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Title:
ULTRASONIC CLEANING DEVICE
Document Type and Number:
WIPO Patent Application WO/2005/030407
Kind Code:
A1
Abstract:
An ultrasonic cleaning (1) device is provided, which has the capability of safely and efficiently cleaning an object to be cleaned such as parts of a living body. This cleaning device comprises a housing (10) having an opening, ultrasonic transducer (20) accommodated in the housing, and an ultrasonic transmission member (30) having an ultrasonic incident surface (31) for receiving an ultrasonic wave provided from the ultrasonic transducer, and an ultrasonic radiation surface (33) . The transmission member is supported in the housing such that the ultrasonic radiation surface is exposed to outside through the opening (12) . Since the transmission member is made of a rubber material, preferably silicon rubber, the object can be safely cleaned by contact with the ultrasonic radiation surface.

Inventors:
NUNOMURA MAHITO (JP)
KISHIMOTO TAKASHI (JP)
Application Number:
PCT/JP2004/014578
Publication Date:
April 07, 2005
Filing Date:
September 28, 2004
Export Citation:
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Assignee:
MATSUSHITA ELECTRIC WORKS LTD (JP)
NUNOMURA MAHITO (JP)
KISHIMOTO TAKASHI (JP)
International Classes:
A47K7/04; A45D29/17; A61C17/00; A61C19/00; B06B1/04; B06B3/00; B08B3/02; B08B3/12; B08B7/02; (IPC1-7): B08B7/02; B06B1/04
Foreign References:
EP0420758A11991-04-03
DE8604441U11988-02-04
Other References:
PATENT ABSTRACTS OF JAPAN vol. 014, no. 301 (P - 1069) 28 June 1990 (1990-06-28)
PATENT ABSTRACTS OF JAPAN vol. 016, no. 139 (P - 1334) 8 April 1992 (1992-04-08)
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 06 31 March 1999 (1999-03-31)
Attorney, Agent or Firm:
Nishikawa, Yoshikiyo (5th Floor 12-17, Umeda 1-chome, Kita-k, Osaka-shi Osaka 01, JP)
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Claims:
CLAIMS
1. An ultrasonic cleaning device comprising: a housing having an opening; an ultrasonic transducer accommodated in said housing; and an ultrasonic transmission member having an ultrasonic incident surface for receiving an ultrasonic wave provided from said ultrasonic transducer, and an ultrasonic radiation surface; wherein said transmission member is made of a rubber material, and supported in said housing such that said ultrasonic radiation surface is exposed to outside through said opening, so that said ultrasonic wave is applied to an object to be cleaned by contact of said ultrasonic radiation surface with said object.
2. The ultrasonic cleaning device as set forth in claim 1, further comprising an ultrasonic reflector disposed between a side surface of said transmission member and an inner surface of said housing.
3. The ultrasonic cleaning device as set forth in claim 1, wherein said transmission member is of a tapered shape configured such that an area of said ultrasonic radiation surface is smaller than the area of said ultrasonic incident surface.
4. The ultrasonic cleaning device as set forth in claim 1, wherein said rubber material has an acoustic impedance value approximately equal to the acoustic impedance value of water.
5. The ultrasonic cleaning device as set forth in claim 1, wherein said rubber material comprises silicon rubber.
6. The ultrasonic cleaning device as set forth in claim 1, wherein said ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface of said horn member, and wherein an opposite end surface of said horn member connected to said ultrasonic incident surface of said transmission member is inclined at a required angle with respect to a plane perpendicular to a longitudinal axis of said horn member.
7. The ultrasonic cleaning device as set forth in claim 6, wherein said required angle is within a range of 30 to 45 degrees.
8. The ultrasonic cleaning device as set forth in claim 1, wherein said ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface portion of said horn member, and wherein said horn member has at least one recess formed in its opposite end surface such that an intensity of said ultrasonic wave propagating in said transmission member through said ultrasonic incident surface is amplified by interference.
9. The ultrasonic cleaning device as set forth in claim 1, wherein said ultrasonic wave has a frequency of vibration, which provides a standing wave that a wave number of said ultrasonic wave in a total axial length of said ultrasonic transducer and said transmission member is an integral multiple of a half wavelength of said ultrasonic wave.
10. The ultrasonic cleaning device as set forth in claim 1, wherein said ultrasonic transducer is a Langevintype transducer activated in a thickness vibration mode.
11. The ultrasonic cleaning device as set forth in claim 1, wherein said ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface of said horn member, and wherein the ultrasonic cleaning device further comprises a support member disposed to contact a side surface of said horn member, said transmission member and the inner surface of said housing, so that said transmission member is stably supported at a required position in said housing.
12. The ultrasonic cleaning device as set forth in claim 1, further comprises a heater disposed in said transmission member, and a controller for controlling a supply amount of electric power to said heater such that the object can be cleaned by contact with said ultrasonic radiation surface heated at a desired temperature by said heater.
Description:
DESCRIPTION ULTRASONIC CLEANING DEVICE TECHNICAL FIELD The present invention relates to an ultrasonic cleaning device for cleaning an object to be cleaned (preferably, parts of a living body) by contact of the object with an ultrasonic transmission member, to which an ultrasonic wave is being applied.

BACKGROUND ART In the past, ultrasonic cleaning devices have been widely utilized to remove stains from objects to be cleaned by use of ultrasonic vibrations.

For example, Japanese Patent Early Publication [kokai] No. 9-206130 discloses an ultrasonic cleaning device 1R for selectively cleaning a desired portion of an object to be cleaned. That is, as shown in FIG. 12, this cleaning device 1R comprises a base 10R, tubular sponge member 20R, ultrasonic generator 30R disposed at an interior space of the tubular sponge member, and a liquid supply unit 40R for feeding a liquid 2R as a cleaning medium in the interior space of the tubular sponge member. In the case of cleaning the object by use of this cleaning device, the tubular sponge member 20R is set on the object, and then the liquid 2R is supplied from the liquid supply unit 40R to obtain a pool of the liquid 2R in a space surrounded by the inner surface of the tubular sponge member 20R, the ultrasonic generator 30R and the object.

Next, an ultrasonic wave is applied to the pool of the liquid 2R, so that stains on the object can be removed by contact of the liquid with the object. However, since the ultrasonic wave is transmitted to the object through the liquid, there is a case that tough stains can not be sufficiently removed from the object.

Thus, this cleaning device still has plenty of room for improvement in cleaning effect.

On the other hand, Japanese Patent Early Publication [kokai] No.

2001-310165 discloses an ultrasonic cleaning device 1S having a high cleaning

capability. As shown in FIG. 13, this cleaning device 1S comprises a housing 10S having an opening 12s, ultrasonic transducer 20S disposed in the housing, and a horn member 30S connected to the ultrasonic transducer. A cleaning operation can be performed by contact of an object to be cleaned with a top end surface 32S of the horn member, to which an ultrasonic wave is being applied.

According to this cleaning device, since ultrasonic vibrations can be directly transmitted from the horn member 30S to the object, a high cleaning effect is obtained ; By the way, when a sensitive object such as parts of a living body is cleaned in the presence of ultrasonic vibrations, the safety is an important factor, as well as the cleaning capability. In the above cleaning device, the housing 10S has a guide ring 14S formed at the vicinity of the opening 12S to prevent that the user touches the horn member 30S by mistake. However, since the horn member 30S is made of a metal material such as aluminum, there is a fear that injury or pain occurs is caused by contact of the parts of the living body with the horn member, to which the ultrasonic wave is being applied. Thus, in the case of cleaning the parts of the living body by use of the ultrasonic vibrations, this cleaning device still has plenty of room for improvement in safety.

SUMMARY OF THE INVENTION Therefore, a primary concern of the present invention is to provide an ultrasonic cleaning device having a high cleaning capability and improved safety in the case of cleaning an object such as parts of a living body.

That is, the ultrasonic cleaning device of the present invention comprises a housing having an opening, ultrasonic transducer accommodated in the housing, and an ultrasonic transmission member having an ultrasonic incident surface for receiving an ultrasonic wave provided from the ultrasonic transducer, and an ultrasonic radiation surface. The transmission member is made of a rubber material, and supported in the housing such that the ultrasonic radiation surface is exposed to outside through the opening, so that

the ultrasonic wave is applied to an object to be cleaned by contact of the ultrasonic radiation surface with the object.

According to the present invention, the object can be efficiently cleaned by contact with the transmission member, to which the ultrasonic wave is being applied. In addition, since the transmission member is made of the rubber material, there is an advantage of preventing the occurrence of damage in the object during the cleaning operation. In particular, when cleaning parts of the living body as the object, it is possible to provide a safe cleaning operation without causing pain or injury.

In the present invention, it is preferred to use the rubber material having an acoustic impedance value approximately equal to the acoustic impedance value of water, which is a main component of the living body, and more preferably silicon rubber. In this case, it is possible to prevent damping of standing wave vibrations of the ultrasonic wave, which is caused by the contact of the transmission member with the parts of the living body as the object, while keeping the safety of the cleaning operation.

In the above-described cleaning device, it is also preferred that an ultrasonic reflector is disposed between a side surface of the transmission member and an inner surface of the housing. In this case, since the ultrasonic wave propagating in the transmission member is interfered with the ultrasonic wave reflected by the reflector to obtain an amplified ultrasonic wave, it is possible to further improve the cleaning capability.

In addition, it is preferred that the transmission member is of a tapered shape configured such that an area of the ultrasonic radiation surface is smaller than the area of the ultrasonic incident surface. In this case, since the ultrasonic wave is amplified as it propagates from the ultrasonic incident surface toward the ultrasonic radiation surface along the tapered shape of the transmission member, it is effective to improve the cleaning capability.

As a preferred embodiment of the present invention, the ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed

in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface of the horn member, and an opposite end surface of the horn member connected to the ultrasonic incident surface of the transmission member is inclined at a required angle with respect to a plane perpendicular to a longitudinal axis of the horn member. It is also preferred that the required angle is within a range of 30 to 45 degrees. In this case, even if the object is located in a narrow space, it is possible to easily contact the ultrasonic radiation surface of the transmission member to the object. For example, it is very convenience to clean the top or biting surface of a back tooth (molar or premolar).

As another preferred embodiment of the present invention, the ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface of the horn member, and the horn member has at least one recess formed in its opposite end surface such that an intensity of the ultrasonic wave propagating in the transmission member through the ultrasonic incident surface is amplified by interference. In this case, it is possible to apply the amplified ultrasonic wave to the object through the ultrasonic radiation surface of the transmission member, and therefore further improve the cleaning capability.

In addition, it is preferred that the ultrasonic transducer comprises a horn member and an ultrasonic wave generator formed in a laminate structure by alternately placing electrodes and piezoelectric members, and connected to an end surface of the horn member, and wherein the ultrasonic cleaning device further comprises a support member disposed to contact a side surface of the horn member, the transmission member and the inner surface of the housing, so that the transmission member is stably supported at a required position in the housing.

It is also preferred that the above ultrasonic cleaning device comprises a heater disposed in the transmission member, and a controller for controlling a

supply amount of electric power to the heater such that the object is cleaned by contact with the ultrasonic radiation surface heated at a desired temperature by the heater. In this case, it is possible to further increase the cleaning capability by use of the heated transmission member.

Further characteristics of the present invention and effects brought thereby will be clearly understood from the best mode for carrying out the invention described below.

BREIF EXPLANATION OF THE DRAWINGS FIG. 1A is a schematic cross-sectional view of an ultrasonic cleaning device according to a first embodiment of the present invention, and FIG. 1B is a perspective view of an ultrasonic transmission member of the cleaning device; FIG. 2 is an exploded perspective view of an ultrasonic transducer of the cleaning device; FIG. 3 is a partially cross-sectional view of the cleaning device; FIG. 4 is a conceptual diagram showing standing wave vibrations developed by the ultrasonic transducer; In FIGS. 5A to 5F, FIG. 5A is a schematic cross-sectional view of an ultrasonic cleaning device according to a modification of the first embodiment, FIG. 5B is perspective view of a horn member of the cleaning device, FIG. 5C is a partially cross-sectional view of the horn member, and FIGS 5D to 5F are partially cross-sectional views of another horn members; FIGS. 6A and 6B are side views of another horn members available in the present invention FIGS. 7A and 7B are cross-sectional views of the cleaning device according to another modification of the first embodiment; FIGS. 8A and 8B are schematic diagrams showing electrical connections between electrodes of the ultrasonic transducer and a drive circuit of the cleaning device; FIGS. 9A and 9B are schematic diagrams showing how to support the horn member in a housing of the cleaning device;

FIG. 10 is a waveform diagram of an ultrasonic wave provided by a second frequency controller of the drive circuit ; FIG. 11A is a schematic cross-sectional view of an ultrasonic cleaning device according to a second embodiment of the present invention, and FIG. 11B is a partially cross-sectional view showing a cleaning operation with the cleaning device ; FIG. 12 is a perspective view of a conventional ultrasonic cleaning device; and FIG. 13 is a partially cross-sectional view of another conventional ultrasonic cleaning device.

BEST MODE FOR CARRYING OUT THE INVENTION An ultrasonic cleaning device of the present invention is explained in detail according to preferred embodiments, referring to the attached drawings.

<First Embodiment As shown in FIG. 1A, the ultrasonic cleaning device 1 of this embodiment comprises a housing 10 having an opening 12, ultrasonic transducer 20 accommodated in the housing, drive unit 40 for driving the ultrasonic transducer, an ultrasonic transmission member 30 having an ultrasonic incident surface 31 for receiving an ultrasonic wave provided from the ultrasonic transducer 20, and an ultrasonic radiation surface 33.

The housing 10 can be made of an insulating material such as synthetic resins, and has a tapered portion 11 configured such that a cross section perpendicular to an axial direction of the housing gradually decreases toward the opening 12. In addition, since the housing 10 has a handle portion 13 formed in an elongate shape that is east to grip, the user can carry the cleaning device accurately to a desired portion of an object to be cleaned. If necessary, <BR> <BR> a slip stopper, e. g. , a patterned rubber sheet may be provided on the handle portion 13.

The ultrasonic transducer 20 comprises a vibration generator 21 and a horn member 25. The vibration generator 21 has a laminate structure formed by alternately placing ring-like electrodes 22 and piezoelectric ceramic rings 23,

as shown in FIG. 2. The electrodes 22 can be made of nickel or beryllium, and the piezoelectric ceramic rings 23 can be made of lead titanate or crystalline quartz. The vibration generator 21 is fixed to a bottom surface of the horn member 25 by use of a bolt 90. The horn member 25 can be made of a metal material, for example, a light alloy such as aluminum alloys or a light metal such as aluminum. In this embodiment, the horn member 25 is of an exponential type that a cross section perpendicular to the axial direction of the horn member exponentially changes in the axial direction. The ultrasonic transducer 20 having the above-mentioned structure is called as a Langevin-type transducer.

The ultrasonic transducer 20 is activated in a thickness-vibration mode by the drive circuit 40. The drive circuit 40 can be formed by mounting electronic parts for an oscillating circuit on a substrate, and powered by use of a rechargeable battery (not shown) detachably attached to the housing, or a commercial power source. In addition, when the rechargeable battery is built in the housing 10, it is preferred that a terminal for charging the battery is formed at an end of the handle portion 13 opposed to the ultrasonic radiation surface of the cleaning device. In this case, the charging operation can be performed in a state that the cleaning device is stood on a battery charger.

In this embodiment, the ultrasonic transmission member 30 is configured in a circular truncated cone shape comprising a base used as the ultrasonic incident surface 31, cap having a smaller area than the base and used as the ultrasonic radiation surface 33, and a side surface 35 supported by an inner surface of the housing 10, as shown in FIG. 1B. The transmission member 30 is supported in the housing 10 such that its top end portion having the ultrasonic radiation surface 33 is projected outside through the opening 12, so that the ultrasonic wave is applied to an object T to be cleaned by contact of the ultrasonic radiation surface with the object.

To avoid the risk of pain or injury during the cleaning operation, the transmission member 30 of the present invention is made of a rubber material,

preferably silicon rubber. In addition, an acoustic impedance value (1.0 x 106 N s/m3 to 3.0 x 106 N s/m3) of the silicon rubber is approximately equal to the acoustic impedance value (1.5 x 106 N-s/m3) of water, which is a main component of the living body. Therefore, it is possible to prevent damping of standing wave vibrations of the ultrasonic wave when the transmission member contacts parts of the living body as the object. As a result, this provides an improvement in energy efficiency. As the rubber material, natural rubber having an acoustic impedance value in the above range may be used.

In this embodiment, as shown in FIG. 3, an ultrasonic reflector 50 made of a metal material such as aluminum is disposed between the inner surface of the housing 10 and the side surface 35 of the transmission member 30. As described in detail later, since the ultrasonic wave propagating in the transmission member 30 toward the housing is reflected by the ultrasonic reflector 50, it is possible to reduce transmission loss of the ultrasonic wave, and save energy used for the cleaning operation. Alternately, a part of the tapered portion 11 of the housing 10, to which the side surface 35 of the transmission member 30 contacts, may be made of the metal material. In FIG.

3, the numeral 60 designates a support member disposed to contact a side surface of the horn member 25, the base of the transmission member 30 and the inner surface of the housing 10. By the presence of this support member 60, the transmission member 30 can be more stably supported at a required position in the housing 10.

Next, an operation of the ultrasonic cleaning device is explained. The ultrasonic wave provided from an end surface of the horn member 25 propagates in the transmission member 30 through the ultrasonic incident surface 31. As shown by the arrows in FIG. 3, a part of the ultrasonic wave in the transmission member 30 is reflected by the ultrasonic reflector 50. The reflected wave is interfered with the ultrasonic wave propagating in the axial direction of the transmission member, so that an amplified ultrasonic wave is radiated from the ultrasonic radiation surface 33. By use of the thus obtained

strong ultrasonic wave, tough strains can be effectively removed from the object.

Simultaneously, by using the transmission member 30 made of the rubber material, and preferably silicon rubber, it is possible to avoid a situation that pain or injury is caused by the contact of the transmission member 30 with the parts of the living body as the object, and safely provide the high cleaning capability.

The ultrasonic wave provided from the ultrasonic transducer 20 of this embodiment has a frequency of vibration, which provides a standing wave that a wave number of the ultrasonic wave in a total axial length of the ultrasonic transducer 20 and the transmission member 30 is an integral multiple of a half wavelength of the ultrasonic wave. That is, the drive unit 40 activates the ultrasonic transducer 20 at a frequency that the standing wave is formed in the total axial length of them. For example, FIG. 4 shows standing wave vibrations formed in the axial length LT of the ultrasonic transducer 20. Fundamentally, the ultrasonic wave is longitudinal wave. However, in this figure, it is drawn as transverse wave as a matter of convenience. At both ends of the ultrasonic transducer 30, the antinode of the standing wave is located. In the fundamental wave FWI, the axial length LT corresponds to a half wavelength.

In the second harmonic wave FW2, the axial length LT corresponds to one wavelength. In the third harmonic wave FW3, the axial length LT corresponds to three times of the half wavelength. In a higher harmonic wave FWN, the axial length LT corresponds to N times of the half wavelength.

In the case of using the third harmonic wave FW3, the output needed to obtain the approximately same cleaning effect becomes smaller, as compared with the case of using the higher harmonic wave FWN. Therefore, it is effective to downsize the cleaning device. In addition, since the horn member 25 is connected to the vibration generator 21 at a position substantially corresponding to the antinode of the standing wave, it is possible to effectively prevent a mechanical damage caused by vibrations of the ultrasonic transducer 20. As the frequency of vibration of the ultrasonic wave, it is preferred to use

the ultrasonic wave having a relatively low frequency of 20 to 60 kHz, which is better suited for removing tough stains. It is further preferred that the cleaning device comprises a means for allowing the user to select the frequency of the ultrasonic wave depending on the degree of contamination.

From the viewpoint of further increasing the cleaning capability of the cleaning device, it is preferred that the end surface of the horn member 25 connected to the ultrasonic incident surface 31 of the transmission member 30 has at least one recess 26 formed such that an intensity of the ultrasonic wave propagating in the transmission member is amplified by interference. For example, as shown in FIGS. 5A and 5B, when a plurality of recesses 26 are formed in the end surface of the horn member 25, the ultrasonic wave radiated from a hemispheric surface of each of the recesses propagates toward a center of the hemispheric surface, as shown by the arrows in FIG. 5C, so that the intensity of the ultrasonic wave is amplified by the interference. Since the amplified ultrasonic wave is applied to the object through the transmission member 30, an improvement in cleaning capability can be achieved. The number of recesses 26, shape and size of the respective recess are not specifically restricted. For example, another horn members having recesses shown in FIGS. 5D to 5F may be used.

As a modification of this embodiment, in place of the horn member 25 shown in FIG. 1A, it is preferred to use a horn member 25A of step type configured such that two cylinder solids having different cross sectional areas are connected to one another to have the same longitudinal axis, as shown in FIG. 6A. Alternatively, a horn member 25B of conical type may be used, which is configured such that the cross sectional area perpendicular to the axial direction linearly decreases at a constant rate, as shown in FIG. 6B. The former one is excellent in amplification rate of the ultrasonic wave, and the latter one is excellent in durability.

As another modification of this embodiment, the housing 10 may be provided with a first housing 10A for accommodating the drive unit 40 and

ultrasonic transducer 20 therein, and a second housing lOB having the ultrasonic transmission member 30, as shown in FIG. 7A. In this case, the first housing 10A is detachably attached to the second housing lOB by a screw engagement 92 therebetween, as shown in FIG. 7B. In addition, since the second housing lOB can be replaced by another second housing (not shown), to which the ultrasonic transmission member 30 having a different area of the ultrasonic radiation surface 33 is being attached, it is possible to flexibly deal with different cleaning operations. Moreover, due to the common use of the first housing 10A, this ultrasonic cleaning device is excellent in cost performance. Furthermore, there is an advantage that maintenance is easy.

To surely prevent electric leakage to the object, for example, it is preferred to make electrical connections between the drive unit 40 and the electrodes 22 of the ultrasonic transducer 20 such that a center one of the electrodes is at the positive potential and the remaining two electrodes are at the negative potential, as shown in FIG. 8A. Alternatively, it is possible to make an electrical connection with an end surface of the horn member 25 such that the horn member is at the negative potential, as shown in FIG. 8B. In this case, it is possible to reduce the number of electrodes 22.

As shown in FIG. 9A, it is preferred that the horn member 25 is supported in the housing 10 by engaging a projection 15 formed on the inner surface of the housing into a groove 27 formed in the side surface of the horn member.

Alternatively, as shown in FIG. 9B, the horn member 25 may be supported in the housing 10 by fitting an elastic member 70 such as O-ring attached to the horn member in a groove 17 formed in the inner surface of the housing. In either case, by forming the projection 15 or the groove 17 at a position substantially corresponding to the node of the standing wave, it is possible to effectively reduce transmission loss of the ultrasonic vibrations.

The drive unit 40 has the main purpose of activating the ultrasonic transducer 20 to generate the ultrasonic wave. If necessary, the drive unit may comprise at least one of the following controllers.

That is, the drive unit 40 may comprise a temperature controller 41 for controlling the temperature of the ultrasonic transmission member 30. In this case, as shown in FIG. 1A, the temperature controller 41 supply an electric power to a heater 43 embedded in the transmission member 30 to heat the transmission member. By contact of the heated ultrasonic radiation surface 33 of the transmission member 30 with the object in the presence of ultrasonic vibrations, it is possible to further increase the cleaning capability. As the heater, a Peltier device can be used.

The drive unit 40 may comprise a conversion rate controller (not shown) for controlling an electric-acoustic conversion efficiency. In this case, by changing the electric-acoustic conversion efficiency between the ultrasonic transducer 20 and the transmission member 30, it is possible to control the temperature of the transmission member. As the electric-acoustic conversion efficiency decreases, a heat generation amount of the transmission member increases.

The drive unit 40 may comprise a first frequency controller (not shown) for controlling the frequency of the ultrasonic wave output from the ultrasonic transducer 20. In this case, it is possible to select an adequate frequency of the standing wave depending on the degree of contamination of the object. In the standing wave, a high cleaning effect is obtained at the node position, and the cleaning effect becomes lower at the antinode position. Therefore, there is an advantage that a uniform cleaning effect is obtained by changing the frequency of the standing wave. For example, it is preferred that the frequency is selectable within a range of 20 to 60 kHz.

The drive unit 40 may comprise an output controller (not shown) for controlling an ultrasonic power generated by the ultrasonic transducer 20. In this case, by controlling an amount of electric power supplied to the ultrasonic transducer 20, the cleaning operation can be performed under an ultrasonic intensity suitable to the individual object.

The drive unit 40 may comprise a second frequency controller (not shown)

for allowing the ultrasonic transducer 20 to intermittently oscillate the ultrasonic wave, and controlling a period of blocking oscillation. In this case, as shown in FIG. 10, the ultrasonic wave is output such that an oscillation period T1 for generating the ultrasonic wave, and a rest period T2, at which the ultrasonic wave is not generated, are alternately repeated. In addition, during the respective oscillation period Tl, the ultrasonic transducer 20 provides a sinusoidal vibration having a constant period TW. In this figure, TB designates the period of blocking oscillation. Therefore, the frequency of blocking oscillation is represented by 1/TB. As the oscillation period T1 is longer, or the rest period T2 is shorter, a higher cleaning effect is obtained. As an example, the period of blocking oscillation can be controlled by changing a width of the rest period T2 under the oscillation period T1 is constant (e. g. , 0.5 seconds). In the case of using the blocking oscillation, there are another advantages of preventing the generation of heat in the ultrasonic transducer 20, and a wearing down of the elastic member 70 disposed between the horn member 25 and the housing 10.

<Second Embodiment> An ultrasonic cleaning device 1 of this embodiment is substantially the same as the first embodiment except for the following features. Therefore, the same components in the ultrasonic cleaning device shown in FIG. 11A are assigned the same numerals used in the first embodiment, and duplicate explanations are omitted.

As shown in FIG. 11A, this embodiment is characterized in that an end surface of the horn member 25 connected to the ultrasonic incident surface 31 of the transmission member 30 is inclined at a required angle B with respect to a plane perpendicular to a longitudinal axis of the horn member. Since a reduction in intensity of the ultrasonic wave transmitted to the ultrasonic radiation surface 33 depends on sind7, it is preferred to select the required angle smaller than 45 degrees. In the case of selecting the required angle from a range of 30 to 45 degrees, there is an advantage of easily performing the

cleaning operation even when the object is located in a narrow space. For example, as shown in FIG. 11B, it is very convenience to clean the top or biting surface of a back tooth (molar or premolar) as the object T.

INDUSTRIAL APPLICABILITY As described above, according to the ultrasonic cleaning device of the present invention, since the ultrasonic transmission member is made of a rubber material, preferably silicon rubber, it is possible to provide a safe cleaning operation despite the direct contact between the ultrasonic radiation surface and the object. In addition, the ultrasonic vibration is efficiently applied to the object through the ultrasonic radiation surface, a high cleaning effect can be achieved. From these advantages, it is expected that the ultrasonic cleaning device of the present invention will be widely used to clean various objects, particularly parts of a living body.