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JPH07100434

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH07100434
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic cleaning apparatus, and more particularly, to the structure of an ultrasonic vibrator
which forms a strong focused sound field at a position separated by a predetermined distance
from the radiation surface of ultrasonic waves.
[0002]
2. Description of the Related Art Recently, in the field of ultrasonic application, ultra-precision
cleaning equipment using ultrasonic waves in the megahertz band has been actively used. Among
the ultrasonic cleaning devices of this type, those of the nozzle shower type are an ultrasonic
vibrator that resonates with ultrasonic vibration generated by the ultrasonic wave generation
means and radiates ultrasonic waves from its radiation surface; An ultra-precision cleaning is
performed by effectively causing ultrasonic waves in the discharged medium liquid to act on the
wetted part of the object to be cleaned.
[0003]
FIG. 6 is a cross-sectional view of a conventional ultrasonic vibrator used in the ultrasonic
cleaning apparatus. Referring to FIG. 6, the conventional ultrasonic vibrator 60 has a structure in
which the piezoelectric element 63 is attached to the flat surface 61 of a cylindrical vibrating
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member made of, for example, titanium etc., and resonates with the ultrasonic vibration
generated by the piezoelectric element 63. At the same time, the opposing radiation surface 62 is
formed into a concave curve lens having a focal point O on its central axis. In the ultrasonic
cleaning apparatus using the ultrasonic vibrator 60 having such a structure, by aligning the
position of the focal point O in the vicinity of the nozzle port, a strong focused sound field is
formed at the position and the object to be cleaned is Since the ultrasonic waves act more
effectively, the cleaning effect is greatly enhanced.
[0004]
FIG. 7 shows a cross-sectional structure of a nozzle shower type ultrasonic cleaning apparatus
incorporating the above-mentioned ultrasonic vibrator 60. As shown in FIG. Referring to FIG. 7,
the cleaning apparatus has a housing 70 for fixing the ultrasonic vibrator 60 via a packing 71. In
the housing 70, an inlet 73 for introducing the medium liquid 72 from medium liquid supply
means (not shown), a nozzle 74 for converging the medium liquid 72 downward, and the medium
liquid 72 guided to the nozzle 74 A spot or slit-like discharge port 75 to be discharged onto the
object to be cleaned (not shown) is formed.
[0005]
The radiation surface of the ultrasonic vibration member 60 is directed to the discharge port 75
as shown, and the focal position thereof is set in the vicinity of the discharge port 75 as
described above. Furthermore, a piezoelectric element (ultrasonic transducer) 63 is attached to
the back of the ultrasonic vibrator 60. The inflow port 73 supplies a flow rate of the medium
liquid 72 temporarily stored in the housing 70. In this state, when an alternating electric field is
applied from a high frequency oscillator (not shown), the piezoelectric element 63 vibrates at a
predetermined frequency. The ultrasonic transducer 60 resonates with this vibration, and
transmits ultrasonic waves in the form of sound pressure from the radiation surface 62 into the
medium liquid 72. At this time, the ultrasonic wave (sound pressure) is focused in the vicinity of
the discharge port 75 by the concave lens effect of the radiation surface 62, so that ultra
precision cleaning is performed without depositing particles on the wetted part of the object to
be cleaned.
[0006]
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As described above, in the conventional ultrasonic cleaning apparatus, the radiation surface 62 of
the ultrasonic vibrator 60 is formed into a concave curved lens, and the discharge effect is
obtained by utilizing the lens effect. A strong focused sound field is formed near 75. However, as
apparent from FIGS. 6 and 7, in the ultrasonic vibrator 60 having such a structure, the thickness
is increased as the outer edge portion is approached. Therefore, there is a problem that the
ultrasonic vibration body 60 itself and hence the ultrasonic cleaning device are enlarged, and the
ultrasonic vibration is absorbed as it goes to the outer edge, and the sound pressure of the
expected distribution can not be obtained.
[0007]
Further, in the ultrasonic vibrator 60 having the above-described structure, the depression is the
largest at the center, so that when air bubbles are contained in the inflowing medium liquid 72,
the air bubbles are retained at the maximum depression site, and ultrasonic And the problem of
worsening the cleaning effect.
[0008]
The present invention has been made in view of the above problems, and an object thereof is to
provide a small and lightweight ultrasonic vibrator capable of forming a focused sound field and
suppressing stagnation of air bubbles. is there.
Another object of the present invention is to provide an ultrasonic cleaning apparatus capable of
obtaining a high precision cleaning effect.
[0009]
An ultrasonic vibrator according to a first aspect of the present invention is an ultrasonic vibrator
having a radiation surface for radiating ultrasonic waves, wherein the radiation surface has a
plurality of common focal positions. It is characterized in that it is formed of a concave curved
lens group, and the distance from each surface of the concave curved lens group to the focal
position in the same plane is gradually increased in the direction from the center to the outer
edge. In this configuration, the distances from the respective surfaces of the concave curved lens
group to the focal position within the same plane are sequentially 1st, 3rd ... kth (k is a natural
number of odd numbers) with respect to the used resonance frequency It is preferable that it is
the distance which becomes the Fresnel zone of.
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[0010]
The ultrasonic cleaning apparatus according to the second aspect of the invention includes
ultrasonic wave generating means for generating ultrasonic vibration, ultrasonic vibrator for
resonating with the ultrasonic vibration and radiating ultrasonic waves from the radiation
surface, and inflow. And a housing for applying the ultrasonic wave to the medium liquid and
discharging the liquid from the nozzle port, and the ultrasonic vibrator has the focal position in
the vicinity of the nozzle port of the housing. The ultrasonic vibrator according to the first aspect
of the invention is characterized.
[0011]
In addition to the configuration of the ultrasonic cleaning device according to the second aspect
of the present invention, the ultrasonic cleaning device according to the other configuration
further includes the radiation surface of the ultrasonic vibrator in the direction in which the
medium liquid flows. An exhaust hole is formed in the casing at the top of the bonding portion,
and air bubbles staying on the radiation surface are discharged from the exhaust hole to the
outside.
[0012]
In the ultrasonic vibrator according to the first aspect of the invention, ultrasonic waves are
respectively radiated from the plurality of concave curved lens groups, but since the focal
positions of the concave curved lenses are common, the radiated ultrasonic waves are common.
Focus on the focal position.
Therefore, a strong sound field is formed at this focal position.
In this case, since the distance from the concave surface lens surface to the focal position is
gradually increased from the central portion toward the outer edge portion, the thickness from
the back surface of the radiation surface is the conventional product having the same focal
length. Relatively and gradually thinner. If the above distance is a distance that forms an oddorder Fresnel band with respect to the resonance frequency to be used, a plurality of ultrasonic
waves of the same phase will be focused on the focal position, and a stronger sound field is
formed. Ru.
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[0013]
The ultrasonic cleaning apparatus according to the second invention incorporates the abovementioned ultrasonic vibrator and sets its focal position in the vicinity of the nozzle port of the
housing, so a strong sound field is formed there, and it is in the medium liquid to be discharged.
Sound pressure level becomes strong. In addition, since the ultrasonic vibrators gradually
decrease in thickness toward the outer edge as described above, the overall shape of the
apparatus can also be miniaturized. During normal operation, the radiation surface of the
ultrasonic vibrator points vertically downward, but since the outer edge of the ultrasonic vibrator
is relatively thin as described above, the bubbles contained in the medium liquid are radiation
surfaces. It is easily discharged from the exhaust port without staying in the air.
[0014]
Embodiments of the present invention will be described in detail below with reference to the
drawings. First, the ultrasonic vibrator of the present invention will be described. FIG. 1 is a front
view of an ultrasonic vibrator according to one embodiment, and FIG. 2 is a top view. In these
figures, 10 is a cylindrical ultrasonic vibrator made of, for example, titanium, 11 is a flat surface,
and 12 is a radiation surface. The diameter of the ultrasonic vibrator 10 is preferably at least five
times the wavelength of the ultrasonic wave to be used, and the height is preferably five times
the wavelength. In this embodiment, the resonance frequency is 1 MHz and the wavelength is 6
mm. It was decided to use the longitudinal wave of and the diameter was designed to 50 [mm]
and the height 30 [mm] as a result of various verifications.
[0015]
The radiation surface 12 is formed of a concave curved surface lens 121 at a central portion on
concentric circles and four band-shaped concave curved surface lenses 122 to 125. L <b> 1 to L
<b> 5 indicate the distances from the surfaces of the concave curved lenses 121 to 125 to the
common focus O. This length gradually increases from the center to the outer edge, and is a
distance for forming first, third, fifth, seventh, and ninth order Fresnel bands (Fresnel lens). The
steps between the lenses are formed in parallel with the focal point O so as not to be an obstacle
to the radiated ultrasonic waves.
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[0016]
A piezoelectric element (ultrasonic transducer) 13 has a diameter of 30 mm and a thickness of
2.3 mm in order to obtain a resonance frequency of 1 MHz. The piezoelectric element 13 is fixed
to the flat surface 11 of the ultrasonic vibrator 10 and vibrates in response to an alternating
electric field from the high frequency oscillator 1.
[0017]
In the ultrasonic vibrator having such a structure, the overall thickness can be made uniform
while retaining the concave lens effect similar to that of the conventional product shown in FIG.
Since the ultrasonic waves of the same phase are focused on, a stronger sound field is formed. As
an example of forming a spot-like focused sound field, in addition to a cylindrical shape as shown
in FIG. 2, it is also possible to use a polygonal pillar such as a regular hexagonal prism or an
octagonal prism.
[0018]
Also, as an application of the above embodiment, it is possible to make the focused sound field
linear. FIG. 3 shows an example in which the radiation surface 22 of the rectangular
parallelepiped ultrasonic vibration member 20 is formed by a plurality of band-shaped concave
curved lenses 221 to 225, and the focal points of the lenses 221 to 225 are common. In this way,
the focused sound field becomes linear in the longitudinal direction, and an ultrasonic vibrator
suitable for a slit nozzle type cleaning device can be realized.
[0019]
Next, an ultrasonic cleaning apparatus using the above-mentioned ultrasonic vibrator will be
described. FIG. 4 is a cross-sectional view of a nozzle shower type cleaning apparatus, which
corresponds to FIG. 7 showing a conventional apparatus. Parts denoted by the same reference
numerals as in FIG. 7 indicate that the parts are the same as in the conventional device.
[0020]
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In this embodiment, the ultrasonic vibrator 10 having the structure shown in FIG. 2 is fixed to the
housing 70 via the packing 71. At that time, the radiation surface 12 is directed to the discharge
port 75 as shown, and the focal position thereof is set in the vicinity of the discharge port 75.
Furthermore, a piezoelectric element 13 is attached to the back of the ultrasonic vibrator 10. The
inflow port 73 supplies a flow rate of the medium liquid 72 temporarily stored in the housing 70.
In this state, when an alternating electric field is applied from a high frequency oscillator (not
shown), the piezoelectric element 13 vibrates at 1 [MHz]. The ultrasonic transducer 10 resonates
with this vibration, and transmits an ultrasonic wave in the form of sound pressure from the
radiation surface 12 (surface of each concave curved lens) into the medium liquid 72. At this
time, ultrasonic waves (sound pressure) of the same phase converge from the radiation surface
12 in the vicinity of the discharge port 75 by the principle of Fresnel, so the wetted part of the
cleaning object (not shown) placed below the discharge port 75. Ultrasonic waves are effectively
applied, and highly accurate ultra-precision cleaning is performed.
[0021]
FIG. 5 shows an example of an ultrasonic cleaning apparatus according to another configuration.
Compared with the structure of FIG. 4, the difference is that an exhaust hole 76 is formed in the
topmost housing 70 of the bonding portion of the ultrasonic vibrator 10 with the radiation
surface 12 in the direction in which the medium liquid 72 flows. In the ultrasonic cleaning
apparatus having such a structure, as described above, since the thickness of the ultrasonic
vibrator 10 is uniformed as a whole, the air bubbles 50 contained in the medium liquid 72 stay
on the radiation surface 12 It is easily discharged to the outside from the exhaust hole 76
without doing it. Therefore, the conventional problem that impedes the propagation of the
ultrasonic wave to the medium liquid 72 is eliminated.
[0022]
Although the ultrasonic cleaning apparatus shown in FIGS. 4 and 5 is an example in which the
cylindrical ultrasonic vibration body 10 is incorporated, ultrasonic vibration in which the focused
sound field becomes linear as shown in FIG. Of course, the same effect can be obtained by
incorporating the body 20. In this case, the discharge port 75 at the tip of the nozzle 74 is
usually formed in a slit shape.
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[0023]
As mentioned above, although this invention was demonstrated using each Example, this
invention is not limited to the said Example, The implementation in a various different aspect is
possible. For example, in the ultrasonic vibrator having the structure shown in FIGS. 1 to 3, the
number of concave surface lenses can be arbitrarily designed, and a configuration other than the
Fresnel lens can also be used. Further, as an application of the present invention in which the
radiation surface of the ultrasonic vibrator is constituted by a plurality of lens groups, a radiation
surface can be formed by combining a plurality of convex lens groups in addition to the concave
curve lens. This structure has the effect of diffusing the sound field and forming a uniform sound
field area. This is a suitable example mainly for a cleaning tank type ultrasonic cleaning
apparatus.
[0024]
As is apparent from the above description, the radiation surface of the ultrasonic vibrator of the
present invention is formed of a plurality of concave surface lens groups having common focal
positions, and the focal position from the concave surface lens group is Since the distance to the
end is gradually increased in the direction from the center to the outer edge, the thickness of the
outer edge is relatively thin, and the entire surface is flattened. Therefore, it becomes possible to
achieve miniaturization while maintaining the concave lens effect. By setting the above distance
to the first, third, ... fresnel band sequentially with respect to the resonance frequency to be used,
ultrasonic waves of the same phase are focused on the focal position, and a stronger sound can
be obtained. There is an effect that a field is formed.
[0025]
In addition, since the ultrasonic cleaning apparatus of the present invention incorporates the
above-mentioned ultrasonic vibrator, the apparatus can be reduced in size and weight, and a
more powerful focused sound field can be easily formed. Furthermore, since the thickness of the
ultrasonic vibrator is made uniform as a whole, air bubbles in the medium liquid are easily
discharged from the exhaust port to the outside, and the reduction of the cleaning effect due to
the ultrasonic wave propagation failure is suppressed. Thus, it is possible to provide an ultrasonic
cleaning apparatus capable of obtaining a highly accurate cleaning effect.
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