ULTRASONIC CLEANING DEVICE FOR ORAL APPLIANCES

Abstract

An ultrasonic cleaning device 2 for oral appliances, comprises a tank 102 for holding a liquid and at least one oral appliance, an ultrasonic transducer 104 arranged to convey ultrasound signals to the tank, and a control circuit for driving the transducer, the control circuit arranged to provide at least a first mode and a second mode, the first mode comprising a first period during which an ultrasound signal is arranged to be provided at a first amplitude (step 216), and the second mode comprising at least a second period during which an ultrasound signal is arranged to be provided at the second amplitude (step 220) followed by a third period during which an ultrasound signal is arranged to be provided at the third amplitude (step 222), following by a fourth period during which an ultrasound signal is arranged to be provided substantially at the second amplitude (step 224), and wherein the second, third and fourth periods are substantially equal and shorter than the first period and the third amplitude is substantially lower than the second amplitude. The second mode may further comprise a fifth period during which an ultrasound signal is arranged to be provided at substantially the third amplitude (step 226) and a sixth period during which an ultrasound signal is arranged to be provided substantially at the second amplitude (step 228).

Claims

1. An ultrasonic cleaning device for oral appliances, comprising a tank for holding a liquid and at least one oral appliance, an ultrasonic transducer arranged to convey ultrasound signals to the tank, and a control circuit for driving the transducer, the control circuit arranged to provide at least a first mode and a second mode, the first mode comprising a first period during which an ultrasound signal is arranged to be provided at a first amplitude, and the second mode comprising at least a second period during which an ultrasound signal is arranged to be provided at the second amplitude followed by a third period during which an ultrasound signal is arranged to be provided at the third amplitude, following by a fourth period during which an ultrasound signal is arranged to be provided substantially at the second amplitude, and wherein the second, third and fourth periods are substantially equal and shorter than the first period and the third amplitude is substantially lower than the second amplitude.

2. The device of claim 1, wherein the second mode further comprises a fifth period during which an ultrasound signal is arranged to be provided substantially at the third amplitude and a sixth period during which an ultrasound signal is arranged to be provided substantially at the second amplitude.

3. The device of A-device-as-claimed-in-claim 2, wherein the fifth and sixth periods are substantially equal to the second, third and fourth periods.

4. The device of claim 1, wherein the first period is 10 minutes or less.

5. The device of claim 4, wherein the first period is between 3 minutes and 7 minutes.

6. The device of claim 5, wherein the first period is between 4 minutes and 6 minutes.

7. The device of claim 1, wherein the second amplitude is substantially the same as the first amplitude.

8. The device of claim 1, further comprising a current sensor arranged to detect the current drawn by the ultrasonic transducer and wherein the control circuit is further arranged to activate the transducer to emit a range of frequencies while measuring the current, the control circuit being further arranged to select a frequency corresponding substantially to the highest current drawn.

9. The device of claim 8, wherein the range of frequencies are emitted over a duration of substantially 10 seconds.

10. The device of claim 1, wherein the power of the ultrasonic transducer is between 20 and 40 W.

11. The device of claim 10, wherein the power of the ultrasonic transducer is between 24 and 31 W.

12. The device of claim 11, wherein the power of the ultrasonic transducer is between 29 and 31 W.

13. The device of claim 1, wherein the control circuit is arranged to vary the frequency of the drive signal to the ultrasonic transducer during the first, second, fourth and sixth periods.

14. The device of claim 13, wherein the control circuit is arranged to vary the frequency over a range of between 2 kHz and 10 kHz.

15. The device of claim 24, wherein the control circuit is arranged to pulse the drive signal to the ultrasonic transducer during the first, second, fourth and sixth periods.

16. The device of claim 15, wherein the control circuit is arranged to pulse the drive signal at substantially 20 times per second.

17. The device of claim 24, wherein the control circuit is arranged to pulse the drive signal to the ultrasonic transducer during the third and fifth periods.

18. The device of claim 17, wherein the control circuit is arranged to pulse the drive signal at a rate of between 5 times per second and once every 5 seconds during the third and fifth periods.

19. The device of claim 1, wherein the third amplitude is zero.

20. A cleaning method for oral appliances using the device of claim 1, the method comprising: filling the tank of the device with liquid; introducing one or more oral appliances into the tank; mounting the container on the power supply base; driving the ultrasonic transducer via the power supply base; and vibrating the liquid with ultrasonic waves to clean the or each oral appliance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] The present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

[0112] FIG. 1 is a side view of an ultrasonic cleaning device comprising a container and a base, according to one embodiment of the present invention;

[0113] FIG. 2 is a plan view of a lid of the container;

[0114] FIG. 3 is a side view of the lid of FIG. 2;

[0115] FIG. 4 is a plan view of the ultrasonic cleaning device of FIG. 1;

[0116] FIG. 5 is a plan view of the ultrasonic cleaning device of FIG. 1 with the lid removed;

[0117] FIG. 6A is a side view of a tank to be housed in the container;

[0118] FIG. 6B is a plan view of the tank;

[0119] FIG. 7 is an exploded top and side perspective view of the ultrasonic cleaning device showing a mounting surface of the base;

[0120] FIG. 8 is an exploded bottom and side perspective view of the ultrasonic cleaning device showing a mounting surface of the container;

[0121] FIG. 9 is a plan view of the mounting surface of the container;

[0122] FIG. 10 is a plan view of the mounting surface of the base;

[0123] FIG. 11 is a perspective, vertical cross-sectional view through a central axis of the ultrasonic cleaning device of FIG. 1;

[0124] FIG. 12 is a perspective, vertical cross-sectional view through a central axis of the ultrasonic cleaning device of FIG. 1 with the container detached from the base;

[0125] FIG. 13 is a horizontal cross-sectional view through the base;

[0126] FIG. 14 is perspective view of an underside of the mounting surface of the container, separated from the rest of the container;

[0127] FIG. 15 is a block schematic diagram of a drive circuit for an ultrasonic cleaning device flow chart of one embodiment of a dual cleaning mode; and

[0128] FIG. 16 is a flowchart showing different modes of operation of an ultrasonic cleaning device.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0129] Referring to FIG. 1, an ultrasonic cleaning device 2 for oral appliances comprises a container 4 and a base 6.

[0130] Base 6 may be weighted for stability during operation of the ultrasonic cleaning device. In one example, the base weighs 150 grams.

[0131] Base 6 optionally has feet 8 to provide stability (shown in FIG. 1 only). Feet 8 may be of a relatively high-friction material such as acrylonitrile butadiene styrene to hinder travel of the ultrasonic cleaning device along a surface during use.

[0132] In this embodiment, container 4 is substantially dome-shaped with a substantially circular perimeter in plan view and base 6 is substantially circular in plan view.

[0133] Container 4 is provided with a removable lid 10 having a handle portion 12 on its upper surface, as shown in FIGS. 1 to 4. Referring to FIG. 3, the lid has an inner surface portion 14 which faces the tank opening and acts as a gasket.

[0134] Referring to FIGS. 5, 6A and 6B, container 4 comprises a tank 16 which is cylindrical in shape in this embodiment. Tank 16 has a base portion 16B and one or more side portions 16S upstanding from the base portion to define an internal cleaning chamber C for receiving one or more oral appliances. In use of ultrasonic cleaning device 2, ultrasonic waves are conveyed to a liquid in tank 16. Lid 10 is configured to seal the tank.

[0135] The tank has an internal diameter of 85 mm and a volume of 215 ml in one example.

[0136] Container 4 is detachably mounted on base 6.

[0137] Referring to FIGS. 7 and 10, base 6 is a power supply base comprising electrical connection means provided by base inner contact member 18 and base outer contact member 20. In this embodiment, base inner contact member 18 is a projection and base outer contact member 20 is a projection. Base outer contact member 20 is radially spaced from base inner contact member 18.

[0138] Base 6 is provided with a socket for connection of the electrical connection means to a cable (not shown) to an external electrical source. Base 6 may be connected to a 5V DC output voltage power supply using a power jack or powered using a USB-C connection. Alternatively, base 4 may be powered by a battery being a disposable or re-chargeable battery.

[0139] Referring to FIGS. 8 and 9, container 4 is provided with corresponding electrical connection means configured for cooperation with the electrical connection means of base 6 when the container is mounted on the base. The electrical connection means of container 4 is provided by container inner contact member 24 and container outer contact member 26. In this embodiment, container inner contact member 24 is circular and container outer contact member 26 is annular and concentric with container inner contact member 24. These contact members are generally planar, providing planar contact surfaces.

[0140] The respective contact members are generally made from metals and metal alloys with high electrical conductivity. The most commonly used metal surfaces for electrical contacts are silver, copper, gold, platinum, and palladium.

[0141] Base inner contact member 18 is adapted to contact container inner contact member 24 in use to make an electrical connection. Base outer contact member 20 is adapted to contact container outer contact member 26 in use to make an electrical connection.

[0142] Container 4 is provided with a groove 28 configured to accommodate a barrier ridge 30 provided on base 6. Barrier ridge 30 surrounds the inner and outer contact members of the base and of the container when the container is mounted on the base, thereby hindering ingress of liquid towards the respective inner and outer contact members in use of the ultrasonic cleaning device. In this embodiment, groove 28 and barrier ridge 30 are annular. Neither groove 28 nor barrier ridge 30 are electrical connection means: they are physical features rather than electrical features.

[0143] The barrier ridge prevents wicking of liquid by capillary action towards the respective inner and outer contact members of container 4 and base 6, providing a barrier to water ingress to prevent corrosion of these contact members.

[0144] Barrier ridge 30 also hinders relative sliding motion between opposing mounting surfaces of container 4 and base 6 and therefore prevents damage to the projecting base contact members 18, 20 (which may be connector pins) when the container is mounted and detached from the base.

[0145] Barrier ridge 30, base inner contact member 18 and base outer contact member 20 extend from the same surface of base 6, being a mounting surface 32. The projections of base contact members 18, 20 may be retractable.

[0146] Container inner contact member 24 and container outer contact member 26 are provided on an opposing mounting surface 34 of the container.

[0147] The respective inner contact members are centrally positioned at an axis of rotation of the ultrasonic cleaning device.

[0148] The opposing mounting surfaces 32, 34 are substantially planar: they may be hydrophobic.

[0149] Mounting surface 32 of base 6 is provided with an annular projecting portion 36 and barrier ridge 30.

[0150] Mounting surface 34 of container 4 is provided with an annular recessed portion 38 and groove 28. When the container is mounted on the base, opposing mounting surfaces of the container and the base are thereby shaped to substantially inter-fit.

[0151] In this embodiment, these protrusions on the base (ie projecting portion 36 and barrier ridge 30) and these recesses on the container (ie recessed portion 38 and groove 28) are respective means for alignment of the container on the base in any radial orientation of the container relative to a central axis of the base.

[0152] Container 4 is rotatable on base 6 about the central axis of the base. Container 4 is detachably mounted on base 6 via a central connection, provided at least in part by projecting portion 36 and recessed portion 38, to provide a centring arrangement.

[0153] Referring to FIGS. 11 and 12, container 4 comprises a housing 40 for tank 16 and other components of the ultrasonic cleaning device. The housing also provides sound insulation.

[0154] An ultrasonic transducer 42 is located in the housing externally of the tank. The ultrasonic transducer is therefore located externally of cleaning chamber C and is adjacent the base portion 16B of the tank.

[0155] Ultrasonic transducer 42 is connected to a container circuit board 44 which is connected to a base circuit board 46 via the electrical connection means of container 4 and base 6 (ie base inner contact member 18, base outer contact member 20, container inner contact member 24, container outer contact member 26) when the container is mounted on the base. A power supply is electrically connected to ultrasonic transducer 42 via these contact members.

[0156] Referring to FIGS. 11 to 13, base circuit board 46 is connected to socket 22 (for a DC plug in this example) and an on/off button 48, all provided by base 6.

[0157] Housing 40 is provided with a tank fixing plate 50 surrounding the sides of the tank and a bottom cover plate 52 which provides container mounting surface 34. A sealing ring 54 seals against water ingress adjacent the bottom cover plate.

[0158] Housing 40 is also provided with a tank sealing ring 60 adjacent lid inner surface portion 14 which acts as a gasket: together, tank sealing ring 60 and lid inner surface portion 14 act to seal the tank during use of the ultrasonic cleaning device to prevent aerosols containing potentially-harmful bacteria escaping from the tank.

[0159] Base 6 comprises a housing 56 which is provided with a cover plate 58 which provides base mounting surface 32.

[0160] The underside of bottom cover plate 52 of the container is shown in FIG. 14 separated from the remainder of housing 40.

[0161] Bottom cover plate 52 is provided with six magnets 62 to allow container mounting surface 34 to magnetically connect to base mounting surface 32 via ferromagnetic portions (not shown) provided in base 6, thereby supplementing the connection between the container and the base. Magnets 62 are annularly-spaced by angles of approximately 60 degrees measured from the centre of the container mounting surface which is a central axis of the container and, in this embodiment, is the location of container inner contact member 24. The presence of magnets is optional and the number of magnets when present may be less than or more than six.

[0162] The underside of groove 28 is visible in FIG. 14 as are screw hole plugs 64, the exterior surface of these plugs also being visible in FIGS. 8 and 9.

[0163] A suitable material for tank 16 is austenitic stainless steel such as SUS 316 stainless steel which is available from available from POSCO (Zhangjiagang) Stainless Steel Co., Ltd, Zhangjiagang City, PRC. This stainless steel has antibacterial properties.

[0164] The composition of an example of a suitable stainless steel is: [0165] 0.0191 wt % carbon [0166] 0.571 wt % Silicon [0167] 1.360 wt % Manganese [0168] 0.0302 wt % Potassium [0169] 0.0010 wt % Sulphur [0170] 16.632 wt % Chromium [0171] 10.028 wt % Nickel [0172] 129 ppm Nitrogen [0173] Balance Iron

[0174] The following experiments were carried out to demonstrate the antibacterial effect of this stainless steel. No ultrasound was applied during the experiments. The bacteria were placed in a tank of antibacterial stainless steel for 24 hours (the treated specimen) and compared with bacteria placed on a non-antibacterial plastic sheet for 24 hours (the untreated specimen).

[0175] BacteriaEscherichia coli ATCC 8739Concentration of inoculum 9.410.sup.5 CFU/mL.

TABLE-US-00001 Average number The logarithm of the of viable average number bacteria of viable recovered from bacteria Test test specimen recovered from Specimen (CFU/cm.sup.2) test specimen The untreated specimen, 1.7 10.sup.4 4.23 immediately after inoculation The untreated specimen, 3.8 10.sup.5 5.58 inoculated, after 24 hours The treated specimen, 8.1 0.91 inoculated, after 24 hours

[0176] It can be seen that the material of the tank had a powerful antibacterial effect.

[0177] Lid 10 comprises silicone rubber on its inner surface facing the tank opening and on the perimeter of the lid to provide lid inner surface portion 14. This perimeter of the lid is able to seal the tank opening such that lid inner surface portion 14 acts as a gasket.

[0178] The silicone rubber comprises fumed silica. Inner surface portion 14 of the lid is thereby provided with antibacterial and hydrophobic properties. The thickness of the silicone rubber used for the inner surface of the lid is 2.25 mm in one embodiment.

[0179] A suitable example of a silicone rubber is a heat cured silicone rubber such as CENUSIL R250 CN HCR silicone rubber from Wacker Chemie AG, Germany. It has a Hardness Shore A of 50, a density of 1.1 4 g/cm.sup.3, a tensile strength of 10 N/mm.sup.2 and a tear strength of 22 N/mm.

[0180] The lid may also comprise acrylonitrile butadiene styrene, for example on its outer surface. This plastic material tends to have a soft touch and be easy to wipe clean. The housing of the container and/or the base may also comprise acrylonitrile butadiene styrene.

[0181] FIG. 15 shows a block schematic diagram 100 of a drive circuit for an ultrasonic cleaning device. A tank 102 is provided which is mechanically coupled to a piezo electric transducer (PZT) 104. The PZT is preferably attached at the bottom of the tank as shown: it is mounted in any manner that conveys the oscillations of the PZT to the tank, and hence to any contents of the tank.

[0182] The PZT 104 is driven by a transformer 106 which is fed from an amplifier 108 via a current sensor 110. A master control unit (MCU) 112 includes an oscillator 114, an analogue-to-digital converter (ADC) 116 and a touch sensor 118. The oscillator 114 of the MCU is connected to the amplifier 108 and the ADC of the MCU is connected to receive an output from the current sensor 110.

[0183] The drive circuit also comprises a temperature sensor 120 for measuring the temperature of the PZT 104 and a tank sensor 122 for measuring the contents of the tank. Both sensor 120 and sensor 122 are connected to MCU 112.

[0184] The drive circuit is thus arranged to oscillate the contents of the tank, measure the drive current and temperature of the PZT and measure the contents of the tank. An example of the operation of the drive circuit will be described with reference to FIG. 16.

[0185] FIG. 16 shows a flowchart 200 showing different modes of operation of an ultrasonic cleaning device. After power up at step 202, the drive circuit enters a standby mode and at decision step 206, it detects whether it has been activated, for example via the touch sensor 118. If not, processing returns to standby step 204.

[0186] If decision step 206 determines that the unit has been activated, then processing continues to check the tank at step 208, for example using the tank sensor 122. The tank is checked at least to ensure that there is an adequate level of liquid therein. If the liquid level (or further checks) is/are not adequate then the unit returns to standby mode 204.

[0187] If the tank check(s) is/are performed satisfactorily then processing continues to a frequency scan 210 and a temperature test 212. The frequency scan step comprises operating the PZT at a range of different frequencies, for example a sweep between 35 kHz and 45 kHz while measuring the current drawn by the PZT. By scanning a range of frequency points and recording the electric current, it is possible to identify the most effective operational frequency under the current conditions (which vary dependent upon the level of cleaning liquid and what appliance is in the tank). That is the frequency that corresponds to a higher (or highest) electric current. The MCU then selects this frequency for the cleaning operation as the choice indicative of enhanced cleaning capability. The frequency scanning step preferably lasts around 10 seconds.

[0188] The temperature test is to ensure that the PZT is sufficiently cool to be operated.

[0189] Processing continues to step 214 at which a mode is selected. The mode may be selected in response to the frequency scan and/or temperature test, or in response to user input. If mode 1 is selected then processing continues to step 216 at which the PZT is activated for 5 minutes at high power. While 5 minutes is a preferred duration, the high power activation may be maintained for between 1 and 7 minutes up to a maximum of 10 minutes. After the high power duration has ended at step 218, processing continues to standby step 204.

[0190] If, at step 214, mode 2 is selected then processing continues to step 220 at which the PZT is activated for 3 minutes at high power. While 3 minutes is the preferred duration, the high power activation may be maintained for between 2 to 5 minutes. After the high power step 220, processing continues to a low power step 222 which is maintained for three minutes. The low power step may comprise the PZT being deactivated, i.e. no drive current is supplied or it may comprise a power level of up to 10% of the high power level. While a duration of three minutes is preferred, the low power step may have a duration of between 2 and 5 minutes, or longer.

[0191] After low power step 224, processing continues to step 226 at which high power is maintained for three minutes, as for step 220. The duration may be varied as discussed above. After step 226 processing continues to step 228 in which low power is maintained for 3 minutes. The power level and duration of step 226 may be varied as discussed above. After step 226 processing continues to step 228 which comprises 3 minutes of high power activation of the PZT. Again, the duration of this step may be varied as discussed above. Mode 2 terminates at step 218 and as for mode 1, the drive circuit returns to a standby mode at step 204.

[0192] The benefit of the first mode is that the cleaning cycle is completed as quickly as possible.

[0193] Benefits of the low power or off period in the second mode include settling and reduction in hot spots. They further include optimised heat management, enhanced cleaning efficiency and prolonged device life.

[0194] Ultrasonic cleaning generates heat as a by-product so heat management is important. This mode is intended to be used for users who want to cycle the machine more than once. The off, or low power, cycles in the cleaning protocol are designed to allow the heat to disperse, preventing overheating of both the device and the cleaning solution. This controlled temperature management is important for ensuring that the oral appliances are not exposed to excessive heat, which could potentially warp or damage them.

[0195] The intermittent pauses (such as 3 minutes off) cause the cleaning solution to de-gas (an important need for ultrasonic cleaning effectiveness) and allow a potential reorientation of the oral appliance to promote cleaning of new areas that might not have been adequately cleaned in the previous on cycle. This ensures a more thorough and uniform cleaning process across the entire surface of the oral appliance.

[0196] The off, or low power, cycles also enable an oral appliance which has floated during the ultrasonication to sink towards the bottom of the tank which is adjacent the ultrasonic transducer in this embodiment: the ultrasonic cleaning effect is therefore strongest at the base of the tank. Once resubmerged in the liquid in tank, the oral appliance is ready for a subsequent cycle of ultrasonic cleaning.

[0197] The alternating cycles also help in maintaining the longevity of the device itself. Continuous operation can strain the ultrasonic generator and other components. By incorporating rest periods, the protocol reduces wear and tear, thereby extending the lifespan of the device. Additionally, this approach minimizes the risk of overheating, ensuring safe operation.

[0198] The power range applied to the PZT is typically 29-31 W. Should the PZT be subject to overheating, this may be lowered to between 24 and 27 W.

[0199] In both modes, it is preferred to vary the frequency at which the PZT is excited, over a range of at least 2 kHz.

[0200] In a preferred embodiment, in both modes, the frequency of the drive signal is pulsed at substantially 20 times per second. The frequency is also preferably swept 5 times per second over a range of at least 2 kHz.

[0201] In another preferred embodiment for mode 2, referred to as an active off protocol, the controller is arranged to also provide the low power periods with periodic pulsing, preferably at a rate of between 5 pulses per second and 1 pulse every 5 seconds. The pulses are provided at full power and preferably no longer than 1000 microseconds to maintain cooling of the liquid during the low power period.

[0202] In use of the ultrasonic cleaning device, container 4 is detached from base 6 and lid 10 is removed from container 4. Tank 16 within container 4 is filled with room temperature water up to a minimum level. An oral appliance is placed into tank 16 (optionally with sterilising tablets) such that the oral appliance is fully submerged. Lid 10 is replaced and container 4 is mounted on base 6 which is connected to a power supply. The ultrasonic cleaning device is switched on using the power button to activate ultrasonic cleaning. A cleaning mode is selected. After waiting for an allotted cleaning time, the cleaned oral appliance is retrieved and rinsed for wearing.