Pumps – Motor driven – Including manual – mechanical – or diverse drive
Reexamination Certificate
2002-04-09
2004-01-20
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Including manual, mechanical, or diverse drive
C417S044100, C417S205000, C222S333000, C239S537000, C239S581200, C239S586000
Reexamination Certificate
active
06679685
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and device for discharging a fluid at a very small flow rate, which is required in fields such as information and precision mechanical equipment, machine tool, FA (Factory Automation), and the like or in various processes of producing a semiconductor device, liquid crystal display, and display unit; and surface mounting; and the like.
The processing precision in machine work is changing from the order of microns to the order of submicrons. Submicron processing is usually performed in the field of semiconductor and electronic components, but demand for ultraprecision machining is also rapidly increasing in the field of machine work, which is progressing along with mechatronics. In recent years, an electro-magnetostrictive element represented by a giant-magnetostrictive element and a piezoelectric element is being used as a micro actuator along with introduction of ultraprecision machining techniques.
A jet device, which jets a very small flow rate of droplets at high speed by utilizing this electro-magnetostrictive element as a source for generating a fluid pressure, is used in various fields.
FIG. 21
shows an example of a conventional head in an inkjet recording device (Unexamined Japanese Patent Publication No. 11-10866). Reference numeral
3401
denotes a base. Reference numeral
3402
denotes an oscillation (vibration) plate. Reference numeral
3403
denotes a laminated piezoelectric element. Reference numeral
3404
denotes an ink chamber. Reference numeral
3405
denotes a common ink chamber. Reference numeral
3406
denotes an ink flow passage. Reference numeral
3407
denotes a nozzle plate. Reference numeral
3408
is a discharge nozzle.
When a voltage is applied to the piezoelectric element
3403
, which is a pressure applying means, the piezoelectric element
3403
deforms the oscillation plate
3402
in the thickness direction, thereby reducing the volume of the ink chamber
3404
.
Since a fluid is compressed and a pressure in the ink chamber is increased, a part of the fluid is passed through the ink flow passage and flows back to the common ink chamber
3405
side. The remaining portion is discharged from the nozzle to the atmosphere.
A method of jetting an arbitrary droplet by using a giant-magnetostrictive element is disclosed in, for example, Unexamined Japanese Patent Publication No. 2000-167467.
In
FIG. 22
, reference numeral
3502
denotes a cylinder made of a nonmagnetic material such as a glass pipe, stainless pipe, or the like. A fluid reservoir
3503
and a jet nozzle
3504
having a very small jet port are formed at an end portion of this cylinder
3502
.
An actuator
3505
made of a giant-magnetostrictive material in a rod-like shape is housed movably inside the cylinder
3502
. A piston
3506
is removably disposed at an end portion of the actuator
3505
facing the jet nozzle
3504
.
A spring
3508
is disposed between the other end portion of the actuator
3505
and a stopper
3507
at an end portion so that the actuator
3505
is energized to proceed by the spring
3508
. Furthermore, a coil
3509
is wound to the outer periphery of the cylinder
3502
at a position close to the piston
3506
.
In the jet device having the above constitution, a current is allowed to flow in the coil
3509
instantaneously so that an instantaneous magnetic field is allowed to act on the giant-magnetostrictive material to generate an instantaneous transitional displacement due to an elastic wave at an axial end portion of the giant-magnetostrictive material. The fluid filled in the cylinder can be jet from the nozzle as one very small droplet by this action.
Conventionally, as a fluid discharge device, an air pulse-type dispenser as shown in
FIG. 23
is widely used, and such a technique is introduced in, for example, Automation Technique '93, vol. 25 (7) or the like.
In a dispenser of this type, a fixed amount of pulsed air supplied from a constant pressure source is applied to the inside
152
of a container
150
(cylinder) so that a certain amount of fluid corresponding to a rise of the pressure in a cylinder
150
is discharged from a nozzle
151
.
In a field of formation of a circuit, which is increasingly made highly precise and ultrafine in recent years, or a field of manufacturing processes of electrodes and ribs of imaging tubes such as PDP, CRT, and the like, fluorescent screens, liquid crystal displays, optical discs, and so forth, most of fluids for fine coating are high-viscosity powder fluids.
The most significant challenge is to coat a target board with the powder fluid containing ultrafine particles at high speed, in high precision, and with high reliability, without blocking the flow passage.
For example, in the case of coating an imaging tube such as PDP, CRT, or the like with a fluorescent substance, the grain size of the fine particle is usually 7-9 &mgr;m, and the specific weight is about 4.0-5.0 kg/m
3
.
Conventionally, an attempt is made that the imaging tube is coated with the fluorescent substance by using an air nozzle-type dispenser conventionally used in a field of circuit mounting or the like. Since continuous coating with high-viscosity fluid at high speed is difficult in the case of the air nozzle-type dispenser, fine particles are diluted with a low-viscosity fluid before coating. However, in this case, there is a problem that, when the flow of the fluid is stopped, the fine particles are immediately deposited inside the flow passage due to the weight of a single particle.
Furthermore, the discharge device using a piezoelectric material or giant-magnetostrictive material as a drive source as described above is originally used for coating with a low-viscosity fluid containing no powder. It is difficult to respond to the aforementioned challenge related to the coating process of high-viscosity fluids and powder fluids.
In order to respond to various demands related to coating at a very small flow rate in recent years, the inventors of the present invention proposed a coating method wherein the discharge amount is controlled by applying a relative linear motion and rotary motion between a piston and a cylinder, transporting a fluid by the rotary motion, and changing a relative gap between the fixed side and the rotated side by the linear motion, and applied this method as “device and method for feeding fluid” (Japanese Patent Application No.2000-188899; Unexamined Japanese Patent Publication No. 2002-11929).
Accordingly, an object of the present invention is to provide a method for further simplifying the structure of the above proposal by performing a strict theoretical analysis by limiting the above proposal to the case of intermittent coating and finding a specific structural condition for improving a pump performance based on its results.
SUMMARY OF THE INVENTION
In accomplishing these and other aspects, according to a first aspect of the present invention, there is provided a method of discharging a fluid, comprising feeding a fluid into a gap defined between two surfaces in a closed space, and relatively oscillating the two surfaces to apply relative oscillation with high frequency to the gap so as to occur a squeeze pressure to the gap, and thus intermittently discharging the fed fluid through a discharge port provided in either one of the two surfaces by using the squeeze pressure.
According to a second aspect of the present invention, there is provided a method of discharging a fluid according to the 1 st aspect, wherein the discharge amount Q
s
(mm
3
) per dot generally represented by
Q
s
=
1
R
n
+
R
p
{
(
r
0
2
-
r
i
2
)
+
2
r
i
2
ln
r
i
r
0
}
(
6
μ
Δ
h
h
0
3
)
where an amplitude of a change of the gap between the two surfaces is &Dgr;h (mm), a central value of a size of the gap is h
0
(mm), a mean radius of outer peripheries of the two surfaces is r
0
(mm), a mean radius of an opening of the discharge port is r
i
(mm), a viscosity coefficient of the fluid is &mg
Maruyama Teruo
Sonoda Takashi
Belena John F
Freay Charles G.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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