Fluid ejection device

A fluid ejection device includes a fluid ejection unit that ejects a fluid, an ejection control unit that receives a fluid ejection command input, and controls the ejection of the fluid from the fluid ejection unit, a fluid container that accommodates the fluid to be supplied to the fluid ejection unit; and a supply control unit that controls the supply of the fluid from the fluid container to the fluid ejection unit, and determines whether the fluid can be supplied to the fluid ejection unit from the fluid container. When the supply control unit determines that the fluid cannot be supplied even after the ejection command input is received, and then a predetermined amount of time has elapsed, the ejection control unit reports a fault, and prohibits the fluid ejection unit from ejecting the fluid until the ejection command input is canceled.

This application claims the benefit of Japanese patent application No. 2014-080824, filed on Apr. 10, 2014. The content of the aforementioned application is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a fluid ejection device.

2. Related Art

A fluid ejection device for medical purposes that can incise and excise living tissue by ejecting a fluid has been developed.

JP-A-2013-213422 is an example of the related art.

It is assumed that the fluid in the fluid ejection device may not have a sufficiently high pressure, or the fluid ejection device may not be filled with the fluid when there is a demand for the ejection of the fluid present. In this case, for example, the fluid ejection device may eject the fluid at an unintended time. Accordingly, it is desirable to provide a fluid ejection device with high safety which avoids such an unintended ejection of the fluid.

SUMMARY

An advantage of some aspects of the invention is to provide a fluid ejection device with high safety.

A fluid ejection device according to an aspect of the invention includes: a fluid ejection unit that ejects a fluid; an ejection control unit that receives a fluid ejection command input, and controls the ejection of the fluid from the fluid ejection unit; a fluid container that accommodates the fluid to be supplied to the fluid ejection unit; and a supply control unit that controls the supply of the fluid from the fluid container to the fluid ejection unit, and determines whether the fluid can be supplied to the fluid ejection unit from the fluid container. When the supply control unit determines that the fluid cannot be supplied even after the ejection command input is received, and then a predetermined amount of time has elapsed, the ejection control unit reports a fault, and prohibits the fluid ejection unit from ejecting the fluid until the ejection command input is canceled.

Other features of the invention will be made apparent by the description of this specification and the accompanying drawings.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

At least the following facts are apparent from this specification and the accompanying drawings.

A fluid ejection device includes: a fluid ejection unit that ejects a fluid; an ejection control unit that receives a fluid ejection command input, and controls the ejection of the fluid from the fluid ejection unit; a fluid container that accommodates the fluid to be supplied to the fluid ejection unit; and a supply control unit that controls the supply of the fluid from the fluid container to the fluid ejection unit, and determines whether the fluid can be supplied to the fluid ejection unit from the fluid container. When the supply control unit determines that the fluid cannot be supplied even after the ejection command input is received, and then a predetermined amount of time has elapsed, the ejection control unit reports a fault, and prohibits the fluid ejection unit from ejecting the fluid until the ejection command input is canceled.

In this manner, when the fluid cannot be supplied even after the fluid ejection command input is received, and then the predetermined amount of time has elapsed, the ejection control unit reports a fault, and prohibits the ejection of the fluid until the ejection command input is canceled, and thereby it is possible to prevent the fluid from being ejected at an unintended time. It is possible to provide a high safety fluid ejection device.

In the fluid ejection device, it is preferable that a flag is configured to be set when the fault is reported, and when the flag is set, the ejection control unit prohibits the fluid ejection unit form ejecting the fluid.

In this manner, it is possible to prohibit the ejection of the fluid based on the flag that is set when the fault is reported.

In the fluid ejection device, it is preferable that, when the ejection command input is canceled, and then the ejection command input is made again, the flag is cleared.

In this manner, it is possible to allow the ejection of the fluid when the ejection command input is canceled, and then the ejection command input is made again.

In the fluid ejection device, it is preferable that, when the ejection control unit receives the ejection command input, the ejection control unit sends a demand for the supply of the fluid to the supply control unit, and the supply control unit receives the demand for the supply of the fluid, and notifies the ejection control unit whether the fluid can be supplied.

In this manner, the supply control unit can notify whether the fluid can be supplied in response to the demand for the supply of the fluid from the ejection control unit.

In the fluid ejection device, it is preferable that, when the ejection control unit does not receive the ejection command input, the ejection control unit does not send the demand for the supply of the fluid to the supply control unit, and thereby the ejection control unit prohibits the fluid ejection unit from ejecting the fluid.

In this manner, in the fluid ejection device that receives the notification of whether the fluid can be supplied and determines whether the ejection of the fluid is prohibited, it is possible to prohibit the ejection of the fluid.

In the fluid ejection device, it is preferable that the supply control unit adjusts an inner pressure of the fluid container in response to a first threshold value and a second threshold value closer to a target pressure than the first threshold value for the inner pressure of the fluid container, and in a case where the inner pressure of the fluid container is lower than the target pressure, and when the inner pressure of the fluid container is separated from the target pressure by the first threshold value or greater, the supply control unit performs a first pressure increase control operation in which the inner pressure is increased by reducing an inner volume of the fluid container by a first amount of volume, and when the inner pressure of the fluid container is closer to the target pressure than the first threshold value, and is separated from the target pressure by the second threshold value or greater, the supply control unit performs a second pressure increase control operation in which the inner pressure is increased by reducing the inner volume of the fluid container by a second amount of volume less than the first amount of volume.

In this manner, when the inner pressure of the fluid container is separated from the target pressure by the first threshold value or greater, it is possible to increase the pressure to approach the target pressure by reducing the inner volume of the fluid container by the first amount of volume. In contrast, when the inner pressure of the fluid container is closer to the target pressure than the first threshold value, and is separated from the target pressure by the second threshold value or greater, it is possible to finely increase the pressure by reducing the inner volume of the fluid container by the second amount of volume less than the first amount of volume.

In the fluid ejection device, it is preferable that a state in which the fluid cannot be supplied is defined as a state in which the inner pressure of the fluid container is separated from the target pressure by the first threshold value or greater.

In this manner, it is possible to prohibit the ejection of the fluid when the pressure of the fluid is not at an appropriate level of pressure.

Embodiment

Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings. A fluid ejection device according to the embodiment can be used in various procedures such as the cleaning or cutting of a fine object or structure, living tissue, or the like; however, an example of the embodiment given in the following description is the fluid ejection device suitable for use as an operation scalpel to incise or excise living tissue. Accordingly, a fluid used in the fluid ejecting device according to the embodiment is water, physiologic saline, a predetermined fluid medicine, or the like. The drawings referenced in the following description are schematic views in which a portion not being defined as a member is vertically and horizontally scaled differently from an actual scale for illustrative purposes.

Entire Configuration

FIG. 1is a view illustrating the configuration of a fluid ejection device1as an operation scalpel according to the embodiment. The fluid ejection device1includes a pump700for supplying a fluid; a pulsation generator (equivalent to a fluid ejection unit)100that converts the form of the fluid supplied from the pump700into a pulsed flow, and ejects a pulsed flow of the fluid; a drive control unit (equivalent to an ejection control unit)600that controls the fluid ejection device1in cooperation with the pump700; and a connection tube (equivalent to a connection channel)25as a connection path through which the pump700and the pulsation generator100are connected to each other, and the fluid flows.

The pulsation generator100includes a fluid chamber501that accommodates the fluid supplied from the pump700; a diaphragm400that changes the volume of the fluid chamber501; and a piezoelectric element401that vibrates the diaphragm400, all of which will be described later in detail.

The pulsation generator100includes a thin pipe-like fluid ejection tube200that acts as a channel of the fluid discharged from the fluid chamber501, and a nozzle211that is mounted on a tip end portion of the fluid ejection tube200and has a reduced channel diameter.

The pulsation generator100converts a form of the fluid into a pulsed flow and ejects a pulsed flow of the fluid at a high speed via the fluid ejection tube200and the nozzle211by driving the piezoelectric element401in response to drive signals output from the drive control unit600, and changing the volume of the fluid chamber501.

The drive control unit600and the pulsation generator100are connected to each other via a control cable630, and drive signals for driving the piezoelectric element401are output from the drive control unit600and are transmitted to the pulsation generator100via the control cable630.

The drive control unit600and the pump700are connected to each other via a communication cable640, and the drive control unit600and the pump700transmit and receive various commands or data therebetween according to a predetermined communication protocol such as a controller area network (CAN).

The drive control unit600receives signals from various switches operated by a practitioner who performs an operation using the pulsation generator100, and controls the pump700or the pulsation generator100via the control cable630or the communication cable640.

The switches that input signals to the drive control unit600are a pulsation generator start-up switch, an ejection intensity switching switch, a flushing switch, and the like (not illustrated).

The pulsation generator start-up switch (not illustrated) is a switch for switching a state of ejection of the fluid from the pulsation generator100between an ejection mode and a non-ejection mode. When a practitioner who performs an operation using the pulsation generator100operates the pulsation generator start-up switch (not illustrated), the drive control unit600controls the pulsation generator100to eject the fluid or stop the ejection of the fluid in cooperation with the pump700. The pulsation generator start-up switch (not illustrated) can be a switch configured to be operated by the practitioner's feet, or a switch that is provided integrally with the pulsation generator100grasped by the practitioner, and configured to be operated by the practitioner's hands or fingers.

The ejection intensity switching switch (not illustrated) is a switch for changing the intensity of fluid ejection from the pulsation generator100. When the ejection intensity switching switch (not illustrated) is operated, the drive control unit600controls the pulsation generator100and the pump700so as to increase and decrease the intensity of fluid ejection.

The flushing switch (not illustrated) will be described later.

In the embodiment, a pulsed flow implies a flow of a fluid, a flow direction of which is constant, and the flow rate or flow speed of which is changed periodically or non-periodically. The pulsed flow may be an intermittent flow in which the flowing and stopping of the fluid are repeated; however, since the flow rate or flow speed of the fluid is preferably changed periodically or non-periodically, the pulsed flow is not necessarily an intermittent flow.

Similarly, the ejection of a fluid in a pulsed form implies the ejection of the fluid by which the flow rate or moving speed of an ejected fluid is changed periodically or non-periodically. An example of the pulsed ejection is an intermittent ejection by which the ejection and non-ejection of a fluid are repeated; however, since the flow rate or moving speed of an ejected fluid is preferably changed periodically or non-periodically, the pulsed ejection is not necessarily an intermittent ejection.

When the driving of the pulsation generator100is stopped, that is, when the volume of the fluid chamber501is not changed, the fluid supplied from the pump700as a fluid supply unit at a predetermined pressure continuously flows out of the nozzle211via the fluid chamber501.

The fluid ejection device1according to the embodiment may be configured to include a plurality of the pumps700.

FIG. 2is a view illustrating the configuration of the fluid ejection device1configured to include two pumps700. In this case, the fluid ejection device1includes a first pump700aand a second pump700b. A first connection tube25a, a second connection tube25b, the connection tube25, and a three way stopcock26form a connection path which connects the pulsation generator100and the first pump700aand the pulsation generator100and the second pump700b, and through which the fluid flows.

The three way stopcock26is a valve configured to be able to communicate the first connection tube25aand the connection tube25, or the second connection tube25band the connection tube25, and either one of the first pump700aand the second pump700bis selectively used.

In this configuration, for example, when the first pump700acannot supply the fluid for unknown reasons such as a malfunction while being selected and used, it is possible to continuously use the fluid ejection device1and to minimize adverse effects associated with the non-supply of the fluid from the first pump700aby switching the three way stopcock26so as to communicate the second connection tube25band the connection tube25, and starting the supply of the fluid from the second pump700b.

When the fluid ejection device1is configured to include a plurality of the pumps700, but the pumps700are not required to be distinctively described, in the following description, the pumps700are collectively expressed by the pump700.

In contrast, when the plurality of pumps700are required to be distinctively described, suffixes such as “a” and “b” are properly added to reference sign700of the pump, and each of the pumps700is distinctively expressed by the first pump700aor the second pump700b. In this case, each configuration element of the first pump700ais expressed by adding the suffix “a” to a reference sign of each configuration element, and each configuration element of the second pump700bis expressed by adding the suffix “b” to a reference sign of each configuration element.

Subsequently, an outline of the configuration and operation of the pump700according to the embodiment will be described.FIG. 3is a schematic view illustrating the configuration of the pump700according to the embodiment.

The pump700according to the embodiment includes a pump control unit (equivalent to a supply control unit)710; a slider720; a motor730; a linear guide740; and a pinch valve750. The pump700is configured to have a fluid container mounting unit770for attachably and detachably mounting a fluid container760that accommodates the fluid. The fluid container mounting unit770is formed so as to hold the fluid container760at a specific position when the fluid container760is mounted thereon.

The following switches (which will be described later in detail) (not illustrated) input signals to the pump control unit710: a slider release switch; a slider set switch; a fluid supply ready switch; a priming switch; and a pinch valve switch.

In the embodiment, for example, the fluid container760is formed of a medical syringe configured to include a syringe761and a plunger762.

In the fluid container760, a protrusive cylinder-shaped opening764is formed in a tip end portion of the syringe761. When the fluid container760is mounted on the fluid container mounting unit770, an end portion of the connection tube25is inserted into the opening764, and a fluid channel is formed from the inside of the syringe761to the connection tube25.

The pinch valve750is a valve that is provided on a path of the connection tube25, and opens and closes a fluid channel between the fluid container760and the pulsation generator100.

The pump control unit710controls the opening and closing of the pinch valve750. When the pump control unit710opens the pinch valve750, the fluid container760and the pulsation generator100communicate with each other via the channel therebetween. When the pump control unit710closes the pinch valve750, the channel between the fluid container760and the pulsation generator100is shut off.

In a state where the fluid container760is mounted on the fluid container mounting unit770, and the pinch valve750is opened, when the plunger762of the fluid container760moves in a direction (hereinafter, also referred to as a push-in direction) in which the plunger762is pushed into the syringe761, the volume of a space (hereinafter, also referred to as a fluid accommodation portion765) is reduced, the space being enveloped by an end surface of a gasket763made of resin such as elastic rubber and mounted at the tip of the plunger762in the push-in direction, and an inner wall of the syringe761, and the fluid in the fluid accommodation portion765is discharged via the opening764of the tip end portion of the syringe761. The connection tube25is filled with the fluid discharged via the opening764, and the discharged fluid is supplied to the pulsation generator100.

In contrast, in a state where the fluid container760is mounted on the fluid container mounting unit770, and the pinch valve750is closed, when the plunger762of the fluid container760moves in the push-in direction, it is possible to reduce the volume of the fluid accommodation portion765, the fluid accommodation portion765being enveloped by the gasket763mounted at the tip of the plunger762and the inner wall of the syringe761, and it is possible to increase the pressure of the fluid in the fluid accommodation portion765.

The pump control unit710moves the slider720along a direction (in the push-in direction and the opposite direction of the push-in direction) in which the plunger762moves in a state where the fluid container760is mounted on the fluid container mounting unit770, and the plunger762moves in accordance with the movement of the slider720.

Specifically, the slider720is attached to the linear guide740in such a manner that a pedestal721of the slider720engages with a rail (not illustrated) formed linearly on the linear guide740along the slide direction of the plunger762. The linear guide740moves the pedestal721of the slider720along the rail using power transmitted from the motor730driven by the pump control unit710, and thereby the slider720moves along the slide direction of the plunger762.

As illustrated inFIG. 3, the following sensors are provided along the rail of the linear guide740: a first limit sensor741; a residue sensor742; a home sensor743; and a second limit sensor744.

All of the first limit sensor741, the residue sensor742, the home sensor743, and the second limit sensor744are sensors for detecting the position of the slider720that moves on the rail of the linear guide740, and signals detected by these sensors are input to the pump control unit710.

The home sensor743is a sensor used to determine an initial position (hereinafter, also referred to as a home position) of the slider720on the linear guide740. The home position is a position in which the slider720is held when the fluid container760is mounted or replaced.

The residue sensor742is a sensor for detecting the position (hereinafter, also referred to as a residual position) of the slider720when the residue of the fluid in the fluid container760is less than or equal to a predetermined value while the slider720moves from the home position in the push-in direction of the plunger762. When the slider720reaches the residual position in which the residue sensor742is provided, a predetermined alarm is output to an operator (a practitioner or an assistant). The fluid container760currently in use is replaced with a new fluid container760at an appropriate time determined by the operator. Alternatively, when the second pump700bhaving the same configuration as that of the pump700(the first pump700a) is prepared, a switching operation is performed so as to supply the fluid from an auxiliary second pump700bto the pulsation generator100.

The first limit sensor741indicates a limit position (hereinafter, referred to as a first limit position) in a movable range in which the slider720can move from the home position in the push-in direction of the plunger762. When the slider720reaches the first limit position in which the first limit sensor741is provided, the residue of the fluid in the fluid container760is much less than the residue indicating that the slider720is present at the residual position, and a predetermined alarm is output to the operator. In this case, the fluid container760currently in use is also replaced with a new fluid container760, or a switching operation is also performed so as to supply the fluid from an auxiliary second pump700b.

In contrast, the second limit sensor744indicates a limit position (hereinafter, also referred to as a second limit position) in a movable range in which the slider720can move from the home position in the opposite direction of the push-in direction of the plunger762. When the slider720reaches the second limit position in which the second limit sensor744is provided, a predetermined alarm is output.

A touch sensor723and a pressure sensor722are mounted on the slider720.

The touch sensor723is a sensor for detecting whether the slider720is in contact with the plunger762of the fluid container760.

The pressure sensor722is a sensor that detects the pressure of the fluid in the fluid accommodation portion765formed by the inner wall of the syringe761and the gasket763, and outputs signals in response to a detected pressure.

When the pinch valve750is closed, and the slider720moves in the push-in direction, and after the slider720comes into contact with the plunger762, the pressure of the fluid in the fluid accommodation portion765increases to the extent that the slider720moves further in the push-in direction.

In contrast, when the pinch valve750is opened, and the slider720moves in the push-in direction, and even after the slider720comes into contact with the plunger762, the fluid in the fluid accommodation portion765flows out of the nozzle211of the pulsation generator100via the connection tube25, and thereby the pressure of the fluid in the fluid accommodation portion765increases to a certain level, but the pressure of the fluid does not increase even though the slider720moves further in the push-in direction.

The touch sensor723and the pressure sensor722input signals to the pump control unit710.

A description to be given hereinafter is regarding a preparation operation configured to include a process of mounting a fluid container760filled with the fluid on the fluid container mounting unit770; a process of supplying the fluid in the fluid container760to the pulsation generator100; and a process of bringing the fluid ejection device1into a state in which the pulsation generator100can eject the fluid in the form of a pulsed flow.

First, the operator inputs an ON signal of the slider release switch to the pump control unit710by operating the slider release switch (not illustrated). Thus, the pump control unit710moves the slider720to the home position.

The operator mounts the fluid container760connected to the connection tube25in advance on the fluid container mounting unit770. The syringe761of the fluid container760is already filled with the fluid.

When the operator sets the connection tube25to the pinch valve750, and then inputs an ON signal of the pinch valve switch (not illustrated) to the pump control unit710by operating the pinch valve switch, the pump control unit710closes the pinch valve750.

Subsequently, the operator inputs an ON signal of the slider set switch (not illustrated) to the pump control unit710by operating the slider set switch. Thus, the pump control unit710starts a control operation in such a manner that the slider720moves in the push-in direction and the pressure of the fluid accommodated in the fluid accommodation portion765of the fluid container760reaches a predetermined target pressure value.

Thereafter, when the operator inputs an ON signal of the fluid supply ready switch (not illustrated) to the pump control unit710by pushing the fluid supply ready switch (not illustrated), and the pressure of the fluid in the fluid accommodation portion765enters a specific range (hereinafter, also referred to as a rough window) for the target pressure value, the pump control unit710is brought into a fluid suppliable state in which the fluid is allowed to be supplied from the pump700to the pulsation generator100.

When the pump control unit710is in a fluid suppliable state, and the operator inputs an ON signal of the priming switch to the pump control unit710by operating the priming switch, the pump control unit710starts a priming process. The priming process is a process by which a fluid channel from the fluid container760to the connection tube25and to a fluid ejection opening212of the pulsation generator100is filled up with the fluid.

When the priming process starts, the pump control unit710opens the pinch valve750, and starts moving the slider720in the push-in direction at the same time or substantially the same time (for example, a time gap of approximately several tens of milliseconds or approximately several hundreds of milliseconds) as when the pinch valve750is opened. The slider720moves at a predetermined speed in such a manner that a constant amount of the fluid per unit time is supplied from the fluid container760. The priming process is performed until a predetermined amount of time required to complete the priming process has elapsed (or the slider720moves by a predetermined distance), or the operator inputs an OFF signal of the priming switch (not illustrated) by operating the priming switch.

Accordingly, a predetermined amount of the fluid in the fluid accommodation portion765is supplied at a predetermined flow speed (the amount of discharge of the fluid per unit time) from the pump700, the connection tube25from the pinch valve750to the pulsation generator100is filled up with the fluid, and the fluid chamber501of the pulsation generator100, the fluid ejection tube200and the like are filled up with the fluid. Air present in the connection tube25or the pulsation generator100prior to the start of the priming process is released to the atmosphere via the nozzle211of the pulsation generator100as the fluid flows into the connection tube25or the pulsation generator100.

The pump control unit710pre-stores the predetermined speed, the predetermined distance, and the predetermined amount of time in relation to the movement of the slider720during the priming process.

As such, the priming process is completed.

Subsequently, when the operator inputs an ON signal of the flushing switch (not illustrated) to the drive control unit600by operating the flushing switch, the drive control unit600and the pump control unit710start a deaeration process.

The deaeration process is a process by which air bubbles remaining in the connection tube25or the pulsation generator100are discharged via the nozzle211of the pulsation generator100.

In the deaeration process, in a state in which the pinch valve750is opened, the pump control unit710moves the slider720in the push-in direction at the predetermined speed in such a manner that a constant amount of the fluid per unit time is supplied from the fluid container760, and the fluid is supplied to the pulsation generator100. The drive control unit600drives the piezoelectric element401of the pulsation generator100in conjunction with the discharge of the fluid by the pump700, and thereby the pulsation generator100to eject the fluid. Accordingly, air bubbles remaining in the connection tube25or the pulsation generator100are discharged via the nozzle211of the pulsation generator100. The deaeration process is performed until a predetermined amount of time has elapsed (or the slider720moves by a predetermined distance), or the operator inputs an OFF signal of the flushing switch (not illustrated) by operating the flushing switch.

The drive control unit600and the pump control unit710pre-store the predetermined speed, the predetermined distance, and the predetermined amount of time in relation to the movement of the slider720during the deaeration process.

When the deaeration process is completed, the pump control unit710closes the pinch valve750, and detects the pressure of the fluid accommodated in the fluid accommodation portion765of the fluid container760. The pump control unit710performs a control operation of adjusting the position of the slider720in such a manner that the pressure reaches the target pressure value.

Thereafter, when the pressure of the fluid in the fluid accommodation portion765enters a specific range (a rough window) for the target pressure value, the pump control unit710is brought into a fluid ejectable state in which the fluid can be ejected in the form of a pulsed flow from the pulsation generator100.

In this state, when the operator inputs an ON signal of the pulsation generator start-up switch (not illustrated) to the drive control unit600by operating the pulsation generator start-up switch via the feet, the pump control unit710opens the pinch valve750in response to signals transmitted from the drive control unit600, and starts the supply of the fluid to the pulsation generator100by moving the slider720at a predetermined speed in the push-in direction at the same time or substantially the same time (for example, a time gap of approximately several tens of milliseconds or approximately several hundreds of milliseconds) as when the pinch valve750is opened. In contrast, the drive control unit600generates a pulsed flow by starting the driving of the piezoelectric element401and changing the volume of the fluid chamber501. Accordingly, a pulsed flow of the fluid is ejected at a high speed via the nozzle211at the tip of the pulsation generator100.

Thereafter, when the operator inputs an OFF signal of the pulsation generator start-up switch (not illustrated) to the drive control unit600by operating the pulsation generator start-up switch via the feet, the drive control unit600stops the driving of the piezoelectric element401. The pump control unit710stops the movement of the slider720in response to signals transmitted from the drive control unit600, and closes the pinch valve750. As such, the pulsation generator100stops the ejection of the fluid.

The pump700according to the embodiment is configured such that the slider720presses the fluid container760that is formed of a medical syringe configured to include the syringe761and the plunger762; however, the pump700may be configured as illustrated inFIG. 4.

FIG. 4is a view illustrating the pump700with a different configuration. The pump700illustrated inFIG. 4has the following configuration: the fluid container760(an infusion solution bag that accommodates a fluid) is mounted in a pressurized chamber800, and after air supplied from a compressor810is regulated by a regulator811, the air is pressure-fed into the pressurized chamber800, and thereby the fluid container760is pressed.

When the pinch valve750is opened in a state where the fluid container760is pressed by the pressurization of air in the pressurized chamber800, the fluid accommodated in the fluid accommodation portion765of the fluid container760flows out of the opening764, and is supplied to the pulsation generator100via the connection tube25.

The air in the pressurized chamber800is released to the atmosphere by the opening of an air vent valve812. In a case where the pressure of the air in the pressurized chamber800exceeds a predetermined pressure, even when the air vent valve812is not opened, a safety valve813is opened, and thereby the air in the pressurized chamber800is released to the atmosphere.

The pump control unit710controls the compressor810; the regulator811; the air vent valve812; and the pinch valve750, the control scheme of which is not illustrated inFIG. 4. The followings sensors input detected output signals to the pump control unit710: the pressure sensor722that detects the pressure of the fluid in the fluid container760, and the residue sensor742that detects the residue of the fluid in the fluid container760.

When the pump700with this configuration is adopted, it is possible to increase the amount of supply of the fluid which can be supplied to the pulsation generator100per unit time. Since the pulsation generator100can supply the fluid at a high pressure, and an infusion solution bag that accommodates the fluid is used as the fluid container760as it is, it is possible to prevent the fluid from being contaminated. The pulsation generator100can continuously supply the fluid without generating pulsation.

In addition, in the embodiment, the drive control unit600is provided separately from the pump700and the pulsation generator100; however, the drive control unit600may be provided integrally with the pump700.

When the practitioner performs an operation using the fluid ejection device1, the practitioner grasps the pulsation generator100. Accordingly, the connection tube25up to the pulsation generator100is preferably as flexible as possible. For this reason, a flexible thin tube is used as the connection tube25, and a fluid discharge pressure of the pump700is preferably set to a low pressure in a pressure range in which the fluid can be supplied to the pulsation generator100. For this reason, the discharge pressure of the pump700is set to approximately 0.3 atm (0.03 MPa) or less.

In particular, in a case where a malfunction of an apparatus may lead to a serious accident, for example, for brain surgery, it is necessary to prevent the cutting of the connection tube25from causing the ejection of the fluid at a high pressure, and also, for this reason, the discharge pressure of the pump700is required to be set to a low pressure.

Pulsation Generator

Subsequently, the structure of the pulsation generator100according to the embodiment will be described.

FIG. 5is a cross-sectional view illustrating the structure of the pulsation generator100according to the embodiment. InFIG. 5, the pulsation generator100includes a pulse generation unit that generates the pulsation of the fluid, and is connected to the fluid ejection tube200having a connection channel201as a channel through which the fluid is discharged.

In the pulsation generator100, an upper case500and a lower case301are screwed together with four fixation screws350(not illustrated) while the respective facing surfaces thereof are bonded to each other. The lower case301is a cylindrical member having a flange, and one end portion of the lower case301is sealed with a bottom plate311. The piezoelectric element401is provided in an inner space of the lower case301.

The piezoelectric element401is a stack-type piezoelectric element, and acts as an actuator. One end portion of the piezoelectric element401is firmly fixed to the diaphragm400via an upper plate411, and the other end portion is firmly fixed to an upper surface312of the bottom plate311.

The diaphragm400is made of a circular disc-like thin metal plate, and a circumferential edge portion of the diaphragm400is firmly fixed to a bottom surface of a concave portion303in the lower case301while being in close contact with the bottom surface of the concave portion303. When drive signals are input to the piezoelectric element401that acts as a volume change unit, the piezoelectric element401changes the volume of the fluid chamber501via the diaphragm400through the extension and contraction thereof.

A reinforcement plate410is provided in such a manner as to be stacked on an upper surface of the diaphragm400, and is made of a circular disc-like thin metal plate having an opening at the center thereof.

The upper case500has a concave portion formed in a center portion of the surface facing the lower case301, and the fluid chamber501is a rotator-shaped space formed by this concave portion and the diaphragm400and filled with the fluid. That is, the fluid chamber501is a space enveloped by a sealing surface505and an inner side wall501aof the concave portion of the upper case500, and the diaphragm400. An outlet channel511is drilled in an approximately center portion of the fluid chamber501.

The outlet channel511passes through the outlet channel tube510from the fluid chamber501to an end portion of an outlet channel tube510provided in such a manner as to protrude from one end surface of the upper case500. A connection portion between the outlet channel511and the sealing surface505of the fluid chamber501is smoothly rounded so as to reduce fluid resistance.

In the embodiment (refer toFIG. 5), the fluid chamber501has a substantially cylindrical shape having sealed opposite ends; however, the fluid chamber501may have a conical shape, a trapezoidal shape, a hemispherical shape, or the like in a side view, and the shape of the fluid chamber501is not limited to a cylindrical shape. For example, when the connection portion between the outlet channel511and the sealing surface505has a funnel shape, air bubbles in the fluid chamber501(to be described later) are easily discharged.

The fluid ejection tube200is connected to the outlet channel tube510. The connection channel201is drilled in the fluid ejection tube200, and the diameter of the connection channel201is larger than that of the outlet channel511. In addition, the tube thickness of the fluid ejection tube200is formed so as to have a range of rigidity in which the fluid ejection tube200does not absorb pressure pulsation of the fluid.

The nozzle211is inserted into the tip end portion of the fluid ejection tube200. A fluid ejection opening212is drilled in the nozzle211. The diameter of the fluid ejection opening212is smaller than that of the connection channel201.

An inlet channel tube502is provided in such a manner as to protrude from a side surface of the upper case500, and is inserted into the connection tube25through which the fluid is supplied from the pump700. A connection channel504for the inlet channel is drilled in the inlet channel tube502. The connection channel504communicates with an inlet channel503. The inlet channel503is formed in a groove shape in a circumferential edge portion of the sealing surface505of the fluid chamber501, and communicates with the fluid chamber501.

A packing box304and a packing box506are respectively formed in the bonded surfaces of the lower case301and the upper case500at positions separated from an outer circumferential direction of the diaphragm400, and a ring-shaped packing450is mounted in a space formed by the packing boxes304and506.

Here, when the upper case500and the lower case301are assembled together, the circumferential edge portion of the diaphragm400is in close contact with a circumferential edge portion of the reinforcement plate410due to the circumferential edge portion of the sealing surface505of the upper case500and the bottom surface of the concave portion303of the lower case301. At this time, the packing450is pressed by the upper case500and the lower case301, and thereby the fluid is prevented from leaking from the fluid chamber501.

Since the inner pressure of the fluid chamber501becomes a high pressure of 30 atm (3 MPa) or greater during the discharge of the fluid, the fluid may slightly leak from the respective connections between the diaphragm400, the reinforcement plate410, the upper case500, and the lower case301; however, the leakage of the fluid is prevented due to the packing450.

As illustrated inFIG. 5, in the case where the packing450is provided, since the packing450is compressed due to the pressure of the fluid leaking from the fluid chamber501at a high pressure, and is strongly pressed against the respective walls of the packing boxes304and506, it is possible to more reliably prevent the leakage of the fluid. For this reason, it is possible to maintain a considerable increase in the inner pressure of the fluid chamber501during the driving of the pulsation generator100.

Subsequently, the inlet channel503formed in the upper case500will be described with reference to the drawings in more detail.FIG. 6is a plan view illustrating the shape of the inlet channel503.FIG. 6illustrates the state of the upper case500when the surface of the upper case500bonded to the lower case301is seen.

InFIG. 6, the inlet channel503is formed in a groove shape in the circumferential edge portion of the sealing surface505of the upper case500.

One end portion of the inlet channel503communicates with the fluid chamber501, and the other end portion communicates with the connection channel504. A fluid sump507is formed in a connection portion between the inlet channel503and the connection channel504. A connection portion between the fluid sump507and the inlet channel503is smoothly rounded, and thereby fluid resistance is reduced.

The inlet channel503communicates with the fluid chamber501in a substantially tangential direction with respect to an inner circumferential side wall501aof the fluid chamber501. The fluid supplied from the pump700(refer toFIG. 1) at a predetermined pressure flows along the inner circumferential side wall501a(in a direction illustrated by the arrow inFIG. 6), and generates a swirl flow in the fluid chamber501. The swirl flow is pushed against the inner circumferential side wall501adue to a centrifugal force associated with the swirling of the fluid, and air bubbles in the fluid chamber501are concentrated in a center portion of the swirl flow.

The air bubbles concentrated in the center portion are discharged via the outlet channel511. For this reason, the outlet channel511is preferably provided in the vicinity of the center of the swirl flow, that is, in an axial center portion of a rotor shape.

As illustrated inFIG. 6, the inlet channel503is curved. The inlet channel503may communicate with the fluid chamber501while not being curved but being linearly formed; however, when the inlet channel503is curved, a channel length is increased, and a desired inertance (to be described later) is obtained in a small space.

As illustrated inFIG. 6, the reinforcement plate410is provided between the diaphragm400and the circumferential edge portion of the sealing surface505, in which the inlet channel503is formed. The reinforcement plate410is provided so as to improve the durability of the diaphragm400. Since a cut-out connection opening509is formed in a connection portion between the inlet channel503and the fluid chamber501, when the diaphragm400is driven at a high frequency, stress may be concentrated in the vicinity of the connection opening509, and thereby a fatigue failure may occur in the vicinity of the connection opening509. It is possible to prevent stress from being concentrated on the diaphragm400by providing the reinforcement plate410with an opening not having a cut-out portion and being continuously formed.

Four screw holes500aare respectively provided in outer circumferential corner portions of the upper case500, and the upper case500and the lower case301are bonded to each other via screwing at the positions of the screw holes.

It is possible to firmly fix the reinforcement plate410and the diaphragm400in an integrally stacked state by bonding together the reinforcement plate410and the diaphragm400, which is not illustrated. An adhesive method using an adhesive, a solid-state diffusion bonding method, a welding method, or the like may be used so as to firmly fix together the reinforcement plate410and the diaphragm400; however, the respective bonded surfaces of the reinforcement plate410and the diaphragm400are preferably in close contact with each other.

Operation of Pulsation Generator

Subsequently, an operation of the pulsation generator100according to the embodiment will be described with reference toFIGS. 1 to 6. The pulsation generator100according to the embodiment discharges the fluid due to a difference between an inertance L1(may be referred to as a combined inertance L1) of the inlet channel503and the peripherals and an inertance L2(may be referred to as a combined inertance L2) of the outlet channel511and the peripherals.

First, the inertance will be described.

An inertance L is expressed by L=ρ×h/S, and here, ρ is the density of a fluid, S is the cross-sectional area of a channel, and h is a channel length. When ΔP is a differential pressure of the channel, and Q is a flow rate of the fluid flowing through the channel, it is possible to deduce a relationship ΔP=L×dQ/dt by modifying an equation of motion in the channel using the inertance L.

That is, the inertance L indicates a degree of influence on a change in flow rate with time, and a change in flow rate with time decreases to the extent that the inertance L is large, and a change in flow rate with time increases to the extent that the inertance L is small.

Similar to a parallel connection or a series connection of inductances in an electric circuit, it is possible to calculate a combined inertance with respect to a parallel connection of a plurality of channels or a series connection of a plurality of channels having different shapes by combining an inertance of each of the channels.

Since the diameter of the connection channel504is set to be larger much than that of the inlet channel503, the inertance L1of the inlet channel503and the peripherals can be calculated from a boundary of the inlet channel503. At this time, since the connection tube25that connects the pump700and the inlet channel503is flexible, the connection tube25may not be taken into consideration in calculating the inertance L1.

Since the diameter of the connection channel201is larger much than that of the outlet channel511, and the tube (tube wall) thickness of the fluid ejection tube200is thin, the connection tube25and the fluid ejection device1have a negligible influence on the inertance L2of the outlet channel511and the peripherals. Accordingly, the inertance L2of the outlet channel511and the peripherals may be replaced with an inertance of the outlet channel511.

The rigidity of the tube wall thickness of the fluid ejection tube200is sufficient to propagate the pressure of the fluid.

In the embodiment, a channel length and a cross-sectional area of the inlet channel503and a channel length and a cross-sectional area of the outlet channel511are set in such a manner that the inertance L1of the inlet channel503and the peripherals is greater than the inertance L2of the outlet channel511and the peripherals.

Ejection of Fluid

Subsequently, an operation of the pulsation generator100will be described.

The pump700supplies the fluid to the inlet channel503at a predetermined pressure. As a result, when the piezoelectric element401is not operated, the fluid flows into the fluid chamber501due to a difference between a discharge force of the pump700and a fluid resistance value for the entirety of the inlet channel503and the peripherals.

Here, in a case where the inertance L1of the inlet channel503and the peripherals and the inertance L2of the outlet channel511and the peripherals are considerably large, when a drive signal is input to the piezoelectric element401, and the piezoelectric element401extends rapidly, the inner pressure of the fluid chamber501increases rapidly, and reaches several tens of atmosphere.

Since the inner pressure of the fluid chamber501is larger much than the pressure applied to the inlet channel503by the pump700, the flow of the fluid from the inlet channel503to the fluid chamber501decreases due to the pressure, and the flow of the fluid out of the outlet channel511increases.

Since the inertance L1of the inlet channel503is larger than the inertance L2of the outlet channel511, an increase in a flow rate of the fluid discharged from the outlet channel511is larger than a decrease in a flow rate of the fluid flowing from the inlet channel503into the fluid chamber501. Accordingly, the fluid is discharged in the form of a pulsed flow to the connection channel201, that is, a pulsed flow occurs. Discharge pressure pulsation propagates in the fluid ejection tube200, and the fluid is ejected via the fluid ejection opening212of the nozzle211at the tip end.

Here, since the diameter of the fluid ejection opening212of the nozzle211is smaller than that of the outlet channel511, a pulsed flow of the fluid is ejected as droplets at a higher pressure and speed.

In contrast, immediately after a pressure increase, the inner pressure of the fluid chamber501becomes negative due to interaction between a decrease in the amount of inflow of the fluid from the inlet channel503and an increase in the amount of outflow of the fluid from the outlet channel511. As a result, after a predetermined amount of time has elapsed, due to both of the pressure of the pump700and the negative inner pressure of the fluid chamber501, the fluid flows from the inlet channel503into the fluid chamber501again at the same speed as that before the operation of the piezoelectric element401.

When the piezoelectric element401extends after the outflow of the fluid from the inlet channel503is restored, it is possible to continuously eject the fluid in the form of a pulsed flow via the nozzle211.

Discharge of Air Bubbles

Subsequently, an operation of discharging air bubbles from the fluid chamber501will be described.

As described above, the inlet channel503communicates with the fluid chamber501via a path that approaches the fluid chamber501while swirling around the fluid chamber501. The outlet channel511is provided in the vicinity of a rotational axis of a substantially rotor-shaped fluid chamber501.

For this reason, the fluid flowing from the inlet channel503into the fluid chamber501swirls along the inner circumferential side wall501aof the fluid chamber501. The fluid is pushed against the inner circumferential side wall501aof the fluid chamber501due to a centrifugal force, and air bubbles contained in the fluid are concentrated in the center portion of the fluid chamber501, and are discharged via the outlet channel511.

Accordingly, even when a small amount of the volume of the fluid chamber501is changed in association with the operation of the piezoelectric element401, it is possible to obtain a sufficient pressure increase while a pressure pulsation is not adversely affected.

In the embodiment, since the pump700supplies the fluid to the inlet channel503at a predetermined pressure, even when the driving of the pulsation generator100is stopped, the fluid is supplied to the inlet channel503and the fluid chamber501. Accordingly, it is possible to start an initial operation without an aid of a prime operation.

Since the fluid is ejected via the fluid ejection opening212having a diameter smaller than that of the outlet channel511, an inner fluid pressure increases higher than that of the outlet channel511, and thereby it is possible to eject the fluid at a high speed.

Since the rigidity of the fluid ejection tube200is sufficient to transmit a pulsation of the fluid from the fluid chamber501to the fluid ejection opening212, it is possible to eject the fluid in the form of a desired pulsed flow without disturbing pressure propagation of the fluid from the pulsation generator100.

Since the inertance of the inlet channel503is set to be larger than that of the outlet channel511, an increase in the amount of outflow of the fluid from the outlet channel511is larger than a decrease in the amount of flow of the fluid from the inlet channel503into the fluid chamber501, and it is possible to discharge the fluid into the fluid ejection tube200in the form of a pulsed flow. Accordingly, a check valve is not required to be provided in the inlet channel503, it is possible to simplify the structure of the pulsation generator100, it is easy to clean the inside of the pulsation generator100, and it is possible to remove a potential durability problem associated with the use of the check valve.

Since the respective inertances of both of the inlet channel503and the outlet channel511are set to be considerably large, it is possible to rapidly increase the inner pressure of the fluid chamber501by rapidly reducing the volume of the fluid chamber501.

Since the piezoelectric element401as a volume change unit and the diaphragm400are configured so as to generate a pulsation, it is possible to simplify the structure of the pulsation generator100and to reduce the size of the pulsation generator100in association therewith. It is possible to set the maximum frequency of a change in the volume of the fluid chamber501to a high frequency of 1 KHz or greater, and the pulsation generator100is optimized to eject a pulsed flow of the fluid at a high speed.

In the pulsation generator100, since the inlet channel503generates a swirl flow of the fluid in the fluid chamber501, the fluid in the fluid chamber501is pushed in an outer circumferential direction of the fluid chamber501due to a centrifugal force, air bubbles contained in the fluid are concentrated in the center portion of the swirl flow, that is, in the vicinity of the axis of the substantially rotor shape, and thereby it is possible to discharge the air bubbles via the outlet channel511provided in the vicinity of the axis of the substantially rotor shape. For this reason, it is possible to prevent a decrease in pressure amplitude associated with the stagnation of air bubbles in the fluid chamber501, and it is possible to continuously and stably drive the pulsation generator100.

Since the inlet channel503is formed in such a manner as to communicate with the fluid chamber501via the path that approaches the fluid chamber501while swirling around the fluid chamber501, it is possible to generate a swirl flow without adopting a structure dedicated for swirling the fluid in the fluid chamber501.

Since the groove-shaped inlet channel503is formed in the outer circumferential edge portion of the sealing surface505of the fluid chamber501, it is possible to form the inlet channel503(a swirl flow generation unit) without increasing the number of components.

Since the reinforcement plate410is provided on the upper surface of the diaphragm400, the diaphragm400is driven with respect to an outer circumference (a fulcrum) of the opening of the reinforcement plate410, and thereby the concentration of stress is unlikely to occur, and it is possible to improve the durability of the diaphragm400.

When corners of the surface of the reinforcement plate410bonded to the diaphragm400is rounded, it is possible to further reduce the concentration of stress on the diaphragm400.

When the reinforcement plate410and the diaphragm400are firmly and integrally fixed together while being stacked on each other, it is possible to improve the assemblability of the pulsation generator100, and it is possible to reinforce the outer circumferential edge portion of the diaphragm400.

Since the fluid sump507for the stagnation of the fluid is provided in the connection portion between the connection channel504on an inlet side for supplying the fluid from the pump700and the inlet channel503, it is possible to prevent the inertance of the connection channel504from affecting the inlet channel503.

In the respective bonded surfaces of the lower case301and the upper case500, the ring-shaped packing450is provided at the position separated from the outer circumferential direction of the diaphragm400, and thereby it is possible to prevent the leakage of the fluid from the fluid chamber501, and to prevent a decrease in the inner pressure of the fluid chamber501.

Control of Inner Pressure of Fluid Container760

FIG. 7is a graph illustrating a transition of the inner pressure of the fluid container760when a pressure control operation is performed.FIG. 7illustrates a pressure P (on a vertical axis) with respect to a time t (on a horizontal axis). The pressure P illustrated here indicates the inner pressure of the fluid container760(hereinafter, the inner pressure of the fluid container760may be simply referred to as the “pressure P”), which is detected by the pressure sensor722.FIG. 7illustrates a target pressure Pt, a pressure R1, a pressure F1higher than the pressure R1, a pressure F2higher than the pressure F1and the target pressure, and a pressure R2higher than the pressure F2. A rough window indicates a range from the pressure R1to the pressure R2. A fine window indicates a range from the pressure F1to the pressure F2.

An outline of the fluid ejection device1according to the embodiment will be described. The drive control unit600of the fluid ejection device1controls the ejection of the fluid from the pulsation generator100. The pump control unit710of the fluid ejection device1controls the inner pressure of the fluid container760.

When the inner pressure P of the fluid container760is higher than the pressure R1and is lower than the pressure R2, the drive control unit600receives a demand for the ejection of the fluid from the pulsation generator start-up switch (not illustrated), and controls the pulsation generator100to eject the fluid. That is, when the pressure P is in the rough window, the fluid is ejected. Even in the case where the pressure P is higher than the pressure R1and is lower than the pressure R2, when the fluid ejection device1is in a trial mode (to be described later), the fluid is ejected, which is an exceptional case. At this time, the pump control unit710does not control the pressure of the fluid container760, and sends a constant amount of the fluid from the fluid container760to the pulsation generator100.

In a pressure adjustment control operation (to be described later), the pump control unit710performs a rough pressure increase adjustment control operation when the pressure P is the pressure R1or lower. When the pressure P is higher than the pressure R1, and is the pressure F1or lower, the pump control unit710performs a fine pressure increase adjustment control operation. When the pressure P is higher than the pressure F1and is lower than the pressure F2(in the fine window), the pump control unit710does not perform a pressure adjustment operation. When the pressure P is the pressure F2or higher, the pump control unit710performs a fine pressure decrease adjustment control operation. When the pump control unit710performs the pressure adjustment control operation, the drive control unit600controls the pulsation generator100not to eject the fluid.

Hereinafter, the pressure adjustment control operation will be described. In the following description, the inner pressure P of the fluid container760is detected by the pressure sensor722, and the pump control unit710performs the pressure adjustment control operation in response to the pressure P.

FIG. 8is a flowchart of the pressure adjustment control operation. When the pulsation generator start-up switch is not pushed, the pressure adjustment control operation is performed every 20 ms.

The pump control unit710determines whether the pressure P of the fluid container760is higher than the pressure F1and is lower than the pressure F2(S102). When the pressure P is higher than the pressure F1and is lower than the pressure F2, the pressure adjustment control operation ends. As such, when the pressure P is higher than the pressure F1and is lower than the pressure F2, the pressure adjustment control operation is not performed, and thereby it is possible to prevent the pressure control operation from being uselessly performed, and to prevent an increase in pressure change.

In contrast, in step S102, when it is not satisfied that the pressure P is higher than the pressure F1and is lower than the pressure F2, the pump control unit710determines whether the pressure P is the pressure F2or higher (S104). When the pressure P is the pressure F2or higher, the pump control unit710performs the fine pressure decrease adjustment control operation (S106).

Hereinafter, the fine pressure decrease adjustment control operation will be described. The pump control unit710according to the embodiment can control the motor730to continuously move the slider720at a predetermined speed, and can control the motor730to move the slider720by a very small distance. The motor730is controlled to rotate by a minimum unit so as to move the slider720by the very small distance. In the fine pressure decrease adjustment control operation, the pump control unit710moves the slider720toward the second limit sensor744by the very small distance. As a result, due to the inner pressure of the fluid container760, the plunger762moves by the very small distance in an increase direction of the inner volume of the fluid accommodation portion765. Accordingly, the inner pressure of the fluid container760decreases by a very small amount of pressure.

In step S104, when the pressure P is not the pressure F2or higher, the pump control unit710determines whether the pressure P is higher than the pressure R1and is the pressure F1or lower (S108). When the pressure P is higher than the pressure R1and is the pressure F1or lower, the pump control unit710performs the fine pressure increase adjustment control operation (S110).

Hereinafter, the fine pressure increase adjustment control operation will be described. In the fine pressure increase adjustment control operation, the pump control unit710moves the slider720toward the first limit sensor741by a very small distance. The plunger762moves in a decrease direction of the inner volume of the fluid accommodation portion765of the fluid container760. Accordingly, the inner pressure of the fluid container760increases by a very small amount of pressure.

In step S108, when it is not satisfied that the pressure P is higher than the pressure R1, and is the pressure F1or lower, the pump control unit710performs the rough pressure increase adjustment control operation (S112to S116). In the rough pressure increase adjustment control operation, the pump control unit710controls the motor730to continuously move the slider720toward the first limit sensor741. Subsequently, the pump control unit710determines whether the pressure P is lower than the target pressure Pt (S114). When the pressure P is lower than the target pressure Pt, the pump control unit710controls the motor730to continuously move the slider720toward the limit sensor741again. In contrast, in step S114, when the pressure P is the target pressure Pt or higher, the pump control unit710ends the movement of the slider720. As such, the pressure adjustment control operation ends.

First, as illustrated inFIG. 7, the rough pressure increase adjustment operation is performed in the execution of the above-mentioned pressure adjustment control operation. Accordingly, the pressure P rapidly increases to approximately the target pressure Pt. When the pressure P increases to the target pressure, the rough pressure increase adjustment control operation ends. While the pressure P is between the pressure F1and the pressure F2, a particular pressure adjustment operation is not performed.

Thereafter, the pressure P decreases gradually due to the gasket763. When the pressure P decreases to the pressure F1or lower, the fine pressure increase adjustment operation is performed. Since the fine pressure increase adjustment control operation is performed so as to move the slider720by the very small distance, and to increase the pressure by the very small amount of pressure as described above, the pressure P stays at approximately the target pressure Pt.

When the pressure P exceeds the pressure F1, the pressure control operation is stopped. Accordingly, due to the gasket763, the pressure P decreases gradually again. Thereafter, similarly as described above, the fine pressure increase adjustment operation is performed. These processes are repeated, and thereby the pressure P is stabilized at approximately the target pressure Pt.

The reason that the pressure adjustment control operation is performed as described above is as follows. That is, when the pressure P is the pressure R1or lower, it is necessary to rapidly increase the pressure P to approximately the target pressure Pt from a pressure at which the fluid cannot be properly ejected. For this reason, when the pressure P is the pressure R1or lower, the pump control unit710rapidly increases the pressure via the rough pressure increase adjustment control operation.

When the pressure P is higher than the pressure R1, and is the pressure F1or lower, the pressure has already increased to a level in which the fluid can be ejected. For this reason, the pressure may increase by a very small amount of pressure observed by the gasket763. Accordingly, when the pressure P is higher than the pressure R1, and is the pressure F1or lower, the pressure is adjusted via the fine pressure increase adjustment control operation.

When the pressure P is higher than the pressure F1and is lower than the pressure F2, the pressure P is very close to the target pressure Pt. When the pump control unit710controls the inner pressure of the fluid container760containing the gasket763in high friction contact with the syringe761, a control delay may occur, and the pressure may be severely changed during the adjustment control operation of the pressure P. Accordingly, when the pressure P is higher than the pressure F1and is lower than the pressure F2, the pressure control operation is stopped.

In this manner, it is possible to rapidly increase the pressure P to the target pressure Pt, and after the pressure P increases to approximately the target pressure Pt, it is possible to maintain the pressure P at approximately the target pressure Pt via the fine pressure increase adjustment control operation. Since it is possible to maintain the pressure P at approximately the target pressure Pt immediately before the fluid is ejected, when there is a demand for the ejection of the fluid present, it is possible to immediately send the fluid to the pulsation generator100at a proper pressure.

Subsequently, a fluid ejection control operation will be described.

In the fluid ejection control operation according to the embodiment, when the pump control unit710determines that the fluid cannot be supplied even after the pulsation generator start-up switch is turned on (equivalent to when an ejection command input is received), and then a predetermined amount of time has elapsed, the drive control unit600reports an output disable fault. In addition, the drive control unit600prohibits the pulsation generator100from ejecting the fluid until the pulsation generator start-up switch is turned on again after the pulsation generator start-up switch is turned off (equivalent to a state in which the ejection command input is cancelled). Hereinafter, the fluid ejection control operation will be described with reference to a flowchart.

FIG. 9is a flowchart illustrating the fluid ejection control operation.

The drive control unit600determines whether the pulsation generator start-up switch is turned on (S202). When the pulsation generator start-up switch is not turned on, an output disable fault flag (equivalent to a flag) is cleared (S226). Here, the output disable fault flag is a flag that will be set on when the fluid cannot be supplied even after the pulsation generator start-up switch is turned on, and then a specific amount of time has elapsed in the process to be described later. Since the fluid cannot be supplied when the output disable fault flag is cleared, it is not possible to eject the fluid.

In contrast, when the pulsation generator start-up switch is turned on, it is determined whether the output disable fault flag is set (S204). When the output disable fault flag is set, step S202is performed again. In this manner, once the output disable fault flag is set, and when the pulsation generator start-up switch is turned off, and thereafter is not turned on again, it is possible to bring the fluid ejection device1into a state in which steps following steps S206cannot be executed. That is, once the output disable fault flag is set, and when the pulsation generator start-up switch is turned off, and thereafter is not turned on again, it is possible to disable the ejection of the fluid.

When the output disable fault flag is cleared in step S204, the drive control unit600sends an output demand signal (equivalent to a demand for the supply of the fluid) to the pump control unit710(S206). Thereafter, the drive control unit600waits for 100 ms (S208). Here, the reason that a wait time of 100 ms is required is that the drive control unit600sends the output demand signal every approximately 100 ms.

When the pump control unit710receives the output demand signal, the pump control unit710determines whether the fluid can be supplied (S210). Here, for example, the state in which the fluid can be supplied can be defined as a state in which the inner pressure of the fluid container760is higher than the pressure R1and is lower than the pressure R2. In addition, for example, the state in which the fluid can be supplied can be defined as a “standby” state. In addition, the state in which the fluid can be supplied can be defined as a state in which the inner pressure of the fluid container760is higher than the pressure R1and is lower than the pressure R2, and the pump control unit710is in the standby state.

The following is examples of a “non-standby” state: state in which syringe761is not set to the pump700; state in which a cover (not illustrated) of the pump700is opened; state in which the priming process is in progress; state in which the deaeration process is in progress; state in which a supply ready button is not pushed; and the like.

When the fluid can be supplied in step S210, the pump control unit710sends an output progress signal to the drive control unit600. When the drive control unit600receives the output progress signal, the drive control unit600drives the piezoelectric element401in order for the pulsation generator100to eject the fluid. In contrast, the pump control unit710opens the pinch valve750(S216), and at substantially the same time, the pump control unit710moves the slider720in the direction in which the plunger762is pushed (S218).

Subsequently, the drive control unit600determines whether the pulsation generator start-up switch is continuously turned on (S220). When the pulsation generator start-up switch is continuously turned on, the process returns to step S220again. This loop is repeated, and thereby it is possible to continuously eject the fluid from the pulsation generator100.

When the pulsation generator start-up switch is turned off in step S220, the drive control unit600stops the driving of the piezoelectric element401. At substantially the same time, the drive control unit600instructs the pump control unit710to stop the movement of the slider720(S222), and to close the pinch valve750(S224). Accordingly, the fluid ejection control operation is completed.

When it determined that the fluid cannot be supplied in step S210, the drive control unit600determines whether the pulsation generator start-up switch is turned on in step S202, and then the specific amount of time has elapsed (S212). Here, the specific amount of time is 500 ms. When the pulsation generator start-up switch is turned on in step S202, and then the specific amount of time has not elapsed, the process returns to step S202. In contrast, when the specific amount of time has not elapsed, the output disable fault flag is set (S214), and the output disable fault is reported. It is possible to report the output disable fault by displaying a message indicative of the output disable fault on a display unit (not illustrated), or generating a predetermined sound. As such, the fluid ejection control operation is completed.

FIG. 10is a diagram illustrating the transmitting and receiving of signals between the pulsation generator100, the drive control unit600, and the pump control unit710. When the ejection control operation illustrated in the flowchart is executed, operations illustrated inFIG. 10are performed.

When the pulsation generator start-up switch is turned on, the drive control unit600sends an output demand signal to the pump control unit710. The pump control unit710receives the sent output demand signal, and determines whether the fluid can be supplied to the pulsation generator100. The state in which the fluid can be supplied is as described above.

When the fluid can be supplied, the pump control unit710sends an output progress signal to the drive control unit600, and starts supplying the fluid to the pulsation generator100. In contrast, when the fluid cannot be supplied, the pump control unit710sends a signal other than the output progress signal back to the drive control unit600. InFIG. 10, when the fluid cannot be supplied because the pump control unit710performs a pressure adjustment operation, the pump control unit710sends a pressure adjustment progress signal back to the drive control unit600.

The output demand signal is sent to the pump control unit710every 100 ms. Despite the fact that the pulsation generator start-up switch is continuously turned on, when the specific amount of time (here, 500 ms) has elapsed, the drive control unit600reports an output disable fault.

When a user receives a notification of the output disable fault, and turns off the pulsation generator start-up switch, the sending of an output demand is stopped. When the pulsation generator start-up switch is turned on again, an output demand signal is sent to the pump control unit710again. The pump control unit710receives the sent output demand signal, and then determines whether the fluid can be supplied. When the fluid can be supplied, the pump control unit710sends an output progress signal to the drive control unit600, and starts supplying the fluid.

When the drive control unit600receives an output progress signal before the specific amount of time has elapsed immediately after the pulsation generator start-up switch is turned on, the drive control unit600starts the driving of the piezoelectric element401and starts the ejection of the fluid. While the pulsation generator start-up switch is turned on, the fluid is continuously ejected.

As such, when the pulsation generator start-up switch is turned on, and the supply of the fluid to the pulsation generator100cannot be ready, it is possible to report an output disable fault, and not to eject the fluid. Accordingly, when the supply of the fluid to the pulsation generator100cannot be ready, it is possible to prevent the fluid from being ejected after the pulsation generator start-up switch is turned on. It is possible to very safely eject the fluid.

Another Embodiment

In the example of the embodiment, the fluid ejection device1is applied to an operation scalpel used to incise or excise living tissue; however, the invention is not limited to the embodiment, and can be applied to other medical tools for excision, cleaning, or the like. Specifically, the fluid ejection device1can be used to clean a fine object or structure.

In the embodiment, the fluid is ejected by using the piezoelectric element; however, a laser bubble method may be adopted by which a fluid in a pressure chamber is powerfully ejected by generating bubbles in the fluid in the pressure chamber with a laser beam. In the embodiment, the fluid is ejected by using the piezoelectric element; however, a laser bubble method may be adopted by which a fluid in a pressure chamber is powerfully ejected by generating bubbles in the fluid in the pressure chamber with a laser beam.

In the embodiment, the fluid is ejected in the form of a pulsed flow; however, the fluid may be continuously ejected. When the fluid container760is formed of an infusion solution bag that accommodates a fluid, it is possible to perform the rough pressure increase adjustment control operation, the fine pressure increase adjustment control operation, and the fine pressure decrease adjustment control operation as follows. That is, in the rough pressure increase adjustment control operation, air is pressure-fed to the pressurized chamber800by continuously operating the compressor810. In the fine pressure increase adjustment control operation, air is pressure-fed to the pressurized chamber800by operating the compressor810for a very small amount of time. In the fine pressure decrease adjustment control operation, the pressure of the pressurized chamber800decreases by a very small amount of pressure by opening the air vent valve812for a very small amount of time.

The embodiment is given to help understanding the invention, and the interpretation of the invention is not limited to the embodiment. Modifications or improvements can be made to the invention insofar as the medications or the improvements do not depart from the spirit of the invention, and the invention includes the equivalent.