U.S. patent application number 11/321284 was filed with the patent office on 2006-06-29 for apparatus and method for supplying liquid and apparatus for processing substrate.
This patent application is currently assigned to Dainippon Screen Mfg. Co., Ltd.. Invention is credited to Yasuhiro Mizohata.
Application Number | 20060137419 11/321284 |
Document ID | / |
Family ID | 36609840 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060137419 |
Kind Code |
A1 |
Mizohata; Yasuhiro |
June 29, 2006 |
Apparatus and method for supplying liquid and apparatus for
processing substrate
Abstract
A liquid supply apparatus comprises a pump mechanism for pumping
out a liquid to a conduit, a flowmeter for measuring a flowrate of
the liquid flowing through the conduit, and a controller for
controlling these mechanisms. The pump mechanism comprises a
flexible chamber made of resin, a pressure chamber housing the
flexible chamber, and an electro-pneumatic regulator for adjusting
pressure in a space between the pressure chamber and the flexible
chamber. The flexible chamber comprises a bellows. In the liquid
supply apparatus, while pressure is applied to the flexible chamber
of the pump mechanism and the liquid in the flexible chamber is
pumped out to the conduit, the pressure applied to the flexible
chamber is controlled by the controller on the basis of a flowrate
of the liquid measured by the flowmeter. This makes it possible to
supply the liquid of a small flowrate while controlling the
flowrate accurately.
Inventors: |
Mizohata; Yasuhiro; (Kyoto,
JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
US
|
Assignee: |
Dainippon Screen Mfg. Co.,
Ltd.
|
Family ID: |
36609840 |
Appl. No.: |
11/321284 |
Filed: |
December 24, 2005 |
Current U.S.
Class: |
72/200 |
Current CPC
Class: |
G01F 1/48 20130101 |
Class at
Publication: |
072/200 |
International
Class: |
B21B 27/06 20060101
B21B027/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2004 |
JP |
2004-375294 |
Claims
1. A liquid supply apparatus for supplying a liquid, comprising: a
pump mechanism for pumping out a liquid to a conduit by applying
pressure to a flexible chamber to reduce a volume of said flexible
chamber; a flowmeter placed in a downstream side of said pump
mechanism for measuring a flowrate of said liquid flowing through
said conduit; and a controller for sending an electrical signal to
said pump mechanism, said electrical signal controlling pressure
applied to said flexible chamber so that said flowrate of said
liquid flowing through said conduit is adjusted to a predetermined
flowrate on the basis of a flowrate of said liquid obtained by said
flowmeter.
2. The liquid supply apparatus according to claim 1, wherein said
flexible chamber is made of resin.
3. The liquid supply apparatus according to claim 1, wherein said
flexible chamber comprises a bellows.
4. The liquid supply apparatus according to claim 1, wherein said
pump mechanism comprises a pressure chamber housing said flexible
chamber; and an electro-pneumatic regulator for adjusting pressure
in a space between said pressure chamber and said flexible
chamber.
5. The liquid supply apparatus according to claim 1, wherein said
flexible chamber comprises a bellows, and said pump mechanism
comprises a pressure chamber housing said flexible chamber; and an
electro-pneumatic regulator for adjusting pressure in a space
between said pressure chamber and said flexible chamber, wherein
one end of said flexible chamber is fixed to said pressure chamber
and the other end is made free.
6. The liquid supply apparatus according to claim 5, wherein said
pump mechanism further comprises a displacement sensor for
detecting a displacement of said other end with respect to said
pressure chamber.
7. The liquid supply apparatus according to claim 4, wherein said
pump mechanism further comprises a leakage sensor located on an
inner side of a bottom of said pressure chamber for detecting a
leakage of said liquid from said flexible chamber.
8. The liquid supply apparatus according to claim 1, wherein said
pump mechanism comprises a motor where an output torque is
controlled; and a press mechanism for applying pressure to said
flexible chamber by a torque outputted from said motor.
9. The liquid supply apparatus according to claim 1, further
comprising: another pump mechanism which has the same structure as
said pump mechanism, wherein compression of one chamber of said
flexible chamber of said pump mechanism and another flexible
chamber of said another pump mechanism and concurrent expansion of
the other chamber of said flexible chamber and said another
flexible chamber are performed alternately to said flexible chamber
and said another flexible chamber by control of said
controller.
10. The liquid supply apparatus according to claim 9, wherein
before compression of said one chamber is stopped, expansion of
said other chamber is stopped and compression of said other chamber
is started.
11. The liquid supply apparatus according to claim 1, wherein said
flowmeter is a differential pressure flowmeter, and said
differential pressure flowmeter comprises a round tube provided as
a part of said conduit in which a flow of said liquid with a
Reynolds number less than or equal to 2000 is formed; a first
pressure sensor placed between said pump mechanism and said round
tube for measuring a pressure of said liquid flowing into said
round tube; and a second pressure sensor placed in a downstream
side of said round tube for measuring a pressure of said liquid
flowing out of said round tube.
12. The liquid supply apparatus according to claim 11, wherein said
round tube is made of resin.
13. A substrate processing apparatus for processing a substrate,
comprising: a first conduit through which a first liquid flows; a
second conduit through which a second liquid flows, said second
conduit connected to said first conduit; a liquid supply apparatus
installed on an upstream side of said second conduit for supplying
said second liquid; and a process bath, located in a downstream
side of a connected point of said first conduit and said second
conduit, for storing a processing liquid which is a mixture of said
first liquid and said second liquid, in which a substrate being
dipped, wherein said liquid supply apparatus comprises a pump
mechanism for pumping out said second liquid to a conduit connected
to said second conduit by applying pressure to a flexible chamber
to reduce a volume of said flexible chamber; a flowmeter placed in
a downstream side of said pump mechanism for measuring a flowrate
of said second liquid flowing through said conduit; and a
controller for sending an electrical signal to said pump mechanism,
said electrical signal controlling pressure applied to said
flexible chamber so that said flowrate of said second liquid
flowing through said conduit is adjusted to a predetermined
flowrate on the basis of a flowrate of said second liquid obtained
by said flowmeter.
14. The substrate processing apparatus according to claim 13,
wherein said flexible chamber is made of resin.
15. The substrate processing apparatus according to claim 13,
wherein said flexible chamber comprises a bellows.
16. The substrate processing apparatus according to claim 13,
wherein said pump mechanism comprises a pressure chamber housing
said flexible chamber; and an electro-pneumatic regulator for
adjusting pressure in a space between said pressure chamber and
said flexible chamber.
17. The substrate processing apparatus according to claim 13,
wherein said liquid supply apparatus further comprises another pump
mechanism which has the same structure as said pump mechanism, and
compression of one chamber of said flexible chamber of said pump
mechanism and another flexible chamber of said another pump
mechanism and concurrent expansion of the other chamber of said
flexible chamber and said another flexible chamber are performed
alternately to said flexible chamber and said another flexible
chamber by control of said controller.
18. The substrate processing apparatus according to claim 17,
wherein before compression of said one chamber is stopped,
expansion of said other chamber is stopped and compression of said
other chamber is started.
19. The substrate processing apparatus according to claim 13,
wherein said flowmeter is a differential pressure flowmeter, and
said differential pressure flowmeter comprises a round tube
provided as a part of said conduit in which a flow of said second
liquid with a Reynolds number less than or equal to 2000 is formed;
a first pressure sensor placed between said pump mechanism and said
round tube for measuring a pressure of said second liquid flowing
into said round tube; and a second pressure sensor placed in a
downstream side of said round tube for measuring a pressure of said
second liquid flowing out of said round tube.
20. A substrate processing apparatus for processing a substrate,
comprising: a substrate holding part for holding a substrate; a
first conduit through which a first liquid flows; a second conduit
through which a second liquid flows, said second conduit connected
to said first conduit; a liquid supply apparatus installed on an
upstream side of said second conduit for supplying said second
liquid; and a processing liquid supply part, located in a
downstream side of a connected point of said first conduit and said
second conduit, for supplying a processing liquid which is a
mixture of said first liquid and said second liquid to said
substrate, wherein said liquid supply apparatus comprises a pump
mechanism for pumping out said second liquid to a conduit connected
to said second conduit by applying pressure to a flexible chamber
to reduce a volume of said flexible chamber; a flowmeter placed in
a downstream side of said pump mechanism for measuring a flowrate
of said second liquid flowing through said conduit; and a
controller for sending an electrical signal to said pump mechanism,
said electrical signal controlling pressure applied to said
flexible chamber so that said flowrate of said second liquid
flowing through said conduit is adjusted to a predetermined
flowrate on the basis of a flowrate of said second liquid obtained
by said flowmeter.
21. The substrate processing apparatus according to claim 20,
wherein said flexible chamber is made of resin.
22. The substrate processing apparatus according to claim 20,
wherein said flexible chamber comprises a bellows.
23. The substrate processing apparatus according to claim 20,
wherein said pump mechanism comprises a pressure chamber housing
said flexible chamber; and an electro-pneumatic regulator for
adjusting pressure in a space between said pressure chamber and
said flexible chamber.
24. The substrate processing apparatus according to claim 20,
wherein said liquid supply apparatus further comprises another pump
mechanism which has the same structure as said pump mechanism, and
compression of one chamber of said flexible chamber of said pump
mechanism and another flexible chamber of said another pump
mechanism and concurrent expansion of the other chamber of said
flexible chamber and said another flexible chamber are performed
alternately to said flexible chamber and said another flexible
chamber by control of said controller.
25. The substrate processing apparatus according to claim 24,
wherein before compression of said one chamber is stopped,
expansion of said other chamber is stopped and compression of said
other chamber is started.
26. The substrate processing apparatus according to claim 20,
wherein said flowmeter is a differential pressure flowmeter, and
said differential pressure flowmeter comprises a round tube
provided as a part of said conduit in which a flow of said second
liquid with a Reynolds number less than or equal to 2000 is formed;
a first pressure sensor placed between said pump mechanism and said
round tube for measuring a pressure of said second liquid flowing
into said round tube; and a second pressure sensor placed in a
downstream side of said round tube for measuring a pressure of said
second liquid flowing out of said round tube.
27. A liquid supply method for supplying a liquid, comprising the
steps of: a) storing a liquid supplied from a liquid supply source
in a flexible chamber by expanding said flexible chamber to
increase a volume of said flexible chamber in a pump mechanism; and
b) pumping out said liquid to a conduit by applying pressure to
said flexible chamber to reduce said volume of said flexible
chamber, wherein said step b) comprises b1) measuring a flowrate of
said liquid flowing through said conduit in a downstream side of
said pump mechanism; and b2) controlling pressure applied to said
flexible chamber so that said flowrate of said liquid flowing
through said conduit is adjusted to a predetermined flowrate on the
basis of said flowrate measured in said step b1).
28. The liquid supply method according to claim 27, further
comprising the steps of: c) storing said liquid supplied from said
liquid supply source in another flexible chamber by expanding said
another flexible chamber to increase a volume of said another
flexible chamber in another pump mechanism; and d) pumping out said
liquid to said conduit by applying pressure to said another
flexible chamber to reduce said volume of said another flexible
chamber, wherein said step d) comprises d1) measuring a flowrate of
said liquid flowing through said conduit in a downstream side of
said another pump mechanism; and d2) controlling pressure applied
to said another flexible chamber so that said flowrate of said
liquid flowing through said conduit is adjusted to said
predetermined flowrate on the basis of said flowrate measured in
said step d1), wherein said step a) and said step d) are performed
almost concurrently, said step b) and said step c) are performed
almost concurrently, and said step a) and said step d), and said
step b) and said step c) are performed alternately.
29. The liquid supply method according to claim 28, wherein said
step b) starts before said step d) ends, and said step d) starts
before said step b) ends.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and a method
for supplying a liquid and preferably, an apparatus for supplying a
liquid is used for an apparatus for processing a substrate.
[0003] 2. Description of the Background Art
[0004] Conventionally, in cleaning a semiconductor substrate
(hereinafter, referred to as simply "substrate"), well known a
technique where a dilute hydrochloric acid (HCl) is used instead of
a pure water as a cleaning liquid, whereby preventing fine
particles in the cleaning liquid from adhering to a surface of the
substrate by a Coulomb force. Also, etching of a substrate is
performed by using a dilute hydrofluoric acid (HF) or final
cleaning of the substrate is performed by using a dilute acid
solution (hydrochloric acid, hydrofluoric acid or the like).
[0005] A cleaning apparatus of a substrate uses a solution which is
obtained by diluting a stock solution of the hydrochloric acid at
less than or equal to 1/1000. For simplification or miniaturization
or the like of a construction of an apparatus, diluted solution is
normally produced by a method (i.e., the so-called direct mixing
method) in which a small amount of an undiluted solution of
hydrochloric acid is directly injected into a tube for pure water
of the cleaning apparatus. In the cleaning apparatus, a flowrate of
the hydrochloric acid injected into the pure water is measured by a
flowmeter and by controlling the flowrate of the hydrochloric acid
on the basis of an output from the flowmeter, the diluted solution
is set at the desired concentration.
[0006] In the above case, U.S. Pat. No. 5,672,832 (Document 1) and
U.S. Pat. No. 6,578,435 (Document 2) disclose a differential
pressure flowmeter for measuring a flowrate by measuring a pressure
difference in the front and back of a nozzle disposed within a
conduit. Japanese Patent Application Laid Open Gazette No.
2004-226142 (Document 3) and Japanese Patent Application Laid Open
Gazette No. 2004-226144 (Document 4) disclose a differential
pressure flowmeter where by measuring a pressure difference in both
ends of a capillary, measurement of a very small flowrate is
performed stably.
[0007] Japanese Patent Application Laid Open Gazette No. 11-94608
(Document 5) discloses a technique for improving the measuring
accuracy of a flowrate in a flowmeter including a float which moves
up and down according to a flowrate of a fluid in a pipe thereof.
Rod-shaped elements project upward and downward from the float, and
a magnet is placed in the pipe surrounding the float and the
rod-shaped elements, whereby the float is kept on a center axis of
the pipe, and slight vibration is prevented. The document 5 also
discloses a technique for adjusting a supply rate of chemicals in a
substrate processing apparatus comprising this flowmeter, where a
pneumatic valve positioned in a supply pipe of chemicals is
controlled on the basis of an output from the flowmeter.
[0008] In producing the diluted solution, an extremely small amount
of undiluted solution needs to be injected into the pure water with
high accuracy. For example, in a batch-type cleaning apparatus, a
flowrate of the undiluted solution is normally less than or equal
to 100 ml/min, this very small flowrate needs to be measured high
accurately and controlled. In a single wafer-type cleaning
apparatus, a flowrate of a stock (or undiluted) solution is set to
be less than or equal to 10 ml/min.
[0009] Since the differential pressure flowmeters of Documents 1
and 2 make turbulent flow in the vicinity of the nozzle to measure
a flowrate, they are not suitable for measurement of a very small
flowrate having a high possibility of a laminar flow. In some
liquid mass flowmeters for measuring a very small flowrate, the
inside of the flowmeter is covered with resin for increasing
durability against chemicals, however, it is needed for the inside
of the flowmeter to be covered with thick resin for durability
against a hydrofluoric acid or the like, and it is difficult to
measure a flowrate accurately by these flowmeters.
[0010] In the differential pressure flowmeters of Documents 3 and
4, a long capillary is used as a pressure loss part and assuming
that a flow of a liquid in the capillary is laminar, a flowrate is
obtained on the basis of an equation with respect to pressure loss
in the laminar flow in a round tube. However, in the case where the
flow is transitional or turbulent, the measuring accuracy of a
flowrate decreases, and thus it is important to make a stable
laminar flow. Also, since the flowrate is obtained by using the
above equation concerning a straight round tube in spite of using
the capillary having a bending part actually, it increases errors
of measured flowrate.
[0011] In the substrate processing apparatus of Document 5, by
controlling the pneumatic valve disposed within the supply pipe of
the chemicals, a valve opening (i.e., a degree of a restriction of
the supply pipe) changes to adjust the flowrate of the chemicals.
It is therefore possible to supply the chemicals with sufficient
accuracy in supply of a large flowrate, but there is a limit for
improving the accuracy of a supply amount in supply of a small
flowrate. In a conduit through which high-concentration
hydrofluoric acid or hydrochloric acid flows, normally, a region of
a valve exposed to a liquid for adjusting a flowrate such as a
pneumatic valve or the like is made of fluorocarbon resin. The
fluorocarbon resin has a low machining accuracy in comparison with
metal or the like and it tends to change by an external force or
surrounding temperature. Since a valve for adjusting a flowrate is
needed to adjust a very small cross section of a very small conduit
accurately, it is difficult to form this valve by such material
with low shape stability.
[0012] On the other hand, when a liquid of a small flowrate is
pumped out, for example, by an air cylinder without the valve such
as the pneumatic valve or the like for adjusting a flowrate, the
piston of the air cylinder needs to move at a very low speed. In
this case, since a frictional resistance between the cylinder and
the piston changes repeatedly between a static friction and a
sliding friction, the piston vibrates or the air cylinder moves at
a higher speed than a predetermined speed repeatedly after the
piston is stopped. This phenomenon is called chattering or jerking
and makes the accuracy of the supply amount low. In a case where
the air cylinder is driven while preventing chattering or the like,
it is difficult to keep the moving speed of the piston 1 mm/sec or
less.
SUMMARY OF THE INVENTION
[0013] The present invention is intended for a liquid supply
apparatus for supplying a liquid. The liquid supply apparatus
comprises a pump mechanism for pumping out a liquid to a conduit by
applying pressure to a flexible chamber to reduce a volume of the
flexible chamber, a flowmeter placed in a downstream side of the
pump mechanism for measuring a flowrate of the liquid flowing
through the conduit, and a controller for sending an electrical
signal to the pump mechanism, the electrical signal controlling
pressure applied to the flexible chamber so that the flowrate of
the liquid flowing through the conduit is adjusted to a
predetermined flowrate on the basis of a flowrate of the liquid
obtained by the flowmeter. According to the liquid supply apparatus
in accordance with the present invention, it is possible to supply
the liquid of a small flowrate while controlling the flowrate
accurately.
[0014] According to one preferred embodiment of the present
invention, since the flexible chamber is made of resin, it is
possible to supply various kinds of liquid. According to another
preferred embodiment of the present invention, since the flexible
chamber comprises a bellows, it is possible to change a volume of
the flexible chamber easily and suppress deterioration of the
flexible chamber.
[0015] According to still another preferred embodiment of the
present invention, the pump mechanism comprises a pressure chamber
housing the flexible chamber, and an electro-pneumatic regulator
for adjusting pressure in a space between the pressure chamber and
the flexible chamber. This makes it possible to control the
pressure in the space between the pressure chamber and the flexible
chamber with high response and high accuracy.
[0016] According to an aspect of the present invention, the liquid
supply apparatus further comprises the other pump mechanism which
has the same constituents as the pump mechanism, and in the
apparatus, compression of one chamber of the flexible chamber of
the pump mechanism and the other flexible chamber of the other pump
mechanism and concurrent expansion of the other chamber of the
flexible chamber and the other flexible chamber are performed
alternately to the flexible chamber and the other flexible chamber
by control of the controller. This makes it possible to supply the
liquid of a small flowrate long hours continuously while
controlling the flowrate accurately.
[0017] According to another aspect of the present invention, the
flowmeter is a differential pressure flowmeter, and the
differential pressure flowmeter comprises a round tube provided as
a part of the conduit in which a flow of the liquid with a Reynolds
number less than or equal to 2000 is formed, a first pressure
sensor placed between the pump mechanism and the round tube for
measuring a pressure of the liquid flowing into the round tube, and
a second pressure sensor placed in a downstream side of the round
tube for measuring a pressure of the liquid flowing out of the
round tube. This makes it possible to measure the flowrate with
high accuracy stably.
[0018] The present invention is also intended for a method for
supplying a liquid and also intended for a substrate processing
apparatus comprising the liquid supply apparatus.
[0019] These and other objects, features, aspects and advantages of
the present invention will become more apparent from the following
detailed description of the present invention when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a view illustrating a construction of a liquid
supply apparatus in accordance with a first preferred
embodiment;
[0021] FIG. 2 and FIG. 3 are enlarged views illustrating the
vicinity of a flexible chamber and a pressure chamber;
[0022] FIG. 4 and FIG. 5 are a front view and a plan view
illustrating a construction of a flowmeter;
[0023] FIG. 6 is a graph illustrating a relation between a pressure
difference and a flowrate;
[0024] FIG. 7 is a view illustrating an operation flow of the
liquid supply apparatus for supplying a liquid;
[0025] FIG. 8 is a view illustrating an operation flow of the
liquid supply apparatus for controlling a flowrate;
[0026] FIG. 9 is a view illustrating a pump mechanism of a
comparative example;
[0027] FIG. 10 is a view illustrating a construction of a liquid
supply apparatus in accordance with a second preferred
embodiment;
[0028] FIG. 11 and FIG. 12 are views illustrating an operation flow
of the liquid supply apparatus for supplying a liquid;
[0029] FIG. 13 is a view illustrating a state of switching between
a first pump mechanism and a second pump mechanism;
[0030] FIG. 14 is a view illustrating an operation flow of the
liquid supply apparatus for controlling a flowrate;
[0031] FIG. 15 is a view illustrating a change of a flowrate;
[0032] FIG. 16 is a view illustrating a pump mechanism of a liquid
supply apparatus in accordance with a third preferred embodiment;
and
[0033] FIG. 17 and FIG. 18 are views illustrating substrate
processing apparatuses in accordance with fourth and fifth
preferred embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] FIG. 1 is a view illustrating a construction of a liquid
supply apparatus 1 in accordance with the first preferred
embodiment of the present invention. The liquid supply apparatus 1
comprises a conduit 11 through which a liquid flows, a liquid
supply source 12 connected to an upstream side of the conduit 11
for storing the liquid, a pump mechanism 13 placed in a downstream
side of the liquid supply source 12 for storing the liquid supplied
from the liquid supply source 12 to pump out the liquid to a
downstream side of the conduit 11, a differential pressure
flowmeter 14 placed in a downstream side of the pump mechanism 13
for measuring a flowrate of the liquid flowing through the conduit
11 (i.e., an amount of the liquid flowing through the conduit 11
per unit time), and a controller 15 for controlling these
mechanisms. On the conduit 11, a first filter 111 and a first check
valve 112 are installed between the liquid supply source 12 and the
pump mechanism 13, a second check valve 113 is installed between
the pump mechanism 13 and the flowmeter 14, and a pressure control
tube 147 and a second filter 114 are installed on a downstream side
of the flowmeter 14. In FIG. 1, hatching of cross sections are
omitted.
[0035] The liquid supply source 12 is a bottle, a region exposed to
the liquid of the bottle is covered with fluorocarbon resin (for
example, PTFE (poly-tetra-fluoro-ethylene)), and the top of the
bottle is open to the atmosphere. Stock solution such as
hydrochloric acid, hydrofluoric acid, or the like is stored in the
liquid supply source 12 and the stock solution is supplied to the
pump mechanism 13 through the conduit 11. The first filter 111 is
made of PTFE, for example and removes impurities such as particles
and the like from the liquid which is supplied to the pump
mechanism 13. The second filter 114 is also made of the
fluorocarbon resin such as PTFE or the like and has a mesh of 0.05
.mu.m, for example. In the liquid supply apparatus 1, the second
filter 114 removes impurities from the liquid which is supplied
from the liquid supply apparatus 1 to other apparatus and the
like.
[0036] The whole of the first check valve 112 and the second check
valve 113 are made of PFA (per-fluoro-alkoxy), for example and the
first check valve 112 and the second check valve 113 prevent the
liquid from flowing back from a downstream side to an upstream side
of each check valve. Each of the first check valve 112 and the
second check valve 113 may have constituents where a sapphire ball
and a sapphire valve seat are provided in its outer casing made of
the fluorocarbon resin.
[0037] The region exposed to the liquid of the liquid supply source
12, the first filter 111, the second filter 114, the first check
valve 112, and the second check valve 113 are made of the
fluorocarbon resin or the like, and thus they have high durability
(mainly, corrosion resistance) against various kinds of liquid. The
pressure control tube 147 will be discussed later together with the
detailed description of the flowmeter 14.
[0038] The pump mechanism 13 comprises a flexible chamber 131 which
is flexible and made of resin, an approximately cylindrical shaped
pressure chamber 132 housing the flexible chamber 131 having an
approximately cylindrical shape, and an electro-pneumatic regulator
133 and an ejector 134 for supplying or discharging air to/from the
pressure chamber 132 to adjust pressure in a space between the
pressure chamber 132 and the flexible chamber 131. The flexible
chamber 131 is connected to the conduit 11 between the first check
valve 112 and the second check valve 113. The electro-pneumatic
regulator 133 and the ejector 134 are respectively connected to the
pressure chamber 132 through pneumatic valves 1331, 1341.
[0039] The flexible chamber 131 comprises a bellows 1311 as a part
thereof. Materials, such as PTFE, PFA, PEEK
(poly-ether-ether-ketone), PCTFE (poly-chloro-trifluoro-ethylene),
ETFE (ethylene-tetrafluoro-ethylene), FEP
(fluorinated-ethylene-propylene) or the like, are available for the
flexible chamber 131. A material for the flexible chamber 131 is
determined on the basis of various kinds of liquid to be pumped
out. In the preferred embodiment, the flexible chamber 131 is made
of PFA or the like such as fluorocarbon resin. Since the pressure
chamber 132 is not, normally, exposed to the liquid stored in the
flexible chamber 131, the pressure chamber 132 may be made of vinyl
chloride or the like which has slightly lower durability against
liquid than the flexible chamber 131.
[0040] The electro-pneumatic regulator 133 comprises an air inlet
connected to an external compressor for applying pressure, an air
outlet for pressure-relief, and an outlet connected into the
pressure chamber 132 for adjusting the pressure in the space
between the pressure chamber 132 and the flexible chamber 131. The
electro-pneumatic regulator 133 controls the pressure in the space
between the pressure chamber 132 and the flexible chamber 131
steplessly and continuously to be a directed pressure on the basis
of an electrical signal (i.e., in proportion to an input current or
the like) sent from a feedback controller 151 of the controller 15.
When the electro-pneumatic regulator 133 controls the pressure in
the pressure chamber 132, the pneumatic valve 1331 is opened by an
electromagnetic valve 1332 which is driven by a sequence controller
152 of the controller 15.
[0041] The ejector 134 is connected to the external compressor
through a regulator 1343 and a pneumatic valve 1344. When the
ejector 134 discharges air in the pressure chamber 132, pneumatic
valves 1341, 1344 are opened by electromagnetic valves 1342, 1345
driven by the sequence controller 152, air supplied from the
external compressor flows out of the ejector 134 at high speed, and
then air in the pressure chamber 132 is discharged through the
ejector 134. In the pump mechanism 13, the electromagnetic valves
may be used instead of the pneumatic valves 1331, 1341, 1344.
[0042] FIG. 2 and FIG. 3 are enlarged views illustrating the
vicinity of the flexible chamber 131 and the pressure chamber 132
of the pump mechanism 13. FIG. 2 and FIG. 3 respectively illustrate
states where the flexible chamber 131 is expanded and compressed.
In the pump mechanism 13, an upper end 1312 of the flexible chamber
131 having the bellows 1311 is fixed to the pressure chamber 132
and an lower end 1313 is made free.
[0043] In the pump mechanism 13, the electro-pneumatic regulator
133 (see FIG. 1) supplies air from the bottom of the pressure
chamber 132 (i.e., a part opposed to the lower end 1313 of the
flexible chamber 131) into the pressure chamber 132, pressure is
applied to the flexible chamber 131, and then the flexible chamber
131 in the state shown in FIG. 2 (hereinafter, referred to as
"expanded state") is compressed and gradually changes to the state
shown in FIG. 3 (hereinafter, referred to as "compressed state").
With this operation, the liquid stored in the flexible chamber 131
is pumped out to the conduit 11 by applying pressure to the
flexible chamber 131 to reduce a (internal) volume of the flexible
chamber 131. The check valve 112 prevents the liquid pumped out of
the flexible chamber 131 from flowing into the liquid supply source
12 (i.e., the upstream side) and the liquid flows to the flowmeter
14 (i.e., the downstream side) through the check valve 113.
[0044] In the pump mechanism 13, the ejector 134 (see FIG. 1)
discharges air from the bottom of the pressure chamber 132, the
pressure in the pressure chamber 132 changes to be negative, and
then the flexible chamber 131 changes gradually from the compressed
state shown in FIG. 3 to the expanded state shown in FIG. 2. With
this operation, by expanding the flexible chamber 131 to increase a
volume of the flexible chamber 131, the liquid is sucked from the
liquid supply source 12 through the conduit 11 and the check valve
112, the sucked liquid flows into the flexible chamber 131, and it
is stored in the flexible chamber 131. At this time, the check
valve 113 prevents suction of the liquid from the downstream side
of the pump mechanism 13.
[0045] In the pump mechanism 13, a volume of a space between the
flexible chamber 131 and the pressure chamber 132, that is to say,
a volume of a space where pressure is controlled by the
electro-pneumatic regulator 133, is made small, and this improves
response of transition between suction of the liquid from the
liquid supply source 12 to the flexible chamber 131 and pumping out
of the liquid from the flexible chamber 131.
[0046] As shown in FIG. 2 and FIG. 3, the pump mechanism 13 further
comprises a displacement sensor 135 for detecting a displacement of
the lower end 1313 which is a free end of the flexible chamber 131
with respect to the pressure chamber 132, and a leakage sensor 136
for detecting a leakage, if there is a leakage of the liquid from
the flexible chamber 131.
[0047] The displacement sensor 135 comprises two pairs of light
emitting parts 1351 and light receiving parts 1352 on a side wall
of the pressure chamber 132 (i.e., inner surface parallel to a
direction of expansion and compression of the bellows 1311). Each
pair of the light emitting parts 1351 and the light receiving parts
1352 is positioned in the both sides of the flexible chamber 131 in
the expanded state shown in FIG. 2. Location of one pair with
respect to the direction of expansion and compression of the
flexible chamber 131 is almost same as the location of the lower
end 1313 of the flexible chamber 131 in the expanded state, and
location of the other pair is slightly lower than the location of
the lower end 1313 of the flexible chamber 131 in the compressed
state shown in FIG. 3.
[0048] In the pump mechanism 13, when the flexible chamber 131 is
in the expanded state shown in FIG. 2, the flexible chamber 131
blocks lights from the two light emitting parts 1351, the
displacement sensor 135 determines the flexible chamber 131 is in
the expanded state. When the flexible chamber 131 is in the
compressed state shown in FIG. 3, lights from the two light
emitting parts 1351 pass through the inner space of the pressure
chamber 132, the light receiving parts 1352 receive the lights, and
then the displacement sensor 135 determines the flexible chamber
131 is in the compressed state. In a case where a light from one
light emitting part 1351 which is located near the bottom of the
pressure chamber 132 is received by the opposed light receiving
part 1352 and a light from the other light emitting part 1351 does
not reach the light receiving part 1352, the displacement sensor
135 determines the flexible chamber 131 is in an intermediate state
between the state of FIG. 2 and that of FIG. 3.
[0049] The leakage sensor 136 comprises a pair of electrodes 1361,
and the pair of electrodes 1361 is positioned in the bottom of
grooves 1321 located on an inner side of the bottom of the pressure
chamber 132. In the pump mechanism 13, in a case where the liquid
leaks from the flexible chamber 131, the leaked liquid collects in
the grooves 1321 at the bottom of the pressure chamber 132, and the
pair of electrodes 1361 is electrically connected each other
through the liquid (electrolyte solution) in the grooves 1321. The
leakage sensor 136 detects conduction between the pair of
electrodes 1361 to detect the leakage of the liquid from the
flexible chamber 131.
[0050] FIG. 4 and FIG. 5 are a front view and a plan view
illustrating a construction of the flowmeter 14, respectively. As
shown in FIG. 4 and FIG. 5, the flowmeter 14 comprises a tube 143
provided as a part of the conduit 11 (see FIG. 1) and which is a
pressure loss part having a circular section (i.e., round tube), a
tube base 144 to which the tube 143 is attached, a first pressure
sensor 141 placed between the pump mechanism 13 (see FIG. 1) and
the tube 143 (in the left of FIG. 4 and FIG. 5) for measuring a
pressure of the liquid flowing into the tube 143 and a second
pressure sensor 142 placed in a downstream side of the tube 143 for
measuring a pressure of the liquid flowing out of the tube 143. As
shown in FIG. 4, the flowmeter 14 further comprises a storage part
145 for storing information and an operation part 146 for
performing various computations.
[0051] The tube 143 is made of resin and has high durability
(mainly, corrosion resistance) against various kinds of liquid. The
tube 143 has flexibility and is formed in a coil above the tube
base 144 as shown in FIG. 4. Materials, such as PEEK, PTFE, PCTFE,
PFA, ETFE, FEP, or the like, are available for the tube 143. A
material for the tube 143 is determined on the basis of various
kinds of liquid to be measured, an inner diameter of the tube 143,
or the like. In the first preferred embodiment, the tube 143 is
made of PFA.
[0052] The inner diameter of the tube 143 is determined on the
basis of the maximum value of a measured flowrate of the flowmeter
14 such that a Reynolds number of a flow of the liquid within the
tube 143 is made at less than or equal to 2000. The Reynolds number
is the dimensionless number indicating the type of a flow (i.e., a
flow is laminar or turbulent). When a Reynolds number of a flow is
smaller than a critical Reynolds number (about 2000 to 2300), the
flow is kept laminar. A Reynolds number Re within the tube 143
having a circular section is expressed as Eq. 1 where D (m) is the
inner diameter of the tube 143. Re=.rho.UD/.mu.=4 .rho.Q/.pi..mu.D
Eq. 1
[0053] In Eq. 1, .rho. is density (kg/m.sup.3) of the liquid
flowing through the tube 143, .mu. is coefficient of viscosity
(Ns/m.sup.2) of the liquid, U is average flowing velocity (m/s) of
the liquid in a cross-sectional area vertical to a longitudinal
direction of the tube 143, and Q is a flowrate (m.sup.3/s) of the
liquid.
[0054] In the flowmeter 14, the maximum value of a Reynolds number
within a measuring range (i.e., a Reynolds number at the maximum of
the measured flowrate) is set to be less than or equal to 2000 and
laminar flow occurs within the tube 143. For this reason, an inlet
length X(m) necessary for full development of the flow of the
liquid (i.e., velocity distribution of the flow within the
cross-sectional area of the tube 143 goes into a constant state) is
expressed as Eq. 2 for the Boussinesq equation by using the
Reynolds number Re and the inner diameter D(m) of the tube 143.
X.gtoreq.0.065 ReD Eq. 2
[0055] The length of the tube 143 is preferably set to be 130 or
more times than the inner diameter of the tube 143 so that the
length of which becomes longer than the inlet length even if the
Reynolds Number is 2000. The length of the tube 143 is determined
on the basis of a pressure loss required in the tube 143 (i.e., a
pressure difference between both ends of the tube 143), and an
outer diameter of the tube 143 is set to be 1.5 or more times
larger than the inner diameter so as to ensure mechanical strength
of the tube 143 of resin.
[0056] The tube base 144 is a block of resin (made of PTFE which is
the fluorocarbon resin, for example) and has two L-shaped channels
therein. As shown in FIG. 4, both ends of the tube 143 are
detachably attached at the top of the tube base 144 through tube
fittings of resin. As the tube fittings, various small diameter
fittings for liquid chromatography or the like can be used. The
inside channels of the tube base 144, the tube 143, inside channels
of the first pressure sensor 141 and the second pressure sensor 142
(later discussed), and pressure transducers 1411, 1421 are also
provided as parts of the conduit 11 of the liquid supply apparatus
1.
[0057] As shown in FIG. 4 and FIG. 5, the first pressure sensor 141
and the second pressure sensor 142 comprise approximately
cylindrical pressure transducers 1411, 1421, and the pressure
transducers 1411, 1421 are easy to exhaust air while injecting the
liquid because their heights are low. As shown in FIG. 4, members
1412, 1422 which are positioned in the pressure transducers 1411,
1421 and exposed to the liquid are made of resin (PTFE which is
fluorocarbon resin, for example). In the first pressure sensor 141
and the second pressure sensor 142, the inside channels and the
pressure transducers 1411, 1421 are connected directly and
therefore this prevents accumulation of the liquid. Both ends of
the inside channels of the first pressure sensor 141 and the second
pressure sensor 142 have fittings which allow easy connection. In
the first preferred embodiment, the first pressure sensor 141 and
the second pressure sensor 142 have a measuring range from 0 to 0.2
Mpa (megapascal).
[0058] In the flowmeter 14, the liquid flows into the first
pressure sensor 141 from the upstream side continuously, the liquid
passes through the first pressure sensor 141, the tube base 144,
the tube 143, and the second pressure sensor 142 sequentially, and
then flows out to the downstream side. While the liquid is passing
through the flowmeter 14, a flowrate of the liquid is measured
continuously. Next discussion will be made on an operation flow of
the flowmeter 14 for measuring a flowrate of the liquid.
[0059] While the liquid is flowing through the flowmeter 14, a
pressure of the liquid flowing into the tube 143 is measured by the
first pressure sensor 141 and a pressure of the liquid flowing out
of the tube 143 is measured by the second pressure sensor 142.
Outputs from the first pressure sensor 141 and the second pressure
sensor 142 (for example, the outputs are values of pressures to be
measured which are converted to electrical signals ranging from 4
to 20 mA (milliampere) by both the pressure sensors) are
transmitted to a subtracter 1461 of an operation part 146, the
output of the second pressure sensor 142 is subtracted from the
output of the first pressure sensor 141 in the subtracter 1461, and
then a pressure difference between both ends of the tube 143 is
obtained.
[0060] FIG. 6 is a graph illustrating a relation (hereinafter
referred to as "flowrate information") between the pressure
difference between both ends of the tube 143 and the flowrate of
the liquid flowing through the tube 143. As shown in FIG. 6, the
pressure difference and the flowrate have an approximately
proportionality relation in the flowmeter 14. Since the flow within
the tube 143 is laminar where the Reynolds number is less than or
equal to 2000, the pressure difference and the flowrate should be
directly proportioned theoretically. The reason why the pressure
difference and the flowrate are not perfectly proportioned is
considered as an effect of the flow in the vicinity of both ends of
the tube 143, a state of an inside surface of the tube 143, and the
like.
[0061] Before the flowmeter 14 is actually installed in the liquid
supply apparatus 1, the flowrate information is obtained by the
following method in advance. A syringe pump is attached to the
upstream side of the first pressure sensor 141 and the liquid
(preferably, the pure water) is injected at a constant ejection
rate. The injected liquid passes through the first pressure sensor
141, the tube base 144, the tube 143, and the second pressure
sensor 142, and flows out of the flowmeter 14. In the first
pressure sensor 141 and the second pressure sensor 142, pressures
in passing of the liquid are measured and a pressure difference is
obtained. After the passage of a predetermined time, a weight of
the liquid flowing out of the flowmeter 14 is measured and a
flowrate corresponding to the pressure difference is obtained.
Then, by changing the ejection rate of the syringe pump and
repeating measurement of the pressure difference and the flowrate,
the flowrate information shown in FIG. 6 is obtained. This obtained
flowrate information is stored in the storage part 145 before
actual use of the flowmeter 14.
[0062] In the flowmeter 14 shown in FIG. 4, the pressure difference
between both ends of the tube 143 obtained by the subtracter 1461
is transmitted to a linearizer 1462 as an electrical signal ranging
from 0 to 5V, for example, and the flowrate information stored in
the storage part 145 in advance is read out by the linearizer 1462.
In the linearizer 1462, a flowrate of the liquid flowing through
the tube 143 is determined automatically on the basis of the
pressure difference and the flowrate information. The flowrate
information stored in the storage part 145 may be a tabular form or
an approximation formula, for example.
[0063] Referring back to FIG. 1, the discussed pressure control
tube 147 is installed between the flowmeter 14 and the second
filter 114. The pressure control tube 147 is made of resin with
high durability against various kinds of liquid. The pressure
control tube 147 also has flexibility and is formed in a coil.
[0064] In the liquid supply apparatus 1, since the liquid passes
through the pressure control tube 147 before the liquid flowing out
of the flowmeter 14 is supplied to another apparatus or the like
through the second filter 114, pressure of the liquid becomes
relatively low. For this reason, even if a required pressure in
supplying the liquid from the liquid supply apparatus 1 is almost
equal to an atmospheric pressure, it can be avoided that a pressure
to be measured (i.e., a pressure difference between a pressure of
the liquid and an atmospheric pressure) in the second pressure
sensor 142 of the flowmeter 14 nears to 0 where the measuring
accuracy becomes low. This improves the measuring accuracy of a
flowrate by the flowmeter 14. From the viewpoint of improving the
measuring accuracy of the flowrate, it is preferable that the
length of the pressure control tube 147 is determined so that the
minimum value of a pressure measured by the second pressure sensor
142 falls in a range 10% or more (in the preferred embodiment, the
range is 20 kPa or more) from the bottom of the measuring range of
the second pressure sensor 142, for example.
[0065] Next discussion will be made on an operation flow of the
liquid supply apparatus 1 for supplying the liquid referring to
FIG. 7. When the liquid is supplied by the liquid supply apparatus
1, a user fills the pump mechanism 13 and the conduit 11 with
liquid for preparation. In the liquid filling, an end of the
downstream side of the conduit 11 is connected to a drain.
[0066] The sequence controller 152 of the controller 15 shown in
FIG. 1 closes the pneumatic valve 1331 of the pump mechanism 13 and
opens the pneumatic valves 1341, 1344. The ejector 134 discharges
air between the flexible chamber 131 and the pressure chamber 132,
and then pressure reduction in the pressure chamber 132 is started.
By this, the flexible chamber 131 which is in the compressed state
(see FIG. 3) in advance is expanded, and the liquid is sucked from
the liquid supply source 12 to be supplied to the flexible chamber
131 and stored therein. The displacement sensor 135 (see FIG. 2)
detects that the flexible chamber 131 changed to the expanded state
(see FIG. 2), and the pneumatic valves 1341, 1344 are closed to
complete liquid supply to the flexible chamber 131 (Step S11). In
the preferred embodiment, an amount of the liquid supplied to the
flexible chamber 131 in one expansion is 30 ml and a volume of the
flexible chamber 131 in the expanded state is 100 ml.
[0067] Subsequently, the user confirms whether or not air remains
in the flexible chamber 131 and the conduit 11 (Step S12). In a
case where air remains, the sequence controller 152 opens the
pneumatic valve 1331, and the electro-pneumatic regulator 133
starts supplying air between the flexible chamber 131 and the
pressure chamber 132 to increase the pressure in the pressure
chamber 132 (i.e., pressure around the flexible chamber 131). The
flexible chamber 131 is compressed by the increase of the pressure,
and air remaining in the flexible chamber 131 and the conduit 11 is
discharged from the downstream side of the conduit 11 to the
outside of the liquid supply apparatus 1.
[0068] After the displacement sensor 135 detects the flexible
chamber 131 changed to the compressed state, the pneumatic valve
1331 is closed and discharge of air in the flexible chamber 131 and
the conduit 11 is stopped (Step S121), and liquid supply to the
flexible chamber 131 is restarted back to Step S11. In the liquid
supply apparatus 1, liquid supply to the flexible chamber 131 and
discharge of air from the flexible chamber 131 and the conduit 11
(Steps S11 to S121) are repeated until air in the flexible chamber
131 and the conduit 11 is completely discharged and the liquid
filling is finished.
[0069] After air in the flexible chamber 131 and the conduit 11 is
completely discharged (Step S12), the end of the downstream side of
the conduit 11 is connected to an external apparatus or the like to
be supplied. Like in Step S121, the electro-pneumatic regulator 133
supplies air to the pressure chamber 132 to apply pressure to the
flexible chamber 131, and the flexible chamber 131 in the expanded
state is compressed. The liquid stored in the flexible chamber 131
is pumped out to the conduit 11 and supplied to the external
apparatus or the like (Step S13). In the liquid supply apparatus 1,
while the pump mechanism 13 is pumping out the liquid from the
flexible chamber 131, a flowrate control shown in FIG. 8 is
continuously performed. Next discussion will be made on an
operation flow of the liquid supply apparatus 1 for controlling a
flowrate.
[0070] In the liquid supply apparatus 1, when pumping out of the
liquid from the pump mechanism 13 to the conduit 11 is started, a
flowrate of the liquid flowing through the conduit 11 is measured
by the flowmeter 14 which is placed in the downstream side of the
pump mechanism 13, and a measured flowrate is sent to the feedback
controller 151 of the controller 15 (Step S131). Subsequently, the
feedback controller 151 determines whether or not the measured
flowrate obtained by the flowmeter 14 is equal to a predetermined
flowrate which is inputted from the outside (Step S132).
[0071] In a case where the measured flowrate differs from the
predetermined flowrate, the feedback controller 151 sends a command
value of pressure as an electrical signal to the electro-pneumatic
regulator 133 of the pump mechanism 13 on the basis of the measured
flowrate and controls pressure applied to the flexible chamber 131
so that the flowrate of the liquid flowing through the conduit 11
is adjusted to the predetermined flowrate (Step S133). In a case
where the measured flowrate is equal to the predetermined flowrate,
the pressure applied to the flexible chamber 131 is kept. In the
preferred embodiment, the feedback controller 151 utilizes a PID
Control as a control method of the flowrate. An electrical signal
sending from the feedback controller 151 to the electro-pneumatic
regulator 133 is a current ranging from 4 to 20 mA.
[0072] In the pump mechanism 13, since a reaction force by the
bellows 1311 of the flexible chamber 131 increases gradually with
compression of the flexible chamber 131, normally, control of the
electro-pneumatic regulator 133 is performed so that the pressure
in the space between the flexible chamber 131 and the pressure
chamber 132 increases gradually to make the measured flowrate equal
to the predetermined flowrate.
[0073] In the liquid supply apparatus 1, it is checked repeatedly
whether pumping out of the liquid from the pump mechanism 13 is
complete or not (Step S134), and while pumping out of the liquid
from the flexible chamber 131 is performed, steps for measuring a
flowrate to control the pressure applied to the flexible chamber
131 (Steps S131 to 133) are repeated. With this operation, in the
liquid supply apparatus 1, liquid supply to the external apparatus
or the like is performed while controlling the flowrate so that the
flowrate of the liquid flowing through the conduit 11 is adjusted
to the predetermined flowrate. After the displacement sensor 135
detects the flexible chamber 131 changed to the compressed state,
the pneumatic valve 1331 is closed, and pumping out of the liquid
from the flexible chamber 131 to the conduit 11 is finished (Step
S134). Flowrate measurement by the flowmeter 14 and control of the
electro-pneumatic regulator 133 by the controller 15 are also
ended, and then liquid supply to the external apparatus or the like
is complete. In the preferred embodiment, an amount of liquid
supply in one compression of the flexible chamber 131 is 30 ml.
[0074] In a case where liquid supply of the liquid supply apparatus
1 is repeated, backing to Step S11 after Step S13, the flexible
chamber 131 is reexpanded and the liquid is sucked from the liquid
supply source 12 (not shown in FIG. 7). In this case, when the
flexible chamber 131 is expanded, since in the flexible chamber 131
and the conduit 11 air does not remain and the liquid is filled,
steps for discharging air from the flexible chamber 131 and the
conduit 11 (Steps S12, S121) are omitted, and then Steps S11 and
S13 are repeated.
[0075] As discussed above, in the liquid supply apparatus 1, while
pressure is applied to the flexible chamber 131 of the pump
mechanism 13 and the liquid in the flexible chamber 131 is pumped
out to the conduit 11, the flowrate of the liquid flowing through
the conduit 11 is measured by the flowmeter 14, and the pressure
applied to the flexible chamber 131 is controlled by the feedback
controller 151 so that the measured flowrate is adjusted to the
predetermined flowrate. In the liquid supply apparatus 1, by
controlling the pressure applied to the flexible chamber 131 with
high accuracy, it is possible to supply the liquid of a small
flowrate while controlling the flowrate accurately.
[0076] In the liquid supply apparatus 1, since the flexible chamber
131 of the pump mechanism 13 and the tube 143 of the flowmeter 14
are made of resin with high durability against various kinds of
liquid and the other various constituent elements which are exposed
to the liquid are made of materials such as fluorocarbon resin or
the like with high durability, it is possible to perform supply of
various kinds of liquid.
[0077] In the pump mechanism 13, since the flexible chamber 131
comprises the bellows 1311, it is possible to change a volume of
the flexible chamber 131 easily, that is to say, by a small
pressure. Since, in compressing the flexible chamber 131, the whole
of the bellows 1311 is compressed, it is prevented that the bending
of the flexible chamber 131 in compressing occurs in a part of the
flexible chamber 131, and it is possible to suppress deterioration
caused by repeats of compression and expansion of the flexible
chamber 131 in using the pump mechanism 13.
[0078] In the pump mechanism 13, since the electro-pneumatic
regulator 133 adjusts the pressure in the pressure chamber 132
housing the flexible chamber 131, it is possible to control the
pressure in the space between the pressure chamber 132 and the
flexible chamber 131 with high response and high accuracy.
[0079] In the pump mechanism 13, the lower end 1313 of the flexible
chamber 131 is made free as shown in FIG. 2. FIG. 9 is a view
illustrating a part of a pump mechanism 93 where a lower end of a
flexible chamber is not made free as a comparative example. In the
pump mechanism 93 of the comparative example, a cylinder part 9322
is provided at a lower part of a pressure chamber 932, and inside
the cylinder part 9322 a piston 9323 passing through the bottom of
the flexible chamber 932 to be connected to a lower end 9313 of a
flexible chamber 931 is provided. The piston 9323 comprises a
disk-shaped bottom part 9324 positioned inside of the cylinder part
9322 and a cylindrical shaft 9325 projecting upward from the bottom
part 9324 to be inserted into a through-hole 9326 in the bottom of
the pressure chamber 932. Sealing is provided between the bottom
part 9324 and an internal surface of the cylinder part 9322, and
between an external surface of the shaft 9325 and an internal
surface of the through-hole 9326 so that air does not leak.
[0080] In the pump mechanism 93, by supplying air between the
pressure chamber 932 and the flexible chamber 931 to compress the
flexible chamber 931, the liquid in the flexible chamber 931 is
pumped out. Also, air is supplied to a space surrounded by the
bottom of the pressure chamber 932, the cylinder part 9322, and the
bottom part 9324 of the piston 9323, the bottom part 9324 of the
piston 9323 gets away from the bottom of the pressure chamber 932
relatively. The flexible chamber 931 is expanded and the liquid is
supplied to the flexible chamber 931.
[0081] In the pump mechanism 93, in any case of pumping out the
liquid from the flexible chamber 931 and supplying the liquid to
the flexible chamber 931, the piston 9323 moves up and down
together with the lower end 9313 of the flexible chamber 931. In
movement of the piston 9323, since the bottom part 9324 rubs with
the internal surface of the cylinder part 9322 and the shaft 9325
rubs with the internal surface of the through-hole 9326, frictional
resistance occurs. When the piston 9323 moves at low speed,
chattering or jerking occurs in up and down movements of the lower
end 9313 of the flexible chamber 931, and compression and expansion
of the flexible chamber 931 becomes unstable.
[0082] On the other hand, in the pump mechanism 13 in accordance
with the above preferred embodiment, since the lower end 1313 of
the flexible chamber 131 is made free as shown in FIG. 2, it is
possible to compress the flexible chamber 131 stably (i.e., while
preventing occurrence of the chattering or jerking) by preventing
rubbing against the pressure chamber 132 of the flexible chamber
131 or by making the frictional resistance very small even if
rubbing occurs. As a result, it is possible to control the flowrate
of the liquid to be supplied with higher accuracy in the liquid
supply apparatus 1.
[0083] In the pump mechanism 13, by providing the displacement
sensor 135 for detecting a displacement of the lower end 1313 of
the flexible chamber 131, it is possible to monitor movement of the
flexible chamber 131 in the pressure chamber 132, and it is
therefore possible to increase reliability of the liquid supply
apparatus 1. By positioning the leakage sensor 136 at the bottom of
the pressure chamber 132, even if the liquid leaks from the
flexible chamber 131, the leakage of the liquid is detected
immediately, and it is further possible to increase reliability of
the liquid supply apparatus 1.
[0084] In the flowmeter 14, the flow of the liquid is kept laminar,
and then the pressure difference between both ends of the tube 143
and the flowrate have the approximately proportionality relation.
This prevents resolution of the pressure difference and the
flowrate from changing considerably and makes the measuring
accuracy of the flowrate almost constant regardless of the pressure
difference. Since a change of the flowrate relative to that of the
pressure difference increases, in comparison with another
measurement within turbulent region where the flowrate is
approximately proportioned to square root of the pressure
difference, the measuring accuracy can be improved and further the
range of the flowrate which can be measured is expanded. In the
flowmeter 14, the Reynolds number of the flow within the tube 143
is kept to be less than or equal to 2000 and a transitional flow
where a state of the flow becomes unstable is avoided. After the
flow is made laminar completely, the pressure difference is
obtained and it is thereby possible to measure the flowrate with
high accuracy stably, even if the flowrate of the liquid is very
small. Consequently, it is possible to supply the liquid of a small
flowrate while controlling the flowrate with higher accuracy in the
liquid supply apparatus 1.
[0085] By using a long tube 143 as a pressure loss part to reduce
the pressure of the liquid gradually in the flowmeter 14, even if
the flowrate of the liquid which has a small flowrate is measured,
a significant pressure difference can be obtained without making
the inner diameter of the tube 143 extremely small. Therefore, it
becomes possible to make the inner diameter of the tube 143
relatively large and there is no need to make the flow velocity of
the liquid flowing through the tube 143 extremely high. This
results in preventing foreign substances from blocking the tube 143
and also occurring cavitation in the vicinity of an end of the tube
143 in the downstream side and the like. The flowmeter 14 is
especially suitable for the liquid supply apparatus 1 which needs
high accurate flowrate measurement of the liquid of the small
flowrate.
[0086] FIG. 10 is a view illustrating a construction of a liquid
supply apparatus 1a in accordance with the second preferred
embodiment of the present invention. As shown in FIG. 10, the
liquid supply apparatus 1a has the same constituents as the liquid
supply apparatus 1 shown in FIG. 1 and further comprises the other
pump mechanism 13a having the same structure as the pump mechanism
13. In the following description, the pump mechanism 13 and the
pump mechanism 13a are respectively described as "first pump
mechanism 13" and "second pump mechanism 13a" for distinctiveness.
Other constituent elements are the same as those of FIG. 1 and the
constituent elements are represented by the same reference signs in
the following description. In FIG. 10, hatching of cross sections
are omitted.
[0087] In the liquid supply apparatus 1a, the conduit 11 is divided
into two conduits between the liquid supply source 12, and the
first pump mechanism 13 and the second pump mechanism 13a. Divided
conduits 11 connect between the first pump mechanism 13 and the
second pump mechanism 13a, and the flowmeter 14. In two divided
parts of the conduit 11, the first pump mechanism 13 is connected
between the first check valve 112 and the second check valve 113
which are installed on one divided conduit, and the second pump
mechanism 13a is connected between the third check valve 112a and
the fourth check valve 113a which are installed on the other
divided conduit. The flowmeter 14 for measuring a flowrate of the
liquid flowing through the conduit 11 is located in a downstream
side of a connected point of the above divided conduits.
[0088] The second pump mechanism 13a comprises, like the first pump
mechanism 13, the flexible chamber 131a which is made of resin
(hereinafter, the flexible chamber 131a is referred to as "second
flexible chamber 131a". The flexible chamber 131 of the first pump
mechanism 13 is referred to as "first flexible chamber 131" for
distinctiveness), a pressure chamber 132a housing the second
flexible chamber 131a, and an electro-pneumatic regulator 133a for
adjusting a pressure in a space between the pressure chamber 132a
and the second flexible chamber 131a.
[0089] The second flexible chamber 131a comprises, like the first
flexible chamber 131, a bellows 1311a, and a lower end of the
bellows 1311a is made free. In the pressure chamber 132a, like the
pressure chamber 132 shown in FIG. 2, provided are a displacement
sensor for detecting a displacement of the lower end of the bellows
1311a with respect to the pressure chamber 132a, and a leakage
sensor for detecting a leakage, if there is a leakage of the liquid
from the second flexible chamber 131a. Also in the second pump
mechanism 13a, the displacement sensor detects whether the second
flexible chamber 131a is in a compressed state, an expanded state,
or an intermediate state between the compressed state and the
expanded state.
[0090] The pressure chamber 132a is connected to the
electro-pneumatic regulator 133a through a pneumatic valve 1331a
and is also connected to the ejector 134 of the first pump
mechanism 13 through a pneumatic valve 1341a. In other words, the
first pump mechanism 13 and the second pump mechanism 13a share the
ejector 134. The pneumatic valves 1331a, 1341a are driven by
electromagnetic valves 1332a, 1342a. In the second pump mechanism
13a, these valves, the electro-pneumatic regulator 133a, and the
ejector 134 are controlled by the controller 15, and the second
flexible chamber 131a is compressed and expanded. By this, the
liquid is sucked from the liquid supply source 12 to be stored in
the second flexible chamber 131a, and it is pumped out to the
conduit 11.
[0091] In the liquid supply apparatus 1a, by control of the
controller 15, compression of one chamber of the first flexible
chamber 131 of the first pump mechanism 13 and the second flexible
chamber 131a of the second pump mechanism 13a and concurrent
expansion of the other chamber of the first flexible chamber 131
and the second flexible chamber 131a are performed alternately to
the first flexible chamber 131 and the second flexible chamber
131a. By this, continuous supply of the liquid is performed.
[0092] FIG. 11 and FIG. 12 are views illustrating an operation flow
of the liquid supply apparatus 1a for supplying the liquid. FIG. 13
is a view illustrating a state of switching between the first pump
mechanism 13 and the second pump mechanism 13a in each step after
the later discussed Step S23. A reference sign of the step is
assigned to a position corresponding to each step. Next, referring
to FIG. 11 to FIG. 13, an operation flow of the liquid supply
apparatus 1a will be discussed.
[0093] When the liquid is supplied by the liquid supply apparatus
1a, like in the first preferred embodiment, a user fills the first
pump mechanism 13, the second pump mechanism 13a, and the conduit
11 with liquid for preparation. The ejector 134 discharges air
between the first flexible chamber 131 and the pressure chamber
132, and pressure in the pressure chamber 132 is reduced. The first
flexible chamber 131 changes from the compressed state (see FIG. 3)
to the expanded state (see FIG. 2), and the liquid is sucked from
the liquid supply source 12 to be stored in the first flexible
chamber 131. Concurrently with this operation, the ejector 134
discharges air between the second flexible chamber 131a and the
pressure chamber 132a, and pressure in the pressure chamber 132a is
reduced. The second flexible chamber 131a changes from the
compressed state to the expanded state, and the liquid is sucked
from the liquid supply source 12 to be supplied to the second
flexible chamber 131a and stored therein (Step S21).
[0094] After the first flexible chamber 131 and the second flexible
chamber 131a becomes the expanded state, it is determined whether
or not air remains in the first flexible chamber 131, the second
flexible chamber 131a, and the conduit 11 (Step S22). In a case
where air remains, the electro-pneumatic regulators 133, 133a
supply air between the first flexible chamber 131 and the pressure
chamber 132, and between the second flexible chamber 131a and the
pressure chamber 132a to increase pressures in the pressure
chambers 132, 132a. With this operation, the first flexible chamber
131 and the second flexible chamber 131a change from the expanded
state to the compressed state, and air in the first flexible
chamber 131, the second flexible chamber 131a, and the conduit 11
is discharged from a downstream side of the conduit 11 to the
outside of the liquid supply apparatus 1a (Step S221).
[0095] After the first flexible chamber 131 and the second flexible
chamber 131a are made to the compressed state, liquid supply to the
first flexible-chamber 131 and the second flexible chamber 131a is
restarted back to Step S21. In the liquid supply apparatus 1a,
liquid supply to the first flexible chamber 131 and the second
flexible chamber 131a and discharge of air from the first flexible
chamber 131, the second flexible chamber 131a, and the conduit 11
are repeated (repeats Steps S21 to S221) until air in the first
flexible chamber 131, the second flexible chamber 131a, and the
conduit 11 is completely discharged and the liquid filling is
finished.
[0096] After air is completely discharged from the first flexible
chamber 131, the second flexible chamber 131a, and the conduit 11
(Step S22), the electro-pneumatic regulator 133 of the first pump
mechanism 13 supplies air to the pressure chamber 132 to apply
pressure to the first flexible chamber 131, and the first flexible
chamber 131 in the expanded state is compressed. Pumping out of the
liquid stored in the first flexible chamber 131 to the conduit 11
is started, and the liquid is supplied to the external apparatus or
the like (Step S23).
[0097] In the second pump mechanism 13a, a little before
compression of the first flexible chamber 131 is stopped and
pumping out of the liquid from the first pump mechanism 13 is
stopped, air supply to the pressure chamber 132a by the
electro-pneumatic regulator 133a is started, and then compression
of the second flexible chamber 131a in the expanded state is
started. The liquid stored in the second flexible chamber 131a is
pumped out to the conduit 11 concurrently with pumping out of the
liquid from the first flexible chamber 131 (Step S24).
[0098] Subsequently, compression of the first flexible chamber 131
is stopped in the first pump mechanism 13 (Step S25). In the liquid
supply apparatus 1a, also after compression of the first flexible
chamber 131 is stopped, compression of the second flexible chamber
131a continues in the second pump mechanism 13a, and the liquid is
continuously pumped out to the conduit 11. In the first pump
mechanism 13, once compression of the first flexible chamber 131 is
stopped, discharge of air from the pressure chamber 132 is started
by the ejector 134 to expand the first flexible chamber 131 in the
compressed state. The liquid is sucked from the liquid supply
source 12 to the first flexible chamber 131 to be stored therein
(Step S26).
[0099] In the first pump mechanism 13, before compression of the
second flexible chamber 131a (i.e., pumping out of the liquid from
the second pump mechanism 13a) is stopped, discharge of air from
the pressure chamber 132 by the ejector 134 (i.e., expansion of the
first flexible chamber 131) is stopped (Step S27). After that, a
little before compression of the second flexible chamber 131a is
stopped, air supply to the pressure chamber 132 by the
electro-pneumatic regulator 133 is started to compress the first
flexible chamber 131 in the expanded state. Then the liquid stored
in the first flexible chamber 131 is pumped out to the conduit 11
concurrently with pumping out of the liquid from the second
flexible chamber 131a (Step S31).
[0100] Subsequently, compression of the second flexible chamber
131a is stopped in the second pump mechanism 13a (Step S32). In the
liquid supply apparatus 1a, also after compression of the second
flexible chamber 131a is stopped, compression of the first flexible
chamber 131 continues in the first pump mechanism 13, and the
liquid is continuously pumped out to the conduit 11. In the second
pump mechanism 13a, once compression of the second flexible chamber
131a is stopped, discharge of air from the pressure chamber 132a is
started by the ejector 134, and the second flexible chamber 131a in
the compressed state is expanded to increase a volume thereof. The
liquid is sucked from the liquid supply source 12 to the second
flexible chamber 131a to be stored therein (Step S33).
[0101] In the second pump mechanism 13a, before compression of the
first flexible chamber 131 (i.e., pumping out of the liquid from
the first pump mechanism 13) is stopped, discharge of air from the
pressure chamber 132a by the ejector 134 (i.e., expansion of the
second flexible chamber 131a) is stopped (Step S34). Back to Step
S24, a little before compression of the first flexible chamber 131
is stopped, air supply to the pressure chamber 132a by the
electro-pneumatic regulator 133a is started to apply pressure to
the second flexible chamber 131a in the expanded state, and the
second flexible chamber 131a is compressed. By reducing a volume of
the second flexible chamber 131a, the liquid stored in the second
flexible chamber 131a is pumped out to the conduit 11 concurrently
with pumping out of the liquid from the first flexible chamber 131
(Step S24).
[0102] Subsequently, compression of the first flexible chamber 131
is complete (Step S25), and the first flexible chamber 131 is
expanded to suck the liquid before stopping compression of the
second flexible chamber 131a (Steps S26, S27). After compression of
the first flexible chamber 131 and pumping out of the liquid are
started, compression of the second flexible chamber 131a is stopped
(Steps S31, S32). After that, before stopping compression of the
first flexible chamber 131, the second flexible chamber 131a is
expanded to suck the liquid (Steps S33, S34), and back to Step S24
again.
[0103] As discussed above, in the liquid supply apparatus 1a, Steps
S24 to S34 are repeated until it is determined liquid supply is
complete. In other words, almost concurrent pumping out of the
liquid from the second flexible chamber 131a to the conduit 11 and
storing of the liquid in the first flexible chamber 131, and almost
concurrent pumping out of the liquid from the first flexible
chamber 131 to the conduit 11 and storing of the liquid in the
second flexible chamber 131a, are alternately repeated. As a
result, pumping out of the liquid from the first pump mechanism 13
and/or the second pump mechanism 13a are continuously performed in
the liquid supply apparatus 1a. In the liquid supply apparatus 1a,
the second flexible chamber 131a may be compressed before
compression of the first flexible chamber 131. The initial liquid
filling may be performed by alternately repeating compression of
one chamber of the first flexible chamber 131 and the second
flexible chamber 131a and concurrent expansion of the other
chamber.
[0104] In the liquid supply apparatus 1a, while the first pump
mechanism 13 and the second pump mechanism 13a are pumping out the
liquid, that is to say, during Step S23 and repeated Step S24 to
S34 shown in FIG. 11 and FIG. 12, a flowrate control shown in FIG.
14 is continuously performed. Next discussion will be made on an
operation flow of the liquid supply apparatus 1a for controlling a
flowrate.
[0105] In the liquid supply apparatus 1a, when the first pump
mechanism 13 starts pumping out of the liquid to the conduit 11 in
Step S23 (see FIG. 11, FIG. 13), like in the first preferred
embodiment, a flowrate of the liquid flowing through the conduit 11
is measured by the flowmeter 14, and a measured flowrate is sent to
the feedback controller 151 of the controller 15 (Step S41).
Subsequently, it is determined whether or not the measured flowrate
obtained by the flowmeter 14 is equal to a predetermined flowrate
(Step S42).
[0106] In a case where the measured flowrate differs from the
predetermined flowrate, the feedback controller 151 controls the
electro-pneumatic regulator 133 of the first pump mechanism 13, and
the pressure applied to the first flexible chamber 131 is
controlled so that the measured flowrate is adjusted to the
predetermined flowrate (Step S43). Also in the second preferred
embodiment, the feedback controller 151 utilizes a PID Control as a
control method of the flowrate.
[0107] In the liquid supply apparatus 1a, it is checked repeatedly
whether or not pumping out of the liquid from the first pump
mechanism 13 and the second pump mechanism 13a is complete (Step
S44), in a case where it is not complete, back to Step S41, the
steps for measuring a flowrate to control pressure(s) applied to
the first flexible chamber 131 and/or the second flexible chamber
131a (Steps S41 to S43) are repeated.
[0108] In the liquid supply apparatus 1a, during Steps S23 to S24
and Steps S32 to S24 shown in FIG. 13, the first pump mechanism 13
is controlled and the measured flowrate is made equal to the
predetermined flowrate. During Steps S25 to S31, a flowrate is
measured by the flowmeter 14 placed in a downstream side of the
second pump mechanism 13a, on the basis of a measured flowrate, the
electro-pneumatic regulator 133a of the second pump mechanism 13a
is controlled. By this, the pressure applied to the second flexible
chamber 131a is controlled so that the measured flowrate is
adjusted to the predetermined flowrate.
[0109] During Steps S24 to S25 and Steps S31 to S32, the
electro-pneumatic regulators 133, 133a of the first pump mechanism
13 and the second pump mechanism 13a are controlled on the basis of
the measured flowrate of the flowmeter 14, so that pressures
applied to the first flexible chamber 131 and the second flexible
chamber 131a are parallel controlled. In other words, in the liquid
supply apparatus 1a, a period after starting pumping out of the
liquid from the first flexible chamber 131 and a period before
ending pumping out of the liquid from the first flexible chamber
131 respectively overlap a period before ending pumping out of the
liquid from the second flexible chamber 131a and a period after
starting pumping out of the liquid from the second flexible chamber
131a. In these overlapping periods, equivalent pressures are
applied to the first flexible chamber 131 and the second flexible
chamber 131a to be controlled so that the measured flowrate of the
flowmeter 14 is made equal to the predetermined flowrate.
[0110] FIG. 15 is a view illustrating a change of a flowrate of the
liquid flowing through the conduit 11 in the liquid supply
apparatus 1a. In the liquid supply apparatus 1a, in a case where
compression of one chamber of the first flexible chamber 131 and
the second flexible chamber 131a is started when compression of the
other chamber continues (i.e., Steps S24, S31), pressure applied to
the one chamber (i.e., a command value of pressure sent to the
electro-pneumatic regulator) is made the same as pressure applied
to the other chamber as discussed above. At this time, since the
flexible chamber started compression is more expanded state than
the flexible chamber under compression, a reaction force by the
bellows of the flexible chamber started compression is small. As a
result, a flowrate of the liquid pumped out to the conduit 11
becomes slightly greater than the predetermined flowrate during
Steps S24 to S25 and Steps S31 to S32 as shown in FIG. 15.
[0111] In the liquid supply apparatus 1a, however, since a flowrate
control is performed on the basis of the measured flowrate of the
flowmeter 14 as discussed above, such slight variations in flowrate
are immediately suppressed. As a result, it is prevented great
flowrate variations causing problems occur in liquid supply, and it
is possible to maintain a constant flowrate always in the liquid
supply apparatus 1a.
[0112] As discussed above, in the liquid supply apparatus 1a,
compression of one chamber of the first flexible chamber 131 of the
first pump mechanism 13 and the second flexible chamber 131a of the
second pump mechanism 13a and concurrent expansion of the other
chamber are alternately performed, the flowrate of the liquid
flowing through the conduit 11 is measured by the flowmeter 14, and
further on the basis of the measured flowrate, the pressures
applied to the first flexible chamber 131 and the second flexible
chamber 131a are controlled by the feedback controller 151. In the
liquid supply apparatus 1a, it is possible to supply the liquid of
a small flowrate long hours continuously while controlling
pressures applied to the first flexible chamber 131 and the second
flexible chamber 131 a with high accuracy to control the flowrate
accurately.
[0113] In the liquid supply apparatus 1a, before compression of one
chamber of the first flexible chamber 131 and the second flexible
chamber 131a is stopped, expansion of the other chamber is complete
to start compression. With this operation, by overlapping a
starting period with an ending period of pumping movement of the
liquid by the first pump mechanism 13 and the second pump mechanism
13a, it is possible to suppress flowrate variations easily which
occur in switching of compressions of the first flexible chamber
131 and the second flexible chamber 131a. As a result, it becomes
possible to perform continuous supply of the liquid of the small
flowrate stably.
[0114] In the liquid supply apparatus 1a, since the second pump
mechanism 13a has the same constituents as the first pump mechanism
13 and the second pump mechanism 13a is made of resin with high
durability against various kinds of liquid, it is possible to
supply various kinds of liquid. Like the first flexible chamber
131, it is possible to change a volume of the second flexible
chamber 131a comprising the bellows 1311a easily, and it is also
possible to suppress deterioration caused by repeats of compression
and expansion of the second flexible chamber 131a.
[0115] In the second pump mechanism 13a, since the
electro-pneumatic regulator 133a is used in compression of the
second flexible chamber 13 la, it is possible to control the
pressure in the space between the pressure chamber 132a and the
second flexible chamber 131a with high response and high accuracy.
By making the lower end of the second flexible chamber 131a free,
it is possible to compress the second flexible chamber 131a stably
and it is also possible to control a flowrate of the liquid to be
supplied with higher accuracy. By positioning the displacement
sensor and the leakage sensor in the pressure chamber 132a, it is
possible to increase reliability of the liquid supply apparatus
1.
[0116] In the liquid supply apparatus 1a, like in the first
preferred embodiment, it is possible to measure a flowrate with
high accuracy stably by the flowmeter 14, even if the flowrate of
the liquid is very small.
[0117] Next, discussion will be made on a liquid supply apparatus
in accordance with the third preferred embodiment of the present
invention. The liquid supply apparatus in accordance with the third
preferred embodiment is provided a pump mechanism 13b shown in FIG.
16 instead of the pump mechanism 13 of the liquid supply apparatus
1 shown in FIG. 1. Other constituent elements are the same as those
of FIG. 1 and the constituent elements are represented by the same
reference signs in the following description.
[0118] In the pump mechanism 13b of the liquid supply apparatus in
accordance with the third preferred embodiment, compression and
expansion of a flexible chamber 131b is performed by a motor which
is a different power source from that of the pump mechanism 13 of
the liquid supply apparatus 1 shown in FIG. 1. As shown in FIG. 16,
in the pump mechanism 13b, a moving mechanism 137 for compressing
or expanding the flexible chamber 131b by moving a lower end of the
flexible chamber 131b in a vertical direction and a motor 138 for
driving the moving mechanism 137 are provided, instead of the
pressure chamber 132 of the pump mechanism 13, the
electro-pneumatic regulator 133, the ejector 134, and various
pneumatic valves and electromagnetic valves shown in FIG. 1.
[0119] The moving mechanism 137 comprises a moving plate 1371
connected to the lower end of the flexible chamber 131b, a ball
screw 1372 extending in the vertical direction, a nut 1373 which is
fixed on the moving plate 1371 and into which the ball screw 1372
is inserted, a guide 1374 for leading the moving plate 1371 in the
vertical direction, and a timing belt 1375 for connecting the ball
screw 1372 to the motor 138. An output torque of the motor 138 is
controllable and to the motor 138 a torque control amplifier 1381
is connected.
[0120] In the moving mechanism 137, the motor 138 rotates the ball
screw 1372, so that the moving plate 1371 moves along the guide
1374 in the vertical direction smoothly. When the moving plate 1371
moves upward to be driven by the motor 138, the lower end of the
flexible chamber 131b also moves upward (i.e., toward an upper end
of the flexible chamber 131b) to apply pressure to the flexible
chamber 131b, and then the liquid in the flexible chamber 131b is
pumped out to the conduit 11. In other words, the moving mechanism
137 functions as a pressure mechanism for applying pressure to the
flexible chamber 131b by a torque outputted from the motor 138.
[0121] When the moving plate 1371 moves downward to be driven by
the motor 138, the lower end of the flexible chamber 131b moves
away from the upper end to reduce pressure in the flexible chamber
131b. By this, the liquid is sucked from the liquid supply source
12 (see FIG. 1) to be supplied to the flexible chamber 131b and
stored therein.
[0122] In the liquid supply apparatus in accordance with the third
preferred embodiment, by compressing the flexible chamber 131b in
the pump mechanism 13b, the liquid in the flexible chamber 131b is
pumped out to the conduit 11. While the liquid is flowing through
the conduit 11, a flowrate of the liquid flowing through the
conduit 11 is measured by the flowmeter 14 (see FIG. 1) placed in a
downstream side of the pump mechanism 13b. On the basis of a
measured flowrate, the output torque of the motor 138 is controlled
by the feedback controller 151 (see FIG. 1) of the controller 15
through the torque control amplifier 1381, and the pressure applied
to the flexible chamber 131b is controlled so that the measured
flowrate is adjusted to a predetermined flowrate.
[0123] As discussed above, in the liquid supply apparatus in
accordance with the third preferred embodiment, since the pump
mechanism 13b can be driven without a compressor or a vacuum
source, it is possible to simplify the construction of the liquid
supply apparatus.
[0124] Next, referring to FIG. 17, a substrate processing apparatus
2 comprising the liquid supply apparatus 1 shown in FIG. 1 in
accordance with the fourth preferred embodiment of the present
invention will be discussed. The substrate processing apparatus 2
is a so-called single wafer-type processing apparatus for etching
one semiconductor substrate 9 (hereinafter, referred to as simply
"substrate 9").
[0125] As shown in FIG. 17, the substrate processing apparatus 2
includes a first conduit 21 through which pure water flows and a
second conduit 22 through which hydrofluoric acid flows. The first
conduit 21 and the second conduit 22 are connected at a downstream
of both conduits. At a connected point of the first conduit 21 and
the second conduit 22 a mixing valve 241 is installed, the pure
water from the first conduit 21 and the hydrofluoric acid from the
second conduit 22 are mixed in the mixing valve 241 and a
processing liquid is generated.
[0126] The first conduit 21 is connected to an external pure water
supply apparatus through a valve 211 and a regulator 212 in an
upstream side of the first conduit 21. In an upstream side of the
second conduit 22, the liquid supply apparatus 1 for supplying the
hydrofluoric acid in accordance with the first preferred embodiment
is placed. In the flowing description, the constituent elements of
the liquid supply apparatus 1 will be discussed referring to the
reference signs in FIG. 1.
[0127] In the substrate processing apparatus 2, a third conduit 24
through which the processing liquid which is a mixture of the pure
water and the hydrofluoric acid flows is provided in a downstream
side of the mixing valve 241, and in a downstream side of the third
conduit 24 (i.e., a downstream side of the connected point of the
first conduit 21 and the second conduit 22) a substrate holding
part 26 for holding the substrate 9 is positioned. A nozzle 27 is
located in an upper part of the substrate holding part 26, and the
nozzle 27 serves as a processing liquid supply part which is
connected to the downstream side of the third conduit 24 and
supplies the processing liquid to the substrate 9.
[0128] The substrate holding part 26 has a chuck 261 for holding
the approximately disk-shaped substrate 9 on the lower surface and
the periphery of the substrate 9, a rotating mechanism 262 for
rotating the substrate 9, and a process cup 263 for covering the
circumference of the chuck 261. The rotating mechanism 262 has a
shaft 2621 coupled to the bottom of the chuck 261 and a motor 2622
for rotating the shaft 2621. By driving the motor 2622, the
substrate 9 rotates together with the shaft 2621 and the chuck 261.
The process cup 263 has a side wall 2631, placed in the
circumference of the chuck 261, for preventing the processing
liquid supplied to the substrate 9 from splashing around, and an
outlet 2632, provided in the bottom of the process cup 263, for
discharging the processing liquid supplied to the substrate 9.
[0129] In the substrate processing apparatus 2, by opening the
valve 211, the pure water is supplied from the pure water supply
apparatus to the first conduit 21. At the same time, by driving the
pump mechanism 13 (see FIG. 1) of the liquid supply apparatus 1 to
apply pressure to the flexible chamber 131 where the hydrofluoric
acid is stored in advance, the hydrofluoric acid is pumped out from
the flexible chamber 131 to the conduit 11 and is supplied to the
second conduit 22. In the mixing valve 241, the hydrofluoric acid
supplied to the second conduit 22 is mixed with the pure water
supplied to the first conduit 21 and the processing liquid of a
dilute hydrofluoric acid is generated.
[0130] The processing liquid generated in the mixing valve 241 is
supplied to the nozzle 27 through the third conduit 24 and is
ejected from the nozzle 27 toward the center of the substrate 9
only a required amount. The substrate 9 is hold by the substrate
holding part 26 and is rotated. The processing liquid supplied from
the nozzle 27 spreads in all areas of the top of the substrate 9
while moving a top of the substrate 9 toward the outside thereof by
the centripetal force, and then etching of the substrate 9 is
performed. When the processing liquid moves out of the edge of the
substrate 9, it is away from the substrate 9 and is received by the
side wall 2631 of the process cup 263 or falls on the bottom of the
process cup 263 directly and then the processing liquid is
discharged from the outlet 2632.
[0131] In the liquid supply apparatus 1 of the substrate processing
apparatus 2, the flowrate of the hydrofluoric acid flowing at a
small flowrate is measured by the flowmeter 14 (see FIG. 1) with
high accuracy stably, the pressure applied to the flexible chamber
131 of the pump mechanism 13 is controlled by the controller 15
(see FIG. 1) on the basis of a measured flowrate and a flowrate
predetermined in advance, and thus it becomes possible to supply
the hydrofluoric acid to the second conduit 22 while performing the
flowrate control of the hydrofluoric acid of the small flowrate
accurately. With this operation, in the substrate processing
apparatus 2, a small supply rate of the hydrofluoric acid to the
mixing valve 241 is controlled with high accuracy, and the
processing liquid where the hydrofluoric acid is mixed at the
desired concentration accurately is generated. Consequently, in the
substrate processing apparatus 2, it is possible to perform etching
of the substrate 9 with the processing liquid where the
hydrofluoric acid is mixed at the desired concentration accurately.
By performing etching with the dilute hydrofluoric acid of a
concentration controlled with high accuracy, the etching rate is
controlled high accurately and a more preferable processing result
can be obtained. Also, by lowering the etching rate to suppress
processing time variation in the center and the edge of the
substrate 9, it is possible to improve uniformity of etching
quality in a whole upper surface of the substrate 9.
[0132] Next, referring to FIG. 18, a substrate processing apparatus
2a comprising the liquid supply apparatus 1a shown in FIG. 10 in
accordance with the fifth preferred embodiment of the present
invention will be discussed. The substrate processing apparatus 2a
is a so-called batch-type processing apparatus for etching a
plurality of substrates 9 simultaneously. As shown in FIG. 18, in
the substrate processing apparatus 2a, the liquid supply apparatus
1a shown in FIG. 10 is placed instead of the liquid supply
apparatus 1 of the substrate processing apparatus 2 shown in FIG.
17, and instead of the substrate holding part 26 and the nozzle 27,
a process bath 25 is located in the downstream side of the third
conduit 24 (i.e., the downstream side of the connected point of the
first conduit 21 and the second conduit 22). The process bath 25
stores the processing liquid and where the approximately
disk-shaped substrates 9 are dipped vertically. Other constituent
elements are the same as those of FIG. 17 and the constituent
elements are represented by the same reference signs in the
following description. The constituent elements of the liquid
supply apparatus 1a will be discussed referring to the reference
signs in FIG. 10.
[0133] As shown in FIG. 18, the substrate processing apparatus 2a,
like in the fourth preferred embodiment, includes the first conduit
21 through which the pure water flows, the second conduit 22
through which the hydrofluoric acid flows and connected to the
first conduit 21 in the mixing valve 241, the liquid supply
apparatus 1a in accordance with the second preferred embodiment,
placed in the upstream side of the second conduit 22 to supply the
hydrofluoric acid to the second conduit 22, and the third conduit
24 installed in the downstream side of the mixing valve 241 and
through which the processing liquid, which is the mixture of the
pure water and the hydrofluoric acid, flows.
[0134] In the substrate processing apparatus 2a, like in the fourth
preferred embodiment, the pure water supplied to the first conduit
21 and the hydrofluoric acid supplied to the second conduit 22 are
mixed in the mixing valve 241 and the processing liquid of the
dilute hydrofluoric acid solution is generated. At this time, in
the liquid supply apparatus 1a, the flowrate of the hydrofluoric
acid flowing at the very small flowrate is stably measured by the
flowmeter 14 (see FIG. 10) with high accuracy, pressures applied to
the first flexible chamber 131 and the second flexible chamber 131a
(see FIG. 10) are controlled by the controller 15 (see FIG. 10) on
the basis of the measured flowrate and the predetermined flowrate,
and thus the hydrofluoric acid is supplied to the mixing valve 241
through the second conduit 22 while performing the flowrate control
of the hydrofluoric acid of the small flowrate accurately. As a
result, the processing liquid where the hydrofluoric acid is mixed
accurately at the desired concentration is generated.
[0135] The processing liquid generated in the mixing valve 241 is
supplied to the process bath 25 from the bottom thereof through the
third conduit 24. In the process bath 25, the plurality of
substrates 9 held in the process bath 25 are dipped gradually from
the bottoms into the processing liquid which is supplied to the
process bath 25 and is stored therein, and then etching of the
substrates 9 is performed.
[0136] In the substrate processing apparatus 2a, like in the fourth
preferred embodiment, it is possible to perform etching of the
substrate 9 with the processing liquid where the hydrofluoric acid
is mixed accurately at the desired concentration. By performing
etching with the dilute hydrofluoric acid of a concentration
controlled with high accuracy, the etching rate is controlled high
accurately and it is possible to obtain a more preferable
processing result. Also, by lowering the etching rate to suppress
processing time variation in an upper side and a lower side of the
substrate 9, it is possible to improve uniformity of etching
quality in a whole upper surface of the substrate 9.
[0137] Since in the substrate processing apparatus 2a it is
possible to supply the hydrofluoric acid of a small flowrate long
hours continuously while controlling the flowrate accurately by the
liquid supply apparatus 1a, the substrate processing apparatus 2a
is especially suitable for batch-type etching (and the other
substrate processing) which requires a large amount of processing
liquid in one process. In the liquid supply apparatus 1a, by
overlapping a starting period with an ending period of pumping
movement of the liquid by the first pump mechanism 13 and the
second pump mechanism 13a, it is possible to suppress flowrate
variations easily which occur in switching of compressions of the
first flexible chamber 131 and the second flexible chamber 131a,
and thus it becomes possible to keep the processing liquid for
etching of the substrates 9 at the desired concentration
easily.
[0138] Though the preferred embodiments of the present invention
have been discussed above, the present invention is not limited to
the above-discussed preferred embodiments, but allows various
variations.
[0139] The flexible chambers provided in respective pump mechanisms
of the liquid supply apparatuses in accordance with the above
preferred embodiments may be made of various materials except
resin. Each flexible chamber does not necessarily comprise the
bellows and for example, the whole of the flexible chamber may be
almost spherical. Also in this case, in the liquid supply
apparatuses in accordance with the first and second preferred
embodiments, an almost spherical flexible chamber applied pressure
in the pressure chamber is compressed, and the liquid is pumped out
to the conduit 11.
[0140] In the liquid supply apparatuses in accordance with the
first and second preferred embodiments, in sucking the liquid from
the liquid supply source 12 by expanding the flexible chamber,
pressure reduction is not necessarily performed until pressure in
the pressure chamber becomes negative. For example, the bellows
expands by a reaction force of the bellows compressed by reducing
pressure around the flexible chamber to a certain degree, and the
liquid may be sucked from the liquid supply source 12. After
sealing the liquid supply source 12, a pump mechanism is provided,
by applying pressure to the liquid in the liquid supply source 12
to pump out the liquid to the pump mechanism, the liquid may be
supplied to the flexible chamber.
[0141] In the liquid supply apparatus 1a in accordance with the
second preferred embodiment, two pump mechanisms 13b of the liquid
supply apparatus in accordance with the third preferred embodiment
may be provided instead of the first pump mechanism 13 and the
second pump mechanism 13a.
[0142] The displacement sensor 135 and the leakage sensor 136
positioned in the pump mechanism 13 are not limited to the
structures described in the above preferred embodiments and they
may have various structures. For example, a float type leakage
sensor 136 may be used. In a case where electricity is not
available in a liquid detection because of low conductivity of a
liquid in the flexible chamber or the like, the leakage sensor 136
may have a structure where the leakage sensor 136 receives a
reflection light of a light emitted toward the bottom of the
pressure chamber and detects a leakage according to a change of
optical properties of the reflection light.
[0143] The tube 143 of the flowmeter 14 is not necessarily made of
resin and it may be made of other materials. In this case, it is
preferable that the tube 143 is made of materials with high
durability against various kinds of liquid. The storage part 145
and the operation part 146 of the flowmeter 14 may be formed
integrally with the feedback controller 151 of the controller
15.
[0144] In the substrate processing apparatus 2 in accordance with
the fourth preferred embodiment, the liquid supply apparatus 1a
having the two flexible chambers or the liquid supply apparatus in
accordance with the third preferred embodiment where the motor 138
is the power source may be placed instead of the liquid supply
apparatus 1 having one flexible chamber 131. In the substrate
processing apparatus 2a in accordance with the fifth preferred
embodiment, the liquid supply apparatus 1 or the liquid supply
apparatus in accordance with the third preferred embodiment may be
placed instead of the liquid supply apparatus 1a.
[0145] In the substrate processing apparatuses in accordance with
the fourth and fifth preferred embodiments, liquids except the pure
water and the hydrofluoric acid may be mixed, and other processes
(cleaning process, for example) except etching of the substrate 9
may be performed.
[0146] While the invention has been shown and described in detail,
the foregoing description is in all aspects illustrative and not
restrictive. It is therefore understood that numerous modifications
and variations can be devised without departing from the scope of
the invention.
[0147] This application claims priority benefit under 35 U.S.C.
Section 119 of Japanese Patent Application No. 2004-375294 filed in
the Japan Patent Office on Dec. 27, 2004, the entire disclosure of
which is incorporated herein by reference.
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