Ultrasonic surgical tool system

Abstract

An ultrasonic tool system has a console (230) and a tip (142) having a distal end that vibrates longitudinally and torsionally when vibrated. The console applies a drive signal to a driver (36) that causes the tip to vibrate at a longitudinal mechanical cancellation frequency. Thus, when the tip vibrates, the longitudinal component of a first resonant mode of the tip at the distal end cancels the longitudinal component of a second resonant mode of the tip, so that the distal end of the tip participates in a vibration that is substantially torsional and only minimally longitudinal.

Description

[0001] This application is a divisional application of patent application 201680082077.5, whose application date is December 14, 2016 and whose invention name is “Ultrasonic surgical tool system”. Technical Field

[0002] The present invention relates generally to ultrasonically driven surgical handpieces. More particularly, the present invention relates to an ultrasonically driven handpiece having multiple vibration modes and a method of driving the handpiece such that the tip head undergoes vibrations that are torsional in nature. Background Art

[0003] Ultrasonic surgical instruments are useful surgical instruments for performing specific medical and surgical procedures. Typically, ultrasonic surgical tools include a handpiece that contains at least one piezoelectric driver. The tip is mechanically coupled to the driver and extends forward from a housing or shell in which the driver is provided. The tip has a head. The head is provided with features that are generally teeth, and its size is suitable for completing specific medical / surgical tasks. The ultrasonic tool system also includes a console. The console provides an AC drive signal to the driver. When the drive signal is applied to the driver, the driver expands and contracts cyclically. The expansion / contraction of the driver causes sound waves that propagate along the tip. The sound waves cause the tip (especially the head) to enter a forward and backward motion. When the tip moves in this way, the tip is considered to be vibrating. The vibrating head of the tip is applied against the tissue to perform a specific surgical or medical task. For example, some tip heads are applied against hard tissue. One form of hard tissue is bone. When this type of tip head is vibrated, the forward and backward vibration of the tip teeth saws off the adjacent hard tissue. There are also other tip heads designed to be placed against soft tissue.

[0004] Some ultrasonic tools remove tissue by causing cavitation in the tissue and surrounding fluid. Cavitation occurs as the tip head moves back and forth at or above the speed that causes cavitation. Cavitation is the formation of small gaps, cavities, in the tissue and surrounding fluid adjacent to the tip. These cavities are very small areas of extremely low pressure. There is a pressure differential across these cavities and the boundaries between the cells that form the adjacent tissue. Due to the relatively large amplitude of this pressure differential, the cell walls burst. The bursting of these cell walls removes and ablates the cells that form the tissue. Some tips are formed with teeth that protrude laterally outward from the sides of the tip head.

[0005] Physically, many tips include an elongated shaft. The proximal or rear end of the shaft is connected to the handpiece. The head (tip head) is located at the distal end, i.e., the free end of the shaft. The head sometimes protrudes outward from the adjacent portion of the shaft. The head of the ultrasonic tip is usually relatively small. Some heads have a diameter of less than 1.0 cm. The ultrasonic tool removes tissue adjacent to the application head. Due to the relatively small surface area of ​​its head, the ultrasonic handpiece has been proven to be a useful tool for accurately removing both hard and soft tissues.

[0006] Other cutting instruments for selectively removing tissue are drills and burs. To make the drill or bur work, the instrument is usually rotating. Here, "rotation" should be understood to mean repeated 360 ° motion around the longitudinal direction of the instrument. When confronted with the resistance of the tissue, the mechanical force of the rotation can make the instrument jump out of the path of cutting. Another undesirable effect of this rotation is that when the shaft of the instrument is always pressed on the tissue that is not intended to be removed, the rotation can tear or otherwise damage the tissue. In contrast, the shaft and head of the ultrasonic tip do not rotate. This means that when this type of instrument is used in a process, the possibility of tissue damage due to the rotation of the tip is basically eliminated.

[0007] Most tips are designed so that when a drive signal is applied, the tip head vibrates primarily in a single mode. Here, a vibration mode is understood to be a travel path along which the tip head travels. Most tips are designed to vibrate longitudinally. This means that the head moves back and forth along an axis that is substantially aligned with the proximal to distal longitudinal axis along the tip.

[0008] One problem arises when the tip vibrates longitudinally. Tips of this type as described above are designed so that when the sides of the tip head are applied against the tissue and vibrated, the teeth cut, excising the tissue. Alternatively, or in combination with the cutting, the teeth may promote cavitation of adjacent tissue to ablate. This problem arises because sometimes the distal end of the tip's shaft may vibrate at a speed that causes cavitation in the tissue compressed by that end of the head. This cavitation may result in the undesirable ablation, removal of tissue that is not the target of removal. The fact that this removal occurs at the distal end of the tip head further complicates the challenge of reducing this undesirable tissue removal. This location is typically hidden from the practitioner's view. Therefore, it may be difficult for the practitioner to determine whether this undesirable tissue ablation is occurring due to the placement of the tip.

[0009] Some tips are available that vibrate in modes other than the longitudinal mode. Some tips are designed so that their heads participate in torsional or rotational vibrations when vibrated. This means that the head rotates around the longitudinal axis of the tip when excited into vibration. Still other tips are designed to flex. This rotation moves back and forth around an arc that subtends an angle of less than 360°. This means that when the tip is excited, the longitudinal axis of the tip bends back and forth. The tip head moves as the tip bends (i.e., flexes).

[0010] A characteristic integrated with the ultrasonic handpiece is the mechanical resonant frequency of the handpiece. Here, the handpiece should be understood to mean both the driver and the components of the handpiece coupled to the driver including the tip. The mechanical resonant frequency is the frequency of these components at which the tip head experiences a peak range of vibrational motion when the tip is vibrated at this frequency. For a tip that vibrates longitudinally, the peak range is understood to be the maximum back and forth distance. For a tip that vibrates torsionally or flexurally, the maximum range is understood to be the maximum arc in a single phase of the vibration cycle. Here, peak range motion is understood to be motion that is greater in magnitude than the motion that occurs when the driver vibrates at a frequency slightly below or slightly above the resonant frequency.

[0011] Due to their structure, some handpieces have multiple mechanical resonance modes. This means that this type of handpiece has multiple frequencies at which the tip head participates in a peak range of movement when the handpiece is vibrated compared to adjacent frequencies. Each mechanical resonance frequency is associated with a single mechanical resonance mode in the mechanical resonance modes.

[0012] The applicant's PCT publication number WO 2015 / 021216A1 / US Patent Publication No. ____ discloses a unit for adjusting the frequency of a drive signal so that the signal is at a frequency that matches the mechanical resonant frequency of the tip as closely as possible, the contents of which are incorporated herein by reference. Generally, the process is performed by determining whether the following equation (Equation (11)) of PCT Publication No. WO 2015 / 021216A1 tests true:

[0013]

[0014] The frequency of the drive signal applied to the driver is used as a variable for the antecedent and the consequent of the ratio. PCT Publication No. WO2015 / 021216A1 teaches adjusting the drive signal frequency so that the frequency is at a resonant frequency for a specific mechanical resonant mode of the handpiece. Typically, this resonant frequency is for a mechanical resonant state of the handpiece that causes vibrations of the maximum peak range of motion of the tip head.

[0015] If the calculations used to determine the above ratios produce a positive result, it is necessary to reduce the frequency of the drive signal in order to more closely match its resonant frequency to produce the maximum desired vibration movement. In general, the variables selected to calculate the ratio are selected to determine the frequency of the drive signal that will cause the tip to vibrate at the resonant frequency in a resonant state in which the longitudinal and torsional modes of vibration have maximum amplitude.

[0016] exist Figure 1, frequency f1 (approximately 24.45 kHz) is the frequency associated with the first of the mechanical resonance modes of the handpiece. This frequency is the resonant frequency of this resonance mode when the tip is in an unloaded state. When the tip is vibrating in free space, the tip is in an unloaded state. When the tip is applied to tissue, the load on the tip increases above the free space load. This results in a change in the resonant frequency (or frequencies) of the mechanical resonance mode (or modes). The resonant frequency (or frequencies) of the tip may also change for other reasons. These reasons include changes in the tip temperature or changes in the acoustic properties of the load applied to the tip. This is why PCT Publication NO. WO 2015 / 021216A1 teaches continuously evaluating whether equation (1) tests to be true. As the tip is applied to tissue, the resonant frequency of the mechanical resonance mode changes. Therefore, to ensure efficient operation of the system (including the tip), PCT Publication No. WO 2015 / 021216A1 teaches continuously adjusting the drive signal applied to the handpiece based on equation (1) so that the signal is at a frequency that matches the real-time resonant frequency of the relevant mechanical resonant mode as closely as possible.

[0017] Some tips are now available that are designed to substantially reduce the undesirable effects caused by longitudinal movement of the tip shaft adjacent to the tip head. Typically, the tip is designed to vibrate simultaneously in two modes. Typically, the tip is designed to vibrate in a longitudinal mode and a torsional mode. One tip that is capable of vibrating simultaneously in these two modes is the Long Micro Claw tip available from the present applicant (Stryker Corporation of Kalamazoo, Michigan). The structure of this tip is disclosed in U.S. Patent No. 6,955,680 (COUPLING VIBRATION ULTRASONIC HAND PIECE), the contents of which are expressly incorporated by reference. In short, this type of tip has the characteristics of decomposing the longitudinal vibration transmitted from the drive into two components. Specifically, these features decompose the vibration so that each vibration has a longitudinal component (longitudinal mode vibration) and a torsional component (torsional mode vibration).

[0018] The tip head vibration is a vibration equal to the sum of the longitudinal mode vibration and the sum of the torsional mode vibration.

[0019] The tip has two mechanical resonance modes in the relevant frequency range. Figure 1, frequency f1 is the resonant frequency associated with the first mechanical resonance mode. Frequency f2 (25.32 kHz) is the resonant frequency associated with the second mechanical resonance mode. When the tip vibrates at the mechanical resonance frequency associated with the first mechanical resonance mode, the distal portion of the tip experiences both longitudinal and torsional movement that are in a peak range compared to the range of movement when the drive signal is slightly below or slightly above the resonant frequency. When the tip vibrates at the mechanical resonance frequency associated with the second mechanical resonance mode, the distal portion of the tip experiences both longitudinal and torsional movement that are in a peak range compared to the range of movement when the drive signal is slightly below or slightly above the resonant frequency. For a tip to which a drive signal of approximately 25 kHz is applied, the definition of "slightly below" can be a frequency of 100 to 300 Hz below the mechanical resonance frequency. For this type of tip, the definition of "slightly above" can be a frequency of 100 to 300 Hz above the mechanical resonance frequency.

[0020] Typically, the peak range of motion produced when the tip vibrates in one of the mechanical resonance modes is a greater range of motion than the peak range of motion when the tip vibrates at a frequency associated with another mechanical resonance mode. PCT Publication No. WO 2015 / 021216A1, incorporated by reference above, teaches the use of providing a drive signal that causes the tip to vibrate at a resonant frequency of the mechanical resonance mode at which the peak range of motion has a maximum amplitude. Figure 1 In this case, this is frequency f1.

[0021] The applicant's PCT application number PCT / US2015 / 044023, published as WO2016 / 022808A1 / US patent number ________ discloses an alternative system for regulating the application of a drive signal applied to a handpiece, the contents of which are incorporated herein by reference. The document relates to a system that discloses how to apply a drive signal having multiple components to a handpiece. The first component of the drive signal has a potential and is at a frequency associated with a first mechanical resonance mode, i.e. Figure 1 The second component of the drive signal has a potential and is at a frequency associated with the second mechanical resonance mode. This is Figure 1The frequency f2 in the vibration is set to f2. By adjusting the potential and frequency of the individual components of the drive signal, the amplitude of the sum of the longitudinal components of the vibrations associated with the two mechanical resonance modes can be adjusted. Adjustment of the potential of the individual components of the drive signal also sets the amplitude of the sum of the torsional components of the vibrations of the two resonant states. By adjusting these individual vibration components, the tip can be vibrated in such a way that the tip head participates in a travel path that can be considered to be nonlinear. Here, a nonlinear travel path is a travel path that, when a single point on the tip head participates in a single back-and-forth vibration cycle, in the first phase of the cycle, the point transitions to a first set of points in space; in the second phase (return phase), the tip transitions to a second set of points in space. The second set of points is different from the first set of points. In one example, the path of travel in a single cycle is substantially elliptical.

[0022] The benefit of driving the tip in a non-linear travel path is that in the first phase, the teeth impact the bone and then rub the bone in the next phase of movement. During the impact phase of the tip teeth movement, the tip fractures the bone to remove the desired amount of bone. During the movement phase of the teeth rubbing the bone, the teeth clear the debris that has just been formed due to the teeth impact phase. The removal of these debris results in a possible reduction in the extent to which the presence of debris during the next vibration cycle adversely affects the bone cutting process.

[0023] For the reasons stated above, it is useful to apply a drive signal to the ultrasonic handpiece that causes the tip to vibrate simultaneously in two vibration modes (longitudinal and torsional).

[0024] However, even a tip designed to be driven to engage in both torsional and longitudinal mode vibrations will experience some longitudinal movement along the axis of the tip. For the reasons discussed above, this movement can result in undesirable cavitation of the distal end adjacent the tip head and, by extension, undesirable tissue ablation. Thus, there remain some circumstances in which it is desirable to apply a drive signal to the handpiece such that the tip is forced into vibrations that are torsional in nature and have minimal, if any, longitudinal components. Summary of the invention

[0025] The present invention relates to a new and useful ultrasonic surgical tool system. The system of the present invention includes a handpiece having a tip and a supplementary control system for providing a drive signal that causes the tip to vibrate. The control console and the tip are collectively arranged so that when the drive signal is applied to the tip, the tip engages in motion that is primarily in a torsional mode.

[0026] The system of the present invention includes a handpiece having a tip. The tip of the present invention has a feature that converts a component of longitudinal vibration into torsional vibration.

[0027] The present invention is based on the principle that due to the characteristics of the mechanical components forming the handpiece including the tip, the handpiece has a longitudinal mechanical cancellation frequency between the resonant frequencies of the first mechanical resonance mode and the second mechanical resonance mode. When a drive signal is applied to the handpiece driver at this frequency, the mechanical components of the handpiece are excited to cause both the first mechanical resonance mode vibration and the second mechanical resonance mode vibration in the tip simultaneously. Another principle on which the present invention is based is that when the mechanical components are excited to vibrate simultaneously in two mechanical resonance modes, the longitudinal vibrations associated with the resonance modes are out of phase with each other and the torsional vibrations are in phase.

[0028] As a result of the handpiece being vibrated in this manner, since the various modes of longitudinal vibration are out of phase, these vibrations cancel each other out. Since the various modes of torsional vibration are in phase, the tip (and more specifically the head and adjacent segments of the shaft) participate in significant torsional vibrations. Thus, the tip of the present invention experiences substantial torsional vibrations while the head and adjacent segments of the shaft experience minimal, if any, longitudinal vibrations.

[0029] The present invention relates to a system that continuously adjusts the characteristics of a drive signal applied to a handpiece by monitoring the characteristics of the drive signal. More specifically, the frequency of the drive signal is continuously adjusted to ensure that the signal is as closely as possible to the longitudinal mechanical cancellation frequency of the handpiece.

[0030] This continuous monitoring of the drive signal and subsequent adjustment of the frequency of that signal is necessary because as the load applied to the mechanical components of the handpiece changes, the longitudinal mechanical cancellation frequency similarly shifts. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is particularly pointed out in the claims. The above features and benefits and other features and benefits of the present invention will be further understood from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 is a graphical representation of the real part of the ratio between the current attributable to the capacitance of the driver of the handpiece and the mechanical equivalent of the current through the handpiece at the frequency of the handpiece, including the handpiece of the present invention;

[0033] Figure 2 Depicting the basic components of an ultrasonic tool system incorporating features of the present invention;

[0034] Figure 3 is a diagrammatic and exploded depiction of the tool's mechanical components, handpiece, tip and sleeve of the system;

[0035] Figure 4 is a block diagram depicting the electrical components of the handpiece and tip and how these components are connected to the console;

[0036] Figure 5 depicts the types of data stored in memory within the handpiece;

[0037] Figure 6 depicts the type of data stored in the memory integrated with the tool tip;

[0038] Figure 7 is a block diagram of the electrical components of the console and handpiece components of the system of the present invention;

[0039] Figure 8 Represents in two dimensions the path of travel of a point of the tip head about the longitudinal axis when the tip is vibrated according to the present invention;

[0040] Fig. 9 is a graphical indication of the locations of boundaries and nodes associated with longitudinal and torsional vibrations of a handpiece including a tip;

[0041] Fig.10 is a graphical representation of the individual components of longitudinal and mechanical vibration of the handpiece during a first phase of the vibration cycle and the sum of these components;

[0042] Fig.11 is a graphical representation of the individual components of the longitudinal vibration and the mechanical vibration and the sum of these vibrations during the second phase of the vibration cycle;

[0043] Fig.12 is a schematic diagram of impedance of applied current and mechanical equivalent value according to the present invention; and

[0044] Fig.13A and Fig. 13B When assembled together forms a flow chart of the operation of the system of the present invention. DETAILED DESCRIPTION

[0045] I. System Overview and Hardware

[0046] Now by reference Figure 2 and Figure 3 An ultrasonic tool system 30 including features of the present invention is generally described. The system 30 includes a handpiece 32. A tip 142 is attached to the handpiece 32 and extends distally forward from the handpiece 32. ("Distal" is understood to mean away from the practitioner, toward the site where the handpiece is applied. "Proximal" is understood to mean toward the practitioner holding the handpiece, away from the site where the handpiece is applied.) The tip 142 is a component of the system 30 that is applied to tissue to perform a desired medical / surgical procedure. The system 30 also includes a console 230. The console 230 provides a drive signal that is applied to the handpiece 32. In response to the application of the drive signal, the handpiece 32 causes the tip 142 to vibrate.

[0047] The handpiece 32 includes a body or housing 34. Figure 2 From Figure 3 and Figure 4 As can be seen, one or more vibrating piezoelectric actuators 36 (four are shown) are disposed within the housing 34. Each actuator 36 is formed of a material that undergoes a momentary expansion or contraction when an electric current is applied to the actuator. The expansion / contraction of the actuator is located on the longitudinal axis of the actuator 36, which extends between the proximal and distal oriented faces of the actuator. A pair of leads 38 extend away from each actuator 36. The leads 38 are attached to the opposing proximal and distal oriented faces of the actuator. Many, but not all, handpieces 32 include disk-shaped actuators 36. The actuators 36 are arranged end to end in a stack. The leads 38 are components of the system 30 through which drive signals are applied to the actuators 36. Optional insulating disks 40 (one is shown) are disposed between adjacent actuators 36. Figure 3 In the embodiment of the present invention, the driver 36 and the insulating disk 40 are shown as being spaced apart from each other. This is for the convenience of illustrating the components. In reality, the driver 36 and the insulating disk 40 are closely adjacent.

[0048] Post 44 extends longitudinally through driver 36, lead 38 and insulating disk. Post 44 extends through driver 36, lead 38 and insulating disk 40 and extends along the colinear longitudinal axis of these components. Not visible are through holes inside driver 36, lead 38 and insulating disk 40 through which post 44 extends. Post 44 protrudes outwardly from the most proximally positioned driver 36 and the most distally positioned driver.

[0049] A proximal block 46 is positioned adjacent to and abutting the proximally oriented face of the most proximally positioned driver 36. The block 46 is attached to the proximal portion of the post 44. If the post 44 is threaded, the block 36 may be a nut.

[0050] Figure 3 The horn 48 visible in the handpiece 32 extends forward from the distally oriented face of the most distally positioned driver 36. The horn 48 has a base having a diameter that is approximately equal to the diameter of the driver 36. Extending distally forward from the driver 36, the diameter of the horn 48 decreases. The exposed distal end portion of the post 44 is fixed to the horn 48. In many versions of the invention, the post 44 and the horn 48 are a single-piece unit. The handpiece 32 is configured so that the stack of drivers 36 and insulating disks are compressed between the proximal block 46 and the horn 48.

[0051] A hand piece memory 56 is also disposed in the hand piece housing 34. The memory 56 contains data for regulating the operation of the hand piece 32 and the tip 142. The memory 56 may be in the form of an EPROM, an EEPROM, or an RFID tag. The structure of the memory is not part of the present invention. For purposes of illustration, the hand piece memory 56 is an RFID tag. The coil 54 is shown as being connected to the memory 56. The coil 54 is a component associated with the hand piece by which the console 230 reads from and writes to the hand piece memory 56.

[0052] Figure 5 The types of data stored in the hand piece memory 56 are shown. These data, as represented by field 62, include data identifying the hand piece 32. These data are useful for verifying that the console 230 is able to apply the drive signal to the hand piece. The data in field 62 may also indicate the type of information about the hand piece presented on the console display 268. Other data in the hand piece memory 56 is used to regulate the provision of the drive signal to the driver 36. The use of these data is discussed below, and the data types are now described. Field 64 contains data indicating the capacitance C O , the capacitance of the stack of drivers 36. The driver capacitance can be determined by analysis during the process of assembling the handpiece 34. The sum of the capacitances of the drivers is typically between 500 and 5000 pF. ) is contained in field 66. Current Typically less than 1Amp peak, more often 0.5Amp peak or less. Field 68 contains the maximum mechanical equivalent value indicating the current discussed below. The current should flow through the mechanical components of the handpiece discussed below. Typically 0.25Amp peak or less. The maximum potential (voltage) of the drive signal ) is stored in field 70. Voltage Typically 1500 volts AC peak.

[0053] Also stored in the hand piece memory 56 is data indicating the minimum and maximum frequencies of the drive signal that should be applied to the hand piece 32. The minimum frequency stored in field 72 is typically the minimum frequency of the drive signal that can be provided by the console. The maximum frequency of the drive signal stored in field 74 is typically 5 kHz to 40 kHz greater than the minimum frequency.

[0054] Field 76 contains coefficients for controlling the control signals output by controller 96. PID control loops are used to establish the final levels for each of these signals. Field 76 contains coefficients for each of these control loops. It should be understood that the data in fields 62, 66, 68, 70, 72, 74 and 76 (like the data in field 64) is stored in handpiece memory 56 as part of the process of assembling the handpiece.

[0055] The handpiece memory 56 also contains field 78 as a usage history field. During use of the handpiece 32, the console 230 writes data to field 128 to provide a log record of the operation of the handpiece.

[0056] return Figure 4 As can be seen, two conductors 132 are also shown inside the handpiece 32. The conductors 132 extend from the coil 54 to the distal end of the handpiece. The conductors 132 are connected to a second coil (coil 134) also disposed in the handpiece 32.

[0057] The tip 142 extends forward from the handpiece horn 48. The tip 142 has a generally cylindrical shaft 144. In some but not all versions of the invention, the shaft 144 has a plurality of sections, each having a different cross-sectional diameter. In the illustrated version of the invention, the tip shaft 144 has a proximal section 146. The shaft proximal section 146 is formed with a coupling feature designed to facilitate removable coupling of the tip to the handpiece 32. In one version of the invention, the handpiece coupling feature is a boss 49 extending forward from the horn 48. The outer surface of the boss 49 is formed with threads (not shown). The tip coupling feature is a closed end hole 145 that extends inwardly from the proximal end of the shaft 144 partially through the shaft proximal section 145. The hole 145 is provided with threads (not shown) that are designed to engage with a threaded boss integrated with the handpiece horn 48.

[0058] In the depicted version of the invention, the shaft 144 has an intermediate section 150 extending forwardly from a shaft proximal section 146. The intermediate section 150 has a smaller diameter than the proximal section 146. The depicted shaft 144 has a distal section 160. The diameter of the shaft distal section 160 is smaller than the diameter of the intermediate section 150. Not identified are the tapered transition sections of the shaft 144. One transition section is between the proximal section 146 and the intermediate section 150. A second transition section is between the intermediate section 150 and the distal section 160. The distal section of the shaft has its own slight taper so that the diameter of the shaft decreases slightly as the section 160 extends distally.

[0059] The head 164 is the most distal portion of the tip 142. The head 164 is located just in front of the shaft distal section 160. The head 164 is sometimes formed with teeth or grooves (not shown). The tip head 164 is the portion of the system 30 that compresses tissue to perform the desired procedure. The teeth or grooves are designed so that when the head 164 moves, the teeth or grooves tear the tissue. Due to the movement of the head, the teeth or grooves remove tissue. The geometry of the tip teeth or grooves is not part of the present invention.

[0060] The handpiece 32 is typically designed so that the back and forth movement of the driver causes similar vibratory motions in the tip 142. These are longitudinal vibrations because the motion is back and forth along the longitudinal axis of the tip (more specifically the shaft). The tip 142 of the present invention is also provided with features that convert the proximal to distal vibratory motion applied to the proximal end of the shaft 144 into two vibratory motions. In the depicted tip 142, these features are spiral grooves 154 that extend inwardly from the outer surface of the middle section 150 of the shaft. Due to the presence of the grooves 154, part of the longitudinal motion applied to the proximal section 146 of the shaft becomes a motion that causes the more distal section of the tip to vibrate rotationally in addition to vibrating longitudinally. Rotational vibration is understood to mean vibration of the shaft and tip in an arc extending around the longitudinal axis of the shaft 144.

[0061] A sleeve 170 is disposed about the tip shaft 144. The sleeve 170 is formed of plastic. The proximal end of the sleeve is formed with features that facilitate releasable coupling of the sleeve to the distal end of the handpiece housing 34. The components forming the system 30 are formed such that the sleeve is spaced radially away from the tip shaft 144 and longitudinally away from the tip head 160. More specifically, the dimensions of these components are adapted such that during normal vibration of the tip, the tip does not abut the sleeve.

[0062] Although not part of the present invention, it can be seen that the sleeve 170 is generally formed with a fitting 172. The fitting 172 is formed to accommodate an irrigation line. During use of the system 30, an irrigation fluid often flows into the sleeve 170. The fluid flows through the gap between the tip 142 and the sleeve 170 and flows out from the open distal end of the sleeve. The handpiece column 44 and the tip 142 are formed with connected holes (holes not shown). During the procedure, the aspirator extracts through these holes. The aspirator extracts the irrigation fluid from the site where the tip head 164 is applied, as well as the debris entrained in the fluid formed by the procedure. The aspirator also draws tissue toward the tip head 164. This extraction of tissue toward the tip head 164 enhances the cutting of tissue by the tip head.

[0063] Tip Memory 184 (in Figure 3Memory 184 is referred to as a tip memory because, even though the memory is disposed in sleeve 170, the memory is used to control the operation of tip 142. In addition, tip 142 and sleeve 170 are typically distributed together as a single package. Typically, tip 142 is initially coupled to hand piece 32 first. After tip 142 is in place, sleeve 170 is assembled to the hand piece. Tip memory 184 is typically the same type of memory as hand piece memory 56. Therefore, in the illustrated version of the invention, tip memory 184 is an RFID tag. Coil 182 embedded in sleeve 170 (only in Figure 4 170 is connected to an input pin of the tip memory 172. The components forming the system 30 are configured so that when the sleeve 170 is assembled to the handpiece 32, the handpiece coil 134 and the coil 182 can participate in an inductive signal exchange.

[0064] Figure 6 The type of data contained in the tip memory 184 is depicted. These data include a tip identification field, as represented by field 188. The data in field 188 identifies the tip and is similar to the data identifying the handpiece in the handpiece memory identification field 112. In field 190 is stored a maximum total mechanical equivalent value indicating the current that should pass through the mechanical components of the handpiece when using a particular tip 142. Field 192 contains data indicating the minimum voltage that should be applied to the drive signal of the handpiece driver for vibrating the tip. Field 193 contains data indicating the maximum voltage that should be applied to the drive signal of the handpiece driver for vibrating the tip. data.

[0065] Field 194 contains data defining the minimum possible frequency (MIN MRM FREQ.) of one of the mechanical resonance modes. Field 195 contains data defining the maximum possible frequency (MAX MRM FREQ.) of the mechanical resonance mode, and field 195 defines the minimum possible frequency of the mechanical vibration mode. Typically, fields 194 and 195 contain data defining a frequency range of a first mechanical resonance mode. The frequency range is a function of the difference between the frequency of the first resonance mode and the frequency of the second resonance mode. For example, if the difference between the frequencies of the two mechanical resonance modes is 2000 Hz or more, the frequency range contained in the data of fields 194 and 195 may be 1000 Hz. More typically, the frequency range around the mechanical resonance frequency defined by the data in fields 194 and 195 is 400 Hz or less. In a more preferred version of the invention, the frequency range around the mechanical resonance frequency is 100 Hz or less.

[0066] Field 196 contains data defining the lowest possible frequency (MINLCM FREQ.) of the longitudinal mechanical cancellation frequency discussed below of the tip 142. Field 198 contains data defining the highest possible frequency (MAX LCM FREQ.) of the longitudinal mechanical cancellation frequency. The frequency range defined by the data in fields 196 and 198 is also a function of the resonant frequencies of the two mechanical resonant modes. This frequency range is generally centered around the longitudinal mechanical cancellation frequency of the tip when the tip is in an unloaded state. This frequency range may partially overlap with the frequency range associated with the mechanical resonant mode into which the tip may be driven. The frequency range of operation of the tip around the longitudinal mechanical cancellation frequency should not extend to the resonant frequency of the mechanical resonant mode into which the tip may be driven.

[0067] PID coefficient field 204 contains control coefficients for the control signals of the tip, which may be more specific than the data in handpiece memory PID coefficient field 76. Tip memory 184 also contains a tip usage history field 206. During operation of system 30, console 230 writes data about the usage of tip 142 into field 206.

[0068] Now refer to Figure 2 , Figure 4 and Figure 7 The described console 230 provides a drive signal to the handpiece 32, which causes the vibration of the tip 142. These components include a power supply 232. The power supply 232 outputs a constant voltage signal typically between 1 and 250 VDC. In many versions of the invention, the maximum potential of the voltage output by the power supply 232 is 200 VDC or less. The voltage generated by the power supply 232 is applied to a variable gain amplifier 234. A control signal (particularly a WAVEFORM_SET (W_S) signal) is applied to the amplifier 234. The WAVEFORM_SET signal varies in both frequency and amplitude. Therefore, the WAVEFORM_SET frequency is used to change the gain and frequency of the signal generated by the amplifier 234, so that the amplifier produces an output signal that varies in both potential and frequency. One such amplifier that can be incorporated into the console 230 is disclosed in U.S. Provisional Patent Application No. 62 / 159,672, the contents of which are disclosed in PCT Publication No. WO 2016 / 183084 / U.S. Patent Publication No. __________, which is incorporated by reference. More specifically, amplifier 234 is capable of outputting a signal having a frequency between 10 kHz and 100 kHz. Typically, the minimum frequency of the signal is 20 kHz and the maximum frequency is 40 kHz.

[0069] The output signal from the amplifier 234 is applied to the primary winding 244 of the transformer 238, which is also part of the console 230. The voltage present across the secondary winding 248 of the transformer 238 is the drive signal applied to the handpiece driver 36. This voltage is typically a maximum of 1500 volts AC peak. The drive signal is applied in parallel across the drivers 36.

[0070] Transformer 238 includes a feedback coil 246. The voltage present across feedback coil 246 is applied to a voltage measurement circuit 252. Based on the signal across feedback coil 246, circuit 252 generates a voltage representative of voltage V S The potential and phase of the signal is the voltage of the drive signal applied to the handpiece 32. The coil 254, also provided in the console 230, is positioned in close proximity to one of the conductors extending from the transformer secondary winding 248. The signal across the coil 254 is applied to the current measurement circuit 256. The circuit 256 generates a current representative of the current i S The amplitude and phase of the signal are provided to the handpiece 32, which is the current of the drive signal.

[0071] The drive signal present across transformer secondary winding 248 is present at two conductive contacts 250 attached to a socket (not shown) integrated with the console.

[0072] By only Figure 2 The cable 228 visible in the figure applies the drive signal to the handpiece driver. In many configurations of the system 30, the handpiece 30 and the cable 228 are a single unit. The cable 228 is connected to a console socket where the contacts 250 are located.

[0073] In versions of the invention in which the handpiece 32 and cable 228 are a single unit, the handpiece coil 54 is disposed in a plug integrated with the cable. The supplemental coil 258 is disposed in a console receptacle. The components forming the system are configured so that when the plug integrated with the cable 228 is located in the handpiece receptacle, the coils 54 and 258 are able to inductively exchange signals.

[0074] Indicates the driving signal voltage V S and current i SThe signal is provided to the hand piece and applied to the processor 266, which is also internal to the console 230. The console 230 also includes a memory reader 262. The memory reader 262 is connected at one end of the controller coil 258 and the opposite end of the processor 266. The memory reader 262 converts the signal present across the coil 258 into a data signal that can be read by the processor 266. The memory reader 262 is also responsive to the signal output by the processor 266, outputting a signal across the coil 258 that causes the coil to output a signal that causes data to be written to the hand piece memory 52 and the tip memory 184. The structure of the memory reader 262 supplements the hand piece memory 102. Therefore, the memory reader 262 can be a component capable of reading data in an EPROM or EEPROM, or a component capable of interrogating and reading data from an RFID tag.

[0075] Processor 266 generates a WAVEFORM_SET signal that is applied to amplifier 234. Processor 266 thus sets the characteristics of the drive signal output by console 230 and applied to hand piece 32. The characteristics of the drive signal set by processor 266 are the voltage and frequency of the drive signal. Processor 266 determines these characteristics based on the characteristics of hand piece 32 and the characteristics of tip 134. Processor 266 also determines the voltage V based on the acquired voltage V S and current i S The driving signal is determined based on the measurement results.

[0076] Display 268 is built into console 230. The images on display 268 are shown as being generated by processor 266. The information depicted on display 268 includes: information identifying handpiece 32 and tip; and information describing characteristics of the operating state of the system. Display 268 is typically a touch screen display. Processor 266 causes images of buttons to be presented on the display. By pressing a button, the practitioner is able to set what he / she desires as a particular operating characteristic of system 30.

[0077] In addition to the buttons presented on the display 268, there is typically at least one on / off switch associated with the console. Figure 2 and Figure 7 2, the on / off switch is represented by a foot switch 270. The foot switch 270 is configured to generate a signal that varies depending on the degree to which the switch is depressed. The signal is provided to the processor 266. Based on the state of the signal provided by the foot switch 270, the processor 266 adjusts the generation of the drive signal to control both whether the tip vibrates and the amplitude of the vibration of the tip head.

[0078] II. Operational basis

[0079] The system 30 of the present invention is designed so that the console 230 outputs a drive signal that causes the tip head 164 to move along a path of travel that can be considered to be substantially torsional. Here, a substantially torsional path of travel is understood to be a path of travel of a point on the tip head 164 that is Figure 8 The tip 142 is formed by a line PT which is at an acute angle α of 30° or less (preferably 15° or less, and more preferably 8° or less) relative to the line PA. The line PA is understood to be perpendicular to the line LA which is the longitudinal axis through the tip 142. The line LA and the line PA are understood to be at an acute angle α of 30° or less (preferably 15° or less, and more preferably 8° or less) relative to the line PA. Figure 8 In the plane. Figure 8 In FIG. 1 , line PT represents the path of travel of a single point of the tip in two dimensions. Thus, to the left of the intersection of lines LA, PA, and PT, line PT extends below line PA. Figure 8 On the right side of the intersection of lines LA, PA, and PT, line PT extends above line PA to Figure 8 164. Thus, in a head that is simultaneously engaged in torsional motion and longitudinal motion, a point on the head 164 will move about the path of travel while a point thereof will partially rotate about the line PA and move up and down along a longitudinal path of travel parallel to the line LA. Under perfect conditions, the tip head 164 will engage in torsional motion and will not engage in any longitudinal motion. If the tip head 164 were to engage in this type of motion, it will be appreciated that the acute angle between the line PA and the line PT would be 0°.

[0080] The main principle upon which the operation of the system 30 is based is that the handpiece including the tip has a first mechanical resonance mode and a second mechanical resonance mode, due to the presence of the slot 154, the feature that converts the longitudinal motion of the tip into torsional motion, with the first mechanical resonance mode and the second mechanical resonance mode having resonance frequencies spaced apart from each other. For many versions of the system operating with a drive signal in the range of 20 kHz to 40 kHz, the resonance frequencies of the two mechanical resonance modes should be spaced apart by at least 250 Hz. In a more preferred version of the invention, these resonance frequencies are spaced apart by at least 500 Hz.

[0081] The first inference principle upon which the operation of the present system is based is that when a drive signal is applied to the handpiece driver 36 at a resonant frequency associated with a first mechanical resonance mode, the tip head undergoes a combined longitudinal and torsional vibration at that frequency. The tip head does not engage in significant vibratory motion that may be associated with a second mechanical resonance mode.

[0082] The second inference principle upon which the operation of the present system is based is that when a drive signal is applied to the handpiece driver 36 at a resonant frequency associated with the second mechanical resonance mode, the tip head undergoes a combined longitudinal and torsional vibration at that frequency. The tip head does not engage in significant vibratory motion that may be associated with the first mechanical resonance mode.

[0083] Reference now Fig. 9 Describe the boundaries and nodes of vibration associated with the handpiece. The proximal end of the proximal block 46 represents the proximal unconstrained boundary of the longitudinal vibration of the handpiece. Here, the handpiece is understood to include the tip 142. There is a first longitudinal node, the proximal longitudinal node, in front of the distal end of the proximal unconstrained longitudinal boundary. This node can be located adjacent to the distal-most driver 36. In front of the proximal longitudinal node, there is a second longitudinal node, the distal longitudinal node. This node is located in the tip 142 near the spiral groove 154. At the longitudinal nodes, the longitudinal expansion / contraction waves in the handpiece caused by the driver neither expand nor contract the handpiece or the tip. On the opposite side of each longitudinal node, the acoustic waves generated by the driver cause opposite expansion and contraction movements of the handpiece. Therefore, when the driver causes the handpiece to expand between the proximal unconstrained boundary and the proximal longitudinal node during each resonant mode of the handpiece, there is contraction between the two longitudinal nodes and expansion at the distal end of the distal longitudinal node. Similarly, when a contraction is induced between the proximal unconstrained boundary and the proximal longitudinal node for a resonant mode driver, the handpiece undergoes expansion between the longitudinal nodes and contraction distal to the distal longitudinal node.

[0084] The hand piece has a fixed torsional boundary at a location distal to the distal longitudinal node and near the slot 154. Distal to this location, a portion of each longitudinal expansion / compression wave passing through the tip is converted into motion of the torsional tip due to the presence of the slot 154, causing torsional motion. In front of the slot 154, there is a torsional node. At the torsional node, the tip does not participate in any torsional motion. Distal to the torsional node, the tip twists in a direction opposite to the direction in which the segment of the tip between the fixed torsional plane and the torsional node twists.

[0085] The distal end of the tip head 164 is an unconstrained boundary for both longitudinal and torsional vibrations of the hand piece. This boundary is an unconstrained boundary because the tip head is not attached to a fixed object that constrains the motion of the tip. This is why when a drive signal is applied to the hand piece, the vibratory motion transmitted to the tip head 164 through the tip shaft 144 causes vibratory movement of the tip head.

[0086] When a drive signal is applied to the hand piece driver at a frequency between the first mechanical resonance mode and the second mechanical resonance mode, the mechanical components of the hand piece are driven to simultaneously participate in multiple vibrations associated with each of the first mechanical resonance mode and the second mechanical resonance mode. Thus, when a drive signal is applied to the hand piece driver at a frequency between the resonant frequency of the first mechanical resonance mode and the resonant frequency of the second mechanical resonance mode, the force applied by the driver 36 to the remainder of the hand piece causes a longitudinal expansion / contraction having a component associated with the first mechanical resonance mode and a component associated with the second resonance mode. It should also be understood that the longitudinal vibration associated with the second mechanical resonance mode is out of phase with the longitudinal vibration associated with the first mechanical resonance mode.

[0087] Similarly, when a drive signal is applied to the handpiece driver at a frequency between the resonant frequency of the first mechanical mode and the resonant frequency of the second mechanical mode, the mechanical components of the tip 142 distal to the slot 154 engage in torsional vibrations having a component associated with the first mechanical resonant mode and a component associated with the second mechanical resonant mode. It should also be understood that the torsional vibration of the tip associated with the second resonant mode is in phase with the torsional vibration of the tip associated with the first resonant mode. This means that when the tip engages in longitudinal contraction (or expansion) motion due to being vibrated in the second mechanical resonant mode, the tip is forced into torsional motion in the same direction as when the tip engages in longitudinal expansion (or contraction) due to being vibrated in the first mechanical resonant mode.

[0088] Based on these principles, the system 30 of the present invention is configured to apply a drive signal to the handpiece driver 36 that is between the resonant frequencies associated with the first and second mechanical resonant modes of the handpiece. The particular frequency at which the drive signal is applied to the driver is now referred to as the longitudinal mechanical cancellation frequency f LC .exist Figure 1 In the graph, the longitudinal mode cancellation frequency f LC It is 24.97kHz.

[0089] When a drive signal is applied to the driver 36 at the longitudinal mechanical cancellation frequency, the handpiece operates in a so-called longitudinal mechanical cancellation mode. Fig.10 and Fig.11 The component of the vibratory movement of the tip when the handpiece is operated in this mode is shown. Fig.10Depicted is what happens when the driver applies a first force to the rest of the handpiece. Arbitrarily, the driver outputs an expansion force represented by the outwardly directed double-headed arrow 280. The driver can be considered to apply this force to the other mechanical components of the tip during the first phase of a single vibration cycle. For the purposes of the present invention, the mechanical components of the handpiece are the vibrating components of the handpiece that apply mechanical energy to the mechanical load. These components include the driver 36, the column 44, the proximal block 46, the horn 48, and the tip 142. The sleeve 170 is generally not considered to be a component through which the equivalent of an electric current flows. This is because when the sleeve 170 vibrates, the vibration of the sleeve is attributed to the vibration of other components. In other words, the sleeve 170 is part of the vibration of the other mechanical components of the handpiece that apply the mechanical load. Therefore, for the purpose of analyzing the motion and signal flow of the present invention, the sleeve 170 is not considered to be one of the mechanical components of the handpiece.

[0090] Since the driver 36 applies an expansion force to the rest of the handpiece at a longitudinal mechanical frequency, the mechanical components of the handpiece are excited to undergo their own longitudinal movement. Since these components tend to vibrate in a first mechanical resonant mode distal to the distal longitudinal node, the movement is a longitudinal expansion movement. This is caused by Fig.10 284. Although this movement appears to be an expansion movement of the driver, this movement is out of phase with the vibration of the driver 36. Due to the presence of the helical groove 154 at the torsional boundary, a portion of this longitudinal movement is converted into torsional movement of the tip 142. Adjacent to the torsional boundary, this movement is in the direction of the curved arrow 288. Looking down at the handpiece from the distal end, this movement will appear as a counterclockwise movement. At a location along the tip from the torsional node to the tip head, this movement will appear from the same perspective as a clockwise rotation, i.e., a rotation represented by arrow 290.

[0091] The mechanical components of the hand piece also desire to vibrate in a second mechanical resonant mode. Thus, the application of the same expansion force applied to the mechanical components of the hand piece causes these components to vibrate in an out-of-phase longitudinal expansion mode in the first mode, causing these same components distal to the distal longitudinal node to enter into out-of-phase longitudinal contraction vibrations in a second mechanical resonant mode. These contraction vibrations are represented by arrows 292 pointing to the left. Due to the presence of the spiral groove 154 distal to the torsional boundary, a portion of these longitudinal vibrations are converted into torsional vibrations. Immediately adjacent to the torsional boundary, these vibrations, represented by curved arrows 294, are in a counterclockwise direction. Distal to the torsional node, these vibrations, represented by arrows 296, are in a clockwise direction.

[0092] Thus, when a drive signal at the longitudinal mechanical cancellation frequency is applied to the driver 36, during one phase of the signal, the tendency of the handpiece mechanical components to expand distal to the longitudinal node is counteracted by the tendency of these components to also contract. Thus, the tip 164 does not substantially participate in the longitudinal movement.

[0093] Also during this phase, due to the presence of the helical groove 154, the opposing forces that would otherwise cause longitudinal motion of the handpiece component are converted into torsional motion at the distal end of the torsional boundary. These torsional motions are in phase with each other, as shown by the arrows. Since these torsional motions are in phase with each other, they are cumulative. In other words, during this phase of the vibration cycle, if the tip head is excited to torsional motion, the torsional motion of the tip head 164 is greater than the torsional motion of the tip head, because the handpiece is driven to vibrate at a single one of the mechanical resonant frequencies. This is why during Fig.10 , curved arrow 302 representing the sum of torsional vibrations at the proximal end of the torsional node is depicted as being longer than either of arrows 288 and 294. For the same reason, curved arrow 304 representing the sum of torsional vibrations at the distal end of the torsional node is depicted as being longer than either of arrows 290 and 296.

[0094] Fig.11 Depicted is what happens when the driver 36 applies a contraction force during the second phase of a single vibration cycle. As the driver contracts, the post 44 pulls the nut 46 and horn 48 toward each other, as represented by the inwardly directed double-headed arrow 310. Due to the application of this force, and the tendency of these components to vibrate in the first mechanical resonant mode, this force manifests as a longitudinal contraction movement distal to the distal longitudinal node. This movement is represented by Fig.11 314. This movement is out of phase with the contraction of the driver 36. Due to the presence of the helical groove 154, at the torsion boundary, a portion of this longitudinal movement is converted into torsional movement of the tip 142. Adjacent to the torsion boundary, this movement is in the clockwise direction of the curved arrow 314. At a location along the tip from the torsion node to the tip head 164, this movement will appear from the same perspective as a counterclockwise rotation, i.e., a rotation represented by arrow 316.

[0095] The mechanical components of the hand piece also want to vibrate in a second mechanical resonant mode. Thus, the application of the same contraction force applied to the mechanical components of the hand piece causes these components to vibrate in an out-of-phase longitudinal contraction vibration in the first mode, causing these same components distal to the distal longitudinal node to enter into out-of-phase longitudinal expansion vibrations in a second mechanical resonant mode. These expansion vibrations are represented by arrows 320 pointing to the right. Due to the presence of the spiral groove 154 distal to the torsional boundary, a portion of these longitudinal vibrations are converted into torsional vibrations. Immediately adjacent to the torsional boundary, these vibrations, represented by curved arrows 322, are in a clockwise direction. Distal to the torsional node, these vibrations, represented by arrows 324, are in a counterclockwise direction.

[0096] Thus, the sum of the vibrational movement of the hand piece in the second phase of the vibration cycle is the partial inverse of the vibrational movement in the first phase of the cycle. Again, the longitudinal vibrations that are out of phase with each other cancel each other out. This is why there is a substantially minimal longitudinal movement of the tip. The torsional vibrations associated with the two mechanical resonant modes are in phase. This is why the tip 142 participates in the torsional movement (twist). As represented by the length of curved arrows 326 and 328 relative to curved arrows 314, 316, 322, and 324, this twist is greater in magnitude than the twist due to the tendency of the hand piece to vibrate in a single one of the mechanical resonant modes.

[0097] Thus, when a drive signal at the longitudinal mechanical cancellation frequency is applied to the driver 36, the handpiece mechanical components are driven to vibrate in a mode in which there is substantial twisting, torsion, vibration of the head with minimal, if any, longitudinal movement of the shaft 144 and tip head 164.

[0098] By initial reference Fig.12 , it can be understood that the characteristics of the drive signal applied to the driver 36 to cause the handpiece to vibrate at the longitudinal mechanical cancellation frequency. This figure shows the current flowing through the components of the handpiece. It can be considered that the current i of the drive signal S It is applied in parallel through three groups of components. The first group of components includes the driver 36 itself. The impedance Z0 through these components is essentially the reactance of the driver:

[0099]

[0100] For the purposes of this invention, the driver capacitance is constant. Therefore, the only variable that affects the driver impedance is ω, the radian frequency of the drive signal.

[0101] Apply drive signal current i SThe second set of components are the mechanical components of the hand piece that cause the hand piece to vibrate in the first mechanical resonant mode. It will be appreciated that the current is not an actual electrical current. Rather, the current is the mechanical equivalent of an electrical current flowing through these components to cause mechanical vibration of these components. These components include the driver 36, post 44, proximal block 46, horn 48, and tip 142. Again, the sleeve 170 is part of the mechanical load that applies the vibration of the other mechanical components of the hand piece. Therefore, it will be appreciated that the sleeve 170 is not one of the components through which the mechanical equivalent of the electrical current flows.

[0102] exist Fig.12 In , the mechanical equivalent value of the current is i1, because it is associated with the first mechanical resonance mode, and the vibration of the handpiece is more specifically the first resonance mode mechanical equivalent value of the current of the handpiece. The impedance Z1 to which the mechanical equivalent value is applied has: a resistance component R1 due to the resistance characteristics of the mechanical parts of the handpiece when vibrating in the first mechanical resonance mode; an inductive resistance component L1 due to the inductive characteristics of the mechanical parts of the handpiece when vibrating in the first mechanical resonance mode; and a capacitive reactance component C1 due to the capacitive characteristics of the mechanical parts of the handpiece when vibrating in the first mechanical resonance mode. Therefore, the impedance Z1 is calculated based on the following equation:

[0103] Z1=R1+jωL1+1 / jωC1 (3)

[0104] As the load on the mechanical components of the handpiece changes, the resistance, inductance, and capacitance of these components also change. Fig.12 , R1, L1 and C1 are shown as variables.

[0105] Apply drive current i S The second group of components of a portion are mechanical components of the handpiece that cause the handpiece to vibrate in a second mechanical resonance mode. The current of this portion (current i2) can be considered as the second resonance mode mechanical equivalent of the current passing through the handpiece. The impedance Z2 of the mechanical equivalent of the applied current i2 has: a resistive component R2 due to the resistive characteristics of the mechanical components of the handpiece when vibrating in the second mechanical resonance mode; an inductive reactance component L2 due to the inductive characteristics of the mechanical components of the handpiece when vibrating in the second mechanical resonance mode; and a capacitive reactance component C2 due to the capacitive characteristics of the mechanical components of the handpiece when vibrating in the second mechanical resonance mode. Therefore, the impedance is calculated based on the following equation:

[0106] Z2=R2+jωL2+1 / jωC2 (4)

[0107] As described above, changes in the load applied to the mechanical components of the handpiece result in changes in the resistive, inductive, and capacitive characteristics of the handpiece. Fig.12 , R2, L2 and C2 are shown as variables.

[0108] Mathematically, and according to Kirchhoff's current law, the driving signal current i S The above decomposition of can therefore be broken down as follows:

[0109] i s =i0+i1+i2 (5A)

[0110] Rearranging equation (5A) yields the following relationship:

[0111] i1+i2=i s -i0 (5B)

[0112] This means that the mechanical equivalent of the current through the mechanical components of the handpiece is equal to the difference between the current of the drive signal and the current through the driver 36. Given equation (2),

[0113] i0=jV s 2πfC0 (6)

[0114] Here f is the angular frequency of the driving signal.

[0115] Substituting equation (6) into equation (5B) yields the following result:

[0116] i1+i2=i s -jV s 2πfC0 (7)

[0117] The longitudinal mechanical cancellation frequency is higher than the resonant frequency of the first mechanical resonance mode. Therefore, when a drive signal at the longitudinal mechanical cancellation frequency is applied to the hand piece, the impedance Z1 is primarily inductive due to jωL1. The longitudinal mechanical cancellation frequency is lower than the resonant frequency of the second mechanical resonance mode. Therefore, when a drive signal at the longitudinal mechanical cancellation frequency is applied to the hand piece, the impedance Z2 is primarily capacitive due to 1 / jωC2. This means that when a drive signal at the longitudinal mechanical cancellation frequency is applied to the driver 36, the impedance Z1 is 180° out of phase with the impedance Z2. Therefore, the reactive components of Z1 and Z2 substantially cancel each other. This means that when a drive signal at the longitudinal mechanical cancellation frequency is applied to the hand piece, the parallel impedance of Z1 and Z2 is purely resistive.

[0118] At the longitudinal mechanical cancellation frequency, as at any frequency, the impedance Z0 of the driver 36 is purely capacitive.

[0119] The presence of the above impedance when a drive signal at the longitudinal mechanical cancellation frequency is applied to the driver means that when the handpiece is in this state, the current i O The phase angle with the mechanical equivalent value i1+i2 of the current is 90° out of phase.

[0120] Since the current through the handpiece and the mechanical equivalent of the current both have magnitude and phase, these currents can be expressed in polar form:

[0121]

[0122] as well as

[0123]

[0124] Dividing i0 by i1+i2, when they are 90° out of phase, produces the following result:

[0125]

[0126] Converting the right side of equation (8A) to rectangular numbers yields the following result:

[0127]

[0128] The final result of equation (10C) is based on the fact that the cosine of 90° is zero and the sine of 90° is 1.

[0129] The above result means that when the drive signal is at the longitudinal mechanical cancellation frequency, the real part of the ratio of the mechanical equivalent of the current flowing through the driver 36 to the current through the mechanical components of the handpiece is equal to zero. Mathematically:

[0130]

[0131] Substituting equations (5) and (7) into equation (11A) means that when the drive signal is at the longitudinal mechanical cancellation frequency,

[0132]

[0133] The antecedent and suffix of equation (11B) are the same as the antecedent and suffix of prior art equation (1). There is a difference between applying a drive signal to the handpiece so that the tip head 164 experiences simultaneous longitudinal vibration and substantially torsional vibration. When it is desired to drive the handpiece to induce simultaneous torsional and longitudinal vibration in the tip head 164, the target frequency is the resonant frequency associated with one of the mechanical resonant modes of the tip. Typically, this is the resonant frequency associated with the first mechanical resonant mode. In contrast, when a drive signal is applied to the handpiece in accordance with the present invention, the target frequency is the longitudinal mechanical cancellation frequency of the tip 142. This frequency is within the frequency range defined by the data in fields 196 and 198 of the tip memory.

[0134] A second difference between the two systems is that the polarity of the ratio of the system of the present invention is opposite to that of the ratio of equation (1). The reason for this is that when the drive signal is adjusted so that the handpiece is in a mechanically resonant mode, the slope of the relationship between the mechanical equivalent of the current applied to the driver and the current applied to the handpiece is positive with respect to frequency. This means that by making the ratio of equation (1) negative, if the evaluation of the system state produces a negative result, the controller interprets the system as being in a state in which it is necessary to increase the frequency of the drive signal in order to apply the drive signal to the handpiece at the resonant frequency of the resonant mode. Conversely, if the evaluation of equation (1) produces a positive number, the controller interprets the system as being in a state in which it is necessary to reduce the frequency of the drive signal in order to apply the drive signal to the handpiece at the resonant frequency of the resonant mode.

[0135] In contrast, when the system is adjusted according to the present invention, in order to apply a drive signal at the longitudinal mechanical cancellation frequency to the handpiece, the slope of the relationship between the current applied to the driver and the mechanical equivalent of the current applied to the handpiece with respect to frequency is negative. As described above, the ratio of equation (11B) has an opposite polarity to the ratio of equation (1). This means that if the evaluation of the system state of the present invention produces a positive result, the processor 266 interprets the system 30 as being in a state in which it is necessary to increase the frequency of the drive signal in order to apply a drive signal at the longitudinal mechanical cancellation frequency to the handpiece at the resonant frequency of the resonant mode. In contrast, if the evaluation of equation (11B) produces a negative number, the processor 266 interprets the system as being in a state in which it is necessary to reduce the frequency of the drive signal in order to apply the drive signal to the handpiece at the longitudinal mechanical cancellation frequency.

[0136] It should also be understood from the above that the total mechanical equivalent of the current through the mechanical components of the handpiece is equal to the sum of the mechanical equivalents of the current through the handpiece. Mathematically,

[0137] i M =i1+i2 (12)

[0138] III. Practical Operation

[0139] Operation of the system 30 of the present invention begins by coupling the tip 142 to the handpiece 32. The sleeve 170 is assembled on the tip and also attached to the handpiece 32. The cable 228 is attached to the console 230. The console 230 is then ready to be turned on. The above sub-steps form the initial assembly and activation of the system, i.e. Fig.13A When the console 230 is initially turned on, the processor 266 reads the data stored in the handpiece memory 56 and the tip memory 184, step 334. The processor 266 receives this data by asserting appropriate commands to the memory reader 262.

[0140] Based on the read data, in step 336, the processor completes the initial configuration of the system. Step 336 includes performing multiple assessments to determine whether the system 30 is properly configured for use. These assessments include: determining whether the handpiece is a handpiece to which the console 230 can provide a drive signal; and determining whether the tip 142 is a tip suitable for actuation by the handpiece. These assessments can be based on data from the handpiece identification field 62 and the tip identification field 188. The processor 266 also assesses whether the handpiece 32 and the tip 142 are in a state for use based on the read data from the handpiece usage history field 78 and the tip usage history field 218. An example of data indicating that use may be inappropriate is an example of data indicating that a particular component (handpiece or tip) has been used multiple times or for a total time exceeding the design life cycle of the component.

[0141] Based on the data in the handpiece memory 56, the tip memory 184 and the practitioner commands, the processor establishes in step 338 the selected maximum equivalent value of the current flowing through the mechanical components of the handpiece Current is understood to be no greater than the maximum mechanical equivalent of the current read from the tip memory 184

[0142] Step 340 represents the processor 266 waiting to determine whether the control member has been actuated to indicate that the tip 142 is to be vibrated. In the described embodiment of the invention, the processor 266 performs step 340 by monitoring the signal output by the foot switch 270. When the practitioner wants to actuate the tip 142, he / she presses the foot switch 270. The amplitude of the tip head vibration is set by the degree to which the practitioner controls the foot switch 270 to be pressed.

[0143] In response to the practitioner depressing the control member, the processor calculates the target current in step 342 Sometimes called the target mechanical equivalent of the current. Target current is the mechanical current that the processor determines should be applied to the mechanical components of the handpiece 32. Target Current Based on the current retrieved from the handpiece memory and the degree to which the foot switch 270 is pressed. The target current can be calculated using a first order equation:

[0144]

[0145] The coefficient D is between 0.0 and 1.0, inclusive. For example, if the practitioner presses the foot switch 270 to cause the handpiece tip 164 to experience a maximum amplitude vibration, the processor 266 sets the coefficient D to one. If the setting of the foot switch 270 indicates that the vibration will be at an amplitude less than the maximum value, the processor 266 sets the coefficient D to a value less than one.

[0146] In step 344, the processor 266 then generates an initial WAVEFORM_SET signal. The potential of this signal is set so that the power supply output is significantly less than the maximum drive signal voltage retrieved from the handpiece memory 58. For example, in some versions of the invention, the potential of the WAVEFORM_SET signal is set so that the output drive signal has a voltage between More specifically, the WAVEFORM_SET signal is set so that the voltage of the drive signal is a voltage between 0.02 and 0.10. The voltage of the WAVEFORM_SET signal is proportional to the drive signal voltage V S The relationship between is typically a first order relationship. The determination of the voltage of the WAVEFORM_SET signal in accordance with the target drive signal voltage is based on the potential of the target drive signal voltage and coefficients and offset values ​​previously stored in processor 96 .

[0147] As part of step 344, processor 266 also establishes the frequency of the WAVEFORM_SET signal. When the control member is initially depressed to actuate the handpiece, processor 266 sets the frequency of the WAVEFORM_SET signal to be between the minimum possible longitudinal mechanical cancellation frequency (the frequency from field 196 of tip memory 184) and the maximum possible mechanical cancellation frequency (the frequency from field 198 of tip memory). Although not specifically illustrated, in step 342, processor 344 asserts any necessary enable signals to power supply 232, amplifier 234, and any safety components within console 230. The assertion of these signals ensures that power supply 232 outputs the necessary track signals to amplifier 234, which applies the desired signal to transformer primary winding 244. The drive signal is induced to develop on secondary winding 248.

[0148] As the signal flows through transformer 238, a drive signal is applied to hand piece 32. This results in cyclic expansion / contraction of driver 36. As the driver vibrates at a frequency between the first and second mechanical resonant modes of the hand piece, the hand piece itself engages in simultaneous out-of-phase vibrations in these two resonant modes. This results in the portion of the tip distal to the torsional boundary engaging in vibrations that are substantially torsional, and only nominally in all longitudinal directions.

[0149] The system 30 then engages in a feedback control process to ensure that the output drive signal causes vibrations of the appropriate magnitude and direction in the tip head 164. To perform this control, in step 346, the console 230 monitors the voltage V of the drive signal across the handpiece. S Specifically, in step 346, the driving signal voltage V output by the voltage measurement circuit 252 is represented by S The signal is applied to the processor 266. Also in step 346, the console 230 monitors the current i S , which is the current of the drive signal provided to the handpiece 32. This portion of step 346 is applying the output signal generated by the current measurement circuit 256 to the processor 266.

[0150] In step 348, processor 96 determines the total mechanical equivalent value i applied to the calculated current. M is based on a combination of equations (7) and (12). Processor 266 is able to make this determination because it has data defining four variables upon which the determination is based: the current i from current measurement circuit 256; S ; A frequency ω based on the fact that the processor sets the frequency of the drive signal; A voltage V from the voltage measurement circuit 252 S ; and driver capacitance C o Although the driver capacitor C o is a variable, but in equation (7), it is a fixed and known variable read from the handpiece memory 56.

[0151] In step 350, the total mechanical equivalent value of the current i M With current A comparison is made. More specifically, the comparison is made to determine whether the actual current flowing through the mechanical components of the handpiece is equal to or substantially the same as the target flow rate. Here, substantially the same is considered to be a state when the currents are within 20 or less mAmp of each other and more commonly 10 or less mAmp of each other (preferably 2 mA or less, more preferably 1 mAmp or less). Alternatively, the currents can be considered to be substantially the same if they are within 10% or less of each other, more preferably within 5% or less of each other, and ideally within 1% or less of each other.

[0152] If the currents are substantially equal, the system 30 is in a state where the equivalent value of the current applied to the mechanical components of the handpiece is at a level at which application of a drive signal at the correct frequency is assumed to cause vibrations of the appropriate amplitude in the tip head 52. If the system 30 is in this state, the processor 96 proceeds to step 164.

[0153] In many cases, the comparison of step 350 indicates the total mechanical equivalent value of the current i M Not substantially equal to the target current When the system 30 is in this state, the processor 96 resets the voltage of the WAVEFORM_SET signal in step 352. More specifically, the processor 96 calculates the drive signal voltage V based on equation (7): S This will result in a regulated current through the mechanical components of the handpiece that is substantially equal to the target current This calculation of step 352 is performed based on the driver capacitance and the drive signal frequency remaining constant.

[0154] The unidentified step is that, due to the resetting of the voltage of the WAVEFORM_SET signal, the amplifier resets the potential of the signal applied to the transformer primary winding 244. This results in the drive signal voltage V S changes.

[0155] In step 356, the processor determines whether the frequency of the drive signal is at or substantially equal to the longitudinal mechanical cancellation frequency of the handpiece. This determination is made by evaluating whether the ratio of equation (11B) is equal to or substantially equal to zero. Here, substantially equal to zero means that the real part of the ratio is 0.10 or less, preferably 0.05 or less, and more ideally 0.01 or less.

[0156] The comparison of step 356 may indicate that the drive signal applied to the hand piece is at or substantially equal to the longitudinal mechanical cancellation frequency of the hand piece. This is the target state for the drive signal. This means that the drive signal causes expansion / contraction of the driver 36, which causes the portion of the tip distal to the torsional boundary to engage in substantial torsional vibration and minimal longitudinal vibration, if any.

[0157] It may be determined in the evaluation of step 356 that the drive signal is not being applied to the hand piece at or near the longitudinal mechanical cancellation frequency. If the processor 266 makes this determination, then in step 358, the processor resets the frequency of the WAVEFORM_SET signal, i.e., step 358. If the result of the evaluation of step 356 is negative, then the processor 266 deems the system to be in such a state that since the ratio on the left side of equation (11B) is negative, in step 358, the processor 266 interprets the system 30 as being in a state where the frequency of the drive signal should be reduced. If the calculation of step 356 produces a positive result, then the processor 96 deems the system 30 to be in a state where it is necessary to increase the frequency of the drive signal to ensure that the drive signal frequency is closer to the longitudinal mechanical cancellation frequency of the hand piece.

[0158] In step 358, the processor assumes that the current i S , voltage V Sand driver capacitor C O is constant. During the iteration process, different frequencies are injected into equation (11B). As a result of the new execution of equation (11B), it can be determined that the real part of the ratio of the equivalent value of the current flowing through the driver to the current applied to the mechanical components of the handpiece is less than (or substantially less than) zero. If this is the case, then in the next iteration, the injected frequency will be less than the previously injected frequency. As a result of the execution and evaluation of equation (11B), it can be determined that the ratio is greater than (or substantially greater than) zero. If this is the case, then in the next iteration, the injected frequency will be greater than the previously injected frequency. If the final result of the calculation is that the ratio is zero or substantially zero, the frequency of the drive signal is set to the injected frequency. The processor 266 then adjusts the frequency of the WAVEFORM_SET signal output to the amplifier 234 based on the results of these calculations. The console 230 then turns to output a drive signal to the handpiece at the longitudinal mechanical cancellation frequency of the handpiece 32.

[0159] Although not shown, it will be appreciated that the characteristics of the drive signal applied to the handpiece 32 are limited by boundary parameters read from the handpiece. Specifically, the regulation of the WAVEFORM_SET signal is limited to ensure that the drive signal does not exceed the maximum voltage level set by The WAVFORM_SET signal is further regulated to ensure that the current of the drive signal applied to the handpiece does not exceed and the mechanical component of the current does not exceed

[0160] It should also be understood that the adjustments to the voltage and frequency of the WAFEFORM_SET signal that occur in steps 352 and 358 are based on the PID coefficients read from the handpiece memory 56 and the tip memory 184. Typically, the coefficients in the tip memory 184 are the coefficients upon which these characteristics of the WAVEFORM_SET signal are adjusted.

[0161] exist Fig.13A and 13B In the example, after executing step 356, or if necessary after step 358, the system is shown as looping back to step 340. This is because recalculating the target current is usually performed as long as the system remains activated. And selectively adjust the potential and frequency of the drive signal.

[0162] There are many reasons why the control loop is repeated. In general, it should be understood that if the frequency of the drive signal is adjusted, the impedance of the driver impedance Z0 and both the impedances Z1 and Z2 of the mechanical components of the handpiece will change. This results in a change in the current flowing through the handpiece, and more specifically, the total mechanical equivalent value i of the current flowing through the mechanical components of the handpiece. M The system 30 detects these changes as measured values ​​V S and i S Therefore, after executing step 356 or 358, the next evaluation of step 350 will most likely indicate that the system is at the total mechanical equivalent value of the current i M The target current This will require re-execution of step 352 to adjust the amplitude of the voltage of the drive signal.

[0163] Similarly, the adjustment of the potential of the drive signal will also result in a voltage V S and current i S This means that the next time step 164 is performed, the evaluation will indicate that the drive signal is no longer at the longitudinal mode cancellation frequency of the mechanical components of the handpiece.

[0164] After a number of cycles through the control loop, the console 266 asserts a drive signal that causes a current through the mechanical components of the handpiece substantially equal to and is at the longitudinal mode cancellation frequency of the handpiece mechanical components. At startup, assuming the tip head is not applied against tissue, the system is believed to reach this state in 2 seconds or less (more typically 1 second or less).

[0165] Another reason the control loop is executed continuously has to do with the nature of how the handpiece 32 is employed. In order for the handpiece to function, the head 164 is placed against the tissue (step not shown). This is because it is the back-and-forth movement of the teeth against the tissue that causes the tissue to be sawed, ablated, emulsified, or removed altogether. Also, in some embodiments of the invention, this back-and-forth movement causes cavitation of fluid adjacent to the tissue and in some cases, the tissue itself.

[0166] When the head 164 is placed against the tissue, a mechanical load is placed on the components forming the handpiece. This mechanical load changes the impedance of the mechanical components of the handpiece. Here, impedance is understood to be the impedance associated with both the first mechanical resonance mode and the second mechanical resonance mode of the handpiece. Moreover, when the system 30 is actuated, the temperature of the mechanical components of the handpiece generally changes. This change in the temperature of the components results in a change in the impedance of these components. The change in the characteristics of the components can result in a shift in the longitudinal mechanical cancellation frequency of the handpiece.

[0167] The resulting change in impedance and longitudinal mechanical cancellation frequency results in a current i through the handpiece S The total mechanical equivalent value of the current i M Therefore, continuous execution of the control loop ensures that when these changes in impedance occur, the drive signal is reset to ensure that the mechanical equivalent of the current is substantially equal to the target current And the frequency of the drive signal is substantially equal to the longitudinal mechanical cancellation frequency of the mechanical components of the handpiece. Maintaining the characteristics of the drive signal close to these target parameters ensures that as the mechanical load to which the tip head 52 is exposed changes, the amplitude of the vibration of the head remains substantially constant and the tip head 164 and the adjacent distal section 160 of the shaft 44 do not engage in substantial longitudinal movement.

[0168] Additionally, during the period that the handpiece 32 is actuated, the practitioner may want to adjust the amplitude of the tip head vibration. This adjustment is made by resetting the control member 270. (Adjustment not shown). Once this adjustment occurs, in subsequent executions of step 148, the newly calculated target current This in turn will likely mean that, as a result of the next execution of step 350, it will be determined that the mechanical equivalent value of the current i1+i2 is no longer substantially equal to the target current This will most likely result in adjustments to the potential and frequency of the drive signal for the reasons discussed above.

[0169] Thus, the above-described control loop starting with the evaluation of step 340 is continuously executed as long as the foot pedal 270 or other on / off control remains actuated. The practitioner deactivates the handpiece by releasing the foot pedal 270. This causes the processor to receive a signal that the control member is in the off position in one of the subsequent executions of step 340. In response to the processor 266 receiving this signal, the processor cancels the application of the asserted signal to cause the output of the drive signal (step not shown). The system 30 returns to the wait state, continuously monitoring the signal from the on / off control member to determine whether the practitioner wants to actuate the handpiece 32.

[0170] It will be appreciated that after actuation of the hand piece, there will eventually come a time when it is no longer necessary to apply the vibrating tip head 164 to the tissue. The practitioner ceases depressing the control member (foot switch 270). The processor 266 detects the occurrence of this event when it subsequently executes step 340. When this event occurs, the processor cancels the application of the WAVEFORM_SRT signal (step not shown). This causes the console to cease applying the drive signal to the hand piece driver 36. This results in the termination of the vibration of the tip 142. The processor 266 continues to repeatedly execute step 340 to determine if the practitioner again desires to vibrate the tip, and the control member 270 is again actuated.

[0171] The system 30 of the present invention is configured such that, as a result of repeated execution of steps 356 and 358, the system maintains the drive signal at a frequency substantially equal to the longitudinal mechanical cancellation frequency of the handpiece 32. This relationship is maintained as the resonant frequencies of the handpiece mechanical components change due to mechanical loading and / or temperature changes of those components.

[0172] The system 30 of the present invention is able to vibrate the tip head at a desired amplitude even when the tip and other components of the handpiece are subjected to mechanical loading or undergo temperature changes. This reduces the need for the operator using the system to have to continuously adjust the drive signal to ensure that the tip head continuously vibrates at the desired amplitude.

[0173] Additionally, during the course of the procedure, the tip head may suddenly press against the tissue. This causes a rapid and significant increase in the impedance of the mechanical components of the handpiece. In response to this rapid change in impedance, the system 30 of the present invention rapidly adjusts the potential and frequency of the drive signal. Adjustments to these characteristics of the drive signal serve to ensure that the tip head vibration maintains the desired amplitude. This reduces the extent to which sudden mechanical loading of the handpiece causes a sudden decrease in the amplitude of the tip head vibration.

[0174] By applying a drive signal at a longitudinal mechanical cancellation frequency to the handpiece, the system 30 of the present invention induces a substantially torsional vibration in the tip 142. The tip shaft 144 engages in minimal, if any, longitudinal vibration movement. During the procedure, the shaft 144 can be pressed against tissue adjacent to the tissue against which the tip head 164 is applied to facilitate placement of the tip head. Since the shaft 144 engages in only minimal longitudinal movement, the possibility that this movement could induce cavitation, which would result in undesired removal of the tissue against which the shaft is pressed, is also substantially, if not completely, eliminated.

[0175] It should also be understood that the system does not require the processor 266 to match the characteristics of the handpiece 32 and tip 142 to the capacitance, resistance, or inductance of components within the console 230. Thus, a single console 230 can be used to construct the system 30 of the present invention with different handpieces 32 and tips 142, each with their own impedance characteristics. The console configures the system 30 for each handpiece and tip assembly based on the data read from the handpiece memory 56 and the tip memory 184. Similarly, the handpieces and tips can be used with different consoles to assemble the system 30 of the present invention.

[0176] It should be similarly understood that in the above-described version of the invention, a plurality of different tips 142, each having its own longitudinal mechanical cancellation frequency, can be attached to a single handpiece 32 and subsequently driven by the single handpiece. One advantage of this feature of the invention is that a plurality of different types of tips can be attached to a common handpiece, each tip having its own physical structure and therefore longitudinal mechanical cancellation frequency. A second advantage of this feature is that it enables each tip to be evaluated after manufacture to determine the longitudinal mechanical cancellation frequency of that tip. This means that the data for each tip used to provide a drive signal for that tip accounts for manufacturing variations between individual tips. Likewise, two types of tips that differ from a basic design or manufacturing variations can be driven by a single handpiece. This facilitates providing a system of the invention that does not require the expense of providing a specially associated handpiece for use with the associated tip 142.

[0177] The system 30 of the present invention is also designed to apply a mechanical equivalent of an electrical current (which is substantially equal to a target current) to the mechanical components of the handpiece. The target current is based on the practitioner's setting of the desired amplitude of the tip head vibration. Thus, the system of the present invention provides the practitioner with a relatively accurate means of controlling the amplitude of the tip head vibration.

[0178] IV. Alternative Embodiments

[0179] The above relates to one specific version of the invention. Alternative versions of the invention may have different features than those already described.

[0180] For example, the components used to construct the invention may differ from those described.In some versions of the invention, handpiece 32 and tip 142 may be a one-piece unit.

[0181] Features integrated with the tip that convert longitudinal vibratory motion into torsional vibratory motion may not always be helical grooves. In some versions of the invention, these features may be grooves, but they may not be helical. An example of an alternative groove structure is an oblique groove. The difference between these two types of grooves is that a helical groove has a longitudinal axis extending along the tip from the proximal end to the distal end, curving around the longitudinal axis of the tip. An oblique groove has a longitudinal axis that is a straight line shape.

[0182] Unless appearing in the claims, the frequencies, voltages, currents, capacitances and other quantitative values ​​are to be understood as examples only and do not limit the scope of the invention.

[0183] The console 230 may include other components that generate a drive signal that varies in both potential and frequency. Depending on the configuration of these components, the console may not include a transformer to which an input signal is applied in order to generate the drive signal. Similarly, in some versions of the invention, a resistor circuit as opposed to an inductor may be incorporated into the console in order to provide a voltage representative of the drive signal voltage V S and the driving signal current i S One or both of the signals.

[0184] Similarly, in some versions of the invention, the console may include a first circuit and a second circuit to set the frequency of the drive signal, and a variable gain amplifier to set the potential of the drive signal. In these versions of the invention, processor 266.

[0185] The type of memory device containing data describing the characteristics of the handpiece and tip required to adjust the output of the drive signal can be different from what has been described. For example, one or more of these memories can be an EEPROM, a bar code, or some other machine-readable device. In some versions of the invention, one or more of the handpiece and tip can even have no memory. In these versions of the invention, a person is required to manually enter the handpiece and tip characteristics into the console in order to ensure that the system 30 is correctly configured.

[0186] The series of steps by which the console 230 sets the potential and frequency of the drive signal may similarly differ from that described. For example, in an alternative configuration of the system, the console may first set the frequency of the drive signal before setting the voltage of the drive signal. Likewise, depending on the structure of the invention, the console may not set the frequency and voltage of the drive signal by setting the corresponding characteristics of a single WAVEFORM_SET signal. In some versions of the invention, in order to regulate the operation of the component that actually generates the drive signal, the processing circuit may generate two control signals. The first of the control signals is used to set the voltage of the drive signal. The second of the control signals is used to set the frequency of the drive signal.

[0187] In the described versions of the invention, the console 230 is configured to initially set the drive signal to a frequency that is the lowest possible longitudinal mechanical cancellation frequency for the tip. Other versions of the invention may be configured to employ an alternative frequency as the initial frequency of the drive signal. For example, in some versions of the invention, the initial frequency of the drive signal may be the highest possible longitudinal mechanical cancellation frequency. Alternatively, the drive signal may be set to a frequency between the lowest longitudinal mechanical cancellation frequency and the highest longitudinal mechanical cancellation frequency for the tip. In some versions of the invention, a memory integrated with the tip may include data defining the initial frequency setting of the longitudinal drive signal.

[0188] In the above description, it is assumed that the driver capacitance C O is constant. This is for the purpose of understanding the invention. In practice, the driver capacitance may drift over time. Such drift may be due to effects such as aging of the driver, or to temperature variations of the driver during a single procedure. Therefore, some consoles integrated into the system of the invention include a unit for determining the driver capacitance. The exact unit that makes this determination is not part of the invention. During a procedure, sometimes such a unit that determines the driver capacitance is used to provide the driver capacitance C O An updated measured value for use in an evaluation for determining the mechanical equivalent value of the current.

[0189] In addition, the system of the present invention can be configured to apply a drive signal to the handpiece that causes the tip to vibrate in one of three states based on the practitioner's preferences and the details of the procedure being performed. By inputting a first set of commands into the console, the system will provide a drive signal that causes the tip to vibrate substantially torsionally as described above with minimal, if any, longitudinal vibration.

[0190] By inputting a second set of alternative commands into the console 230, the system provides a drive signal that causes the tip to vibrate in one of the mechanical resonance modes. In order for the system to operate in this mode, the frequency of the drive signal is set based on the data in fields 194 and 195 of the tip memory 184 that define the frequency range of the drive signal when the tip is vibrated in the mechanical resonance mode. When the console is so set, it will operate as described in PCT Publication No. WO 2015 / 021216A1, which is incorporated by reference. When the system is operated in this mode, it should be understood that at the distal end of the torsional boundary, the tip shaft 14 and the tip head 164 will engage in simultaneous longitudinal and torsional movement. If it is believed that the combined longitudinal and torsional movement of the tip head 164 will result in optimal removal of tissue and the effect of the longitudinal movement of the shaft 144 is tolerable, the practitioner may wish to operate the handpiece in this mode.

[0191] By inputting the third set of commands into the console 230, the present system provides a drive signal across the driver 36 that is a combination of the drive signal required to drive the tip in the first resonant mode and the drive signal required to drive the tip in the second resonant mode. When the console is so configured, the present system operates as described in PCT Application No. PCT / US2015 / 044023, which is incorporated by reference. In situations where it is desirable to engage the tip head 164 in non-linear motion in order to remove tissue and the effects of longitudinal motion of the tip head can be tolerated, the practitioner may wish to operate the handpiece in this mode.

[0192] To enable the system 30 to operate in the third mode, the tip memory will essentially contain two versions of field 194 and two versions of field 195. In the first version of field 194 and field 195, data defining a range of resonant frequencies for the first mechanical resonance mode is stored. The second version of fields 194 and 195 stores data defining a range of resonant frequencies associated with the second mechanical resonance mode.

[0193] Similarly, by inputting a fourth set of commands into the console, the system can be configured to provide a drive signal at a frequency between the resonant frequency of one of the mechanical resonant modes and the longitudinal mechanical cancellation frequency. Thus, when the system is operated in this state, there is a partial cancellation of the longitudinal motion of the tip head 164 and the adjacent distal section 160 of the shaft. This mode of operation may be desirable if, for a given procedure, it is appropriate to excite the tip head 164 to a vibration that causes the tip to engage primarily in torsional motion while also having some, but not complete, longitudinal motion.

[0194] Additional data that may be stored in the tip memory includes data defining a range of mechanically equivalent values ​​of the current for each of the resonant modes.

[0195] Therefore, it is the object of the appended claims to cover all such changes and modifications as come within the true spirit and scope of the invention.

Claims

1. An ultrasonic tool system for controlling an ultrasonic handpiece, the ultrasonic handpiece comprising: at least one actuator that cyclically expands and contracts in response to application of an AC drive signal; and a tip including opposing proximal and distal ends, the proximal end of the tip being coupled to the at least one actuator such that the expansion and contraction of the at least one actuator causes longitudinal vibrations at the proximal end of the tip; and features between the proximal and distal ends of the tip that convert the longitudinal vibrations present at the proximal end of the tip into vibrations having a longitudinal component and a torsional component at the distal end of the tip, the ultrasonic tool system comprising: components for generating the AC drive signal, the AC drive signal being applied to the at least one driver of the ultrasonic hand piece, the AC drive signal having a variable frequency; as well as and a processor configured to set a frequency of the AC drive signal to a frequency between respective resonant frequencies of adjacent first and second mechanical resonance modes of the ultrasonic hand piece, the set frequency corresponding to a first vibration in the tip associated with the first mechanical resonance mode and a second vibration in the tip associated with the second mechanical resonance mode, each of the first vibration and the second vibration having a longitudinal component and a torsional component, the longitudinal component of the first vibration at least partially canceling the longitudinal component of the second vibration.

2. The ultrasonic tool system according to claim 1, wherein: In response to the processor setting the frequency of the AC drive signal to a frequency between the respective resonant frequencies of the first mechanical resonance mode and the second mechanical resonance mode, the distal end of the tip is configured to move in an at least partially torsional path of travel such that during movement of the distal end along the path of travel, an angle between the distal end of the tip and an axis perpendicular to a longitudinal axis of the tip does not exceed 30°.

3. The ultrasonic tool system according to claim 1 or 2, further comprising: a component for measuring the current of the AC drive signal; as well as a component for measuring the voltage of the AC drive signal, Wherein the processor is configured to set the frequency of the AC drive signal to a frequency between respective resonant frequencies of the first mechanical resonance mode and the second mechanical resonance mode based on the measured current and voltage.

4. The ultrasonic tool system according to claim 3, wherein: The processor is configured to: determining a capacitance of the at least one driver; and The frequency of the AC drive signal is set to a frequency between respective resonant frequencies of the first and second mechanical resonance modes based on the measured current and voltage and the capacitance of the at least one driver.

5. The ultrasonic tool system according to claim 4, wherein: The processor is configured to: calculating a mechanical equivalent of the current applied to a mechanical component of the ultrasonic hand piece based on the measured current and voltage, the capacitance of the at least one driver, and the frequency of the AC drive signal; and The frequency of the AC drive signal is set to a frequency between respective resonant frequencies of the first and second mechanical resonance modes based on the mechanical equivalent of the current applied to the mechanical component of the ultrasonic hand piece.

6. The ultrasonic tool system according to claim 5, wherein: The processor is configured to calculate a mechanical equivalent of the current applied to a mechanical component of the ultrasonic handpiece based on the measured current and voltage, the capacitance of the at least one driver, and the frequency of the AC drive signal by being configured to: calculating a current through the at least one driver based on the measured voltage, the capacitance of the at least one driver, and the frequency of the AC drive signal; and A difference between the measured current and the current through the at least one driver is determined.

7. The ultrasonic tool system according to claim 5, wherein: The processor is configured to: calculating a ratio between the current through the at least one driver and the mechanical equivalent of the current applied to the mechanical component of the ultrasonic hand piece; and The frequency of the AC drive signal is set to a frequency between respective resonant frequencies of the first mechanical resonance mode and the second mechanical resonance mode based on the calculated ratio.

8. The ultrasonic tool system according to claim 7, wherein: The processor is configured to set the frequency of the AC drive signal based on the calculated ratio such that the vibration at the distal end of the tip is substantially torsional by being configured to: comparing the calculated ratio to a target ratio; and The frequency of the AC drive signal is set to a frequency between respective resonant frequencies of the first and second mechanical resonance modes based on the comparison of the calculated ratio and the target ratio.

9. The ultrasonic tool system according to claim 8, wherein: The target ratio is 0.

10. The ultrasonic tool system according to claim 8, wherein: The processor is configured to compare the calculated ratio to a target ratio by being configured to compare a real part of the calculated ratio to the target ratio.

11. The ultrasonic tool system according to claim 4, wherein: The processor is configured to determine the capacitance of the at least one driver by being configured to read data indicative of the capacitance of the at least one driver from a memory of the ultrasound hand piece.

12. The ultrasonic tool system according to claim 1 or 2, further comprising the ultrasonic handpiece.

13. The ultrasonic tool system according to claim 12, wherein: The ultrasonic handpiece comprises a sleeve, and the sleeve comprises: a body including an open proximal end and a distal end and defining a lumen extending therebetween, the body being adapted to be disposed about the tip during operation of the ultrasonic hand piece such that the tip extends through the lumen and out of the open distal end of the sleeve; a conduit in fluid communication with the lumen for supplying irrigation fluid to the tip; and a tip memory disposed in the body and storing data specific to the tip for reading by the console when the ultrasonic hand piece is coupled to the console, the data indicating a frequency of a mechanical resonant mode for the tip and a frequency of a longitudinal mechanical cancellation mode for the tip, Wherein the processor is configured to set the frequency of the AC drive signal to a frequency between respective resonant frequencies of the first and second mechanical resonance modes based on data specific to the tip read by the console from the tip memory.

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