U.S. patent application number 12/606470 was filed with the patent office on 2010-05-06 for fluid ejection system, fluid ejection system drive method, and surgical apparatus.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Kazuo KAWASUMI, Shinichi MIYAZAKI, Takeshi SETO, Kunio TABATA.
Application Number | 20100111708 12/606470 |
Document ID | / |
Family ID | 42131611 |
Filed Date | 2010-05-06 |
United States Patent
Application |
20100111708 |
Kind Code |
A1 |
SETO; Takeshi ; et
al. |
May 6, 2010 |
FLUID EJECTION SYSTEM, FLUID EJECTION SYSTEM DRIVE METHOD, AND
SURGICAL APPARATUS
Abstract
A fluid ejection system includes: a pulsation generation section
which, including a fluid chamber, a diaphragm which changes a
volume of the fluid chamber, and a piezoelectric element which
drives the diaphragm, pulsatively ejects a fluid from a nozzle; and
a control apparatus including a pressure generation section which
supplies the fluid to the fluid chamber at a predetermined
pressure, a drive waveform generation section which inputs a drive
waveform into the piezoelectric element, and a load detection
section which detects a load of the pressure generation section,
wherein in the event that the load detection section has detected a
load abnormality of the pressure generation section, a fluid
discharge pressure amplitude of the pulsation generation section or
a fluid supply pressure of the pressure generation section is made
higher than at a normal drive time.
Inventors: |
SETO; Takeshi; (Chofu-shi,
JP) ; KAWASUMI; Kazuo; (Chino-shi, JP) ;
TABATA; Kunio; (Shiojiri-shi, JP) ; MIYAZAKI;
Shinichi; (Suwa-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
SEIKO EPSON CORPORATION
Tokyo
JP
|
Family ID: |
42131611 |
Appl. No.: |
12/606470 |
Filed: |
October 27, 2009 |
Current U.S.
Class: |
417/44.1 |
Current CPC
Class: |
A61B 17/3203 20130101;
F04B 43/046 20130101 |
Class at
Publication: |
417/44.1 |
International
Class: |
F04B 49/06 20060101
F04B049/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2008 |
JP |
2008-279336 |
Claims
1. A fluid ejection system comprising: a pulsation generation
section which, including a fluid chamber, a diaphragm which changes
a volume of the fluid chamber, and a piezoelectric element which
drives the diaphragm, pulsatively ejects a fluid from a nozzle; and
a control apparatus including a pressure generation section which
supplies the fluid to the fluid chamber at a predetermined
pressure, a drive waveform generation section which inputs a drive
waveform into the piezoelectric element, and a load detection
section which detects a load of the pressure generation section,
wherein in the event that the load detection section has detected a
load abnormality of the pressure generation section, a fluid
discharge pressure amplitude of the pulsation generation section or
a fluid supply pressure of the pressure generation section is made
higher than at a normal drive time.
2. The fluid ejection system according to claim 1, wherein the
drive waveform is configured of a pulsation portion and a quiescent
portion, and in the event that the load detection section has
detected a load abnormality of the pressure generation section, the
amplitude of the pulsation portion is made larger than the
amplitude at the normal drive time.
3. The fluid ejection system according to claim 1, wherein the
drive waveform input in the event that the load detection section
has detected a load abnormality of the pressure generation section
is configured of a continuous pulsation portion.
4. The fluid ejection system according to claim 1, wherein a
frequency of the drive waveform input in the event that the load
detection section has detected a load abnormality of the pressure
generation section approximately matches a resonant frequency of a
pressure wave propagated through a space from the fluid chamber to
the nozzle.
5. The fluid ejection system according to claim 2, wherein in the
event that the load detection section has detected a load
abnormality of the pressure generation section, the amplitude of
the pulsation portion is made larger than the amplitude at the
normal drive time, and the pressure at which the pressure
generation section supplies the fluid to the fluid chamber is made
higher than that at the normal drive time.
6. The fluid ejection system according to claim 1, wherein the load
detection section detects a load of the pressure generation section
as a change in a drive speed of a fluid delivery device of the
pressure generation section.
7. The fluid ejection system according to claim 6, wherein the load
detection section, in the event that the drive speed has become
equal to or less than a prescribed value, determines that there is
a load abnormality of the pressure generation section.
8. The fluid ejection system according to claim 1, wherein the load
detection section is a pressure sensor provided inside the pressure
generation section.
9. The fluid ejection system according to claim 1, further
comprising: an alarm which, in the event that the load detection
section has detected a load abnormality of the pressure generation
section, informs of the abnormality.
10. The fluid ejection system according to claim 1, wherein in the
event that the load detection section has detected a load
abnormality of the pressure generation section, the drive of the
pulsation generation section and pressure generation section is
stopped.
11. The fluid ejection system according to claim 1, further
comprising: an operating member which, after the load detection
section has detected a load abnormality of the pressure generation
section, and the drive of the pulsation generation section and
pressure generation section has been stopped, switches in such a
way as to make the fluid discharge pressure of the pulsation
generation section or the fluid supply pressure of the pressure
generation section higher than at the normal drive time.
12. The fluid ejection system according to claim 11, wherein the
operating member is provided on the pulsation generation
section.
13. The fluid ejection system according to claim 1, wherein in an
idle period of the pulsation generation section, the drive waveform
is configured of a combination of a midpoint potential, at which
the piezoelectric element is charged to the extent that the fluid
is moved to a position in which it reaches the leading extremity of
the nozzle, and a potential at which the piezoelectric element is
discharged.
14. A method of driving a fluid ejection system including: a
pulsation generation section which, including a fluid chamber, a
diaphragm which changes a volume of the fluid chamber, and a
piezoelectric element which drives the diaphragm, pulsatively
ejects a fluid from a nozzle; and a control apparatus including a
pressure generation section which supplies the fluid to the fluid
chamber at a predetermined pressure, a drive waveform generation
section which inputs a drive waveform into the piezoelectric
element, and a load detection section which detects a load of the
pressure generation section, the method comprising: a step of,
during a normal drive of the fluid ejection system, detecting a
load of the pressure generation section, which supplies the fluid
to the pulsation generation section at the predetermined pressure,
by means of the load detection section; a step of outputting an
alarm in the event that the load of the pressure generation section
has become equal to or more than a prescribed value; a step of
stopping the drive of the pulsation generation section and pressure
generation section; a cleaning step in which a fluid discharge
pressure of the pulsation generation section or a fluid supply
pressure of the pressure generation section is made higher than at
a normal drive time; and a step of restoring the normal drive after
finishing the cleaning step.
15. A surgical apparatus comprising the fluid ejection system
according to claim 1.
Description
[0001] Japanese Patent Application No. 2008-279336 filed on Oct.
30, 2008, is hereby incorporated by reference in its entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a fluid ejection system
including a fluid ejection apparatus and a control apparatus which
carries out a control of the fluid ejection apparatus, a method of
driving the fluid ejection system, and a surgical apparatus using
the fluid ejection system and its drive method.
[0004] 2. Related Art
[0005] With a surgery using an ejected fluid, it is possible to
incise an organ parenchyma while saving a vasculature of a blood
vessel or the like. Furthermore, as an incidental damage to a body
tissue other than an incision site is light, a burden on a patient
is low. Also, as there is little bleeding, the bleeding does not
hinder a vision of a surgical field, thus enabling a rapid surgery,
which is clinically applied particularly to a hepatic resection or
the like which is hindered by bleeding from microvessels.
[0006] As a fluid ejection apparatus which incises or excises a
body tissue, one has been known which, by changing the volume of a
fluid chamber by means of a diaphragm, discharges a fluid from a
nozzle as high-speed droplets in a pulse form (refer to, for
example, JP-A-2005-152127).
[0007] When incising or excising a body tissue using this kind of
fluid ejection apparatus, it is conceivable that the leading
extremity of the nozzle comes into contact with a body tissue,
blood, and a body fluid, and it is expected that these will cause a
nozzle leading extremity clogging.
[0008] Also, as the diameter of a fluid ejection opening is
extremely small at around 0.1 to 0.2 mm, and the diameter of an
outlet channel communicating with the nozzle from the fluid chamber
is also extremely small at around 0.3 mm, it is also conceivable
that a clogging occurs in a channel from the fluid chamber to the
nozzle.
SUMMARY
[0009] An advantage of some aspect of the invention is to solve at
least a part of the problem described above and the invention can
be realized as the following aspects or application examples.
Application Example 1
[0010] A fluid ejection system includes a pulsation generation
section which, including a fluid chamber, a diaphragm which changes
a volume of the fluid chamber, and a piezoelectric element which
drives the diaphragm, pulsatively ejects a fluid from a nozzle; and
a control apparatus including a pressure generation section which
supplies the fluid to the fluid chamber at a predetermined
pressure, a drive waveform generation section which inputs a drive
waveform into the piezoelectric element, and a load detection
section which detects a load of the pressure generation section. In
the event that the load detection section has detected a load
abnormality of the pressure generation section, a fluid discharge
pressure amplitude of the pulsation generation section or a fluid
supply pressure of the pressure generation section is made higher
than at a normal drive time.
[0011] The normal drive time means a drive status when actually
using the fluid ejection system.
[0012] In the event that the pulsation generation section is driven
normally (in conformity to a design value), the load of the
pressure generation section falls within an approximately constant
range. Herein, in the event that a clogging or the like occurs in a
channel from the fluid chamber to the nozzle, the load of the
pressure generation section increases.
[0013] According to this application example, by detecting that the
load of the pressure generation section has increased (a load
abnormality), it is determined that the heretofore described
clogging has occurred. Therein, it is possible to eliminate the
clogging by making the fluid discharge pressure amplitude of the
pulsation generation section higher than at the normal drive time,
and clean the channel from the fluid chamber to the nozzle.
[0014] Also, it is also possible to eliminate the clogging by
making the fluid supply pressure of the pressure generation section
higher.
Application Example 2
[0015] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that the drive
waveform is configured of a pulsation portion and a quiescent
portion, and that, in the event that the load detection section has
detected a load abnormality of the pressure generation section, the
amplitude of the pulsation portion is made larger than the
amplitude at the normal drive time.
[0016] In the event that the drive waveform is configured of the
pulsation portion formed of a whole number of sequential waveforms,
and the quiescent portion in which no waveform is output, by
appropriately selecting an amplitude (a potential) and frequency of
the pulsation portion, an ejection of a fluid group forms a
pulsation necessary for an excision capability. Also, a quiescent
time enables a control of a flow rate.
[0017] Therein, in the event that a load abnormality of the
pressure generation section has been detected, it being possible to
increase an amount of displacement of a diaphragm by making the
amplitude of the pulsation portion still larger than the amplitude
at the normal drive time, and make the fluid discharge pressure
amplitude higher than at the normal drive time by increasing an
amount of a volume contraction of the fluid chamber, it is possible
to eliminate the clogging.
Application Example 3
[0018] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that the drive
waveform input in the event that the load detection section has
detected a load abnormality of the pressure generation section is
configured of a continuous pulsation portion.
[0019] In this way, it being possible to increase the number of
pulsations per unit time of the fluid by eliminating the quiescent
portion from the drive waveform, and continuously inputting the
pulsation portion, it is possible to increase a capability to
eliminate the clogging.
Application Example 4
[0020] In the fluid ejection system according to the heretofore
mentioned application example, it is desirable that a frequency of
the drive waveform input in the event that the load detection
section has detected a load abnormality of the pressure generation
section approximately matches a resonant frequency of a pressure
wave propagated through a space from the fluid chamber to the
nozzle.
[0021] The fluid discharged from the fluid chamber, by the pressure
wave thereof being propagated from the fluid chamber to the nozzle,
is ejected from the nozzle as pulse-like (pulsation) droplets at a
high speed. At the same time, one portion of the pressure wave is
reflected at a nozzle position, and directed toward the fluid
chamber. Consequently, by matching the frequency of the drive
waveform with the resonant frequency of the pressure wave
propagated between the fluid chamber and nozzle, the amplitude of
the pressure wave increases due to the resonance, and it is
possible to increase the clogging elimination capability.
Application Example 5
[0022] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that, in the event
that the load detection section has detected a load abnormality of
the pressure generation section, the amplitude of the pulsation
portion is made larger than the amplitude at the normal drive time,
and the pressure at which the pressure generation section supplies
the fluid to the fluid chamber is made higher than that at the
normal drive time.
[0023] When the amplitude of the pulsation portion is made larger,
the amount of the volume contraction of the fluid chamber
increases, as previously described. By this means, as well as the
fluid discharge pressure becoming higher, the discharge amount
increases. Therein, as the amount of fluid supplied to the fluid
chamber is increased by increasing the pressure at which the fluid
is supplied by the pressure generation section, it is possible to
supply a sufficient amount of liquid to the pulsation generation
section in response to an increase in the discharge amount.
Application Example 6
[0024] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that a load of the
pressure generation section is detected as a change in a drive
speed of a fluid delivery device of the pressure generation
section.
[0025] Herein, the pressure generation section being, for example,
a pump, it is possible to employ a fluid delivery device such as a
piston pump or a gear pump.
[0026] In the event that a clogging occurs in the channel from the
fluid chamber to the nozzle, the pressure inside this channel
rises. Then, the load of the pressure generation section increases,
and the drive speed of the fluid delivery device of the pump
decreases. Consequently, it is possible to easily carry out a
clogging determination by detecting the decrease in the drive
speed.
[0027] A change in the drive speed of the fluid delivery device can
be easily and accurately measured by a linear encoder in the case
of the piston pump, or a rotary encoder in the case of the gear
pump.
Application Example 7
[0028] In the fluid ejection system according to the heretofore
mentioned application example, it is desirable that the load
detection section, in the event that the drive speed has become
equal to or less than a prescribed value, determines that there is
a load abnormality of the pressure generation section.
[0029] By so doing, it is possible to accurately detect that a
clogging has occurred in the channel from the fluid chamber to the
nozzle.
Application Example 8
[0030] In the fluid ejection system according to the heretofore
mentioned application example, it is desirable that the load
detection section is a pressure sensor provided inside the pressure
generation section.
[0031] In the event that a clogging occurs in the channel from the
fluid chamber to the nozzle, the pressure inside the channel rises,
causing an output load of the pressure generation section, and the
internal pressure of the pressure generation section rises.
Therein, it is possible to directly detect a load by using the
pressure sensor.
Application Example 9
[0032] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that it further
includes an alarm which, in the event that the load detection
section has detected a load abnormality of the pressure generation
section, informs of the abnormality.
[0033] By providing the alarm in this way, it is possible to inform
a user (a surgeon) that a clogging has occurred, and stop surgery
immediately.
Application Example 10
[0034] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that, in the event
that the load detection section has detected a load abnormality of
the pressure generation section, the drive of the pulsation
generation section and pressure generation section is stopped.
[0035] By so doing, it is possible to prevent a failure of the
fluid ejection system, including the pulsation generation section
and pressure generation section, accompanying a pressure rise due
to their continuing to be driven even in the event that a load
abnormality of the pressure generation section has been detected,
and increase safety.
Application Example 11
[0036] In the fluid ejection system according to the heretofore
mentioned application example, it is preferable that it further
includes an operating member which, after the load detection
section has detected a load abnormality of the pressure generation
section, and the drive of the pulsation generation section and
pressure generation section has been stopped, switches in such a
way as to make the fluid discharge pressure of the pulsation
generation section or the fluid supply pressure of the pressure
generation section higher than at the normal drive time.
[0037] By so doing, as it is possible to carry out a clogging
removal while confirming a condition by the surgeon consciously
carrying out a switching operation after detecting an abnormality
such as a clogging, and stopping the drive, it does not happen that
a high pressure liquid ejection is unconsciously started, so it is
possible to increase the safety.
Application Example 12
[0038] In the fluid ejection system according to the heretofore
mentioned application example, it is desirable that the operating
member is provided on the pulsation generation section.
[0039] With the fluid ejection system of the heretofore mentioned
application example, the pulsation generation section is gripped
when operated. Consequently, by providing the operating member on
the pulsation generation section, it is possible for the surgeon
him or herself to carry out the switching operation at hand, and
remove a clogging.
Application Example 13
[0040] In the fluid ejection system according to the heretofore
mentioned application example, it is desirable that, in an idle
period of the pulsation generation section, the drive waveform is
configured of a combination of a midpoint potential, at which the
piezoelectric element is charged to the extent that the fluid is
moved to a position in which it reaches the leading extremity of
the nozzle, and a potential at which the piezoelectric element is
discharged.
[0041] When incising or excising a body tissue using the pulsation
generation section, it is conceivable that the leading extremity of
the nozzle comes into contact with a body tissue, blood, and a body
fluid. At this time, it happens that these become dry in the idle
period of the pulsation generation section during surgery, causing
a clogging at the nozzle leading extremity.
[0042] Therein, in the drive idle period, by constantly repeating a
movement of the liquid to the extent that the liquid is not
discharged from the nozzle, it is possible to suppress the clogging
in a channel from the nozzle leading extremity and nozzle to the
fluid chamber.
Application Example 14
[0043] A fluid ejection system drive method according to this
application example is a method of driving a fluid ejection system
including: a pulsation generation section which, including a fluid
chamber, a diaphragm which changes a volume of the fluid chamber,
and a piezoelectric element which drives the diaphragm, pulsatively
ejects a fluid from a nozzle; and a control apparatus including a
pressure generation section which supplies the fluid to the fluid
chamber at a predetermined pressure, a drive waveform generation
section which inputs a drive waveform into the piezoelectric
element, and a load detection section which detects a load of the
pressure generation section. The method includes a step of, during
a normal drive of the fluid ejection system, detecting a load of
the pressure generation section, which supplies the fluid to the
pulsation generation section at the predetermined pressure, by
means of the load detection section; a step of outputting an alarm
in the event that the load of the pressure generation section has
become equal to or more than a prescribed value; a step of stopping
the drive of the pulsation generation section and pressure
generation section; a cleaning step in which a fluid discharge
pressure of the pulsation generation section or a fluid supply
pressure of the pressure generation section is made higher than at
a normal drive time; and a step of restoring the normal drive after
finishing the cleaning step.
[0044] According to this application example, in the event that a
load of the pressure generation section has been detected due to a
clogging, and the load of the pressure generation section has
become equal to or more than the prescribed value, it is possible
to carry out a cleaning (remove a clogging) by increasing the fluid
discharge pressure or discharge amount of the pulsation generation
section in comparison with at the normal drive time, and it is
possible to maintain the normal drive and safety.
[0045] Also, there is an advantage in that, as it is possible to
continuously use the pulsation generation section without
discarding it due to a failure caused by a clogging, it is possible
to reduce a running cost.
Application Example 15
[0046] A surgical apparatus according to this application example
includes the fluid ejection system described in the heretofore
mentioned application example, and is driven by the previously
described fluid ejection system drive method.
[0047] According to this application example, in the event that a
clogging has occurred in the pulsation generation section during
surgery, it is possible to easily remove the clogging and, as well
as it being possible to maintain a stable pulsation discharge, it
is possible to increase the safety, and perform surgery with
ease.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0049] FIG. 1 is an illustration showing an outline configuration
of a fluid ejection system according to Embodiment 1.
[0050] FIG. 2 is a sectional view showing a main configuration of a
pulsation generation section according to Embodiment 1, taken along
a direction of a channel of a liquid.
[0051] FIG. 3 is a configuration diagram showing a main system
configuration of the fluid ejection system according to Embodiment
1.
[0052] FIG. 4 is an illustration illustrating one example of a
drive waveform according to Embodiment 1.
[0053] FIG. 5 is an illustration showing a method of driving the
fluid ejection system according to Embodiment 1.
[0054] FIG. 6 is an illustration showing a drive waveform input
during an idle period according to Embodiment 5.
[0055] FIGS. 7A to 7C are fragmentary sectional views schematically
representing a behavior of a pulsation generation section according
to Embodiment 5.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0056] Hereafter, a description will be given, based on the
drawings, of embodiments of the invention.
[0057] FIGS. 1 to 5 show a fluid ejection system according to
Embodiment 1, and FIGS. 6 and 7A to 7C show Embodiment 5.
[0058] The drawings to be referred to in the following description
are schematic diagrams in which the vertical and horizontal scales
of members and portions differ from actual ones, for the
convenience of illustration.
[0059] Also, the fluid ejection system according to some aspects of
the invention can be variously employed for a drawing using ink or
the like, a washing of a miniature object and structure, a cutting
off or cutting out of an object, an electronic instrument cooling
device, a surgical knife, and the like, but in the embodiments to
be described hereafter, a description will be given exemplifying
with a surgical apparatus suitable in incising or excising a body
tissue. Consequently, a fluid used in the embodiments being a
liquid such as water, saline, or a chemical, the fluid may be
expressed as the liquid.
Embodiment 1
[0060] FIG. 1 is an illustration showing an outline configuration
of the fluid ejection system according to Embodiment 1. In FIG. 1,
the fluid ejection system 1 is configured of a control apparatus
100, which includes a liquid storage container storing a liquid, a
fluid delivery device of a pump acting as a pressure generation
section, and a drive waveform generation section (which are not
shown), a fluid ejection apparatus 10 which pulsatively ejects the
liquid supplied from the fluid delivery device, and a fluid supply
tube 25 (hereafter expressed simply as a tube 25) which brings the
fluid ejection apparatus 10 into communication with the pump.
[0061] Also, the control apparatus 100 and fluid ejection apparatus
10 are electrically connected by a drive signal cable 15 and
operation switching signal cable 16.
[0062] The liquid storage container, the pump, the drive waveform
generation section, and a system control section, which controls
the whole of the system, are included inside the control apparatus
100, and a display section 161, which displays a drive condition
and drive status, an adjustment member 160, which sets an optimum
drive waveform, and an alarm 144, are provided on the external
side.
[0063] The fluid ejection apparatus 10 includes a pulsation
generation section 30, which causes the supplied liquid to pulsate
at a high pressure and high frequency, and a connection channel
pipe 90, which is connected to the pulsation generation section 30.
A nozzle 95 including a fluid ejection opening 97, which is formed
by reducing the sectional area of the channel, is inserted in the
leading extremity of the connection channel pipe 90.
[0064] Next, a description will be given of a liquid flow in the
fluid ejection system 1. The liquid stored in the liquid storage
container included in the control apparatus 100 is supplied by the
pump at a certain pressure to the pulsation generation section 30
via the tube 25.
[0065] The pulsation generation section 30, being provided with a
fluid chamber 120 (refer to FIG. 2) and the fluid chamber 120's
volume changing unit, by driving the volume changing unit,
generates a pulsation, and ejects the liquid in a pulse form from
the fluid ejection opening 97. A detailed description of the
pulsation generation section 30 will be given hereafter, referring
to FIGS. 2 to 4.
[0066] A discharge pressure of the pump at a normal drive time is
set to approximately three atmospheres (0.3 MPa) or less. When
performing surgery using the fluid ejection system 1, a main
portion which a surgeon grips is the pulsation generation section
30. Consequently, it is preferable that the tube 25 connected to
the pulsation generation section 30 is as flexible as possible. For
that purpose, it is preferable that it is made a flexible and thin
tube, and that the pressure is made low within a range in which it
is possible to send the liquid to the pulsation generation section
30.
[0067] Next, a description will be given of a structure of the
fluid ejection apparatus 10 according to Embodiment 1.
[0068] FIG. 2 is a sectional view showing a main configuration of
the pulsation generation section according to Embodiment 1, taken
along a liquid channel direction. In FIG. 2, the fluid ejection
apparatus 10 is configured of the pulsation generation section 30,
the connection channel pipe 90 connected to the pulsation
generation section 30, and the nozzle 95 inserted in the connection
channel pipe 90.
[0069] The pulsation generation section 30 includes a ring shaped
spacer 60 closely clamped between the mutually opposed surfaces of
a first machine casing 80 and second machine casing 50, and a
diaphragm 70 which, acting as the volume changing unit, is made of
a disk shaped sheet metal, and the fluid chamber 120 is configured
by a wall surface 80a of the first machine casing 80, the diaphragm
70, and the inner peripheral wall surface of the spacer 60.
[0070] A tube connection pipe 81 is protruded from the outer side
surface of the first machine casing 80, and an inflow connection
channel 84 is opened in the tube connection pipe 81. The inflow
connection channel 84 is brought into communication with an inlet
channel 83 communicating with the flow chamber 120.
[0071] The tube 25 is pressed into the tube connection pipe 81. The
tube 25 is connected to the pump provided inside the control
apparatus 100 (refer to FIG. 1), and the liquid is supplied into
the flow chamber 120 via the inflow connection channel 84 and inlet
channel 83.
[0072] Also, an outlet channel 88 is opened, and furthermore, an
outlet connection channel 89 communicating with the outlet channel
88 is opened, in an approximate center of the wall surface 80a so
as to be approximately perpendicular to the wall surface 80a of the
first machine casing 80.
[0073] A connection channel pipe insertion portion 82 is protruded
in a direction opposite to the fluid chamber 120, and the outlet
connection channel 89 communicating with the outlet channel 88 is
provided, in the first machine casing 80. The connection channel
pipe 90 is pressed into and fixed in the connection channel pipe
insertion portion 82.
[0074] Apart from the connection channel pipe 90 being pressed into
and fixed in the connection channel pipe insertion portion 82, it
is also acceptable to adopt a removable structure in which threaded
portions are formed in the connection channel pipe 90 and
connection channel pipe insertion portion 82, and the connection
channel pipe 90 is screwed into and fixed in the connection channel
pipe insertion portion 82.
[0075] The connection channel 92 communicating with the outlet
connection channel 89 is opened in the connection channel pipe 90,
and the nozzle 95 is pressed into a leading extremity of the
connection channel pipe 90 opposite the outlet channel 88. The
nozzle 95 includes a nozzle channel 96 communicating with the
connection channel 92, and the fluid ejection opening 97.
[0076] Herein, the outlet connection channel 89, connection channel
92, and nozzle channel 96 have approximately the same sectional
area, and this sectional area is larger than the sectional area of
the outlet channel 88. Also, the sectional area of the fluid
ejection opening 97 is reduced in comparison with the sectional
area of the connection channel 92, and furthermore, reduced in
comparison with that of the outlet channel 88.
[0077] The sectional area represents the sectional area of the
channel when sectioned perpendicular to a liquid flow
direction.
[0078] In this embodiment, the diameter of the outlet channel 88 is
set to 0.3 mm, the diameter of the connection channel 92 to 1.0 mm,
and the diameter of the fluid ejection opening 97 within a range of
0.1 to 0.2 mm. Also, the channel length from the fluid chamber 120
to the fluid ejection opening 97 is appropriately set within a
range of 100 to 200 mm.
[0079] Meanwhile, the second machine casing 50, being a cylindrical
member, has opened therein a cylindrical hole 52 passing through
the second machine casing 50. One of the openings of the hole 52 is
sealed with a lower plate 102. A piezoelectric element 40 acting as
a drive source is disposed inside the hole 52. The piezoelectric
element 40, being a stacked piezoelectric element, configures a
columnar actuator.
[0080] One extremity of the piezoelectric element 40 is closely
fixed to the diaphragm 70 across an upper plate 101, and the other
extremity to the inner surface of the lower plate 102.
[0081] Drive electrodes (not shown) are provided one on each of the
opposed side surfaces of the piezoelectric element 40, and the
drive signal cable 15 formed of connection leads 15a and 15b coated
in insulation is connected to the drive electrodes.
[0082] The drive signal cable 15, being extended outward through a
through hole 53 opened in a side surface of the second machine
casing 50, is connected to a drive waveform generation section 151
(refer to FIG. 3) included in the control apparatus 100. The
through hole 53 is sealed with a seal member 103 in a condition in
which the drive signal cable 15 is put through the through hole
53.
[0083] The pulsation generation section 30, having its periphery
hermetically sealed, is covered with a contour member which is
attachable to and detachable from the pulsation generation section
30. In this embodiment, the contour member is configured of an
upper casing 35 and lower casing 36 as a case member.
[0084] The upper casing 35 and lower casing 36 hold the pulsation
generation section 30 in such a way as to sandwich the connection
channel pipe insertion portion 82 of the first machine casing 80
and the cylindrical portion of the second machine casing 50. The
upper casing 35 and lower casing 36 are fixed by unshown fixing
screws. Consequently, the upper casing 35 and lower casing 36 are
of a structure such that they are attachable to and detachable from
the pulsation generation section 30.
[0085] Also, a packing (not shown) acting as a seal member, being
provided between the mutually opposed end faces of the upper casing
35 and lower casing 36, hermetically seals the pulsation generation
section 30.
[0086] An operating member 130 is provided on the pulsation
generation section 30. The operating member 130 being a switch, it
is possible to select a push button type, a slide type, a rotary
type, or the like, but the push button type switch is more
preferable from the aspect of a space saving and a simple
operation. The operating member 130, being disposed in such a way
that everything other than an operation section is embedded in the
lower casing 36, is connected to the control apparatus 100 by the
operation switching signal cable 16 (refer to FIG. 1).
[0087] Next, a description will be given of a system configuration
of the fluid ejection system 1.
[0088] FIG. 3 is a configuration diagram showing a main system
configuration of the fluid ejection system according to this
embodiment. The fluid ejection apparatus 10 is configured of the
fluid chamber 120, the diaphragm 70 acting as the volume changing
unit which changes the volume of the fluid chamber 120, the
piezoelectric element 40 which drives the diaphragm 70, and the
operating member 130.
[0089] The control apparatus 100 includes the liquid storage
container 141 (hereafter expressed simply as the container 141),
and a load detection section 142 which, including the pump 140
communicating with the container 141, and a pump drive control
section 143 which controls a drive of the pump 140, detects a load
fluctuation of the pump 140.
[0090] As the pump 140, it is possible to employ a liquid delivery
device such as a piston pump or a gear pump, and it is brought into
communication with the fluid chamber 120 by the tube 25. The load
detection section 142 includes a linear encoder in the case of the
piston pump, and a rotary encoder in the case of the gear pump, and
detects a load fluctuation of the pump 140 as a change in piston
drive speed or gear rotation speed.
[0091] There is provided the alarm 144 which, in the event that a
clogging has occurred in the pulsation generation section 30, and
the load (drive speed) of the pump 140 has become equal to or more
than a prescribed value, determines that the load is abnormal, and
gives an alarm. The alarm 144 can employ a sound of a buzzer or the
like, or a light alert.
[0092] Also, the control apparatus 100 includes an optimum drive
parameter calculation section 152 which calculates a drive waveform
corresponding to the hardness of an excised tissue, the adjustment
member 160 which inputs the excised tissue hardness, and the drive
waveform generation section 151 which, based on an optimum drive
parameter, generates a drive waveform to be input into the
piezoelectric element 40. The control apparatus 100 further
includes the system control section 150 which governs the overall
control of each system component, and the display section 161. The
display section 161 displays a drive condition such as the excised
tissue hardness, a drive status, and the like.
[0093] A rotary switch being suitable as the adjustment member 160,
by rotating a dial thereof, a drive condition such as the excised
tissue hardness is selected, and input into the optimum drive
parameter calculation section 152. An amplitude (a potential),
cycle, waveform quantity (pulse quantity), quiescent time, and the
like, of a pulsation portion compatible with the selected and input
excised tissue hardness or the like, are calculated in the optimum
drive parameter calculation section 152, and input into the
piezoelectric element 40, via the drive signal cable 15, as an
optimum drive waveform in the drive waveform generation section
151.
[0094] Next, a description will be given, referring to the drawing,
of one example of a drive waveform.
[0095] FIG. 4 illustrates one example of a drive waveform according
to this embodiment. Firstly, a description will be given of a drive
waveform at the normal drive time. It is taken that the drive
waveform in this illustration is configured of a pulsation portion
configured of a whole number of sequential sinusoidal waveforms in
which a piezoelectric element drive voltage starts with a phase
-.pi./2, and a quiescent portion (expressed as a quiescent time
I).
[0096] In the drawing, the drive waveform expressed by the solid
line represents the normal drive time, and the waveform of the
pulsation portion is expressed by an amplitude A1, a cycle T, and a
number n of sequential sine waves. In this illustration, the number
of sine waves is taken to be two. The waveform of this pulsation
portion being of a burst wave, it is possible, in the drive
waveform generation section 151, to generate it easily by
specifying the heretofore mentioned parameter.
[0097] The drive waveform not being limited to that of the sine
wave, it is also acceptable that it is of a combination of
rectangular waves.
[0098] Continuing, a description will be given of an operation of
the fluid ejection system 1. Firstly, a description will be given
of a normal drive status (refer to FIGS. 1 to 3).
[0099] The liquid is constantly supplied to the inlet channel 83 at
a certain fluid pressure by the pump 140. As a result, when the
piezoelectric element 40 carries out no operation, the liquid flows
into the fluid chamber 120 due to a difference between a discharge
pressure of the pump 140 and the whole fluid resistance value on
the inlet channel side.
[0100] Herein, supposing that the illustrated drive waveform is
input into the piezoelectric element 40, and the piezoelectric
element 40 expands rapidly, the pressure inside the fluid chamber
120 rises rapidly and reaches several tens of atmospheres in the
event that inlet channel side and outlet channel side combined
inertances L1 and L2 have a sufficient size. As this pressure is
far larger than a pressure applied to the inlet channel 83 by the
pump 140, an inflow of the liquid into the fluid chamber 120 from
the inlet channel 83 decreases due to the pressure, and an outflow
from the outlet channel 88 increases.
[0101] However, as the inlet channel side combined inertance L1 is
larger than the outlet channel side combined inertance L2, an
increased amount of liquid discharged from the outlet channel 88 is
larger than a decreased amount of flow rate in which the liquid
flows from the inlet channel 83 into the fluid chamber 120. For
this reason, a pulse-like fluid discharge, that is, a pulsation
flow, occurs in the outlet channel 88.
[0102] A pressure fluctuation (that is, a pressure wave) at this
discharge time is propagated through the connection channel 92 of
the connection channel pipe 90, and the liquid is ejected in a
pulse form from the fluid ejection opening 97 of the nozzle 95 (for
both of which refer to FIG. 2) at the leading extremity. As the
diameter of the fluid ejection opening 97 is reduced in comparison
with the diameter of the outlet channel 88, the liquid is ejected
as higher-pressure and higher-speed pulse-like droplets.
[0103] Meanwhile, the interior of the fluid chamber 120 attains a
vacuum condition immediately after the pressure rise, due to an
interaction between the decrease in the amount of liquid inflow
from the inlet channel 83 and the increase in the liquid outflow
from the outlet channel 88. As a result, a flow of the liquid in
the inlet channel 83 moving toward the interior of the fluid
chamber 120 at the same speed as that before the piezoelectric
element 40 operates is restored, after a certain time has elapsed,
due to both the pressure of the pump and the vacuum condition
inside the fluid chamber 120. In the event that there is an
expansion of the piezoelectric element 40 after the flow of the
liquid inside the inlet channel 83 has been restored, it is
possible to continuously eject the liquid from the nozzle 95 in the
pulse form.
[0104] In a tissue excision by a pulsating fluid ejection, when a
pulsation intensity is high (that is, a fluid discharge pressure
amplitude is large), it is possible to excise a high hardness
tissue. The fluid discharge pressure amplitude can be realized by
increasing an amplitude A of a piezoelectric element drive voltage.
Meanwhile, however, an amount of fluid ejected per unit time is
also increased at the same time. As a result, an excision depth per
unit time is also increased at the same time.
[0105] When the surgeon does not want the increase in the excision
depth per unit time, it is necessary to increase the amplitude A,
and at the same time, reduce the number n of sequential sine waves
to an appropriate value, increase the quiescent time I, or the
like.
[0106] In this embodiment, on the dial shaped adjustment member 160
being rotationally operated, and the excised tissue hardness being
selected and set, the fluid ejection section drive voltage
amplitude A, which is one of control parameters, changes, and at
the same time, an adjustment is made by the optimum drive parameter
calculation section 152 in such a way that the quiescent time I,
which is another control parameter, changes, and the excision depth
does not change.
[0107] It is also acceptable to use an optimum drive parameter
table in place of the optimum drive parameter calculation section
152. The excised tissue hardness is selected by the adjustment
member 160, and an optimum drive parameter is selected from the
optimum drive parameter table, generating a drive waveform. It is
more preferable that information on the optimum drive parameter
selected is displayed in the display section 161.
[0108] The optimum drive parameter table is a table in which are
combined control parameters such as a surgery type, the diameter of
the fluid ejection opening 97, an excised tissue hardness, and an
excision depth.
[0109] However, when a body tissue is incised or excised using the
fluid ejection system 1 as the surgical apparatus, as a distance
between the nozzle 95 and a surgical site is several millimeters or
less, it is conceivable that the leading extremity of the nozzle 95
comes into contact with a body tissue, blood, and a body fluid, and
it is expected that these will cause a nozzle leading extremity
clogging.
[0110] Also, as the diameter of the fluid ejection opening 97 is
extremely small at around 0.1 to 0.2 mm, and the outlet channel 88
communicating with the nozzle from the fluid chamber 120 is also
extremely small at around 0.3 mm, it is also conceivable that a
clogging occurs in a channel from the fluid chamber 120 to the
fluid ejection opening 97. Consequently, a removal of these
cloggings, that is, a cleaning, is needed.
[0111] Continuing, a description will be given of a drive method
relating to a cleaning of the channel from the fluid chamber 120 to
the fluid ejection opening 97.
[0112] FIG. 5 is an illustration showing the drive method relating
to the cleaning of this embodiment. A description will be given,
referring to FIGS. 2 to 4 too, in accordance with the process shown
in FIG. 5.
[0113] Firstly, the fluid ejection system 1 is started, starting a
normal drive (ST10). While the fluid ejection system is being
driven, a load fluctuation of the pump 140 is being detected by the
load detection section 142 (ST20). As previously described, a load
fluctuation is detected as a change in the drive speed of the fluid
delivery device of the pump 140.
[0114] Herein, in the event that the pulsation generation section
30 is driven normally (in conformity to a design value), the load
of the pump 140 falls within an approximately constant range, and
the fluid delivery device continues to be driven within a certain
drive speed range.
[0115] Herein, in the event that a clogging occurs in the channel
from the fluid chamber 120 to the fluid ejection opening 97, the
pressure inside the channel increases. Then, the load of the pump
140 increases, and the drive speed decreases. Consequently, by
setting a correlation between the drive load and drive speed of the
fluid delivery device, it is possible to detect a change in the
load as a fluctuation in the speed.
[0116] In the event that the load of the pump 140 is less than the
prescribed value, the fluid ejection system 1 continues to be
driven as it is (ST30) and, when the surgery is finished, the fluid
ejection system is stopped (ST40).
[0117] In the event that the load of the fluid delivery device of
the pump 140 has become equal to or more than the prescribed value
(that is, in the even that the drive speed has become equal to or
less than the prescribed value), a signal is input into the system
control section 150 from the load detection section 142, and an
alarm is output using a sound, light, or the like by the alarm 144
(ST50). Together with the alarm output from the alarm 144, a drive
stop command is output to the drive waveform generation section 151
and pump drive control section 143 from the system control section
150, stopping the fluid ejection system 1 (ST60).
[0118] In the event that an alarm has been output, the surgeon
determines that a clogging has occurred, and starts a cleaning
operation. A cleaning start operation, after the pulsation
generation section 30 has been moved away from a living body, is
carried out by means of a switch input from the operating member
130 provided on the pulsation generation section 30. A cleaning
start command from the operating member 130 is input into the
system control section 150 via the operation switching signal cable
16, and the pump 190 and pulsation generation section 30 are
started based on the system control section 150 drive start
command, starting the cleaning operation (ST170).
[0119] At this time, the liquid discharge pressure amplitude of the
pulsation generation section 30 is made higher than at the normal
drive time. The liquid discharge pressure amplitude of the
pulsation generation section 30 can be made higher by making the
amplitude of the pulsation portion of the drive waveform larger
than at the normal drive time.
[0120] The drive waveform in that case is illustrated by the broken
line in FIG. 4. In this illustration, an amplitude A2 is made
approximately twice as high as the amplitude A1 at the normal drive
time. By this means, the amount of expansion of the piezoelectric
element 40 increases, and the amount of volume contraction of the
fluid chamber 120 increases. By this means, the pulsation becomes
stronger, and the liquid discharge pressure amplitude increases,
meaning that it is possible to remove the clogging.
[0121] The surgeon, when determining that the clogging has been
removed, operates the operating member 130 again, stops the
pulsation generation section 30 and pump 140, and finishes the
cleaning operation (ST80).
[0122] The determination of the clogging removal is carried out by
observing a discharge condition of the liquid from the liquid
ejection opening 97.
[0123] Continuing, the operating member 130 is operated, and a
start command from the system control section 150 is input,
starting the fluid ejection system 1 (specifically, the pulsation
generation section 30 and pump 140). A drive waveform output at
this time is the drive waveform at the normal drive time (refer to
FIG. 4). Then, the process in and after ST20 is repeated.
[0124] It is possible to employ a method whereby a pump load is
detected by the load detection section 142 during the cleaning
operation, and the cleaning operation is continued in the event
that the load is equal to or more than the prescribed value, while
the cleaning operation is stopped (a system stop) in the event that
the load is less than the prescribed value.
[0125] With this kind of method, a setting is such that a detection
reference value of the load detection section 192 is matched with
the pump drive speed at a cleaning operation time.
[0126] A restart of the fluid ejection system is carried out by
operating the operating member 130. Consequently, it is preferable
that the operating member 130 is a one-circuit two-contact type
switch.
[0127] Also, in the cleaning operation, it is preferable that, as
well as the amplitude of the pulsation portion of the drive
waveform being made larger, the liquid supply pressure of the pump
140 is made higher. By this means, it is possible to increase a
liquid supply amount per unit time. This is because, as the liquid
discharge amount increases due to the amplitude of the pulsation
portion of the drive waveform being made larger, there is a need to
increase the liquid supply amount.
[0128] With the heretofore described drive waveform at the cleaning
operation time according to this embodiment, the amplitude
(potential) thereof is changed with the cycle T and quiescent time
I thereof remaining the same as those of the pulsation portion at
the normal drive time, but it is also acceptable that the cycle T
is changed, or the quiescent time I is changed.
[0129] Consequently, according to the fluid ejection system of this
embodiment, by detecting that the load of the pump 140 has
increased, it is determined that a clogging has occurred in the
channel from the fluid chamber 120 to the fluid ejection opening
97. Therein, it is possible to eliminate the clogging by making the
fluid discharge pressure amplitude of the pulsation generation
section 30 higher than at the normal drive time, and clean the
channel from the fluid chamber 120 to the fluid ejection opening
97.
[0130] With the fluid discharge pressure amplitude, by making the
amplitude of the pulsation portion still larger than the amplitude
at the normal drive time, the amount of displacement of the
diaphragm 70 is increased, increasing the amount of the volume of
the fluid chamber 120 contracted by the diaphragm 70, as a result
of which it is possible to increase the pressure inside the fluid
chamber 120.
[0131] When the amplitude of the pulsation portion is made higher,
the amount of the volume contraction of the fluid chamber 120
increases, as previously described. By this means, as well as the
fluid discharge pressure amplitude becoming higher, the discharge
amount increases. Therein, as the amount of fluid supplied to the
fluid chamber 120 increases by increasing the fluid supply pressure
applied by the pump 140, it is possible to supply a sufficient
amount of liquid to the pulsation generation section 30 in response
to an increase in the discharge amount.
[0132] Also, a change in load of the pump 140 is detected as a
change in the drive speed of the fluid delivery device of the pump
140. In the event that a clogging occurs in the channel from the
fluid chamber 120 to the fluid ejection opening 97, the pressure
inside this channel rises. Then, the load of the pump 140
increases, and the drive speed decreases. Consequently, it is
possible to carry out a clogging determination by detecting a
decrease in the drive speed.
[0133] Also, there is provided the alarm 144 which informs of an
abnormality in the event that the load detection section 142 has
detected an increase in the load of the pump 140 which is equal to
or more than the prescribed value. By providing the alarm 144 in
this way, it is possible to inform the surgeon of the fact that a
clogging has occurred, and stop the surgery immediately.
[0134] It is also acceptable that the detection of a load
abnormality of the pump 140 is done by a method which determines it
to be abnormal when it is detected instantaneously, or by a method
which determines it to be abnormal when it continues for, for
example, several seconds.
[0135] In this embodiment, the alarm 144 is disposed in the control
apparatus 100, but it is also acceptable that it is disposed in the
pulsation generation section 30. However, it is preferable that the
pulsation generation section 30, as it is the portion which the
surgeon grips, is made as light and small as possible. For this
reason, it is more preferable to dispose it in the control
apparatus 100. Alternatively, it is also acceptable that the alarm
144 is disposed independently in a position which is distant from
the control apparatus 100, the pulsation generation section 30 and
easy to recognize.
[0136] Also, in the event that the load detection section 142 has
detected a load abnormality of the pump 140, as well as an alarm
being given, the drive of the pulsation generation section 30 and
pump 140 is stopped. By so doing, it is possible to prevent a
failure of the fluid ejection system 1, including the pulsation
generation section 30 and pump 140, accompanying a pressure rise
due to their continuing to be driven in the event that a load
abnormality of the pump 140 has been detected, and increase
safety.
[0137] Also, the pulsation generation section 30 includes the
operating member 130. After a clogging has been detected, and the
pulsation generation section has stopped, the surgeon consciously
carries out a switching operation of the operating member 130,
causing a cleaning operation. By so doing, it not happening that a
high pressure liquid ejection is unconsciously started, it is
possible to increase the safety.
[0138] Furthermore, according to this embodiment, there is also an
advantage in that, as it is possible to continuously use the
pulsation generation section 30 without discarding it due to a
failure caused by a clogging, it is possible to reduce a running
cost.
Embodiment 2
[0139] Continuing, a description will be given of a fluid ejection
system according to Embodiment 2. Although the drawings are
omitted, a description will be given referring to FIG. 4. The drive
waveform at the normal drive time of the fluid ejection system
according to this embodiment is configured of a pulsation portion
and quiescent portion, as expressed by the solid line in FIG.
4.
[0140] In this embodiment, the drive waveform input at the cleaning
operation time in the event that the load detection section 142 has
detected an increase in load (a load abnormality) of the pump 140
is configured of a continuous waveform. That is, it is configured
of only a continuous pulsation portion without the quiescent time
I.
[0141] Also, the amplitude of the pulsation portion is larger than
at the normal drive time, and the pulsation portion of the
amplitude A2 expressed in FIG. 4 forms a continuous drive
waveform.
[0142] By eliminating the quiescent portion from the drive
waveform, and continuously inputting the pulsation portion, it is
possible to increase the number of pulsations per unit time at the
cleaning operation time. Furthermore, the amplitude of the
pulsation portion is made larger than at the normal drive time,
thereby increasing the fluid discharge pressure. By this means, it
is possible to increase a capability to eliminate a clogging.
[0143] It is more preferable, at this time, to increase the fluid
supply pressure in response to the fluid discharge pressure.
Embodiment 3
[0144] Continuing, a description will be given, referring to FIG.
2, of Embodiment 3. Embodiment 3 has a feature wherein the
frequency of a drive waveform input in the event that the load
detection section 142 has detected an increase in load (a load
abnormality) of the pump 140 approximately matches the resonant
frequency of a pressure wave propagated through a space from the
fluid chamber 120 to the nozzle 95.
[0145] The liquid converted into a pulsation flow by the pulsation
generation section 30, by the pressure wave propagated from the
fluid chamber 120 to the nozzle 95, is ejected from the nozzle 95
as pulse-like droplets at a high speed. At the same time, one
portion of the pressure wave is reflected at a nozzle position, and
directed toward the fluid chamber 120. Specifically, the pressure
wave reciprocates in a portion, whose sectional area is extremely
small, of a channel from the fluid chamber 120 to the nozzle
95.
[0146] In this embodiment, a distance from the fluid chamber 120 to
the nozzle 95 is set to be 100 to 200 mm. Also, the propagation
speed of the pressure wave from the fluid chamber 120 to the nozzle
95 is approximately 1500 m per second. Herein, supposing that the
distance from the fluid chamber 120 to the nozzle 95 is 150 mm, it
is 300 mm there and back, and the resonant frequency of the
pressure wave is 5 kHz. Consequently, the frequency of the drive
waveform is taken to be 5 kHz.
[0147] By matching the resonant frequency of the pressure wave with
the frequency of the drive waveform in this way, the amplitude of
the pressure wave increases due to the resonance, and it is
possible to increase the clogging elimination capability.
Embodiment 4
[0148] Continuing, a description will be given of Embodiment 4.
Although the illustration is omitted, a description will be given
referring to FIG. 3. Embodiment 4 has a feature wherein a pressure
sensor is included inside the pump 140.
[0149] In the event that a clogging occurs in the channel from the
fluid chamber 120 to the fluid ejection opening 97, the pressure
inside the channel rises, causing an output load of the pump 140.
As a result, the internal pressure of the pump 140 rises. Therein,
the pressure sensor is disposed in a fluid chamber (a pressure
chamber) inside the pump 140.
[0150] Then, a difference between an internal pressure of the pump
140 at the normal drive time and at a clogging occurrence time is
set in advance and, in the event that a rise in the pressure is
equal to or more than a prescribed value, a cleaning operation is
started. The cleaning operation can be carried out in accordance
with the process described in the illustration shown in FIG. 5.
[0151] By so doing, it is possible to directly detect a change in
the internal pressure of the pump 140 accompanying the
clogging.
Embodiment 5
[0152] Continuing, a description will be given, referring to the
drawings, of a fluid ejection system according to Embodiment 5.
Embodiment 5 has a feature wherein a drive waveform is formed such
that it is possible to prevent a clogging due to a drying or the
like in the channel from the fluid chamber 120 to the fluid
ejection opening 97 while temporarily halting the fluid ejection
system halfway through a surgery.
[0153] FIG. 6 is an illustration showing a drive waveform input
during an idle period according to this embodiment, and FIGS. 7A to
7C are fragmentary sectional views schematically representing a
behavior of the pulsation generation section in response to the
drive waveform. In FIG. 6, one cycle of the drive waveform is
configured of a combination of, firstly, an area 1 in which a
midpoint potential is held for a certain time, continuing, an area
2 in which the piezoelectric element 40 is discharged, and an area
3 in which the piezoelectric element 40 is charged with the
midpoint potential after a certain time elapses.
[0154] A description will be given of a behavior of the liquid in
each area. FIG. 7A represents a condition in which the midpoint
potential (indicated by a potential A3) shown by 1 in FIG. 6 is
applied to the piezoelectric element 40. In this condition, the
amount of charge of the piezoelectric element 40 is intermediate
with respect to a full charge, and the amount of expansion is also
intermediate with respect to a full charge amount. Consequently,
the amount of the volume of the fluid chamber 120 contracted by the
diaphragm 70 is also of an intermediate value.
[0155] In the case of this kind of midpoint potential, the liquid,
rather than being discharged from the fluid ejection opening 97 of
the nozzle 95, remains to the extent that one portion thereof peeps
out of the leading extremity.
[0156] On the discharge potential (a potential -A3) expressed by 2
in FIG. 6 being applied in this condition, the piezoelectric
element 40 is discharged, attaining the condition represented in
FIG. 7B. That is, a condition is attained in which the diaphragm 70
expands the volume of the fluid chamber 120.
[0157] Then, the pressure of the fluid chamber 120 decreases
instantaneously, and the liquid in the nozzle 95 is retracted into
the fluid chamber 120 by an amount by which the volume of the fluid
chamber 120 has increased.
[0158] On the midpoint potential (the potential A3) shown in 3 of
FIG. 6 being applied, the condition of FIG. 7A is attained in this
condition. On this kind of drive waveform being repeatedly
continued, the liquid in the nozzle 95 repeats the conditions of
FIGS. 7A and 7B in the fluid ejection opening 97.
[0159] With the drive waveform when discharging the liquid, as
expressed by 4 in FIG. 6, a potential A1 higher than the midpoint
potential is applied to the piezoelectric element 40. In this kind
of case, as represented in FIG. 7C, the piezoelectric element 40
expands by being fully charged, the volume of the fluid chamber 120
is contracted to the maximum by the diaphragm 70, and the liquid is
discharged as droplets 200 in the pulse form.
[0160] When incising or excising a body tissue, it is conceivable
that the leading extremity of the nozzle 95 comes into contact with
a body tissue, blood, and a body fluid. At this time, it happens
that these become dry in an idle period of the pulsation generation
section 30, causing a clogging at the nozzle 95 leading extremity
(or in the fluid ejection opening 97).
[0161] Therein, in the pulsation generation section drive idle
period (a surgery suspension period), by constantly repeating a
movement of the liquid to the extent that the liquid is not
discharged from the nozzle 95, it is possible to suppress the
clogging in the channel from the fluid ejection opening 97 to the
fluid chamber 120.
[0162] FIG. 6 illustrates the case in which the drive waveform is
of a rectangular wave, but it is also acceptable that the drive
waveform is of a combined sine wave.
[0163] Also, in the drive using the drive waveform of Embodiment 5
too, by implementing the clogging removals described in Embodiment
1 to Embodiment 4, it is possible to use the fluid ejection system
with more ease.
[0164] The fluid ejection system 1 according to some aspects of the
invention can be variously employed for a drawing using ink or the
like, a washing of a miniature object and structure, a cutting off
or cutting out of an object, a surgical knife, and the like, but is
suitable as a surgical instrument with which a body tissue is
incised or excised.
* * * * *