Abstract:
An ultrasonic dental scaler automatically supplies a frequency to match a handpiece connecting thereto. A handpiece connector includes one or more passive elements, which affect the resonant frequency produced by the generator. Multiple handpieces, each operating at a different resonant frequency, may thus be used with the same ultrasonic generator. The ultrasonic dental scaler also supports two footswitches. One footswitch includes a foot-controlled power level adjuster. When connected, the footswitch automatically disables the manual power adjuster. Another on-off footswitch includes no power adjustment mechanism. When connected, the manual power adjustment feature of the generator is maintained. Orders for different handpiece frequencies and footswitch types can thus be filled with an inventory of one generator model.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to dental equipment and, more particularly, to enhancements to dental scaler devices.  
       BACKGROUND OF THE INVENTION  
       [0002]     Dental work is performed using a variety of tools. Tools such as strippers, forceps, tweezers, pliers, and scalers, are simple and effective for cleaning and maintaining dental work.  
         [0003]     Dental scalers, for example, come in a variety of forms. Used to scrape plaque, stains, and bacterial debris from teeth, scalers may include a tip with a curved hook, a hoe-shaped tip, and so on. Some scaler tips are for general surface cleaning, while other tips are useful for particular cleaning jobs, such as scraping near the gum line. In addition to the variety of tip types, tips may also be available in many different sizes.  
         [0004]     Manually-operated dental scrapers are common. Recently, however, dental scrapers have entered the realm of high technology. Automatic dental scalers, also know as ultrasonic scalers, for example, automatically resonate a tip connected to an insert in a handpiece at a high frequency to remove plaque from teeth.  
         [0005]     The ultrasonic scalers include a generator that electrically causes the scaling tip to vibrate at a very high rate. An alternating current is passed through an induction coil in a handpiece that induces vibration of the magnetostrictive element of an insert in the handpiece. The vibration is transmitted to the tip by a velocity transducer on the end of the magnetostrictive element. The vibration may cause the tip to move elliptically, in a curved linear fashion, or in a “Fig. eight” pattern.  
         [0006]     Because of the high rate of tip vibration, the high-speed ultrasonic scalers generate a significant amount of heat. Accordingly, ultrasonic scalers operate with a water jet in the tip. The water cools the magnetostrictive element and the tip, as well as the tooth being treated, while the scaler operates.  
         [0007]     The tip, for example, may vibrate 25,000 times per second (25 KHz). Some tips operate at a lower frequency, while other tips operate at a higher one. If a tip is connected to a generator and handpiece/insert that operate at the improper frequency, the tip does not operate correctly, or can break during operation.  
         [0008]     Typically, the generator portion of the ultrasonic scaler produces a single frequency range, to support a single handpiece/insert that operates at that frequency range. To use a handpiece/insert that operates at a different frequency range, a different generator is used. To use handpiece/inserts of different frequencies associated generators for each must be obtained.  
         [0009]     Further, given the variety of tip types and sizes, the task of identifying that tips can operate at which frequency ranges may be problematic for the dental professional.  
         [0010]     Thus, there is a need to provide an ultrasonic dental scaler that operates at multiple frequencies for multiple handpieces.  
       SUMMARY OF THE INVENTION  
       [0011]     According to the embodiments described herein, an ultrasonic dental scaler is disclosed comprising a dental generator unit, the dental generator unit comprising circuitry for producing a base resonance signal, and a handpiece connector for coupling a handpiece to the dental generator unit, wherein the ultrasonic dental scaler comprises a passive circuit element which adjusts the base frequency of the resonance signal to a second frequency, matching a resonant frequency of the handpiece.  
         [0012]     In one embodiment, the ultrasonic dental scaler further comprises a first potentiometer in the dental generator unit for adjusting the power level of the resonance signal. In a second embodiment, the ultrasonic dental scaler comprises a footswitch connector for coupling a power level controlling footswitch to the dental generator unit, wherein the footswitch connector disables the first potentiometer and couples a second potentiometer in the footswitch to the dental generator unit.  
         [0013]     A method is also disclosed in which a handpiece which operates at a resonant frequency is paired with a handpiece connector as a package, wherein the handpiece assembly comprises a passive element which is associated with the resonant frequency; an order from a customer for an ultrasonic dental scaler is taken, the order comprising a first request for a handpiece, wherein the handpiece operates at the resonant frequency; and the package with the dental generator unit is sent to the customer.  
         [0014]     In another embodiment, the method further comprises receiving a second request for a footswitch, wherein the second request specifies either a power level control footswitch or an on/off footswitch. The requested footswitch is sent to the customer.  
         [0015]     In another embodiment, an inventory of ultrasonic dental scalers with interchangeable handpiece assemblies is disclosed, comprising a plurality of essentially identical generator units comprising circuitry for producing a base resonance signal and a first potentiometer for adjusting the power level of the resonance signal; a plurality of interchangeable handpieces including at least two different sets of assemblies operable at different resonant frequencies, wherein each handpiece includes passive circuitry elements for matching the base resonance signal to the resonant frequency of the handpiece; and first and second sets of footswitches including on/off circuitry, wherein the first set of footswitches enables the first potentiometer and the second set of footswitches disables the first potentiometer and enables a second potentiometer in the second footswitch. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a block diagram of an ultrasonic dental scaler according to one embodiment of the invention.  
         [0017]      FIGS. 2A-2C  are diagrams of handpiece and cable assemblies which operate at three different frequencies according to one embodiment of the invention.  
         [0018]      FIG. 3  is a second block diagram of the ultrasonic dental scaler of  FIG. 1  according to one embodiment of the invention.  
         [0019]      FIGS. 4A-4C  are diagrams of the handpiece in association with the dental generator unit according to one embodiment of the invention.  
         [0020]      FIG. 5  is a block diagram of the dental generator unit according to one embodiment of the invention.  
         [0021]      FIGS. 6A and 6B  are block diagrams of the on/off and power level control footswitches used by the ultrasonic dental scaler according to one embodiment of the invention.  
         [0022]      FIGS. 7A and 7B  are a schematic circuit diagram of the dental generator unit of  FIG. 1  according to one embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0023]     In  FIG. 1 , according to one embodiment, an ultrasonic dental scaler  100  comprises a dental generator unit  50 , a handpiece  14 , and a cable assembly  12 . A handpiece connector  10  at the end of the cable assembly  12  couples the handpiece  14  to the dental generator unit  50 .  
         [0024]     The handpiece  14  includes an insert  16 , for holding a tip  20 . The insert  16  has a magnetostrictive element  17 , a velocity transducer  15 , and the tip  20 . The insert  16  can be a unitary, two-piece, or three-piece assembly, as in U.S. Pat. No. 6,164,968, entitled “Trimodular Ultrasonic Dental Device,” which is hereby incorporated by reference as if set forth in its entirety. In one embodiment, the insert  16  may receive many different tips  20  in a variety of shapes. Dental scalers are known to vary by the size and shape of the tip.  
         [0025]     The dental generator unit  50  produces a high-frequency resonance signal that passes through the circuitry of the ultrasonic dental scaler  100 . This signal produces high-frequency impacts at the insert  16  of the scaler. These impacts are used to remove plaque and other debris from the teeth during cleaning. The ultrasonic dental scaler  100  also includes a footswitch  44 , footswitch connector  42 , and a programmable logic controller  82 . The footswitch and programmable logic controllers are described further, below.  
         [0000]     Handpiece  
         [0026]     The handpiece  14  and insert  16  can generally be considered conventional in the art. Briefly, the handpiece  14  has a well for receiving the insert  16  about which an inductive coil is disposed for imposing an alternating magnetic field that oscillates the magnetostrictive element  17  at an ultrasonic frequency. The ultrasonic vibrations are transmitted from the magnetostrictive element  17  through the velocity transducer  15  and the tip  20 , as is well known in the art. Electrical current from a power supply and control unit (not shown) and water are conventionally supplied to a proximal end of the handpiece  14  via the cable assembly  12 .  
         [0027]     Each different handpiece  14  is associated with a distinct frequency of operation. Accordingly, each handpiece  14  has its own handpiece connector  10 , for coupling the handpiece to the dental generator unit  50 .  
         [0028]     In  FIGS. 2A-2C , for example, three handpieces are associated with three different operating frequencies. A handpiece  14   a  ( FIG. 2A ) has a resonant frequency of 40 KHz. A different handpiece  14   b  ( FIG. 2B ) has a resonant frequency of 30 KHz. A still different handpiece  14   c  ( FIG. 2C ) has a resonant frequency of 25 KHz.  
         [0029]     Each handpiece  14  has a distinct cable assembly  12  associated therewith, according to one embodiment. For example, the handpiece  14   a , for 40 KHz operation, is connected to a cable assembly  12   a ; the handpiece  14   b  is connected to cable assembly  12   b , for 30 KHz operation; and the handpiece  14   c  is connected to cable assembly  12   c , for 25 KHz operation.  
         [0030]     Each of the handpieces  14   a - 14   c  may utilize different inserts  16  and/or tips  20 . For example, the 40 KHz handpiece  14   a  may receive any of the 40 KHz tips  18   a - 18   c  shown in  FIG. 2A . Likewise, the 30 KHz handpiece  14   b  may receive tips  18   d - 18   f  while the 25 KHz handpiece  14   c  may receive tips  18   g - 18   i.    
         [0031]     In one embodiment, the dental generator unit  50  may receive any of the three handpieces  14   a ,  14   b , or  14   c  (as well as cable assemblies  12   a ,  12   b , or  12   c , respectively). As will be shown below, the dental generator unit  50  produces a resonant frequency that depends on which handpiece and cable assembly pair is connected to the unit.  
         [0032]     By automatically matching the resonant frequency of the dental generator unit  50  to the connected handpiece, the dental professional need not ascertain which generator unit is being used. Instead, distinct handpieces  14 , operating at a variety of frequencies, may be used with a single ultrasonic dental scaler  100 .  
         [0033]     In one embodiment, the dental generator unit  50  includes resonance signal generation circuitry  74 , for producing a resonance signal  40  at a base frequency that may be received at the handpiece/insert. As shown in  FIG. 3 , the dental generator unit  50  also includes a potentiometer  46 , for adjusting the power sent to the unit, up or down, within a minimum and a maximum power amount.  
         [0034]     In one embodiment, an on/off circuit  76  controls the power sent to the circuitry  74  once a footswitch  44  is connected to the unit  50 . Power is received from a power source  86 , such as by connecting to a wall outlet supplying electrical power. Alternatively, the dental generator unit can be powered using a battery or other type of power source.  
         [0035]     A potentiometer knob  38  that is external to the dental generator unit is shown coupled to a potentiometer  46 . A potentiometer is a variable resistor whose resistance is adjustable, such as by turning the knob. The knob  38  controls the magnitude of power supplied to the resonance signal generation circuit  74 . Alternatively, a potentiometer  80  within a footswitch  44  may control the power magnitude. Alternative footswitch configurations of the ultrasonic dental scaler  100  are described in more detail, below.  
         [0036]     In one embodiment, a coupling of inductors and capacitors produces the resonance signal  40  created in the dental generator unit  50 , e.g., an LC circuit, to create a harmonic oscillation of current. Part of the circuit resides within either the handpiece connector  10  or in the handpiece  14 .  
         [0037]     When the handpiece connector  10  is not coupled to the dental generator unit  50 , the LC circuit portion of the generator is not operational, e.g., is open. When the handpiece connector  10  is coupled to the dental generator unit  50 , the LC circuit is closed, producing a harmonic oscillation of current. The frequency of the current must match the resonant frequency of the insert  16  in order for the scaler to function properly.  
         [0038]     In addition to automatically generating or not generating a resonance signal  40 , the ultrasonic dental scaler  100  also automatically determines the proper frequency range for the handpiece  14  that is coupled to the dental generator unit  50 . This automatic detection occurs as soon as the handpiece connector  10  is coupled to the unit  50 .  
         [0039]     In one embodiment, the handpiece connector  10  is a five-pin connector, as depicted in  FIGS. 4A, 4B  and  4 C. The fifth pin  31  is used as a water port, such that water may flow to the handpiece  14  during use, allowing the instrument to cool during operation while providing lavage.  
         [0040]     The other four pins  22 ,  24 ,  26 , and  28  connect the resonance signal generation circuitry to the handpiece. In  FIG. 4A , an inductor  30  is disposed in the handpiece  14 , with wires  23  and  25  on either end of the inductor. When the handpiece is connected to the generator  50 , wires  23  and  25  connect to the pins  22  and  24 , respectively. Accordingly, the inductor  30  in the handpiece is coupled, in parallel, to an inductor  32  and a capacitor  34  within the resonance signal generation circuit  74 . Upon receiving a current from a source (not shown), the elements  30 ,  32 , and  34  produce a resonant frequency in the handpiece  14 .  
         [0041]     The capacitor  34  is of sufficient strength to allow the source signal to resonate at a predetermined frequency. The predetermined frequency may be one of the operating frequencies supported by the ultrasonic dental scaler  100 . However, to support additional frequencies, the capacitance may be adjusted.  
         [0042]     When capacitors in a circuit are lined up in parallel, their values are added together. A higher capacitance produces a lower resonant frequency  40 . Thus, according to one embodiment, additional capacitors are added to the circuit  74  in parallel, in order to lower the operating frequency of the dental generator unit  50 .  
         [0043]     Capacitors are configured in parallel in various ways. For example, a capacitor is added to the circuit in the handpiece connector  10 , as depicted in  FIG. 4B , according to one embodiment. A capacitor  33  is disposed in the connector  10  between wires  27  and  29 . Wire  27  engages with pin  26  while wire  29  engages with pin  28 . Thus, when the connector  10  is coupled to the resonance signal generation circuit  74 , the capacitor  32  becomes part of the circuit  74 . The capacitor  32  is parallel to the capacitor  34 . Thus, the capacitances are added together to lower the operating frequency of the dental generator unit  50 .  
         [0044]     Alternatively, a capacitor may be present but not operational inside the resonance signal generation circuitry  74 . When the handpiece connector  10  is coupled to the generator  50 , the capacitor becomes operational. Such a scheme is depicted in  FIG. 4C , according to one embodiment.  
         [0045]     Before connection, the capacitor  36  is not coupled to the inductor  32  or the capacitor  34  of the resonance circuit. When the handpiece connector  10  is engaged to the generator  50 , the resulting capacitance of the circuit increases, due to the parallel configuration of the capacitor  36  with the capacitor  34 , again, producing a lower resonant frequency.  
         [0046]     By connecting the inductor  30  within the handpiece to the dental generator unit  50 , as in  FIG. 4A , a base resonant frequency can be generated that will match the resonant frequency of the handpiece/tip.  
         [0047]     Further, the frequency can be changed to automatically support a variety of handpieces  14  by introducing or removing capacitance in the handpiece connector  10 , such as in  FIG. 4B , or from within the resonance signal generation circuit  74 , such as in  FIG. 4C . In this manner, the same generator  50  can be used with handpiece/tip combinations that operate at different resonant frequencies.  
         [0048]     The value of the capacitor  32  that is wired into the handpiece connector  10  may be determined empirically, based on the other circuitry (see  FIGS. 7A-7B ) and the frequency desired. In one embodiment, the circuit board is configured to produce at the highest resonant frequency when no capacitance is added at the connector  10  (see  FIG. 4A ).  
         [0000]     Footswitch  
         [0049]     In addition to automatically supporting multiple handpieces, the ultrasonic dental scaler  100  also supports multiple footswitches or foot pedals. Returning to  FIG. 1 , a footswitch  44  is shown, coupled to the dental generator unit  50  by a footswitch connector  42 .  
         [0050]     In one embodiment, the dental generator unit  50  may receive either of two types of footswitches  44  (and associated footswitch connectors  42 ). The dental generator unit  50  automatically recognizes which footswitch  44  is connected, and adjusts operation of the dental scaler  100  accordingly.  
         [0051]     A footswitch  44   a , known herein as an on/off footswitch, performs a power-on function. When the on/off footswitch  44   a  is depressed, the dental generator unit  50  is turned on. When the on/off footswitch  44   a  is released, the dental generator unit  50  is turned off. No further adjustment of the resonance signal  40  occurs with the footswitch  44   a . A potentiometer knob  38  mounted on a panel of the generator unit  50  can adjust the level of power supplied.  
         [0052]     A second type of footswitch  44   b  is a type of power level control footswitch. Recall that power from the dental generator unit  50  is converted to a resonant frequency. Rather than supplying the power to the handpiece  14  corresponding to the set point of the potentiometer  38 , the power sent to the handpiece  14  is adjusted using a potentiometer inside the power level control footswitch  44   b . In this manner, the power level control footswitch  44   b  allows the dental professional to control the power level supplied to the resonance signal generation circuit  74 .  
         [0053]     In  FIG. 1 , the dental generator unit  50  includes a potentiometer knob  38 . In one embodiment, the potentiometer knob  38  is connected to the potentiometer  46 , inside the unit  50  (see  FIG. 3 ). The potentiometer knob  38  is a knob that is adjusted, up or down, to control the power sent from the dental generator unit  50  to the handpiece  14 .  
         [0054]     In one embodiment, where an on/off footswitch  44   a  is plugged into the unit, the potentiometer knob  38  is operative. Where the power level control footswitch  44   b  is used, however, the potentiometer knob  38  is inoperative.  
         [0055]     In one embodiment, the footswitch connector  42  is a seven-pin connector that engages to the dental generator unit  50 . One pin is dedicated as a ground pin. The other pins couple to circuitry of the dental generator unit  50  to activate the circuitry and operate the dental scaling function.  
         [0056]     In  FIG. 5 , the seven pins  62 ,  64 ,  66 ,  68 ,  70 ,  72 , and  92  are shown. The resonance signal generation circuitry  74  connects to four of the pins  62 ,  64 ,  66 , and  68 , for connection to the footswitch  44 . The potentiometer  46  is connected to the potentiometer knob  38  and, by pins  70  and  72 , to the footswitch connector  42 .  
         [0057]      FIGS. 6A and 6B  depict the on/off and power level control footswitches, respectively, to be connected to the dental generator unit  50 , according to one embodiment. In  FIG. 6A , the on/off footswitch connector  42   a  and the on/off footswitch  44   a  connect to the dental generation unit  50  at the seven pins ( 62 ,  64 ,  66 ,  68 ,  70 ,  72 , and  92 ). The on/off footswitch  44   a  includes on/off circuitry  76 , which couples to the dental generator unit  50  by pins  62  and  64 . Thus, the on/off circuitry  76  is coupled directly to the resonance signal generation circuitry  74 , allowing the on/off footswitch  44   a  to control power to the dental generator unit  50 .  
         [0058]     Further, the on/off footswitch connector  42   a  ties two pairs of connectors together, such as using a pair of wires. When engaged to the dental generator unit  50 , pins  66  and  70  are coupled together. Likewise, pins  68  and  72  are coupled together. The configuration couples the potentiometer  46  to the resonance signal generation circuitry  74 . Without the on/off footswitch connector  42   a , the signal generation circuitry  74  and the potentiometer  46  remain separated. Adjusting the potentiometer knob  38  has no effect. Once the on/off footswitch connector  42   a  is engaged, however, the potentiometer  46  may be adjusted to effect the desired power input to the circuitry  74 .  
         [0059]     In  FIG. 6B , a power level control footswitch connector  42   b  and a power level control footswitch  44   b  connect to the dental generation unit  50 , at the seven pins ( 62 ,  64 ,  66 ,  68 ,  70 ,  72 , and  92 ). As compared to the on/off footswitch connector  42   a , the power level control footswitch connector  42   b  produces different results.  
         [0060]     In one embodiment, the power level control footswitch  44   b  includes on/off circuitry  76 , which couples to the dental generator unit  50  by pins  62  and  64 . As with the on/off footswitch  44   a , the on/off circuitry  76  is coupled directly to the resonance signal generation circuitry  74 , allowing the power level control footswitch  44   b  to control power to the dental generator unit  50 .  
         [0061]     The power level control footswitch connector  42   b  includes its own potentiometer  80 . The potentiometer  80  is coupled to the resonance signal generation circuitry  74  by pins  66  and  68 , as shown in  FIG. 6B . This allows the power level control footswitch  44   b  to adjust both the power sent to the resonance signal generation circuitry  76  and the strength of the power sent.  
         [0062]     The power level control footswitch connector  42   b  includes no connections for connectors  70  and  72 . This has the effect of isolating the potentiometer  46  from the resonance signal generation circuitry  74 . The potentiometer  80  replaces the potentiometer  46 .  
         [0063]     Thus, the ultrasonic dental scaler  100  automatically receives at least two different types of footswitches. Further, each footswitch is fully functional as intended. The ultrasonic dental scaler  100  further receives a variety of different handpiece and cable assemblies and automatically adjusts the resonant frequency produced to comply with the frequency requirements and limitations of each.  
         [0000]     Programmable Logic Controller  
         [0064]     In addition to the handpiece and footswitch features described above, the ultrasonic dental scaler  100  supports a programmable logic controller, in one embodiment. The programmable logic controller is a plug-in connector device, which changes the parameters of the calibration of the dental generator unit  50 .  
         [0065]     Returning to  FIG. 1 , a programmable logic controller  82  is depicted, coupling to the dental generator unit  50 . Although shown as connecting to the dental generator unit  50  at a distinct point, the programmable logic controller  82  alternatively couples to the unit through one of the other connectors, at the handpiece connector  10  or the footswitch connector  42 .  
         [0066]     When engaged, the programmable logic controller  82  changes the operation of the dental generator unit  50 . In one embodiment, the programmable logic controller  82  changes characteristics, such as the frequency, of the resonance signal  40 .  
         [0067]     The programmable logic controller  82  modifies the operational behavior of the dental generator unit  50  in other ways as well. For example, the programmable logic controller  82  controls or adjusts the generator frequency range and the power ratio, as examples. Using the programmable logic controller  82 , a dental professional may “customize” the ultrasonic dental scaler  100  to suit specific needs.  
         [0068]     In one embodiment, a distinct programmable logic controller  82  is used with for each thickness range of tips. In other words, each programmable logic controller  82  limits the maximum power of the resonance signal  40  such that tips associated with the programmable logic controller are used, ensuring that the tips are not broken through excessive power.  
         [0069]     In another embodiment, the programmable logic controller  82  expands the range of the potentiometer  46  so that the entire range of the potentiometer is within the safe range of the tip(s), rather than reaching the maximum power supported by the dental generator unit.  
         [0070]     Like the handpiece and footswitch circuitry, the programmable logic controller  82  can include passive elements, such as resistors, capacitors, inductors, connecting wires, and so on, in one embodiment. When coupled to the dental generator unit  50 , these passive elements change the operation of the underlying circuitry. These passive elements become part of the circuitry much as the passive elements in the handpiece and footswitch circuitry became part of the unit (see  FIGS. 4A-4C  and  6 A- 6 B).  
         [0071]     The programmable logic controller  82  can alternatively or additionally include a read only memory or ROM chip that communicates with the generator unit  50  to receive data concerning the handpiece or handpiece connector and send instructions to the generator unit  50  limiting the maximum power output to match the maximum power accepted by the handpiece.  
         [0072]     A circuit  60 , enclosed in the dental generator unit  50 , is depicted in  FIGS. 7A-7B , according to one embodiment. The circuit  60  employs one or more of the techniques described above.  
         [0000]     Customer Satisfaction  
         [0073]     The ultrasonic dental scaler  100  enhances customer satisfaction by simplifying the ordering process. A customer can make a first request for multiple handpieces according to the resonant frequency desired. Since the dental generator unit operates with handpieces that operate at different resonance frequencies, a single dental generator unit can be purchased. Alternatively or additionally, the customer can make a second request for either or both of the footswitches, as each is operable with the dental generator unit. These first and/or second requests can, if desired, be made independently or together in individual, separate or combined orders.  
         [0074]     Rather than match handpieces to generators, then generators to footswitches, a supplier of the ultrasonic dental scaler ships a single generator to all customers. The handpiece connector, which includes a capacitor that is associated with a particular resonant frequency, can be paired with the handpiece in advance of customer orders. When orders are received, the likelihood of mistakes is reduced, in some embodiments, due to a much simpler procedure for the supplier.  
         [0075]     While the invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the invention.