The liquid ejecting apparatus is characterized in that the vibration generating unit vibrates the liquid transport pipe in a direction perpendicular to the liquid transport direction.

7. The liquid ejection apparatus according to any one of claims 1 to 6, The liquid ejecting apparatus is characterized in that the vibration generating unit includes a piezoelectric element.

8. The liquid ejection apparatus according to any one of claims 1 to 6, The liquid ejecting apparatus, wherein the vibration generating unit includes an electrostatic actuator.

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