JP2010059939A - Fluid injection device, method of controlling fluid injection device, and surgical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the depth of incision or excision from increasing when a fluid injection device for incising or excising an object by jetting a fluid starts the jetting. <P>SOLUTION: The fluid injection device 1 includes a waveform storage part 31 for storing an initial voltage pulse waveform group and working voltage pulse waveforms. When the fluid is jetted, the voltage pulse waveforms of the initial voltage pulse waveform group are applied in order to a piezoelectric element 401 during an increase in the output, and then the working voltage pulse waveforms are repeatedly applied to the piezoelectric element 401 during the stable output. Therefore, when the fluid is jetted, the depth of incision or excision is prevented from increasing during the start of jetting since the jetting pressure is gradually changed from a low pressure to a high pressure. Namely, the depth of incision or excision is prevented from increasing when the fluid injection device for incising or excising the object by jetting the fluid is prevented from increasing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluid ejection device capable of incising or excising a target site by ejecting fluid, a control method for a fluid ejection device, and a surgical apparatus.

Conventionally, as a fluid ejection device for incising or excising biological tissue, one end is connected to a micropump that performs a fluid ejection operation by changing the volume of a pump chamber by a piezoelectric element, and an outlet flow path of the micropump, A connecting channel provided with an opening (nozzle) whose other end is smaller than the diameter of the outlet channel, and a pulsation of fluid flowing from the micropump through the connecting channel. There is known a fluid ejecting apparatus that includes a connecting pipe having rigidity that can be transmitted, fluid flows through repetition of a pulsating wave group and a resting part, and is ejected from an opening at high speed (for example, Patent Document 1).
According to the technique described in Patent Document 1, it is possible to eject a pulsating fluid at high speed, and the control thereof is easy. In addition, jetting of the pulsating fluid has a high tissue incising ability in surgery and the like, but the amount of fluid is small, so that the fluid does not stay in the surgical field. Therefore, the visibility is improved and there is an effect of preventing the scattering of the tissue.
JP 2008-82202 A

However, in the fluid ejecting apparatus that includes the technique described in Patent Document 1 and changes the volume of a fluid storage chamber (hereinafter referred to as a “fluid chamber”) using a piezoelectric element to discharge the fluid, When the fluid is incised or excised, the portion of the object where the fluid is first ejected (hereinafter referred to as “ejection start point”) can be incised or excised deeper than the portion where the fluid is ejected thereafter. There is sex.
This is considered to be because the fluid that was ejected and hit the object flows into the injection start point.

Therefore, for example, in an operation or the like, when the operator moves the nozzle at a constant speed for the purpose of incising the tissue, the incision depth at the injection start point may be deeper than the operator intends. .
As described above, in the conventional fluid ejecting apparatus that incises or excises the target site by ejecting the fluid, there is a possibility that the depth of incision or excision increases at the start of discharge.
An object of the present invention is to prevent a situation in which the depth of incision or excision increases at the start of ejection in an apparatus for incising or excising a target site by ejecting fluid.

In order to solve the above problems, the first invention is
Volume changing means (for example, a fluid chamber 501 in FIG. 2) into which a fluid flows and a pressure generating element (for example, piezoelectric element 401 in FIG. 2) for changing the volume of the fluid chamber by a drive signal (for example, piezoelectric element 401). 2 and a pulsation generator (for example, pulsation generator 100 of FIG. 2) having an inlet channel and an outlet channel communicating with the fluid chamber, and the outlet channel. A fluid ejection port (for example, the fluid ejection port 212 in FIG. 2) that ejects fluid that has flowed out from the fluid, and a fluid supply means (for example, the fluid container 10 and the pump 20 in FIG. 1) that supplies fluid to the inlet channel; Control means for applying a drive signal to the pressure generating element and controlling the change of the volume of the fluid chamber by the volume changing means (for example, the control unit 30 in FIG. 4), and the control means discharges fluid After starting It is characterized by increasing the discharge pressure of the fluid in Kaiteki.
With such a configuration, since the fluid discharge pressure can be gradually increased at the start of fluid discharge, fluid ejection that can prevent a situation where the depth of incision or excision increases at the start of fluid discharge An apparatus can be realized.

In addition, the second invention,
A waveform storage unit (for example, the waveform storage unit 31 in FIG. 4) that stores a plurality of waveforms of the drive signals with different fluid discharge pressures is provided, and the control unit stores a plurality of waveforms stored in the waveform storage unit. The waveform of the drive signal is read out in order from the one having a different fluid discharge pressure and applied to the pressure generating element.
With such a configuration, the characteristics of the voltage pulse waveform (how to change the amplitude, frequency to be applied, etc.) can be easily changed by rewriting the stored contents of the waveform storage means.

In addition, the third invention,
The control means is characterized in that waveforms with different amplitudes of the drive signal are applied to the pressure generating element in order from a waveform having a smaller amplitude.
With such a configuration, the discharge pressure of the fluid can be gradually increased by drive signals having different waveform amplitudes.
In addition, the fourth invention is
The control means is characterized in that waveforms having different slew rates of the drive signals are applied to the pressure generating elements in order from a waveform having a smaller slew rate.
With such a configuration, the fluid discharge pressure can be gradually increased by drive signals having different waveform slew rates.

In addition, the fifth invention,
The control means applies a waveform in which the frequency of the drive signal increases with time to the pressure generating element.
With such a configuration, the discharge pressure of the fluid can be gradually increased by a drive signal whose frequency increases.
In addition, the sixth invention,
The control means is characterized in that the interval between the waveforms of the drive signals is reduced with time and applied to the pressure generating element.
With such a configuration, the discharge pressure of the fluid can be gradually increased by using a drive signal in which the interval between applied waveforms is reduced with the passage of time while using the same waveform.

In addition, the seventh invention,
A pulsation generator having a fluid chamber into which fluid flows, a volume changing unit having a pressure generating element that changes the volume of the fluid chamber by a drive signal, and an inlet channel and an outlet channel communicating with the fluid chamber A fluid ejection port that ejects fluid that has flowed out of the outlet channel, a fluid supply unit that supplies fluid to the inlet channel, a drive signal that is applied to the pressure generating element, and the fluid by the volume changing unit An output increasing step (for example, executed by the control unit 30) that increases the fluid discharge pressure stepwise after the start of fluid discharge. Control in the output increase period in FIG. 5).
Accordingly, since the fluid discharge pressure can be gradually increased at the start of fluid discharge, it is possible to prevent a situation where the depth of incision or excision increases at the start of fluid discharge.

Further, the eighth invention is
A pulsation generator having a fluid chamber into which fluid flows, a volume changing unit having a pressure generating element that changes the volume of the fluid chamber by a drive signal, and an inlet channel and an outlet channel communicating with the fluid chamber A fluid ejection port that ejects fluid that has flowed out of the outlet channel, a fluid supply unit that supplies fluid to the inlet channel, a drive signal that is applied to the pressure generating element, and the fluid by the volume changing unit Control means for controlling the change in the volume of the chamber, and the control means increases the fluid discharge pressure stepwise after the start of fluid discharge.
Accordingly, since the fluid discharge pressure can be gradually increased at the start of fluid discharge, a surgical apparatus capable of preventing a situation where the depth of incision or excision increases at the start of fluid discharge is realized. be able to.
As described above, according to the present invention, it is possible to prevent a situation in which the depth of incision or excision increases at the start of discharge in an apparatus for incising or excising a target site by ejecting fluid.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms. The drawings referred to in the following description are schematic views in which the vertical and horizontal scales of members or parts are different from actual ones for convenience of illustration.
In addition, the fluid ejecting apparatus according to the present invention can be used in various ways such as drawing with ink, washing fine objects and structures, cutting and excision of objects, and a water pulse knife for surgery. In the embodiment, a fluid ejecting apparatus as a surgical apparatus suitable for incising or excising a living tissue will be described as an example. Therefore, the fluid used in the embodiment is water, physiological saline, chemical solution, or the like.

(First embodiment)
FIG. 1 is an explanatory diagram showing a schematic configuration of a fluid ejection device 1 according to the first embodiment of the present invention. In FIG. 1, a fluid ejecting apparatus 1 includes a fluid container 10 that stores fluid as a basic configuration, a pump 20 that generates a constant pressure and supplies fluid to a pulsation generating unit 100, and a control unit that controls fluid ejection. 30 and a pulsation generator 100 that pulsates and flows the fluid supplied from the pump 20. In the present embodiment, the control unit 30 and the pump 20 are configured as an integral unit, and the control unit 30 and the pulsation generating unit 100 are connected by signal lines for inputting and outputting various signals.

(Configuration of fluid path)
First, the configuration of the fluid path of the fluid ejecting apparatus 1 will be described.
In the present embodiment, the pulsation generator 100 constitutes a fluid ejecting unit that ejects fluid by pressure generated by a piezoelectric element. Note that the fluid ejecting unit corresponds to a handpiece that is grasped and used by an operator in an operation or the like when the liquid ejecting apparatus 1 is configured as a water pulse knife.
The pulsation generator 100 is connected to a thin pipe-shaped connecting flow channel pipe 200, and a nozzle 211 with a reduced flow channel is inserted into the tip of the connecting flow channel pipe 200.
In addition, it is also possible to insert the nozzle 211 in the edge part on the opposite side to a fluid chamber among the two edge parts of an exit flow path, without providing the connection flow path pipe | tube 200. FIG. In this case, a simpler configuration can be obtained. However, when the fluid ejecting apparatus 1 is used for surgery, it is preferable that the connecting channel tube 200 is provided and the handpiece body and the fluid ejecting port have a certain distance.

The flow of fluid in the fluid ejecting apparatus 1 will be briefly described. The fluid stored in the fluid container 10 is sucked by the pump 20 through the connection tube 15 and supplied to the pulsation generator 100 through the connection tube 25 at a constant pressure. The pulsation generating unit 100 includes a fluid chamber 501 (see FIG. 2) and a volume changing unit for the fluid chamber 501. The pulsation generating unit 100 drives the volume changing unit to generate pulsation. The fluid is ejected through the nozzle 211 at high speed. A detailed description of the pulsation generator 100 will be described later with reference to FIGS.
The pressure generating unit is not limited to the pump 20, and the infusion bag may be held at a position higher than the pulsation generating unit 100 by a stand or the like. Therefore, the pump 20 is unnecessary, and the configuration can be simplified, and there are advantages that sterilization and the like are facilitated.

The discharge pressure of the pump 20 is generally set to 3 atm (0.3 MPa) or less. Moreover, when using an infusion bag, the altitude difference between the pulsation generator 100 and the top surface of the infusion bag is the pressure. When using an infusion bag, it is desirable to set the altitude difference so as to be about 0.1 to 0.15 atm (0.01 to 0.15 MPa).
In addition, when performing an operation using the fluid ejecting apparatus 1, the part grasped by the operator is the pulsation generator 100. Therefore, it is preferable that the connection tube 25 up to the pulsation generator 100 be as flexible as possible. For this purpose, it is preferable that the pressure is reduced within a range in which fluid can be sent to the pulsation generator 100 with a flexible and thin tube.
In particular, when there is a possibility that a failure of the device may cause a serious accident as in the case of brain surgery, it is necessary to avoid a high-pressure fluid from being ejected when the connection tube 25 is disconnected. Therefore, it is required to keep the pressure low.

Next, the structure of the pulsation generator 100 according to the present embodiment will be described.
2A and 2B are diagrams showing the structure of the pulsation generator 100 according to the present embodiment, where FIG. 2A is a cross-sectional view and FIG. 2B is an exploded view. 2A is a cross-sectional view taken along line AA ′ in FIG. 3 to be described later.
In FIG. 2, a pulsation generating unit 100 is connected to a connection flow channel pipe 200 that includes a pulsation generation unit that generates a pulsation of fluid and has a connection flow channel 201 as a flow channel for discharging fluid.
The pulsation generator 100 is joined to the upper case 500 and the lower case 301 on the opposing surfaces, and is screwed by four fixing screws (not shown). The lower case 301 is a cylindrical member having a flange, and one end is sealed with a bottom plate 311. A piezoelectric element 401 is disposed in the internal space of the lower case 301.

The piezoelectric element 401 is a laminated piezoelectric element and constitutes an actuator. One end of the piezoelectric element 401 is fixed to the diaphragm 400 via the upper plate 411, and the other end is fixed to the upper surface 312 of the bottom plate 311.
Diaphragm 400 is formed of a disk-shaped thin metal plate, and a peripheral edge thereof is closely fixed to the bottom surface of recess 303 in recess 303 of lower case 301. By inputting a drive signal to the piezoelectric element 401, the volume of the fluid chamber 501 is changed via the diaphragm 400 as the piezoelectric element 401 expands and contracts.
On the upper surface of the diaphragm 400, a reinforcing plate 410 made of a disk-shaped thin metal plate having an opening at the center is laminated.

The upper case 500 is formed with a concave portion at the center of the surface facing the lower case 301, and the fluid chamber 501 is formed of the concave portion and the diaphragm 400 and filled with fluid. That is, the fluid chamber 501 is a space surrounded by the sealing surface 505 of the recess of the upper case 500, the inner peripheral side wall 501 a, and the diaphragm 400. An outlet channel 511 is formed in a substantially central portion of the fluid chamber 501.
The outlet channel 511 is penetrated from the fluid chamber 501 to the end of the outlet channel pipe 510 projecting from one end face of the upper case 500. A connection portion between the outlet channel 511 and the sealing surface 505 of the fluid chamber 501 is smoothly rounded to reduce fluid resistance.

The shape of the fluid chamber 501 described above is a substantially cylindrical shape with both ends sealed in the present embodiment (see FIG. 2), but it may be conical, trapezoidal, hemispherical, or the like when viewed from the side. It is not limited well. For example, if the connecting portion between the outlet channel 511 and the sealing surface 505 is shaped like a funnel, bubbles in the fluid chamber 501 described later can be easily discharged.
A connection channel pipe 200 is connected to the outlet channel pipe 510. A connection channel 201 is perforated in the connection channel pipe 200, and the diameter of the connection channel 201 is larger than the diameter of the outlet channel 511. Further, the thickness of the pipe portion of the connection flow path pipe 200 is formed in a range having rigidity that does not absorb the pressure pulsation of the fluid.

A nozzle 211 is inserted into the distal end portion of the connection flow channel pipe 200. The nozzle 211 is formed with a fluid ejection opening 212. The diameter of the fluid ejection opening 212 is smaller than the diameter of the connection channel 201.
On the side surface of the upper case 500, an inlet channel tube 502 for inserting the connection tube 25 for supplying fluid from the pump 20 is projected, and the inlet channel tube 502 is provided with a connection channel 504 on the inlet channel side. I'm leaning. The connection channel 504 communicates with the inlet channel 503. The inlet channel 503 is formed in a groove shape on the peripheral edge of the sealing surface 505 of the fluid chamber 501 and communicates with the fluid chamber 501.

A packing box 304 is formed on the lower case 301 side, and a packing box 506 is formed on the upper case 500 side at positions separated from each other in the outer peripheral direction of the diaphragm 400 on the joint surface between the upper case 500 and the lower case 301. A ring-shaped packing 450 is mounted in a space formed by 304 and 506.
Here, when the upper case 500 and the lower case 301 are assembled, the peripheral portion of the diaphragm 400 and the peripheral portion of the reinforcing plate 410 are the peripheral portion of the sealing surface 505 of the upper case 500 and the concave portion 303 of the lower case 301. It is closely attached by the bottom. At this time, the packing 450 is pressed by the upper case 500 and the lower case 301 to prevent fluid leakage from the fluid chamber 501.

The fluid chamber 501 is in a high pressure state of 30 atm (3 MPa) or more when fluid is discharged, and the fluid may slightly leak at the joints of the diaphragm 400, the reinforcing plate 410, the upper case 500, and the lower case 301. However, the packing 450 prevents leakage.
When the packing 450 is disposed as shown in FIG. 2, the packing 450 is compressed by the pressure of the fluid leaking from the fluid chamber 501 at a high pressure, and is further pressed against the walls in the packing boxes 304 and 506. Leakage can be more reliably prevented. From this, a high pressure rise in the fluid chamber 501 can be maintained during driving.

Next, the inlet channel 503 formed in the upper case 500 will be described in more detail with reference to the drawings.
FIG. 3 is a plan view showing the form of the inlet channel 503, and shows a state in which the upper case 500 is viewed from the joint surface side with the lower case 301.
In FIG. 3, the inlet channel 503 is formed in a peripheral groove shape of the sealing surface 505 of the upper case 500.
The inlet channel 503 has one end communicating with the fluid chamber 501 and the other end communicating with the connection channel 504. A fluid reservoir 507 is formed at a connection portion between the inlet channel 503 and the connection channel 504. The connection between the fluid reservoir 507 and the inlet channel 503 is smoothly rounded to reduce the fluid resistance.

In addition, the inlet channel 503 communicates with the inner peripheral side wall 501a of the fluid chamber 501 in a substantially tangential direction. The fluid supplied at a constant pressure from the pump 20 (see FIG. 1) flows along the inner peripheral wall 501a (in the direction indicated by the arrow in the figure) to generate a swirling flow in the fluid chamber 501. The swirling flow is pressed against the inner peripheral side wall 501a by the centrifugal force caused by swirling, and the bubbles contained in the fluid chamber 501 are concentrated at the center of the swirling flow.
Then, the bubbles collected at the center are excluded from the outlet channel 511. For this reason, it is more preferable that the outlet channel 511 is provided in the vicinity of the center of the swirling flow, that is, in the axial center portion of the rotating body. Therefore, in the present embodiment, the inlet flow path 503 is a swirl flow generator. In FIG. 3, the planar shape of the inlet channel 503 is curved. The inlet channel 503 may be communicated with the fluid chamber 501 in a straight line, but is curved from the necessity of increasing the channel length of the inlet channel 503 in order to obtain a desired inertance in a narrow space. .

  In addition, as shown in FIG. 2, the reinforcement board 410 is arrange | positioned between the diaphragm 400 and the peripheral part of the sealing surface 505 in which the inlet flow path 503 is formed. The meaning of providing the reinforcing plate 410 is to improve the durability of the diaphragm 400. Since the notch-like connection opening 509 is formed in the connection portion of the inlet channel 503 with the fluid chamber 501, stress concentration occurs in the vicinity of the connection opening 509 when the diaphragm 400 is driven at a high frequency. May cause fatigue failure. Therefore, by providing the reinforcing plate 410 having a continuous opening without a notch, stress concentration does not occur in the diaphragm 400.

Further, four screw holes 500a are formed at the outer peripheral corner of the upper case 500, and the upper case 500 and the lower case 301 are screwed and joined at the screw hole positions.
Although illustration is omitted, the reinforcing plate 410 and the diaphragm 400 can be joined and integrally laminated and fixed. As an adhering means, solid layer diffusion bonding, welding, or the like can be adopted even when sticking using an adhesive, but the reinforcing plate 410 and the diaphragm 400 are more closely attached to each other at the joining surface. preferable.

(Functional configuration of control system)
Next, the functional configuration of the control system of the fluid ejection device 1 will be described.
In this embodiment, when a drive signal is input to the piezoelectric element 401 in order to discharge the fluid from the pulsation generating unit 100, the control unit 30 gradually increases the output of the piezoelectric element 401 from the start of fluid discharge and sets Control is performed so that the output is constant after the elapse of time.
Specifically, in the process of inputting the drive signal to the piezoelectric element 401, the fluid is discharged at a constant discharge pressure following the output increase period in which the fluid discharge pressure is increased from the fluid discharge start time and the output increase period. And an output stabilization period.

FIG. 4 is a functional configuration diagram illustrating a control system of the fluid ejecting apparatus 1.
In FIG. 4, the control system of the liquid ejection apparatus 1 includes a waveform storage unit 31, a signal control unit 32, and a voltage amplifier 33.
The waveform storage unit 31 stores various voltage pulse waveforms representing the drive signal of the piezoelectric element (however, the original signal before amplification).

FIG. 5 is a schematic diagram illustrating a specific example of a voltage pulse waveform stored in the waveform storage unit 31. The waveform storage unit 31 stores the voltage pulse waveform as a digital value. However, in FIG. 5, the voltage pulse waveform is shown in an analog format for convenience of explanation. Further, here, as the voltage pulse waveform, a sine wave that amplitudes from the negative electrode to the positive electrode is shown as an example.
As shown in FIG. 5, the waveform storage unit 31 includes a plurality of voltage pulse waveforms (hereinafter referred to as “initial voltage pulses”) whose amplitudes are changed stepwise from a small amplitude to a large amplitude in time series of the output increase period. And a single voltage pulse waveform corresponding to the output stabilization period (hereinafter referred to as “steady voltage pulse waveform”). The amplitude of the initial voltage pulse waveform group is set so as to increase stepwise from a small value, and the maximum value is set to a value smaller by one step than the amplitude of the steady voltage pulse waveform.

As described above, the voltage pulse waveform shown in FIG. 5 is a schematic diagram. In the storage area of the waveform storage unit 31, each of the initial voltage pulse waveform groups shown in FIG. The voltage value indicating the voltage pulse waveform and the voltage value indicating the steady voltage pulse waveform during the output stabilization period are stored as digital values for each predetermined time (sampling interval).
By storing the voltage pulse waveform as a digital value in the waveform storage unit 31, the characteristics of the initial voltage pulse waveform group (how to change the amplitude, applied frequency, etc.) can be easily changed by rewriting the stored contents. can do.

The signal control unit 32 has a function of controlling the entire fluid ejection device 1. Specifically, the signal control unit 32 executes a discharge control process to be described later, and when a discharge start signal instructing the start of fluid discharge is input from a foot switch (not shown) or the like, within the output increase period from the discharge start. The discharge pressure is gradually increased, and after the output increase period has elapsed, discharge control is performed to maintain a constant discharge pressure when the output stabilization period is reached.
Specifically, when the ejection start signal is input, the signal control unit 32 reads out each voltage pulse waveform of the initial voltage pulse waveform group and the steady voltage pulse waveform from the waveform storage unit 31. Then, a digital signal (original signal before amplification) indicating each read voltage pulse waveform is output to the voltage amplifier 33 in the set time series order.

That is, the signal control unit 32 outputs each voltage pulse waveform of the initial voltage pulse waveform group to the voltage amplifier 33 in descending order of amplitude at the start of fluid discharge, and subsequently outputs the steady voltage pulse waveform to the voltage amplifier 33. Output to. Thereafter, the signal control unit 32 repeatedly outputs a steady voltage pulse waveform to the voltage amplifier 33 while the ejection start signal is input.
The discharge start signal is a signal that is input by an operator operating a switch in order to start fluid ejection from the fluid ejection device 1 when performing incision or the like of a target site.
The voltage amplifier 33 is configured by, for example, an amplifier including a push-pull circuit, converts a digital signal having a voltage pulse waveform input from the signal control unit 32 into an analog signal, amplifies the analog signal, and outputs the piezoelectric of the pulsation generation unit 100. Applied to the element 401.

(Operation)
Next, the operation in this embodiment will be described.
(Control operation of fluid ejecting apparatus 1)
FIG. 6 is a flowchart showing the discharge control process executed by the signal control unit 32.
The discharge control process is started when the fluid ejection device 1 is turned on, and is repeatedly executed while the power is turned on.
In FIG. 6, when the discharge control process is started, the signal control unit 32 determines whether or not the discharge start signal is input (step S1), and determines that the discharge start signal is not input. The process of step S1 is repeated.

On the other hand, when it is determined in step S1 that the ejection start signal is input, the signal control unit 32 sets “1” as an initial value (i = 1) to the parameter i indicating the order of the voltage pulse waveform (i = 1) ( Step S2).
Next, the signal control unit 32 reads the i-th voltage pulse waveform in the time series from the initial voltage pulse waveform group stored in the waveform storage unit 31 (step S3).
Then, the signal control unit 32 outputs a digital signal indicating the read voltage pulse waveform to the voltage amplifier 33 (step S4).

Further, the signal control unit 32 determines whether or not the parameter i matches the number imax of voltage pulse waveforms included in the initial voltage pulse waveform group (step S5). That is, in step S5, it is determined whether or not all voltage pulse waveforms of the initial voltage pulse waveform group have been output.
If it is determined in step S5 that the parameter i does not match imax, the signal control unit 32 increments the parameter i by “1” (i = i + 1) (step S6), and the process proceeds to step S3. .
On the other hand, if it is determined in step S5 that the parameter i matches imax, the signal control unit 32 reads the steady voltage pulse waveform stored in the waveform storage unit 31 (step S7), and reads the read steady voltage pulse. A digital signal indicating the waveform is output to the voltage amplifier 33 (step S8).

Next, the signal control unit 32 determines whether or not the input of the discharge start signal is stopped (step S9), and when it is determined that the input of the discharge start signal is not stopped, the signal control unit 32 When the process proceeds to S8 and it is determined that the input of the discharge start signal is stopped, the discharge control process is repeated.
By executing the discharge control process, the fluid can be discharged at a low discharge pressure immediately after the start of discharge, and the discharge pressure can be gradually increased to a predetermined discharge pressure.

(Operation of fluid ejecting apparatus 1 as a whole)
Next, the overall operation of the fluid ejection device 1 when the above control operation is performed will be described.
The fluid discharge of the pulsation generating unit 100 of the present embodiment is performed by the difference between the inertance L1 on the inlet channel side (sometimes referred to as the synthetic inertance L1) and the inertance L2 on the outlet channel side (sometimes referred to as the synthetic inertance L2). Is called.
First, inertance will be described.
The inertance L is expressed by L = ρ × h / S, where ρ is the density of the fluid, S is the cross-sectional area of the flow path, and h is the length of the flow path. When the pressure difference in the flow path is ΔP and the flow rate of the fluid flowing through the flow path is Q, the relationship of ΔP = L × dQ / dt is derived by modifying the equation of motion in the flow path using the inertance L. It is.

That is, the inertance L indicates the degree of influence on the time change of the flow rate. The larger the inertance L, the less the time change of the flow rate, and the smaller the inertance L, the greater the time change of the flow rate.
In addition, the combined inertance related to the parallel connection of a plurality of flow paths and the series connection of a plurality of flow paths having different shapes is obtained by combining the inertance of individual flow paths in the same way as the parallel connection or series connection of inductances in an electric circuit. Can be calculated.
The inertance L1 on the inlet flow path side is calculated in the range of the inlet flow path 503 because the connection flow path 504 is set to have a sufficiently large diameter with respect to the inlet flow path 503. At this time, since the connection tube connecting the pump 20 and the inlet channel has flexibility, it may be deleted from the calculation of the inertance L1.

Further, the inertance L2 on the outlet flow channel side has a much larger diameter of the connection flow channel 201 than the outlet flow channel, and the pipe portion (tube wall) of the connection flow channel pipe 200 has a small thickness. Minor. Therefore, the inertance L2 on the outlet channel side may be replaced with the inertance of the outlet channel 511.
Note that the thickness of the pipe wall of the connection flow path pipe 200 has sufficient rigidity for the pressure propagation of the fluid.
In this embodiment, the flow path length and cross-sectional area of the inlet flow path 503 and the flow path length and cross-sectional area of the outlet flow path 511 are such that the inertance L1 on the inlet flow path side is larger than the inertance L2 on the outlet flow path side. Set.

Next, the operation of the pulsation generator 100 will be described.
The fluid is always supplied to the inlet channel 503 by the pump 20 at a constant hydraulic pressure. As a result, when the piezoelectric element 401 does not operate, the fluid flows into the fluid chamber 501 due to the difference between the discharge force of the pump 20 and the fluid resistance value of the entire inlet channel side.
Here, it is assumed that a discharge start signal is input to the control unit 30 by an operation of a foot switch or the like.
At this time, the voltage pulse waveform of the initial voltage pulse waveform group is sequentially read from the waveform storage unit 31 by the signal control unit 32 that executes the discharge control process, and is applied to the piezoelectric element 401 through the voltage amplifier 33.

As a result, during the output increase period, voltage pulse waveforms whose amplitudes are gradually changed from a small amplitude to a large amplitude are sequentially applied to the piezoelectric element 401.
Subsequently, the steady voltage pulse waveform is read from the waveform storage unit 31 by the signal control unit 32 and repeatedly applied to the piezoelectric element 401 through the voltage amplifier 33.
When these voltage pulse waveforms are input to the piezoelectric element 401 and the piezoelectric element 401 expands suddenly, the pressure in the fluid chamber 501 is such that the inertances L1 and L2 on the inlet channel side and the outlet channel side are sufficiently large. If it has, it will rise rapidly and reach several tens of atmospheres.

Since this pressure is much larger than the pressure by the pump 20 applied to the inlet channel 503, the inflow of fluid from the inlet channel side into the fluid chamber 501 is reduced by the pressure, and the outflow from the outlet channel 511. Will increase. Therefore, the check valve provided on the inlet channel side as in the fluid ejecting apparatus according to Patent Document 1 described above is not necessary.
However, since the inertance L1 of the inlet channel 503 is larger than the inertance L2 of the outlet channel 511, the inertance L1 is discharged from the outlet channel more than the reduction amount of the flow rate of fluid flowing from the inlet channel 503 into the fluid chamber 501. Since the increase amount of the fluid is larger, a pulsed fluid discharge, that is, a pulsating flow is generated in the connection channel 201. The pressure fluctuation at the time of discharge propagates through the connection flow channel pipe 200, and the fluid is ejected from the fluid ejection opening 212 of the nozzle 211 at the tip.

Here, since the diameter of the fluid ejection opening 212 of the nozzle 211 is smaller than the diameter of the outlet channel 511, the fluid is ejected as a high-pressure, high-speed pulsed droplet.
On the other hand, the inside of the fluid chamber 501 is in a vacuum state immediately after the pressure rises due to the interaction between the decrease in the fluid inflow amount from the inlet channel 503 and the increase in the fluid outflow from the outlet channel 511. As a result, after a predetermined time has elapsed due to both the pressure of the pump 20 and the vacuum state in the fluid chamber 501, the fluid in the inlet channel 503 flows toward the fluid chamber 501 at the same speed as before the operation of the piezoelectric element 401. Return.
After the fluid flow in the inlet channel 503 is restored, the pulsating flow from the nozzle 211 can be continuously ejected if the piezoelectric element 401 expands.

Next, the operation for removing bubbles in the fluid chamber 501 will be described.
In the operation of the pulsation generating unit 100 described above, the fluid chamber 501 has a substantially rotating body shape and includes an inlet channel 503 as a swirl flow generating unit, and the outlet channel 511 rotates in a substantially rotating body shape. Since it is established in the vicinity of the shaft, a swirling flow is generated in the fluid chamber 501, and the bubbles contained in the fluid are quickly discharged from the outlet channel 511 to the outside.
Therefore, even in a minute volume change of the fluid chamber 501 by the piezoelectric element 401, a sufficient pressure increase can be obtained without hindering the pressure fluctuation by the bubbles.

Therefore, according to the first embodiment described above, the fluid is supplied to the inlet flow path 503 by the pump 20 at a constant pressure, and therefore, the inlet flow path 503 and the fluid chamber 501 are placed in the state where the driving of the pulsation generator 100 is stopped. Since the fluid is supplied, the initial operation can be started without performing the priming operation.
In addition, since the fluid is ejected from the fluid ejection opening 212 that is smaller than the diameter of the outlet channel 511, the fluid pressure is higher than that in the outlet channel 511, thereby enabling high-speed fluid ejection.
Furthermore, since the connecting flow channel pipe 200 has rigidity capable of transmitting the pulsation of the fluid flowing from the fluid chamber 501 to the fluid ejection opening 212, the pressure propagation of the fluid from the pulsation generating unit 100 is not hindered. The desired pulsating flow can be injected.

Further, since the inertance of the inlet channel 503 is set to be larger than the inertance of the outlet channel 511, the increase in the outflow amount is larger than the decrease in the inflow amount of fluid from the inlet channel 503 to the fluid chamber 501. It is generated in the outlet channel 511, and pulsed fluid can be discharged into the connection channel tube 200. Therefore, it is not necessary to provide a check valve on the inlet flow path 503 side as in Patent Document 1 described above, the structure of the pulsation generating unit 100 can be simplified, the inside can be easily cleaned, and the check valve There is an effect that durability anxiety caused by using can be eliminated.
If the volume of the fluid chamber 501 is rapidly reduced by setting the inertance of both the inlet channel 503 and the outlet channel 511 sufficiently large, the pressure in the fluid chamber 501 can be rapidly increased.

Further, by adopting a structure in which the piezoelectric element 401 and the diaphragm 400 are employed as the volume changing means, the structure can be simplified and the size can be reduced accordingly. Moreover, the maximum frequency of volume change of the fluid chamber 501 can be set to a high frequency of 1 KHz or more, which is optimal for high-speed pulsating flow injection.
Further, by generating a swirling flow in the fluid in the fluid chamber 501 by the swirling flow generating portion, the fluid is pushed in the outer peripheral direction of the fluid chamber by centrifugal force, and the center portion of the swirling flow, that is, a shaft having a substantially rotating body shape. Air bubbles contained in the fluid are concentrated in the vicinity, and the air bubbles can be eliminated from the outlet channel 511 provided in the vicinity of the substantially rotating body-shaped shaft. From this, it is possible to prevent the pressure amplitude from decreasing due to the bubbles remaining in the fluid chamber 501, and to continue the stable driving of the pulsation generator 100.

Furthermore, since the swirl flow generating part is formed by the inlet flow path 503, the swirl flow can be generated without using a dedicated swirl flow generating part.
In addition, since the groove-shaped inlet channel 503 is formed at the outer peripheral edge of the sealing surface 505 of the fluid chamber 501, the inlet channel 503 as a swirl flow generating unit can be formed without increasing the number of components. Can do.
In addition, since the diaphragm 400 is provided on the upper surface of the diaphragm 400, the diaphragm 400 is driven using the outer periphery of the opening of the reinforcement plate 410 as a fulcrum, so that stress concentration hardly occurs and the durability of the diaphragm 400 is improved. Can do.

If the corners of the joint surface of the reinforcing plate 410 with the diaphragm 400 are rounded, the stress concentration of the diaphragm 400 can be further reduced.
Further, if the reinforcing plate 410 and the diaphragm 400 are laminated and fixed together, the assemblability of the pulsation generating unit 100 can be improved and the outer peripheral edge of the diaphragm 400 can be reinforced.
In addition, since the fluid reservoir 507 for retaining fluid is provided at the connection portion between the inlet-side connection flow path 504 and the inlet flow path 503 for supplying fluid from the pump 20, the inertance of the connection flow path 504 causes the inlet flow to flow. The influence on the path 503 can be suppressed.

Furthermore, since the ring-shaped packing 450 is provided at a position spaced apart in the outer peripheral direction of the diaphragm 400 on the joint surface between the upper case 500 and the lower case 301, fluid leakage from the fluid chamber 501 is prevented, and the fluid chamber It is possible to prevent a pressure drop in the 501.
As described above, the fluid ejection device 1 according to this embodiment includes the waveform storage unit 31 that stores the initial voltage pulse waveform group and the steady voltage pulse waveform. When the fluid is discharged, the voltage pulse waveform of the initial voltage pulse waveform group is sequentially applied to the piezoelectric element 401 during the output increase period, and then the steady voltage pulse waveform is repeatedly applied to the piezoelectric element 401 during the output stabilization period. The

Therefore, when the fluid is discharged, the discharge pressure gradually changes from a low discharge pressure to a high discharge pressure, so that a situation where the depth of incision or excision increases at the start of discharge can be prevented.
That is, according to the present invention, it is possible to prevent a situation in which the depth of incision or excision increases at the start of ejection in a fluid ejecting apparatus that incises or excises a target site by ejecting fluid.
In the present embodiment, the voltage pulse waveform has been described as a sine wave that swings from the negative electrode to the positive electrode. However, the specific form of the voltage pulse waveform may be other than a sine wave.

FIG. 7 is a schematic diagram showing a case where an impulse waveform (for example, a waveform obtained by cutting out the positive side of a sine wave) whose amplitude gradually increases is used as an initial voltage pulse waveform group.
As shown in FIG. 7, the fluid discharge pressure can be gradually increased in the output increase period by gradually increasing the amplitude of the impulse waveform applied as the voltage pulse waveform.

(Application 1)
In the first embodiment, as the initial voltage pulse waveform group, a plurality of voltage pulse waveforms whose amplitudes are gradually changed from a small amplitude to a large amplitude are applied to the piezoelectric element 401 in time series of the output increase period. However, the characteristics to be changed in the voltage pulse waveform can be other than the amplitude.
FIG. 8 is a schematic diagram showing a case where a triangular wave whose slew rate gradually increases is an initial voltage pulse waveform group.

Here, the slew rate is defined as the slope of the voltage in the voltage waveform with time on the horizontal axis and voltage on the vertical axis.
In FIG. 8, each triangular wave has a waveform that amplitudes in the order from the negative electrode to the positive electrode, and a voltage change region (hereinafter referred to as “extension portion”) from the maximum amplitude of the negative electrode to the maximum amplitude of the positive electrode. 401 is an area where the volume of the fluid chamber 501 is reduced.
In the first application example, in the voltage pulse waveform applied during the output increase period, the slew rate (slope) of the expansion portion increases in order from the first wave.

FIG. 9 is a schematic diagram showing a case where an impulse waveform having a gradually increasing slew rate is used as an initial voltage pulse waveform group.
As shown in FIG. 9, the slew rate of the expansion portion can be gradually increased in the case of an impulse waveform in addition to the triangular wave.
In this way, the fluid discharge pressure can be gradually increased by gradually increasing the slew rate of the voltage pulse waveform.

(Application example 2)
Further, the characteristic to be changed in the voltage pulse waveform during the output increase period can be a frequency in addition to the amplitude and the slew rate.
FIG. 10 is a schematic diagram showing a case where a triangular wave with a gradually increasing frequency is used as an initial voltage pulse waveform group.
In FIG. 10, each triangular wave has a waveform that amplitudes in the order from the negative electrode to the positive electrode, and the frequency of the voltage pulse waveform applied during the output increase period increases in order from the first wave.
Thus, the fluid discharge pressure can be gradually increased by gradually increasing the frequency of the voltage pulse waveform.

(Application 3)
When a flat signal portion is inserted between a plurality of voltage pulse waveforms applied in the output increase period, the fluid discharge pressure can be gradually increased by gradually reducing the period of the flat signal portion. .
FIG. 11 is a schematic diagram showing an initial voltage pulse waveform group having a flat signal portion between impulse waveforms.
In FIG. 11, the voltage pulse waveforms in the output increase period are the same, and the period of the flat signal portion between the voltage pulse waveforms gradually decreases.
FIG. 12 is a diagram showing an initial voltage pulse waveform group having a plurality of trapezoidal waves that swing in order from the negative electrode to the positive electrode and a flat signal portion between the voltage pulse waveforms.

In the case of the waveform shown in FIG. 12 in addition to the case of the impulse waveform, the discharge pressure of the fluid can be gradually increased by reducing the period of the flat portion between the voltage pulse waveforms.
As shown in FIGS. 11 and 12, when the same voltage pulse waveform is applied while reducing the interval, there is a method in which waveforms having different lengths of flat signal portions are stored in the waveform memory 31 and sequentially read out. The waveform storage 31 may store one voltage pulse waveform, and the signal control unit 32 may repeatedly apply the same voltage pulse waveform while counting the time and controlling the application interval.
As described above, even when the same voltage pulse waveform is repeatedly applied, the discharge pressure of the fluid can be gradually increased by applying the voltage pulse waveform while gradually decreasing the interval between the voltage pulse waveforms.

It is explanatory drawing which shows schematic structure of the fluid injection apparatus 1 which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the pulsation generation | occurrence | production part 100 which concerns on this embodiment. It is a top view which shows the form of the inlet channel 503. FIG. 2 is a functional configuration diagram illustrating a control system of the fluid ejection device 1. FIG. It is a schematic diagram which shows the specific example of the voltage pulse waveform which the waveform memory | storage part 31 has memorize | stored. 4 is a flowchart illustrating a discharge control process executed by a signal control unit 32. It is a schematic diagram which shows the case where the impulse waveform which an amplitude becomes large gradually is made into the initial voltage pulse waveform group. It is a schematic diagram which shows the case where the triangular wave from which a slew rate becomes high gradually is made into the initial voltage pulse waveform group. It is a schematic diagram which shows the case where the impulse waveform which a slew rate becomes high gradually is made into the initial voltage pulse waveform group. It is a schematic diagram which shows the case where the triangular wave whose frequency becomes high gradually is made into the initial voltage pulse waveform group. It is a schematic diagram showing an initial voltage pulse waveform group having a flat signal portion between impulse waveforms. It is a figure which shows the initial voltage pulse waveform group which has a some trapezoid wave which amplitudes in order of a negative electrode to a positive electrode, and a flat signal part between each voltage pulse waveform.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid injection apparatus, 10 Fluid container, 15, 25 Connection tube, 20 Pump, 30 Control part, 31 Waveform memory part, 32 Signal control part, 33 Voltage amplifier, 100 Pulsation generation part, 200 Connection flow path pipe, 201 Connection flow Path, 211 nozzle, 212 fluid ejection opening, 401 piezoelectric element, 501 fluid chamber, 503 inlet channel, 511 outlet channel

Claims (8)

A pulsation generator having a fluid chamber into which fluid flows, a volume changing unit having a pressure generating element that changes the volume of the fluid chamber by a drive signal, and an inlet channel and an outlet channel communicating with the fluid chamber When,
A fluid ejection port for ejecting fluid that has flowed out of the outlet channel;
Fluid supply means for supplying fluid to the inlet channel;
Control means for applying a drive signal to the pressure generating element and controlling the change of the volume of the fluid chamber by the volume changing means;
With
The fluid ejecting apparatus according to claim 1, wherein the control means increases the fluid ejection pressure stepwise after the fluid ejection is started. Waveform storage means for storing a plurality of waveforms of the drive signals that have different fluid discharge pressures,
The said control means reads the waveform of the said some drive signal memorize | stored in the said waveform memory | storage means in an order from the thing from which the discharge pressure of a fluid differs, and applies it to the said pressure generating element. Fluid ejection device.   3. The fluid ejecting apparatus according to claim 1, wherein the control unit applies waveforms having different amplitudes of the drive signal to the pressure generating element in order from a waveform having a smaller amplitude. 4.   3. The fluid ejecting apparatus according to claim 1, wherein the control unit applies waveforms having different slew rates of the drive signals to the pressure generating elements in order from a waveform having a smaller slew rate.   The fluid ejecting apparatus according to claim 1, wherein the control unit applies a waveform in which a frequency of the driving signal increases with time to the pressure generating element.   3. The fluid ejecting apparatus according to claim 1, wherein the control unit reduces the interval between the waveforms of the drive signals with the passage of time and applies it to the pressure generating element. A pulsation generator having a fluid chamber into which fluid flows, a volume changing unit having a pressure generating element that changes the volume of the fluid chamber by a drive signal, and an inlet channel and an outlet channel communicating with the fluid chamber When,
A fluid ejection port for ejecting fluid that has flowed out of the outlet channel;
Fluid supply means for supplying fluid to the inlet channel;
Control means for applying a drive signal to the pressure generating element and controlling the change of the volume of the fluid chamber by the volume changing means;
A control method of a fluid ejection device comprising:
A control method for a fluid ejecting apparatus, comprising: an output increasing step for gradually increasing a fluid discharge pressure after the start of fluid discharge. A pulsation generator having a fluid chamber into which fluid flows, a volume changing unit having a pressure generating element that changes the volume of the fluid chamber by a drive signal, and an inlet channel and an outlet channel communicating with the fluid chamber When,
A fluid ejection port for ejecting fluid that has flowed out of the outlet channel;
Fluid supply means for supplying fluid to the inlet channel;
Control means for applying a drive signal to the pressure generating element and controlling the change of the volume of the fluid chamber by the volume changing means;
With
The operating device is characterized in that the control means increases the fluid discharge pressure stepwise after the start of fluid discharge.

Images