Patent ID: 12194744

DESCRIPTION OF EMBODIMENTS

Detailed explanation follows regarding exemplary embodiments of the present disclosure, with reference to the drawings.

First Exemplary Embodiment

Device Configuration

First, explanation follows regarding a liquid jet discharge device10according to a first exemplary embodiment, with reference toFIG.1. The liquid jet discharge device10includes a container12inside which an ink11serving as an example of a liquid is filled (housed) and that is formed with a nozzle28, described later, at a lower end portion. The liquid jet discharge device10also includes a moving mechanism14that moves the container12in an up-down direction, a stopper16that is abutted by the container12when moving downward so as to stop the container12, and a replenishment device18that supplies the ink11into the container12.

The container12is formed in a circular cylinder shape, and includes an upper wall20, a bottom wall22, and a peripheral wall24running around so as to connect the upper wall20and the bottom wall22.

A section of the container12enclosed by the upper wall20, the bottom wall22, and the peripheral wall24configures a pressure generation chamber26in which the ink11is housed. The pressure generation chamber26corresponds to a “pressure generation section”.

The nozzle28is formed penetrating a central portion of the bottom wall22from top to bottom. The nozzle28corresponds to an “ejection section”.

As illustrated inFIG.1, the nozzle28is formed with a a cross-sectional area in an orthogonal direction to the axial (up-down) direction of the nozzle28(simply “cross sectional area” thereafter that is smaller than the area of a portion (referred to hereafter as the “bottom face22A”) of the bottom wall22configuring the pressure generation chamber26(i.e. smaller than the cross-sectional area of the pressure generation chamber26).

Moreover, an axial direction length (lt, described later) of the pressure generation chamber26is set longer than an axial direction length (lm, described later) from a pressure generation chamber-side end portion of the nozzle28to a liquid surface (such that lt/lm>1). The pressure generation chamber26and the nozzle28are disposed coaxially with each other. Note that this axial direction corresponds to a “liquid jet discharge direction”.

The pressure generation chamber26is filled with the ink11. A contact angle θ between the ink11and an inner peripheral face of the nozzle28is set to less than 90°. Accordingly, the ink11that has entered the nozzle28from the pressure generation chamber26forms an upwardly convex (downwardly concave) meniscus (liquid surface LS) inside the nozzle28.

The moving mechanism14is provided above the container12in order to move the container12up and down. The moving mechanism14includes a rod32extending in an upward direction from a central portion of the upper wall20of the container12, and a solenoid34installed above the container12such that the rod32passes through the solenoid34. Namely, the rod32is moved up and down, thereby moving the container12up and down, by driving the solenoid34. Note that the container12is normally (except when discharging a liquid jet) positioned separated from and at a specific distance above the stopper16.

An opening35is formed in an upper portion of the peripheral wall24of the container12so as to place the interior and exterior of the pressure generation chamber26in communication with each other.

The stopper16is installed below the bottom wall22of the container12.

The stopper16includes a circular plate portion38and a peripheral wall40. The circular plate portion38has a donut shape centrally formed with a hole36that is larger than the cross-sectional area of the nozzle28. The peripheral wall40is disposed coaxially with the container12, and has a larger internal diameter than the external diameter of the container12(peripheral wall24).

A spacing between a lower end of the container12and an abutting face38A configuring an upper face of the circular plate portion38of the stopper16is set smaller than a stroke of the rod32when the solenoid34is driven. Accordingly, when the solenoid34is driven to lower the container12, the bottom wall22of the container12abuts the abutting face38A of the circular plate portion38of the stopper16.

The moving mechanism14and the stopper16correspond to an “impulse force impartation means”.

Paper42, serving as a discharge target, is loaded below the circular plate portion38of the stopper16. Configuration is made such that a liquid jet MJ, described later, discharged from the nozzle28, lands on the paper42. The paper42is fed by a non-illustrated paper feed mechanism.

As illustrated inFIG.1, the replenishment device18includes a replenishment tank44serving as a replenishment section disposed at a side of the container12, and a replenishment tube46serving as a liquid supply path that places the replenishment tank44in communication with the pressure generation chamber26.

The replenishment tank44is an open-topped tank inside which the ink11is held. A liquid surface50of the ink11is maintained so as to be higher than the bottom face22A of the pressure generation chamber26by a non-illustrated regulating means. For example, a mechanism to raise the replenishment tank44as the ink11is supplied may be provided as the regulating means.

The replenishment tube46is flexible, and has one end connected to the opening35formed in the peripheral wall24of the container12, and has another end disposed inside the ink11held in the replenishment tank44.

Operation

Explanation follows regarding operation of the liquid jet discharge device10configured in the above manner.

First, the solenoid34is driven to lower the rod32at a predetermined speed. Since the spacing (up-down direction length) between the bottom wall22of the container12and the abutting face38A of the stopper16is set shorter than the stroke of the rod32, the bottom wall22of the container12impacts the abutting face38A of the stopper16.

An impulse force acts on the container12from this impact. When this occurs, as illustrated inFIG.2, the meniscus (liquid surface LS) that was formed with a concave surface profile due to the contact angle θ of the ink11being less than 90° adopts a horizontal surface profile inside the nozzle28, and a liquid jet MJ that is thinner than the nozzle28is ejected (discharged) from a central portion of the meniscus.

In the liquid jet MJ, due to this impulse force there is a large velocity increase ratio (=U0′/U0) of an initial velocity U0′ of the ink11inside the nozzle28relative to an initial velocity U0of the ink11inside the pressure generation chamber26, resulting in a large velocity increase ratio β (=Vjet/U0) of a jet velocity Vjet, described later.

Thus when a given amount of energy is imparted, a high proportion of energy from the ink11can be concentrated in the liquid jet MJ due to achieving a higher velocity increase ratio β (enabling the liquid jet MJ to be discharged extremely fast). This enables even ink11with a high viscosity, which would hitherto not be possible to discharge using a liquid jet with a low velocity increase ratio, to be discharged when a given amount of energy is imparted to the ink11of the liquid jet discharge device10.

Parameters

Parameters employed to explain an analysis model for analyzing the liquid jet MJ discharged by the liquid jet discharge device10are described below.

An analysis model according to an Example is an analysis model of cases in which the liquid jet MJ is discharged using the liquid jet discharge device10.

The parameters are as set out below (seeFIG.3andFIG.4).lt: an axial direction distance (first length) from the bottom face22A to an upper face20A of the pressure generation chamber26(mm).lm: an axial direction distance (second length) from a pressure generation chamber-side end portion of the nozzle28(the bottom face22A of the pressure generation chamber26) to a meniscus formation position of the liquid surface LS inside the nozzle28(mm).d: nozzle28internal diameter (mm).ν: kinetic viscosity of the ink11(mm2/s) (in the present specification, the “viscosity” refers to the kinetic viscosity).
Analysis Model

First, explanation follows regarding a physical model relating to the jet velocity Vjetof the liquid jet MJ generated by the liquid jet discharge device10.

In cases in which the ink11inside the container12is suddenly accelerated by impulse force, the velocity of the ink11during the sudden change, and the velocity in the vicinity of a wall configuring the pressure generation chamber26, are not large. Thus, terms in Navier-Stokes equations that only include velocity and spatial differentials can be ignored since they are sufficiently small compared to other terms. Doing so, the Navier-Stokes equations give an initial velocity U0imparted to the ink11inside the pressure generation chamber26as below, wherein ρ is density.

U0=-1ρ⁢∂∏∂z(1)

Wherein Π is the pressure impulse, and z is tube axial direction distance. The pressure impulse Π is expressed by the following equation, wherein p is pressure, and τ is impulse force duration.
Π=∫0τpdt(2)

When the bottom wall22of the container12impacts the abutting face38A of the stopper16, as illustrated inFIG.5, a pressure impulse gradient ∂Π/∂z arises in the container12(pressure generation chamber26). The pressure impulse gradient ∂Π/∂z is constant, irrespective of the tube axial direction distance z.

The pressure impulse generated by imparting the impulse force to the container12increases on a constant gradient (first gradient) from the upper face20A to the bottom face22A of the pressure generation chamber26, and decreases on a constant gradient (second gradient) toward the meniscus surface (liquid surface LS) inside the nozzle28(so as to become 0 at the position of the meniscus) (seeFIG.5).

The pressure impulse gradient ∂Π/∂z in the pressure generation chamber26of the container12changes to a pressure impulse gradient ∂Π′/∂z′ inside the nozzle at the upper end of the nozzle28, namely at a boundary with the bottom face22A of the pressure generation chamber26.

Due to the geometric relationship illustrated inFIG.5, when employing the pressure impulse gradient ∂Π/∂z of the pressure generation chamber26, the first length lt, and the second length lm, the pressure impulse gradient ∂Π′/∂z′ of the ink11inside the nozzle becomes:

∂∏′∂z′=ltlm⁢∂∏∂z(3)

Similarly to in Equation (1), the initial velocity U0′ imparted to the ink11inside the nozzle28is:

U0′=-1ρ⁢∂∏′∂z′(4)

According to Equation (1), Equation (3), and Equation (4), the initial velocity U0′ imparted to the ink11inside the nozzle28is:

U0′=-1ρ⁢ltlm⁢∂∏∂z=ltlm⁢U0(5)

According to Equation (5), the initial velocity U0′ imparted to the ink11inside the nozzle28is (lt/lm) times greater than the initial velocity U0imparted to the ink11inside the pressure generation chamber26. The jet velocity (liquid jet MJ discharge velocity) Vjetgenerated in the nozzle28is:

Vjet=β⁢U0′=β⁢ltlm⁢U0(6)

proportionally to the initial velocity U0′ of the ink11inside a fine tube.

The pressure generation chamber26that has a larger cross-sectional area than the cross-sectional area of the nozzle28(the internal diameter D is larger than the internal diameter d of the nozzle28(D/d>1)) and the first length ltthat is longer than the second length lm(lt/lm>1) is thus provided inside the container12above the nozzle28. This enables the initial velocity U0′ imparted to the ink11inside the nozzle28to be sped up in comparison to the initial velocity U0inside the pressure generation chamber26. This enables the jet velocity Vjetgenerated by the nozzle28to likewise be sped up.

Namely, the velocity increase ratio β of the jet velocity Vjetcan be increased by increasing the first length lt, or by reducing the second length lm.

Numerical Calculations

The following numerical calculations were performed to confirm the operation described above and interpretations based on the analysis model.

A liquid jet discharge device10according to an Example with the same configuration as that illustrated inFIG.1was employed.

Numerical values were set as follows:first length lt=40 mmsecond length lm=1.5 mminternal diameter D of pressure generation chamber=10 mminternal diameter d of nozzle=2 mminitial velocity U0of ink in pressure generation chamber=1.25 m/skinetic viscosity ν of ink11: 100 mm2/s.

FIG.6toFIG.10illustrate logical values and numerical calculation results under the above conditions when varying any one of the first length lt, the second length lm, the internal diameter d of the nozzle, or the kinetic viscosity ν of the ink11. Note that the logical values are indicated for the analysis model (seeFIG.5).

1. When Varying First Length lt

FIG.6illustrates logical values and numerical calculation results for the distribution of the pressure impulse imparted to the ink in the container when varying the first length ltto either 40 mm or 80 mm. The bold lines represent the numerical calculation results, and the fine lines represent the logical values.

As can be seen fromFIG.6, even in cases in which the first length lthas been varied to 40 mm or 80 mm, the numerical calculation results are closely aligned with the logical values, with the exception of in the vicinity of the bottom face22A of the container12(the connection location between the pressure generation chamber26and the nozzle28). Moreover, it is confirmed that increasing the first length ltcauses the pressure impulse gradient to increase as predicted by the logic.

When the logically derived initial velocity U0′ imparted to the ink11inside the nozzle28is compared against the numerical calculation results for the initial velocity U0′ imparted to the ink11inside the nozzle28:for the case in which ltis 40 mm, the logical value is 33.3 m/s whereas the numerical calculation result is 21.6 m/s; andfor the case in which ltis 80 mm, the logical value is 66.7 m/s whereas the numerical calculation result is 44.1 m/s.
2. When Varying Second Length lm

FIG.7illustrates logical values and numerical calculation results for the distribution of the pressure impulse imparted to the ink in the container when varying the second length lmto 1.5 mm, 5 mm, and 10 mm. The bold lines represent the numerical calculation results, and the fine lines represent the logical values.

As can be seen fromFIG.7, even in cases in which the second length lmhas been varied to 1.5 mm, 5 mm, and 10 mm, the numerical calculation results are closely aligned with the logical values, with the exception of in the vicinity of bottom face22A of the container12(the connection location between the pressure generation chamber26and the nozzle28). Moreover, it is confirmed that increasing the second length lmcauses the pressure impulse gradient to decrease as predicted by the logic.

When the logically derived initial velocity U0′ imparted to the ink11inside the nozzle28is compared against the numerical calculation results for the initial velocity U0′ imparted to the ink11inside the nozzle28:for the case in which lmis 1.5 mm, the logical value is 33.3 m/s whereas the numerical calculation result is 21.6 m/s;for the case in which lmis 5 mm, the logical value is 10 m/s whereas the numerical calculation result is 8.4 m/s; andfor the case in which lmis 10 mm, the logical value is 5 m/s whereas the numerical calculation result is 4.5 m/s.
3. When Varying Initial Velocity U0of Ink Inside Pressure Generation Chamber

FIG.8illustrates logical values and numerical calculation results for the distribution of the pressure impulse imparted to the ink inside the container when varying the initial velocity U0of the ink inside the pressure generation chamber to either 1.25 m/s or 2.5 m/s. The bold lines represent the numerical calculation results, and the fine lines represent the logical values.

As can be seen fromFIG.8, even in cases in which the initial velocity U0of the ink inside the pressure generation chamber has been varied to 1.25 m/s or 2.5 m/s, the numerical calculation results are almost aligned with the logical values, with the exception of in the vicinity of the bottom face22A of the container12(the connection location between the pressure generation chamber26and the nozzle28). Moreover, it is confirmed that increasing the initial velocity U0of the ink inside the pressure generation chamber causes the pressure impulse gradient to increase as predicted by the logic.

When the logically derived initial velocity U0′ imparted to the ink11inside the nozzle28is compared against the numerical calculation results for the initial velocity U0′ imparted to the ink11inside the nozzle28:for the case in which U0is 1.25 m/s, the logical value is 33.3 m/s whereas the numerical calculation result is 21.6 m/s; andfor the case in which U0is 2.5 m/s, the logical value is 66.7 m/s whereas the numerical calculation result is 43.8 m/s.
4. When Varying Internal Diameter d of Nozzle

FIG.9illustrates logical values and numerical calculation results for the distribution of the pressure impulse imparted to the ink inside the container when varying the internal diameter d of the nozzle to 0.5 mm, 1 mm, and 2 mm. The bold lines represent the numerical calculation results, and the fine line represents the logical value.

Since the logic assumes the internal diameter d of the nozzle to be small enough to ignore, the pressure impulse gradient inside the nozzle may be expected to deviate from the logical values as the internal diameter d of the nozzle becomes larger.

As illustrated inFIG.9, in the cases in which the internal diameter d of the nozzle was varied to 0.5 mm, 1 mm, and 2 mm, deviation from the logical values is confirmed as the internal diameter d of the nozzle increased in size.

When the logically derived initial velocity U0′ imparted to the ink11inside the nozzle28is compared against the numerical calculation results for the initial velocity U0′ imparted to the ink11inside the nozzle28:for the case in which d is 0.5 mm, the logical value is 33.3 m/s whereas the numerical calculation result is 29.3 m/s;for the case in which d is 1.0 mm, the logical value is 33.3 m/s whereas the numerical calculation result is 26.4 m/s; andfor the case in which d is 1.5 mm, the logical value is 33.3 m/s whereas the numerical calculation result is 21.6 m/s.
5. When Varying Kinetic Viscosity ν of Ink

FIG.10illustrates logical values and numerical calculation results for the distribution of the pressure impulse imparted to the ink inside the container when varying the kinetic viscosity ν of the ink to either 100 mm2/s or 1000 mm2/s. The bold lines represent the numerical calculation results, and the fine line represents the logical value.

Since the logic assumes the kinetic viscosity of the ink to be ignorable, the pressure impulse gradient in the nozzle may be expected to deviate from the logical values as the kinetic viscosity ν of the ink becomes larger.

As illustrated inFIG.10, in the cases in which the kinetic viscosity ν of the ink was varied to either 100 mm2/s or 1000 mm2/s, some slight deviation from the logical value is confirmed as the kinetic viscosity of the ink increased.

When the logically derived initial velocity U0′ imparted to the ink11inside the nozzle28is compared against the numerical calculation results for the initial velocity U0′ imparted to the ink11inside the nozzle28:for the case in which ν is 100 mm2/s, the logical value is 33.3 m/s whereas the numerical calculation result is 21.6 m/s; andfor the case in which ν is 1000 mm2/s, the logical value is 33.3 m/s whereas the numerical calculation result is 19.9 m/s.

SUMMARY

As described above, in the liquid jet discharge device10according to the present exemplary embodiment, the nozzle28that has a smaller cross-sectional area than the cross-sectional area of the pressure generation chamber26is formed in the bottom wall22of the container12(pressure generation chamber26), and the contact angle θ of the inner peripheral face of the nozzle28with respect to the ink11is less than 90°. Accordingly, the upwardly concave meniscus (liquid surface) is formed in the nozzle28. In this state, the container12is caused to impact the stopper16(an impulse force is imparted to the container12), such that a long, fine tapered liquid jet MJ is discharged by speeding up from the vicinity of the axial center of the liquid surface LS.

In particular, in the liquid jet discharge device10, the pressure generation chamber26that has the first length ltthat is longer than the second length lm(lt>lm) and the cross-sectional area (internal diameter D) that is larger than the cross-sectional area (internal diameter d) of the nozzle28(D>d) is provided inside the container12above the nozzle28. This enables the initial velocity U0′ of the ink11inside the nozzle28to be sped up relative to the initial velocity U0of the ink11inside the pressure generation chamber26at the time of imparting the impulse force to the container12. As a result, the discharge velocity of the liquid jet MJ discharged from inside the nozzle28can also be increased in comparison to a liquid jet discharge device provided with only a nozzle (not including a pressure generation chamber).

In particular, by regulating the ratio (lt/lm) of the axial direction length (first length) ltof the pressure generation chamber26relative to the axial direction length (second length) lmof the nozzle28, the velocity increase ratio of the initial velocity U0′ of the ink11inside the nozzle28relative to the initial velocity U0of the ink11inside the pressure generation chamber26can be simply regulated. Namely, the jet velocity Vjetof the liquid jet MJ can be simply regulated.

For example, by increasing the ratio of the first length ltrelative to the second length lm(lt/lm), the initial velocity U0′ of the ink11inside the nozzle28can be sped up relative to the initial velocity U0of the ink11inside the pressure generation chamber26when the impulse force is imparted to the container12. The discharge velocity of the liquid jet MJ discharged from inside the nozzle28can also be increased as a result. This enables ink11with a high viscosity to be discharged.

Namely, discharge of high viscosity pigment inks that have hitherto not been compatible with existing ink jet printers is enabled. Moreover, since the liquid jet MJ discharged from the nozzle28by imparting the impulse force to the container12is long and fine, at about one fifth of the internal diameter of the nozzle28, fine printing on the paper42is enabled.

Moreover, since the velocity increase ratio of the initial velocity U0′ of the ink11inside the nozzle28relative to the initial velocity U0of the ink11inside the pressure generation chamber26is determined by the ratio of the first length ltto the second length lm, the velocity increase ratio can be simply regulated by changing the length of the pressure generation chamber26(container12).

In other words, even if the axial direction length (second length) lmof the nozzle28is short, the velocity increase ratio can be simply increased. Accordingly, in the liquid jet discharge device10, the axial direction length (second length) lmof the nozzle28can be set short. Thus, even in cases in which high viscosity ink11is discharged from the nozzle28, the ink11is prevented or suppressed from adhering to the inner peripheral face of the nozzle28and causing clogging of the nozzle28as a result of slight misalignment in the discharge direction of the liquid jet MJ. Moreover, since the long and fine liquid jet MJ is discharged from the central portion of the liquid surface LS, clogging of the ink11at the liquid surface LS and the like can be suppressed. Namely, in the liquid jet discharge device10, even in cases in which high viscosity ink11is discharged, the ink11can be prevented or suppressed from adhering to the inner peripheral face of the nozzle28and causing clogging of the nozzle28.

Moreover, since the axial direction length (second length) lmof the nozzle28can be made short, a short distance from the discharge position (liquid surface LS) of the liquid jet MJ to the landing position (paper42) is sufficient, enabling the landing precision of the ink11to be secured even if the manufacturing precision during manufacture of the container is not especially strict.

However, if the second length lmbecomes too short, the ink11can no longer form a proper meniscus in the nozzle28. Therefore, the second length lmis preferably at least half the internal diameter device of the nozzle28(lm>d/2). In other words, by setting the second length lmto at least half the internal diameter d of the nozzle28(lm>d/2), a well-formed upwardly concave meniscus can be formed in the nozzle28as long as the contact angle θ of the ink11with respect to the inner peripheral face of the nozzle28is less than 90°.

Moreover in the liquid jet discharge device10, since the nozzle28and the pressure generation chamber26that has a larger cross-sectional area than the nozzle28are formed contiguous to one another in the container12, it is sufficient to impart an impulse force to the container12using the moving mechanism14and the stopper16. This enables the liquid jet discharge device10to be configured with a simple structure.

Since the upper end of the nozzle28is aligned with the bottom face22A of the pressure generation chamber26, pressure loss in the ink11when the ink11in the pressure generation chamber26flows into the nozzle28from the bottom face22A side can be suppressed in comparison to cases in which a protrusion is formed on the bottom face22A, thus enabling the discharge velocity of the liquid jet MJ to be further increased.

In particular, since the upper end of the nozzle28is positioned at the center of the bottom face22A, pressure loss when the ink11inside the pressure generation chamber26flows into the nozzle28can be suppressed, thus enabling the discharge velocity of the liquid jet MJ to be further increased.

Moreover, the position of the liquid surface of the ink11inside the replenishment tank44of the replenishment device18is maintained higher than the bottom face22A of the container12, enabling a good supply of the ink11to the pressure generation chamber26due to the head pressure and the surface tension action of the ink11. Namely, the ink11can be supplied from the replenishment tank44to the pressure generation chamber26without using a mechanical action.

This enables the liquid jet discharge device10to continuously discharge even high viscosity ink11onto the paper42.

Variations

FIG.11illustrates configuration of a liquid jet discharge device10A as a possible variation on the liquid jet discharge device10of the present exemplary embodiment.

In the liquid jet discharge device10A, a tapered face51inclined toward the bottom face22A is provided at a pressure generation chamber-side end portion of the nozzle28.

Forming the nozzle28in this manner enables pressure loss in the ink11flowing from the pressure generation chamber26into the nozzle28to be further suppressed, thus enabling the discharge velocity of the liquid jet MJ to be further increased.

FIG.12illustrates configuration of a liquid jet discharge device10B as another possible variation.

In the liquid jet discharge device10B, a circular plate shaped anchor plate52is provided to an upper end portion of the rod32. Moreover, a stopper54substantially similar to that in the liquid jet discharge device10, through which the rod32can be inserted, is provided between the anchor plate52of the rod32and the solenoid34. Since the shape of the stopper54is similar to that of the stopper16of the first exemplary embodiment with the exception of size, the same reference numerals are allocated, and detailed explanation thereof is omitted.

In the liquid jet discharge device10B, the rod32is moved downward by driving the solenoid34, and the anchor plate52provided to the upper end of the rod32impacts the abutting face38A of the stopper54so as to impart an impulse force to the container12. The liquid jet MJ is discharged from the liquid surface LS in the nozzle28as a result.

In the liquid jet discharge device10B, the stopper54is relocated at the upper side of the container12in this manner, such that the size of the stopper54can be reduced, and a more straightforward configuration can be achieved in which no other members are interposed between the nozzle28and the paper42.

Second Exemplary Embodiment

Explanation follows regarding a liquid jet discharge device according to a second exemplary embodiment of the present disclosure, with reference toFIG.13. The same reference numerals are appended to configuration elements similar to those of the first exemplary embodiment, and description thereof will be omitted. Note that only points differing from the first exemplary embodiment will be described.

As illustrated inFIG.13, in a liquid jet discharge device100, a flexible and elastic bag104inflated with air102is inserted inside the pressure generation chamber26filled with the ink11F.

In the liquid jet discharge device100, the solenoid34is driven to lower the rod32at a predetermined speed. As a result, the container12attached to the rod32impacts the stopper16at the predetermined speed. The impulse force is imparted to the container12due to this impact. Accordingly, the liquid surface LS that was formed with a concave surface profile due to the contact angle θ of the ink11being less than 90° adopts a horizontal surface profile inside the nozzle28, and the liquid jet MJ that is finer than the nozzle28is ejected (discharged) from a central portion of the liquid surface LS.

When this occurs, (the air102inside) the bag104disposed inside the pressure generation chamber26expands due to the action of the impulse force with respect to the container12, promoting movement of the ink11from the pressure generation chamber26to the nozzle28.

In this manner, in the liquid jet discharge device100, the bag104inflated with the air102is inserted into the ink11in the pressure generation chamber26, and the expansion of the bag104when the impulse force is imparted enables the ink11to be reliably supplied into the nozzle28against viscosity loss in the pressure generation chamber26, even when employing high viscosity ink11.

Namely, a liquid jet can be reliably discharged from the nozzle28even when employing a high viscosity liquid.

Note that since it is sufficient that the bag104be capable of expanding when imparted with impulse force, the inside of the bag104may be filled with a gas other than air, or may be filled with a gel or the like that is capable of expanding when imparted with impulse force. Alternatively, the air102may be injected directly into the ink11in the pressure generation chamber26in the form of bubbles without employing the bag104.

Third Exemplary Embodiment

Explanation follows regarding a liquid jet discharge device according to a third exemplary embodiment of the present disclosure, with reference toFIG.14. The same reference numerals are appended to configuration elements similar to those of the first exemplary embodiment, and description thereof will be omitted. Note that only points differing from the first exemplary embodiment will be described.

As illustrated inFIG.14, in a liquid jet discharge device200, the ink11to be discharged from the nozzle28as the liquid jet MJ is housed on the bottom face22A side inside the pressure generation chamber26, and gelatin202is housed on the upper face20A side inside the pressure generation chamber26. The gelatin202corresponds to a “pressure generation medium”.

Specifically, the gelatin202is poured inside the container12(pressure generation chamber26) taking care not to block the nozzle28or the opening35with the gelatin202, and the pressure inside the container12is raised to solidify the gelatin202. The ink11is then supplied into the pressure generation chamber26and the nozzle28from the replenishment device18.

Note that the gelatin202employed has a water content of 95% by mass.

The replenishment tube46of the replenishment device18is in communication with the opening35provided in an ink-placement region of the peripheral wall24configuring the pressure generation chamber26.

Moreover, as illustrated inFIG.14, in the present exemplary embodiment, the liquid surface50of the ink11held in the replenishment tank44of the replenishment device18is at the same height as or lower than the bottom face22A of the pressure generation chamber26.

Explanation follows regarding operation of the liquid jet discharge device200.

The liquid jet discharge device200is, similarly to the liquid jet discharge device10according to the first exemplary embodiment, capable of discharging a long and fine liquid jet MJ at a high velocity increase ratio β from the liquid surface LS inside the nozzle28.

In particular, in the liquid jet discharge device200, the water content of the gelatin202housed inside the container12is 95%, and so there is a small difference between the acoustic impedance of the gelatin202and the acoustic impedance of the ink11. Thus, a fall in the energy transmission rate at the interface between the gelatin202inside the container12and the ink11inside the nozzle28is suppressed, enabling good discharge of the liquid jet MJ.

Note that although the gelatin202employed most preferably has the same acoustic impedance as that of the ink11, there may be a slight difference thereto. Confirmation has been made that the liquid jet MJ is discharged from the liquid jet discharge device200at least for gelatin202with an acoustic impedance up to about 1.5 times the acoustic impedance of the ink11.

Moreover, in the liquid jet discharge device200, since the gelatin202is housed at the upper portion side of the container12(pressure generation chamber26), it is sufficient for the ink11to be housed at a location in communication with the nozzle28on the bottom face22A side of the pressure generation chamber26that is in communication with the nozzle28(a location where the gelatin202is not present). Namely, the amount of ink11required to discharge the liquid jet MJ can be suppressed in this manner. In particular, suppressing the amount of ink11used is especially advantageous in cases in which an expensive ink11or the like is being discharged.

In particular, in cases in which the first length It is increased in order to increase the velocity increase ratio of the liquid jet discharge device200, increasing a region where the gelatin202is housed is advantageous since the amount of ink11used does not increase.

Moreover, when replacing the ink11being used in the liquid jet discharge device200, it is sufficient to drain the ink11from inside the pressure generation chamber26and the nozzle28and then supply a replacement liquid into the region of the pressure generation chamber26where the gelatin202is not housed and into the nozzle28. Namely, this has the advantage of suppressing the amount of replaced liquid, since there is no need to replace the gelatin202housed inside the container12.

Since the gelatin202does not mix or chemically react with the ink11, there is no concern regarding a reduction in the quality of the liquid jet MJ (ink11).

Note that although explanation has been given regarding an example in which the gelatin202is housed in the container12in the present exemplary embodiment, there is no limitation thereto. Another solid (non-fluid substance) that has an acoustic impedance meeting the above conditions relating to the acoustic impedance of the ink11may be applied in the present exemplary embodiment. For example, polydimethylsiloxane (PDMS) or the like may be considered.

Although the liquid surface50of the ink11held in the replenishment tank44of the replenishment device18is at the same height as or lower than the bottom face22A of the pressure generation chamber26in the present exemplary embodiment as illustrated inFIG.14, the ink11may be supplied to the pressure generation chamber26using only the surface tension action of the ink11.

Note that high viscosity ink11may also be applied in the liquid jet discharge device200. In such cases, similarly to in the first exemplary embodiment, the liquid surface50of the ink11in the replenishment tank44should be at the same height as or higher than the bottom face22A.

Variations

Explanation follows regarding a liquid jet discharge device200A as a variation on the liquid jet discharge device200, with reference toFIG.15. Note that the liquid jet discharge device200A differs to the liquid jet discharge device200only in the placement of the liquid inside the pressure generation chamber26, and explanation follows regarding this section only. In the liquid jet discharge device200A, configuration elements equivalent to those of the liquid jet discharge device200are allocated the same reference numerals, and detailed explanation thereof is omitted

In the liquid jet discharge device200A, a film204configured from gelatin with a water content of 95% is placed at a lower end (nozzle-side end portion) of the portion where the gelatin202is placed in the pressure generation chamber26of the liquid jet discharge device200. A liquid206that is different to the ink11, for example water, is housed on the upper face20A side of the film204.

Configuring the liquid jet discharge device200A in this manner enables a liquid jet discharge device MJ to be discharged with a high velocity increase ratio.

Since the pressure generation chamber26is partially filled with the liquid206that is different to the ink11, and the film204partitions the ink11from the liquid206, the ink11and the liquid206are prevented from mixing or chemically reacting with each other (which would cause the quality of the ink11to suffer). Moreover, the amount of the ink11employed in the pressure generation chamber26can be suppressed.

Providing the film204that is configured from gelatin with a water content of 95% results in a small difference in acoustic impedance between the film204, the ink11, and the liquid206. Accordingly, a fall in the energy transmission rate at the interface between the liquid206that is different to the ink11and the film204, and at the interface between the film204and the ink11, when impulse force is imparted is suppressed, enabling good discharge of the liquid jet MJ.

Reference Example

Explanation follows regarding a liquid jet discharge device according to a reference example, with reference toFIG.16. The same reference numerals are appended to configuration elements similar to those of the first exemplary embodiment, and description thereof will be omitted. Note that the only difference to the first exemplary embodiment is the shape of the container12, and so explanation follows regarding this section only.

As illustrated inFIG.16, the container12is configured in a circular cylindrical shape on the upper wall20side, and is configured in a circular conical shape with decreasing diameter on progression from an intermediate location toward the nozzle28. Namely, the nozzle28side of the container12configures a circular conical shaped circular conical portion302, and an inner peripheral face thereof configures a tapered face302A configuring the pressure generation chamber26.

The circular conical portion302of the container12is formed with plural ribs304jutting toward the radial direction outside at predetermined intervals around the circumferential direction. Bottom faces306of the ribs304extend in radial directions, and the bottom faces306abut the abutting face38A when the container12impacts the stopper16.

In a liquid jet discharge device300configured in this manner, the ribs304(bottom faces306) of the container12impact the abutting face38A of the stopper16when driven by the solenoid34so as to impart an impulse force to the container12, thus causing the liquid jet MJ to be discharged from the nozzle28.

Note that from the perspective of increasing the velocity increase ratio, the liquid jet discharge device300configured in this manner is at a disadvantage compared to the liquid jet discharge device10due to the pressure generation chamber26including the tapered face302A.

Other

Although explanation has been given regarding the liquid jet discharge devices according to the first to the third exemplary embodiments, the present disclosure is not limited thereto. Namely, as long an impulse force can be imparted to the container12by a knocking action, configuration is not limited to the moving mechanism14and the stopper16. For example, configuration may be made in which impulse force is imparted from a side of the peripheral wall24of the container12.

Although the discharge direction of the liquid jet MJ (open end of the nozzle28) is directed vertically downward in the first to the third exemplary embodiments, there is no limitation thereto. For example, the discharge direction may be horizontal or vertically upward. Note that in such cases, the internal diameter d of the nozzle28needs to be sufficiently small, and the liquid surface LS needs to be maintained with a concave surface profile recessed toward the upper wall20side of the container12by surface tension action. Replenishment of the ink11from the replenishment device18to the pressure generation chamber26may, for example, be performed by applying pressure to the ink11in the replenishment tank44.

Although the nozzle28and the pressure generation chamber26have circular cross-sections in the first to the third exemplary embodiments, the present disclosure is not limited thereto.

Although the upper end of the nozzle28opens onto the center of the bottom face22A of the pressure generation chamber26in the first to the third exemplary embodiments, the present disclosure is not limited thereto. For example, the upper end of the nozzle28may be positioned at a radial direction outside end portion of the bottom face22A.

Although a single nozzle28is provided to the container12(pressure generation chamber26) in the first to the third exemplary embodiments, plural of the nozzles28may be provided thereto. For example, three of the nozzles28may be provided to the bottom wall22of the pressure generation chamber26.

Although the pressure generation chamber26of the container12is closed and internally filled with the ink11in the first to the third exemplary embodiments, the pressure generation chamber26may be open at an upper portion.

Note that in such cases, the length from the bottom face22A of the pressure generation chamber26to the liquid surface at the upper portion corresponds to the first length lt.

Moreover, although one end portion281of the nozzle28opens onto the bottom face22A of the pressure generation chamber26in the first to the third exemplary embodiments, the one end portion of the nozzle28may project into the pressure generation chamber26. In such cases, the second length lmis the axial direction length from the one end portion of the nozzle28to the liquid surface LS, and the first length It is the axial direction length from the upper face20A to the bottom face22A of the pressure generation chamber26.

Moreover, although cases in which the ink11is employed as the liquid to be discharged are described in the first to the third exemplary embodiments, the present disclosure is not limited thereto. Other liquids may also be applied. For example, since the liquid jet discharge devices of the first to the third exemplary embodiments are capable of discharging the liquid jet MJ at high velocity and also capable of controlling the jet velocity Vjet, these liquid jet discharge devices would conceivably be capable of controlling subcutaneous or intra-muscle medication penetration positions and be applied to a needle-free injection apparatus.

Although the liquid surface50of the ink11in the replenishment tank44is higher than the position of the bottom face22A of the pressure generation chamber26when the liquid jet discharge device is in operation in the first and the second exemplary embodiments, the liquid surface50of the ink11in the replenishment tank44may be lowered to the meniscus formation position in the nozzle28after operation has ended.

Moreover, although the liquid surface50of the ink11held in the replenishment tank44of the replenishment device18is at the height of the bottom face22A of the pressure generation chamber26or lower, and the ink11can be supplied to the pressure generation chamber26using the surface tension of the ink11in the third exemplary embodiment, this configuration is not limited to the third exemplary embodiment, and may also be applied in the first and second exemplary embodiments and so on.

The disclosure of Japanese Patent Application No. 2018-119345, filed on Jun. 22, 2018, is incorporated in its entirety by reference herein.

Supplement

A first aspect of the present disclosure provides a liquid microjet high speed discharge device including an ejection section, a pressure generation section, and an impulse force impartation means. The ejection section is open at both end portions and internally houses a liquid such that a contact angle between the liquid and at least an inner face of the ejection section is less than 90°. The pressure generation section is in communication with one end portion of the ejection section, has a cross-sectional area larger than a cross-sectional area of the ejection section, has a length in a discharge direction of a liquid microjet longer than a length in the discharge direction from the one end portion of the ejection section to a surface of the liquid, and houses the liquid at least at a bottom face side onto which the one end portion opens. The impulse force impartation means is configured to impart an impulse force to the pressure generation section.

A second aspect of the present disclosure provides the liquid microjet high speed discharge device of the first aspect of the present disclosure, wherein the one end portion of the ejection section is aligned with the bottom face.

A third aspect of the present disclosure provides the liquid microjet high speed discharge device of the second aspect of the present disclosure, wherein a tapered face inclined toward the bottom face is formed at the one end portion side of the ejection section.

A fourth aspect of the present disclosure provides the liquid microjet high speed discharge device of any one of the first aspect to the third aspect of the present disclosure, wherein the one end portion of the ejection section opens onto a center of the bottom face of the pressure generation section.

A fifth aspect of the present disclosure provides the liquid microjet high speed discharge device of any one of the first aspect to the fourth aspect of the present disclosure, wherein the liquid is housed on the bottom face side of the pressure generation section, and a pressure generation medium having an acoustic impedance of from 1 to 1.5 times an acoustic impedance of the liquid is housed on an opposite side to the bottom face side without mixing or chemically reacting with the liquid.

A sixth aspect of the present disclosure provides the liquid microjet high speed discharge device of any one of the first aspect to the fifth aspect of the present disclosure, further including a replenishment device. The replenishment device includes a replenishment section inside which the liquid is held, and a liquid supply path that is in communication with a portion of the replenishment section holding the liquid and with a portion of the pressure generation section holding the liquid.

A seventh aspect of the present disclosure provides the liquid microjet high speed discharge device of the sixth aspect, wherein another end portion282of the ejection section opens downward in the liquid jet discharge device. The replenishment device is configured to supply the liquid to the pressure generation section by either an action of a head pressure of the liquid held in the replenishment section and an action of surface tension of the liquid, or by the action of the surface tension of the liquid alone.