System and method for driving an ultrasonic handpiece in response to mechanical impedance of the handpiece - Patents.com

Abstract

To provide an ultrasonic surgical tool system for actuating a handpiece with a tip portion.SOLUTION: An ultrasonic surgical tool system is provided for actuating a handpiece with a tip portion 50. The voltage and frequency of drive signals applied to handpiece drivers 40 are a function of the equivalent of current passing through the mechanical components of the handpiece and the tip portion and the frequency responsiveness of these components.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates generally to ultrasonically driven surgical handpieces. More specifically, the present invention relates to ultrasonically driven surgical handpieces. The present invention relates to a method for detecting the impedance of the mechanical components of a handpiece. applying a drive signal to the handpiece in response to the change. [Background technology]

[0002] Ultrasonic surgical instruments are useful in performing medical and surgical procedures. Generally, ultrasonic surgical tools include at least one piezoelectric driver. A handpiece having a tip mechanically connected to the driver, the tip The head extends forward from a housing or shell in which the driver is disposed. The head has a diameter of 1.5 mm and a diameter of 1.5 mm. The ultrasonic tool system is controlled by a mechanism, often teeth or flutes. The control console also provides the AC drive signals to the driver. When a drive signal is applied to the driver, the driver expands and contracts cyclically. Tension and contraction induce similar movements in the tip, and more specifically in the head of the tip. When the tip moves in this way, it is considered to be vibrating. The head is then applied to tissue to perform a particular surgical or medical task. For example, several tip heads are applied to hard tissue. One form of hard tissue is bone. When the tip of the tip vibrates, it vibrates back and forth, causing the adjacent hard The other tip head is applied to the soft tissue. When this tip head vibrates, the teeth are often cut by a cutting action. Some ultrasonic tools also create cavities in the tissue and surrounding fluids. The tip head moves back and forth to remove tissue by inducing a pulsation. Specifically, these vibrations result in cavitation in the tissue and surrounding body fluids. Small voids or cavities are formed. These cavities are very small areas of extremely low pressure. A pressure difference occurs between the contents of the cells that make up the tissue and these cavities. This pressure The difference is relatively large, causing the cell walls to burst. The cell walls burst, forming tissue. The cells are removed or ablated.

[0003] Ultrasonic tip heads are often relatively small; some heads are less than 1.0 cm The ultrasonic tool essentially cuts the tissue adjacent to where the head is placed. Therefore, ultrasonic handpieces are more efficient because of the relatively small surface area of ​​the head. The laser has proven to be a useful tool for precise removal of both hard and soft tissue. There are.

[0004] Ultrasonic surgical instruments, sometimes called handpieces or tools, operate efficiently. In order for the tool to function properly, a drive signal having suitable characteristics must be applied to the tool. If the head does not have the appropriate characteristics, the head will be subjected to vibrations of less than optimal amplitude. and / or may not vibrate as fast as possible. In either state, the ability of the handpiece to remove tissue at a given time is compromised. The level of the signal may decrease.

[0005] One way to ensure that an ultrasonic handpiece operates efficiently is to The goal is to apply a drive signal to the handpiece that is at the resonant frequency of the If the voltage or current is at the resonant frequency, the drive signal can be applied to move the device off resonance. The tip of the probe is exposed to a relatively large amplitude compared to the same voltage at the same frequency. Vibrations are induced.

[0006] Still other ultrasonic tool systems generate a drive signal at the anti-resonant frequency of the handpiece. The anti-resonance frequency is the frequency at which the handpiece experiences the highest impedance. The frequency may be the frequency that the signal will have.

[0007] Applicant's SONOPET™ ultrasonic aspirator generates a variable drive signal, A console with components designed to apply power to an attached handpiece There is a resonant circuit inside the console. During the manufacture of the console, this The inductance and capacitance of the It is set as a function of the impedance of the particular handpiece being used. The characteristics of the drive signal output from the can be.

[0008] In many procedures, the SONOPET console outputs a drive signal. is essentially the same as the resonant frequency of the mechanical components of the handpiece or However, in most normal use cases, ultrasonic Handpieces with a stylus may be subjected to significant mechanical loads. This can occur, for example, when the tip is pressed into bone. This can occur when the tip is pressed against something. In this situation, the mechanical load on the tip is , which can cause significant changes in the impedance of the mechanical components of the handpiece. When this occurs, the control console detects the resonant frequency of the mechanical components in the handpiece. In some cases, it may not be possible to output a drive signal at a frequency close to the reference frequency.

[0009] Furthermore, impedance circuits within prior art consoles typically The inductance and capacitance are set according to the particular handpiece that will be used. It has different internal inductance, capacitance and resistance. When the handpiece is attached to the console, the drive signal output from the console is: It is quite likely that the handpiece will not have characteristics that are conducive to efficient operation. A console designed for use with one handpiece can be used with another handpiece. This makes it difficult, if not impossible, to use the device as a power source to provide a drive signal for do. Summary of the Invention

[0010] The present invention relates to a new and useful ultrasonic surgical tool system. The system is designed to ensure that, within design limits, the drive signal applied to the system handpiece is It is designed to ensure that it induces vibrations of the appropriate amplitude at the ends. The system operates when various handpieces are attached to the control console. The signal can be set up so that the system can be used with the handpiece. As a result, the characteristics of the drive signal change when the impedance characteristics of the handpiece change. Adjust.

[0011] The system of the present invention includes a control console to which the handpiece is attached. The control console generates and supplies a drive signal to the handpiece. The frequency of the drive signal and the current supplied to the handpiece are set. These characteristics of the drive signal are set by regulating the voltage of It is set according to two variables and one constant. One of the variables is the voltage of the drive signal. The second variable is the current through the handpiece, i.e., the current of the drive signal. The constant is The capacitance of one or more piezoelectric drivers inside the handpiece.

[0012] Based on these three inputs, the control console determines the frequency and voltage level of the drive signal. The frequency of the drive signal is set to match the target frequency as closely as possible. This is done by ensuring that the tip head vibration is at its most efficient frequency. The voltage is set to provide control over the amplitude of vibration of the tip head.

[0013] In some versions of the invention, the drive signal is applied to a mechanical component of the handpiece. The frequency of the drive signal is adjusted to control the equivalent component of the current that is The target frequencies are related to the resonant and / or anti-resonant frequencies of the mechanical components of the piece. The method can be adjusted to ensure that

[0014] The voltage and current of the drive signal are measured by circuitry internal to the control console.

[0015] The driver capacitance is determined by the change in capacitance over many successive adjustments of the drive signal. The eigenvalues ​​are considered to be constants in that they remain unchanged. In the John, the driver capacitance is matched to the handpiece attached to the console. The data is obtained from a set of ring signals. Based on the interrogation signal, the console periodically checks the driver capacitance. It can be requested.

[0016] The target frequency of the handpiece is, in part, a function of the mechanical components of the handpiece. The target frequency is also a function of the varying loads placed on these components. The target frequency may be the resonant frequency of the mechanical components of the handpiece. In some versions, the target frequency is the anti-resonant frequency of the mechanical components of the handpiece. In yet another version of the invention, the target frequency is determined by the mechanical components of the handpiece. The frequency is between the original resonant frequency and the anti-resonant frequency. , the target frequency is outside the band between the resonant and anti-resonant frequencies.

[0017] Therefore, a feature of the system of the present invention is that the console selectively adjusts the drive signal. If the target frequency changes as a result of the handpiece being loaded, the drive signal is adjusted to stay at or near the target frequency.

[0018] A further feature of the invention is that the console is equipped with drivers having different capacitances. Similarly, the handpiece of the present invention is capable of supplying a drive signal to the handpiece. It is not necessary to connect only to a single specific console.

[0019] In some alternative versions of the invention, only the frequency of the drive signal is set. The wave number is the equivalent component of the current that the drive signal applies to the mechanical components of the handpiece. and that the signal is at a frequency close to the desired target frequency for these components. In order to ensure this, the

[0020] The above features and advantages of the invention are as set forth in the appended claims. Further features and advantages will be apparent from the following detailed description taken in conjunction with the following drawings. can be. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is an illustration showing the basic elements of an ultrasonic tool system having features of the present invention. [Diagram 2] FIG. 2 is an illustration of the mechanical components of the tool or handpiece of the system. [Diagram 3] FIG. 2 is an illustration of the electrical components of both the control console and handpiece components of the system of the present invention. [Figure 4A] FIG. 2 is a diagram showing the current flowing through the handpiece and the impedance of different components of the handpiece. [Figure 4B] FIG. 2 is a diagram showing the current flowing through the handpiece and the impedance of different components of the handpiece. [Diagram 5] FIG. 2 is an illustration depicting the types of data stored within memory within the handpiece. [Figure 6A] 6B, which together with FIG. 6B constitute a flow chart of the operation of the system of the present invention. [Figure 6B] 6A and 6B are explanatory diagrams constituting a flow chart of the operation of the system of the present invention. [Figure 7] FIG. 2 is an illustration showing how the impedance circuit formed by components within the handpiece can be thought of as changing shape when the handpiece is subjected to a mechanical load. [Figure 8] FIG. 1 is an illustration depicting an alternative model of the impedance of a handpiece driver and the equivalent impedance of the mechanical components of the handpiece. [Figure 9] 1 is a graph illustrating reactance change of mechanical reactance versus frequency of a handpiece when the tip is in air and the tip is subjected to a load. [Figure 10] FIG. 1 is an illustration depicting the addition of variable impedance to the mechanical components of the handpiece. [Figure 11] 1 is a graph illustrating how the addition of variable impedance of the mechanical components of a handpiece affects the reactance of those components. [Figure 12] FIG. 1 is a block diagram illustrating how data can be provided to a control console from a memory integral with the tip of the present invention. [Figure 13] FIG. 13 is an illustration depicting the types of data stored in memory within the tip. [Figure 14] FIG. 1 is an illustration depicting an alternative model of the impedance of a handpiece driver and the equivalent impedance of the mechanical components of the handpiece. [Figure 15A] 15B form a flow chart illustrating alternative process steps for regulating the ultrasonic surgical tool system of the present invention. [Figure 15B] 15A and 15B are illustrative diagrams that together form a flow chart depicting alternative process steps for regulating the ultrasonic surgical tool system of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] [I. System Overview and Hardware] Please refer to FIGS. 1 and 2 for an ultrasonic tool system 30 having the features of the present invention. The system 30 includes a handpiece 32. 2 has a body or shell 34 which forms the proximal end of the handpiece. ("proximal" means closer to the practitioner holding the handpiece and closer to where the handpiece is touching.) "Distal" should be understood to mean away from the site where the This is understood to mean away from the practitioner and close to the area where the handpiece is applied. sea ​​bream.).

[0023] One or more vibratory piezoelectric drivers 40 (four are shown) are mounted inside the shell 34. Each driver 40 is arranged to expand or contract instantaneously when a current is applied to the driver. These expansions and contractions are caused by the longitudinal axis of the driver 40. The axis extends between the proximal and distal faces of the driver. Leads 41 extend away from each driver 40. The leads 41 are connected to opposing ends of the driver. Many, but not all, handpieces have proximal and distal surfaces. The sensor 32 has disk-shaped piezoelectric drivers 40. These drivers 40 The leads are arranged end-to-end in the stack. The leads 41 are part of the system 3. 0, and a current is applied to the driver 40 in the form of a drive signal. 37 separates adjacent leads 41 connected to adjacent drivers 40 from each other. One of the insulating disks 37 is shown. In FIG. 1 and 2. This is shown as being spaced apart from one another for ease of illustrating the components. In reality, the insulating disk 37 and the driver 40 are in contact with each other without any gap.

[0024] A post 39 extends longitudinally through the insulating disk 37 and the driver 40 . Post 39 extends through the driver along a collinear longitudinal axis of the driver. The insulating disk 37 and the driver 40 are internal to the post 39 passing therethrough. The post 39 is connected to the proximal most driver 40. and the distal-most driver.

[0025] A proximal end mass is provided on the proximal face of the proximal-most driver 40. 36 is attached to the exposed proximal end face of the post 39. If the post 39 is threaded, the mass 36 may be a nut.

[0026] A horn 42 extends forward from the distal face of the distal-most driver 40 . Although not shown, there may be an insulating disk 37 between these components. 2 has a base with a diameter approximately equal to the diameter of the driver 40. As the horn 42 extends forward from the distal end, the diameter of the horn 42 decreases. A horn 42 is secured to the distal end surface of the post 39. When the post 39 is threaded, the horn The base of the pin has a threaded, closed-ended bore (not shown) to receive the post 39. The handpiece 32 may be configured such that the stack of drivers 40 is in contact with the proximal mass 36. The screw 42 is configured to be clamped between the screw 42.

[0027] A tip 48 extends forward from the distal end of the horn 42. The coupling assembly typically connects the tip 48 to the horn 42 and the remainder of the handpiece 32. The structure of the coupling assembly is not part of this invention. The tip 48 has an elongated stem 50. The stem 50 is a portion of the tip and is The shank 50 is attached to the horn 42 through a mating assembly. The tip 48 has a head 52 at the distal end of a shaft 50. Some of the tip heads 52 have a smooth surface. Head 52 is formed with teeth 53. The shape of head 52 is not part of the present invention. Distal head 52 is the portion of handpiece 32 that is applied to the area on the patient where the procedure is to be performed. minutes.

[0028] Some tips 48 have teeth designed to be applied directly to hard tissue, i.e. bone. When this type of tool reciprocates, it cuts tissue in the same way that a traditional saw blade does. In this way the teeth cut the tissue.

[0029] A sleeve 55, which is shown as a ring in FIG. 2, is generally disposed so as to cover the distal shaft portion 50. The sleeve 55 is typically located near where the shaft is attached to the horn 42. The handpiece 32 and the tip extend from the tip to a location approximately 0.5 cm near the head 52. Both the tip 48 and the sleeve 55 have a gap between the outer surface of the tip and the surrounding inner surface of the sleeve. The sleeve is configured to define an extending fluid flow conduit. Also, sleeve 55 is provided adjacent the proximal end of the sleeve and extends to this conduit. The conduit also has a fitting (not shown) that is attached to the sleeve. When the handpiece is in use, cleaning solution may leak from the sleeve fitting down into the sleeve. and exits adjacent to the tip head 52. The fluid acts as a medium through which the mechanical vibrations of the tip head are transmitted to the tissue. This cleaning solution is generated by the tip head as a result of the vibration of the head. It also acts as a heat sink for thermal energy.

[0030] Although not shown, the tip, horn 42 and handpiece post 39 are often A conduit that together defines a fluid flow path from the distal head 52 to the proximal end of the handpiece. When the handpiece is in operation, these conduits are Suction is created through the sleeve 55 and is drawn away from the area where the tip is placed. The suction also draws the tissue towards the tip head. By shortening the distance between the tip head and the tissue, the function from the tip head to the tissue is improved. The transmission of mechanical vibrations is improved.

[0031] The handpiece 32 also includes a memory 58. The memory 58 is discussed below. The memory 58 includes data describing the characteristics of the handpiece, such as EPROM, This can take the form of a PROM or an RFID tag. The structure of the memory is not part of this invention. Most handpieces 32 of the present invention include a memory that can be read out. In addition to containing data that can be used to read and write data, the data is written to memory after the handpiece is manufactured. Auxiliary components, not shown, can read data from the memory. Attached to the handpiece to facilitate reading and writing data to memory. These components include the following components: conductors, exposed contacts / contacts The device may comprise one or more of a contact pin, a coil / antenna or an isolation circuit.

[0032] A control console 64 is also part of the system 30 of the present invention. The drive signal is provided via a cable 62 to which the end piece 32 is connected. In many, but not all, versions, the handpiece 32 and cable 62 are a single The drive signal is applied to a driver 40. At the same time, the same drive signal is applied to each driver 40. By applying the drive signal The drivers expand and contract simultaneously and periodically. In the case of the driver, the length is 1cm to 5cm. The distance of the movement, i.e., the amplitude, can be from 1 micron to 10 microns. 2 amplifies this movement. As a result, from a fully contracted position to a fully expanded position When in motion, the distal end of the horn 42, and by extension the tip head 52, typically moves at a maximum At 48 the tip moves by 1000 microns, and more often by 500 microns or less. In some cases, the longitudinal expansion and contraction of the tip shaft may induce rotational motion in the head. When the handpiece 32 is actuated to cause cyclic movement of the tip, The head 52 can be thought of as vibrating.

[0033] As shown in FIG. 3, components within the control console 64 include a power supply 68. The power supply 68 normally outputs a constant voltage signal of 1 VDC to 250 VDC. In this version, the maximum potential of the voltage output by the power supply 68 is 150 VDC. The potential of the signal output by the power supply 68 can be selectively set. In the described version of the power supply 68 receives a VOLTAGE_SET (V_S) signal. Power supply 68 establishes the level of its output voltage in response to the VOLTAGE_SET signal. The output voltage produced by the power supply 68 is applied to an adjustable amplifier 70. A signal, specifically a FREQUENCY_SET (F_S) signal, is applied to amplifier 70. The frequency of the output signal produced by amplifier 70 is determined by the FREQUENCY_SET signal. The output signal from amplifier 70 is applied to filter 72. In some versions of the invention, amplifier 70 is often a class D amplifier. The output signal from the amplifier 70 is applied to a filter 72. The filter 72 filters the output signal from the amplifier 70. In some versions of the invention, The filter 72 is a bandpass filter. The signal output from the filter 72 is typically 1 0 kHz to 100 kHz. In most cases, signals have a minimum frequency of 20 kHz. .

[0034] The output signal from the filter 72 is passed through a transformer 76, which is also part of the control console 64. The voltage present across the secondary winding 82 of the transformer 76 is applied to the cable 62 to the handpiece driver 40. This voltage is typically The maximum is 1500 volts AC peak. The drive signal is applied in parallel across the driver 40. More specifically, the drive signals are applied to each pair of leads 41 in parallel.

[0035] The transformer 76 includes a regenerative coil 80. The voltage present across the regenerative coil 80 is Based on the signal across the regenerative coil 80, the circuit 86 determines whether Voltage V, which is the voltage of the drive signal applied to handpiece 32 S Signals representing the potential and phase of A coil 90, also located within the control console 64, couples the transformer secondary winding 8 2. The coil 90 is located in close proximity to one of the conductors extending from the The signal is applied to a current measuring circuit 92. Circuit 92 measures the drive signal provided to the handpiece. The current i S The signal generating unit 100 generates a signal representing the magnitude and phase of

[0036] V represents the characteristics of the drive signal supplied to the piezoelectric driver 40. S Signal and i S The signal is also The signal is applied to a processor 96 within the control console 64. The handpiece also includes a memory reader 102. The memory reader 102 reads the data stored in the handpiece memory 58. The memory reader 102 is structured so that the data in the handpiece memory 1 can be read out. 02. Therefore, the memory reader is an EPROM or EEPROM. Assembly that can read data in OM or query RFID tags, R The memory may be an assembly capable of reading data from an FID tag. 8 is read over the conductors that provide the drive signals to the handpiece 32. In some versions of the invention, the memory reader includes an isolation circuit. The data read by the reader 102 is applied to the processor 96. do.

[0037] The processor 96 generates the VOLTAGE_SET signal that is applied to the power supply 68. Processor 96 also generates the FREQUENCY_SET signal that is applied to amplifier 70. These signals correspond to the voltage and frequency of the drive signals provided by the control console 64. The processor 96 is a control signal that regulates the number of The characteristics of the end piece and S and i S The control signal is then adjusted according to the measurements taken on the Support.

[0038] Connected to the control console 64 is an on / off switch. The on / off switch is represented by a foot pedal 104. The state of the pedal 104 is The on / off switch is monitored by the processor 96. A foot pedal 1 is a user-operated control member that regulates the state of the foot pedal. 04 is shown as part of a foot pedal assembly that includes multiple pedals. The pedals can be used to control devices such as irrigation pumps, suction pumps or lights. These auxiliary devices are not part of this invention.

[0039] The control console 64 is shown as having a slide switch 106. Like switch 104 , the state of switch 106 is monitored by processor 96 . The switch 106 is operable by the practitioner to control the magnitude of the vibration amplitude of the distal head 52. The foot pedal 104 and switch 106 control the system 30 to on / off and It should be understood that the term "system" generally refers to any means of inputting a command for setting the amplitude of a signal. In some configurations, a single control member may perform both functions. When the lever or foot pedal is first pressed, the system automatically adjusts the tip head to the correct position. The system can be configured to undergo oscillation cycles of relatively small amplitude. As a result of continuing to press down on the lever or foot pedal, the tip head 52 expands to a larger size. The control console applies a vibration cycle to the handpiece having a magnitude of Reset the drive signal.

[0040] The display 108 is integrated into the control console 64. The image is shown as being generated by the processor 96. On the display 108 The information represented in the table includes information identifying the handpiece and, in some cases, the tip, and and information describing the characteristics of the operating speed of the system.

[0041] [II. Operating Principle] The components that make up the control console 64 together provide drive signals to the handpieces. Ideally, this would result in a relatively large tip head 52. This creates a reciprocating vibration back and forth (the amplitude of the head movement is as large as possible). The effectiveness with which the distal head can remove tissue is generally determined by the movement of the distal head against the tissue. This is because it is related to the length of the

[0042] One means of encouraging large amplitude reciprocating motion of the tip head 52 is to, within design limits, The goal of this experiment is to maximize and maintain the current of the drive signal applied to the handpiece. This is because there is a proportional relationship between the current applied to piece 32 and the amplitude of the tip head movement. The current applied to the handpiece i S Mathematically, the two equations shown in Figs. 4A and 4B can be expressed as The first component is the current i O , i.e. driver 4 The second component is the current applied to a capacitance of 0. M , i.e. Han The electrical current is the mathematically equivalent component of the electrical current applied to the mechanical components of the handpiece 32. The mechanical components of the base are the components of the handpiece that vibrate in response to the application of a drive signal. These components include a proximal end mass 36, a post 39, a driver 40, and a mating adapter. The driver 40 includes a horn 42 having an assembly and a tip 48. The reason is that the driver 40 vibrates, The sleeve 55 is typically part of a mechanical assembly that vibrates at these This is because the sleeve 55 vibrates but the sleeve More specifically, the sleeve 55 does not apply a load to the vibration system. can be considered as components that

[0043] The system of the present invention is independent of the change in impedance of the handpiece and is mechanically Equivalent component of current applied to element i M is designed to keep it constant.

[0044] Based on the impedance of the components forming the handpiece 32, the current i M is required The driver 40 and the mechanical components of the handpiece are connected to each other. It can be thought of as two impedance circuits connected in parallel, where z O Is Dora The impedance of the driver is basically the impedance of the driver stack. Capacitance C of driver 40 O and the frequency of the drive signal. The capacity of the cable 62 and any other components through which the drive signal is applied to the driver It is assumed that impedance is negligible. Therefore, the impedance Z O teeth , capacitive reactance component, 1 / jωC O The variable "ω" represents the angular period of the drive signal. is the wave number. Impedance Z O is a negligible resistive reactance and inductive It has a reactive component.

[0045] Impedance Z M is the mathematical expression of the effective impedance of the mechanical components of the handpiece. Impedance Z M is the inductor of the mechanical components of the handpiece L M and resistor R M and capacitance C M Based on the mechanical equivalent of ance Z H is the impedance of the entire handpiece. Therefore, the impedance Z H is calculated according to the following formula:

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[0046] In the case of the models of Figures 4A and 4B,

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[0047] Regulating the equivalent components of the current applied to the mechanical components of the handpiece 32 In addition, the system 30 of the present invention regulates the frequency of the drive signal. In particular, the drive frequency is set to a target frequency based on the resonant frequencies of the mechanical components of the handpiece 32. Often, but not always, mechanical components are used to regulate the frequency of the The resonant frequency of is the target frequency. Assuming a constant equivalent component of the current, the mechanical components are When vibrating at the resonant frequency, the handpiece experiences the highest periodic expansion and contraction (vibration). The resonance frequency is selected as the target frequency because the amplitude of the resonance is the same as that of the mechanical This is called spatial resonance.

[0048] One process in which the frequency of the drive signal can be set in such a way is to match it to a mechanical resonance. In this embodiment, the currents through the stack and mechanical components of the driver 40 are out of phase by 90 degrees. This is based on the understanding that the capacitive real-time characteristics of the mechanical components of the handpiece should be This is because the phase shift effects of inductance and inductive reactance cancel each other out. The driver has negligible inductive reactance in the frequency range over which the drive signal is applied. As a result, the driver induces a 90 degree phase shift in the current, but the The equivalent components of the currents applied to the mechanical components of the dowel piece induce a phase shift of 90 degrees. I can't.

[0049] current i O and i M can be expressed in polar form as follows:

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[0050] The driver current according to the above formula (4B) and the mechanical configuration of the handpiece according to formula (5) Substituting the equivalent components of the current applied to the element into the relationship in equation (10) gives the following at mechanical resonance: This means that the following relationship holds:

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[0051] [III. Actual Operation] To facilitate operation of the system 30, a memory within the handpiece is 58. These fields, as represented by field 112 in FIG. The data includes data identifying the handpiece 32. These data are stored in the console 6 Field 1 is useful for verifying that the handpiece can be driven. The data in 12 is presented on the console display 108 regarding the handpiece. The type of information may also be indicated. Field 114 indicates the cache of the driver 40 stack. Persistence C O The capacitance of the driver includes data indicative of the This can be determined by analysis during the assembly process. The sum of the capacitances is 500pF to 5000pF. Current, i.e., electric current

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[0052] Also stored in the handpiece memory is the drive signal applied to the handpiece 32. The minimum frequency and maximum frequency of the signal stored in the field 122 are data indicating the minimum and maximum frequencies of the signal. The wave number is usually the minimum frequency of the drive signal that can be supplied by the control console. The maximum frequency of the drive signal stored in field 124 is typically between 5 kHz and 40 kHz. , and is greater than the minimum frequency.

[0053] Field 126 filters the control signal output from controller 96. In many versions of the invention, the VOLTAGE_SET signal and The calculation of the FREQUENCY_SET and FREQUENCY_SET signals begins with the calculation of target values ​​for these signals. A PID control loop is used to establish the final levels for each of these signals. Field 126 contains the respective coefficients for these control loops. The data in fields 112, 116, 118, 120, 122, 124 and 126 are As with the data in Field 114, the handpiece is assembled as part of the process. It should be understood that the pieces are stored in the piece memory 58.

[0054] The handpiece memory 58 also includes a field 128 as a usage history field. The console 64 is used to provide a log of the operation of the handpiece when it is in use. , write data to field 128.

[0055] The operation of the system 30 of the present invention may be understood with reference to the flow chart of FIGS. 6A and 6B. It is understood that step 140 represents an initial configuration of the system 30. , including attaching the tip 48 to the handpiece 32. The cable 62 is 32, the cable must be attached to the handrail as part of step 140. A cable 62 is connected to the handpiece 32 to connect the handpiece to the console. Optionally, a foot pedal 104 may be connected to the control console 64. Before activating the handpiece, the practitioner adjusts the amplitude of the tip head vibration. To set, switch 106 is positioned.

[0056] Once the handpiece 34 is connected to the control console 64, in step 142 the The console processor 96 reads the data in the handpiece memory 58 through the memory reader 102. The console 64 can then apply a drive signal to the handpiece 32. Any checks that processor 96 may perform to verify that These checks are not included and are not part of this invention. These checks are based on the data stored in the console. Verify that the product is designed for use with the product and, based on its usage history, and verifying that the handpiece is in working condition. Assuming the source passes these checks, the system 30 is ready for use. be.

[0057] Step 144 is when the processor 94 receives the action from the foot pedal 104 or other control member. indicates that the operator is waiting for a signal indicating that he or she wishes to activate handpiece 32. Before processor 96 received this signal, the processor was 8 does not assert the signal that would output the power signal.

[0058] The practitioner activates the handpiece by depressing the control member. 96, in response to receiving a signal that this event has occurred, in step 148 Current sometimes called target current

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[0059] Thereafter, in step 150, processor 96 sets the VOLTAGE_SET signal First, the VOLTAGE_SET signal is generated to indicate that the power supply is in the handpiece memory. Maximum drive signal voltage obtained from 58

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[0060] As part of step 150, the FREQUENCY_SET A signal is also generated and output. When the control member is initially depressed to activate the handpiece, When this occurs, processor 64 generates a FREQUENCY_SET signal which The console outputs a drive signal at the initial frequency. is the lowest possible frequency that should be applied to the handpiece or the drive signal should be applied It can be the highest possible frequency or any frequency between these two extreme frequencies. can.

[0061] Although not specifically mentioned, in step 150, the processor Any necessary enablement for the internal power supply 68, amplifier 70 and any safety components. The assertion of these signals causes power supply 68 to supply the required ramp current for the amplifier. The drive signal is then output to the amplifier 70, which outputs the intended square wave. An inductively derived signal is applied to the primary winding 78 of the transfer 76. Ensure that:

[0062] As a result of current flowing through the transformer 76, a drive signal is applied to the handpiece 32. This results in a cyclic expansion and contraction of the driver 40. This movement of the driver 40 The head 52 is vibrated. In this manner, the sag resulting from the execution of step 150 is As a result of step 150, handpiece 34 is actuated. 3. When the practitioner desires to stop the handpiece 32, the processor 9 It will run continuously until 6 makes a decision.

[0063] The system 30 then determines whether the output drive signal produces a vibration of the appropriate amplitude in the tip head 52. To ensure that the induction of To do this, in step 154, the system 96 adjusts the drive signal to flow to the handpiece. Voltage of the number V S This is done by monitoring the profile of the output signal generated by the voltage measurement circuit 86. Also, in step 154, the processor 96 monitors the current i S The handpiece is also monitored by a current measuring circuit 92. The output signal generated by the

[0064] In step 156, the processor 96 determines whether the temperature is applied to the mechanical components of the handpiece. The equivalent component of the current that flows through the

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[0065] In step 158, the current

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[0066] If the currents are substantially equal, the system 30 applies a The drive signal is assumed to be at the correct frequency, with the equivalent component level of the applied current. The applied voltage is at a level that induces vibration of an appropriate amplitude in the tip head 52. When system 30 is in this state, processor 96 performs steps Go to 164.

[0067] In many situations, the comparison in step 158 is

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[0068] Then, in step 160, based on this new target value for the drive signal potential, , the VOLTAGE_SET signal is regulated and output to the generator 68.

[0069] In step 164, the processor determines whether the drive signal is It is determined whether the frequency is at or substantially equal to the resonant frequency. This determination is made by using the formula (11) This is done by evaluating whether the ratio is equal to or substantially equal to 0, where By "substantially equal to 0", Re is equal to or less than 0.10, preferably equal to or less than 0.05. , and more ideally below 0.01.

[0070] The comparison in step 164 determines whether the drive signal applied to the handpiece is It can be shown that the frequency is at or substantially equal to the resonant frequency of the functional component. , is the target state for the drive signal. This is so that the drive signal is at a relatively high amplitude. The driver 40 is expanded or contracted at a frequency that promotes the expansion or contraction of the driver 40. By extension, this means that the tip head operates and produces a relatively large This results in a strong vibration.

[0071] In step 164, evaluation is performed to determine whether the drive signal is at a resonant frequency of the mechanical component or It may be determined that no power is being applied to the handpiece in that vicinity. If the controller 96 makes this determination, then in step 166 the processor Reset the frequency. This gives a negative result because the ratio on the left hand side of equation (11) is negative. The calculation of step 164 determines in step 166 that the frequency of the drive signal should be increased. A positive result of the calculation in step 164 is interpreted as an indication from processor 96 that If the drive frequency is closer to the resonant frequency of the mechanical components of the handpiece, To ensure that the handpiece is in good working order, the processor 96 may then use the results to determine whether the handpiece is in good working order or not. This is interpreted as an indication that the frequency of the signal needs to be lowered.

[0072] Processor 96 adjusts the FREQUENCY_SET signal applied to amplifier 70. Step 1: Reset the frequency of the drive signal applied to the handpiece. At 66, the processor S , voltage V S and driver capacitance C O One In an iterative process, different frequencies are plugged into equation (11). As a result of the new implementation of equation (11), the current through the driver and the mechanical structure of the handpiece are The real component of the ratio of the current applied to the component to the equivalent component is less than 0 (or substantially less). If this occurs, then in the next iteration, The frequency that is input will be higher than the frequency that was input previously. As a result of the evaluation, it may be determined that the ratio is greater than (or substantially greater than) zero. If this occurs, then in the next iteration, the frequency to be entered will be the first to be entered. The end result of this calculation is a ratio of zero or substantially less than the frequency specified. When it reaches 0, the frequency of the drive signal is set to the entered frequency. Based on the result of this calculation, the processor 166 determines the FREQUENC The control console 64 then, in turn, adjusts the Y_SET signal. This results in a drive signal being output to the handpiece at the resonant frequency of the mechanical components of the handpiece.

[0073] Although not shown, the characteristics of the drive signal applied to the handpiece 32 may vary depending on the handpiece. It should be understood that the maximum allowable time is limited by the limit parameters read from the V Adjust the OLTAGE_SET signal until the drive signal reaches the maximum voltage level.

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[0074] 6A and 6B, performing step 160 or, if necessary, step 164 Thereafter, the system is shown to loop back to step 144. This is current

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[0075] There are several reasons why a control loop may be executed repeatedly. Typically, as a result of regulation: If the frequency of the drive signal is adjusted, the driver impedance Z O and the handpiece Impedance of the mechanical components Z M It is understood that both impedances will change. As a result, the current through the handpiece, and more specifically, the function of the handpiece, Current through mechanical components

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[0076] Similarly, adjusting the potential of the drive signal results in a voltage V S and voltage i S There is also a change in This means that the next time step 164 is executed, the evaluation will determine whether the drive signal is This is meant to indicate that the frequency is no longer at the resonant frequency of the mechanical components of the system.

[0077] After cycling through the control loop several times, the console 64 asserts a drive signal, which As a result of this, the current passing through the mechanical components of the handpiece

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[0078] Another reason the control loop is constantly running is because of how the handpiece 32 is being utilized. For a handpiece to function, the head 52 must contact tissue. The teeth are then placed against the tissue (step not shown). This allows for back and forth movement of the teeth against the tissue. As a result of this, tissue is sawed, i.e., removed. In some embodiments, this back and forth motion results in fluid adjacent to the tissue, and in some cases This causes cavitation in the tissue itself.

[0079] When the head is placed against tissue, mechanical loads are applied to the components that form the handpiece. This mechanical load changes the impedance of the handpiece mechanical load. Additionally, as the system 30 operates, the temperature of the mechanical components of the handpiece increases. This change in component temperature causes the properties of these components to change. Changes in component characteristics can cause the target frequency to shift. These shifts in the properties of the mechanical components of the inductance L M , resistance R M and capacity Citans C M The respective changes in are shown in FIG.

[0080] The resulting change in impedance and resonant frequency results in The current i passing through S and the current through the mechanical components

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[0081] Additionally, during operation of the handpiece 32, the practitioner can adjust the amplitude of vibration of the distal head. This adjustment may be accomplished by resetting the switch 106 or a similar control member. This is done by setting the 100% 15 ... The next time step 148 is executed, the newly calculated target current

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[0082] Therefore, the above control loop, beginning with the evaluation of step 144, It will run continuously as long as the 4 or other on-off control remains activated. The handpiece is stopped by releasing the hand pedal 104. The processor determines whether or not this control member is off during any of the subsequent executions of step 144. In response to receiving this signal, processor 96 receives a signal that the The processor negates the application of the signal that has been asserted to output the drive signal. This step is not shown. The system 30 returns to a standby state and the practitioner begins to An on-off control member for determining whether it is desired to operate the piece 32 It constantly monitors signals from

[0083] The system 30 of the present invention performs steps 164 and 166 repeatedly. The system tunes the drive signal to a frequency substantially equal to the resonant frequency of the mechanical components of the handpiece 32. This relationship is determined by the mechanical loads and and / or when the resonant frequencies of the mechanical components of the handpiece change due to temperature changes. Thus, the system of the present invention is such that the tip and other components of the handpiece are at the desired amplitude, even when subjected to mechanical loads or temperature changes The tip head can be vibrated. This allows the tip head to vibrate continuously at a desired amplitude. The drive signal must be constantly adjusted by the surgical personnel using the system to ensure that the system vibrates without any distortion. Reduce the need to adjust

[0084] In addition, during the course of a procedure, the tip head may suddenly be pressed against tissue. This causes a sudden and significant increase in the impedance of the mechanical components of the handpiece. In response to this sudden impedance change, the system 30 of the present invention adjusts the potential and Adjustment of these characteristics of the drive signal allows the tip head vibration to be adjusted to the desired This serves to ensure that the amplitude is maintained. As a result of the sudden load on the head, the amplitude of the head vibration also decreases. .

[0085] A further feature of the system 30 is that the system detects a particular phase difference between the voltage and current of the drive signal. Instead, the system 30 does not track the mechanical components of the handpiece. This tracks the phase of the equivalent component of the drive signal applied to the element. For the reasons explained above, this Ensure that the drive signal provided has characteristics that maintain the mechanical resonance of the handpiece. To bear fruit.

[0086] The system 30 of the present invention is such that control of the handpiece is controlled by a controller within the control console. Based on matching capacitance, resistance or inductance to the characteristics of the handpiece This is further configured to be unique, using a single console 64. Configuring the system 30 of the present invention with another handpiece having driver capacitance The console uses the handpiece memory, which represents the driver capacitance. Based on the data read from memory 58, the system is configured for each handpiece. Similarly, to assemble the system 30 of the present invention, one handpiece may be used with multiple different It can be used with a control console.

[0087] The system 30 of the present invention applies a current substantially equal to the target current to the mechanical components of the handpiece. The target current is further designed to apply an equivalent component of the tip head vibration. The system of the present invention is therefore based on the practitioner setting the desired amplitude of the stimulation. It provides the surgeon with a relatively precise means of controlling the amplitude of tip head vibration.

[0088] IV. First Alternative Method of Drive Signal Frequency Control In an alternative configuration of the system 30 of the present invention, the target frequency of the drive signal is determined based on the functionality of the handpiece. It is set to the anti-resonant frequency of the mechanical components. The anti-resonant frequency is determined by the impedance of the handpiece 32. This is the frequency at which the impedance is maximized. Ideally, this approaches infinity.

[0089] In this version of the invention, in step 164, the The real ratio of the current passing through the handpiece 32 to the equivalent component of the current applied to the mechanical components of the handpiece 32. The components are evaluated as follows:

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[0090] If the evaluation of step 164 results in the ratio not being substantially equal to 1, the processor In step 166, different frequencies are inserted into equation (13). This process is carried out by the processor. This continues until the capacitor determines a frequency that is substantially equal to unity. This frequency is the anti-resonance frequency. The processor then outputs the FREQUENCY_SET signal and the result of that signal As such, the control console provides a drive signal at this frequency.

[0091] In another version of the invention, the processor 96 may select a frequency different from the resonant or anti-resonant frequency. The current supplied to the piezoelectric driver 40 and the handpiece 32 are adjusted to obtain a target frequency of It is possible to evaluate the real component of the ratio of the current applied to the mechanical component of Thus, the evaluation can take place for values ​​between 0 and 1, and even for values ​​greater than 1. .

[0092] V. Second and Third Alternative Methods of Drive Frequency Control For some configurations of the system 30 of the present invention, the circuit of FIG. This is a highly simplified representation of the impedance of the mechanical components of the present invention. In the case of these versions, as shown in Figure 8, mathematically, several ultrasonic tools The mechanical component can be considered as having multiple RLC series circuits connected in parallel with each other. This is because these components have the same characteristics as their counterparts in a certain frequency range. This means that the element has multiple frequencies at which it resonates. Here, The reactive component is 0. and the impedance Z of the tip 48 H is expressed as follows:

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[0093] These multiple resonant frequencies correspond to the frequency of the drive signal that is to be applied to the handpiece. If it is within range, apply a drive signal to this type of handpiece and tip assembly. Difficulties can arise when trying to determine the Here, plot 182 shows the tip of the handpiece when operating in air. It represents the reactance of the mechanical components over a certain frequency range. The driving signal is 25 .20kHz to 25.65kHz range, i.e., the two thick vertical lines 181 and 183. Within this frequency range, The reactance component of the mechanical impedance is a resonant impedance at about 25.54 kHz. The reactance of the handpiece is about 25.86k. Hz, it passes through a point of zero reactance outside the range of the driving frequency. However, the second time The only thing passing through is the mechanical reactor because it is outside the range where the control console 64 applies the drive signal. The fact that the impedance is zero at this frequency does not affect the operation of the system.

[0094] Plot 184 shows the relationship between frequency and the tip as it is pressed against a load during vibration. This load represents the change in reactance of the mechanical components of the handpiece. is understood to be the tissue that is intended to be removed. As discussed above, As a result, the equivalent resistance and reactance of the mechanical components that make up the handpiece change. The reactance at a given frequency changes from plot 182 to plot 184. Here, the mechanical components of the handpiece are adjusted to the frequency range in which the drive signal is applied. The equivalent reactance of the reactor is twice as large at 25.30 kHz and 25.45 kHz. It can be seen that the path may pass through a point with zero impedance.

[0095] For a particular handpiece and tip assembly to function most efficiently, there are usually two Applying a drive signal at or near the lower resonant frequency Therefore, the lower of the two resonant frequencies is the target frequency. At any given time that step 164 is performed, the result of the evaluation of step 164 is teeth,

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[0096] In order to reduce the likelihood of the above-identified events occurring, some versions of the present invention In this case, the system applies a virtual impedance to the impedance of the mechanical components of the handpiece. X adj Schematically, as can be seen in Figure 10, Impedance X adj is a mathematical model of the impedance of the mechanical components of the handpiece. It is considered to be in series with the

[0097] Figure 11 shows the impedance of the mechanical components of the handpiece. In FIG. 11, plot 184 shows the effect of adding , the reactance of the mechanical components of the handpiece when the tip is loaded is Plot 185 is a plot of the virtual impedance X adj Reactance component of Here, the reactance component of the virtual impedance is the mechanical structure of the handpiece. The reactance of the component is assumed to be zero at the frequency where it is zero. Plot 186 is the sum of the reactances of plots 184 and 186. Thus, when the imaginary impedance is added to the mechanical reactance, the total reactance becomes The drive frequency passes through 0 only once in the frequency range to be applied.

[0098] Figure 12 shows the actual impedance of the mechanical components of the handpiece compared to the virtual impedance. A partial block diagram of an alternative component of one version of the invention designed to add The handpiece 190, represented by a rectangle, is the handpiece described above. The handpiece 32 has a mechanism similar to that of the handpiece 32. Conductive sockets or other contacts 196 and 197 for supplying the internal driver 40 8. The drive signal is synchronized with the control console socket to which the handpiece is connected. The electrical connections are provided by pins or other conductive contacts 188 and 189 formed on the body. For simplicity, the cable 62 is not shown in FIG.

[0099] The particular memory 58 inside the handpiece 190 is an RFID tag. Also shown inside handpiece 190 as an ID tag and connected to memory 58 Attached to the control console socket is a coil or antenna 202. It is understood that the coil 202 is at the end of a cable that is connected to the console socket. 187 is arranged to inductively exchange signals with a complementary coil 187 disposed within the Although not shown, the console coil 187 is a console memory register. The memory reader 102 is connected to the coil 187. The signal is converted into a signal that can be read by the processor 96. The data reader 102 writes to the handpiece memory 58 the data that the processor 96 wants to write to the memory. Output the data.

[0100] A second coil, coil 206, is also disposed within the handpiece 190. 202 is typically located adjacent the proximal end of the handpiece 190, while coil 206 is More specifically, the coil 206 is disposed adjacent the distal end of the slit 204. The handpiece 190 is positioned to exchange signals with the probe coil 212. A conductor 204 at the bottom connects the coil 202 to the coil 206 .

[0101] Represented as a tapered unit in FIG. 12 is a sleeve 55. Extending from sleeve 55 is tip 48. Disposed within sleeve 55 is tip memory 48. Even if the memory 214 is in the sleeve 55, the memory 214 It is called "tip memory" for two reasons. First, tip 48 and sleeve 55 , which are separate components but are usually packaged together in a kit. In particular, the data contained in memory 55 is used primarily to control the operation of tip 48. The coil 212 embedded in the sleeve 55 is connected to the tip memory 55 .

[0102] FIG. 13 represents some of the data stored in tip memory 214. The end identification data field 218 is similar to the handpiece identification data in field 112. The minimum current field 220 and the maximum current field 222 include similar tip identification data. 4. Fields 220 and 222 indicate the particular destination with which memory 214 is associated. The range of equivalent components of the current that should be applied to the mechanical components of the handpiece with respect to the end Contains data to determine the maximum voltage field, similar to maximum voltage field 120 in the handpiece memory. There is a field 224. There are drive frequency fields 226 and 228. The data in 6 and 228 are stored in the minimum drive frequency fields 122 and 228 of the handpiece memory. The frequency range of the handpiece drive signal defined in the Maximum Drive Frequency field 124 Each of the drive signals defines a tip-specific frequency range for the drive signal, which may differ from The PID coefficients field 230 contains filtering coefficients for the control signal and is related to the tip. may be more precise than the data in the Handpiece PID Coefficients field 126. Tip usage history field 232 contains data regarding tip usage. The processor 96, through the memory reader 102, writes data to the field 232. It is possible.

[0103] The tip memory also includes a target frequency field 234 and an impedance adjustment factor field 235. The target frequency field 234 also includes a drive signal applied to the handpiece. Frequency ω within the frequency range of target More specifically, the frequency number ω target is the harp where the mechanical reactance is minimum when a load is applied to the tip. The frequency is within the driving frequency range of the end piece. The load to which the tip is exposed varies depending on the procedure. It should be understood that this varies from procedure to procedure and even within a procedure. Within a single procedure, the frequency at which the mechanical reactance of the handpiece reaches its minimum point is not constant. Therefore, at frequency ω target is the handpiece load. This is the frequency within the normally expected range where the reactance minimum is expected. 236 includes the coefficient m described above which defines the change in reactance with respect to frequency.

[0104] The system of the present invention to which the handpiece 190 is attached is driven by the handpiece 32. 6A and 6B. There are some differences between the process steps as outlined above. In step 142, The control processor 96 does more than simply read the data in the handpiece memory 58. Also in step 142, the control processor reads the data in the tip memory 214. The data is read out.

[0105] Based on the data in the handpiece memory 58 and the tip memory 214, the processor Based on this data, the system determines whether or not tip 48 can be vibrated. The step of determining whether the system is suitable for vibrating the tip is not shown. Data indicating that the tip is being used beyond its designed life Other data that indicates the system should not vibrate the tip include This also indicates that the handpiece is not intended to vibrate. The system will drive the tip in its current configuration. If the console is not suitable for use with the controller, the control processor 96 will normally Information is presented on the display 108 indicating why the signal is not being delivered to the handpiece 190. In some versions of the invention, this information is presented only as a warning. After is presented, the practitioner is still given the opportunity to activate the handpiece.

[0106] In step 148, the processor 94 determines the maximum voltage obtained from the tool memory 214. Based on the current value, the target current

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[0107] A further change in how the characteristics of the drive signal are determined occurs at step 164. In this version of the invention, the control processor 96 Evaluation of equation (11) should not be used to determine whether a mechanical component is resonating. Instead, the processor evaluates whether the mechanical components of the handpiece are resonating. The following formula is used to estimate

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[0108] of the real component of the reactance of the mechanical component in the frequency range of the drive signal If multiple zero crossings exist, include the virtual impedance in the evaluation in step 164. By doing so, the evaluation can determine whether the drive signal needs to be lowered for the desired resonant frequency. This ensures that the plot still shows whether the If the evaluation of this version of step 164 gives a negative result when using the example of 186, Obviously, the frequency must be increased to drive the signal into resonance. Similarly, if the evaluation gives a positive result, the frequency of the drive signal is obviously reduced. Must be.

[0109] In this version of the invention, the practitioner first places the tip head 52 against the tissue; This is also useful if it is desired to subsequently activate the handpiece 32. In this situation, the handpiece and tip are already under load when actuated. Due to their mechanical properties, some tips may experience a large load drop when starting under load. The resistance has the property that it immediately dampens the vibration to a level where there is essentially no vibration. When the end piece and tip are in that state, the system is essentially considered to be in a stall condition. When the system is in this state, the rear of the handpiece mechanical components The impedance is essentially constant over the driving frequency range. The mechanical resistance component of the impedance is the mechanical equivalent of the inductive and capacitive impedances. This is shown, for example, by plot 184. This means that the change in reactance with frequency is difficult to detect.

[0110] Thus, in versions of the invention where such conditions exist, the above equation (16 The adjustment part of ) is the main component of the ratio that changes with frequency. Even if the piece and tip are stalled, the processor continues to operate at the drive frequency 164. number required to drive the tip at its resonant frequency under load You still get some information about the drive frequency and how close it is. What typically happens when the system is in this state is that the processor Increasing the frequency of the drive signal in this way increases the number of And the tip vibrates at a frequency that causes the handpiece to exit the stall condition.

[0111] The virtual impedance of all the tips that may be incorporated into the system of the present invention is It should be understood that in some cases, it may not be necessary to consider the tip size. In this case, the impedance adjustment factor m is set to 0. As a result, equation (15) becomes equation (11 )

[0112] In a fourth alternative version of the present invention, the addition of this virtual impedance is used to drive The signal is at the anti-resonant frequency of the impedance of the mechanical components of the handpiece. Thus, the setting of the drive signal frequency is regulated. 15) can be combined as follows:

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[0113] In yet another version of the invention, after modifications on the left-hand side of equations (15) and (16), The ratio can be compared to a target ratio that represents the frequency between the resonant and anti-resonant frequencies.

[0114] [VI. Fourth Alternative Means of Drive Frequency Control] In yet another version of the invention, only the frequency of the drive signal is adjusted. In this version, the frequency of the drive signal is determined by the resonant frequency of the mechanical components of the handpiece or The equivalent component of the current that is in the vicinity and should be applied to the mechanical components of the handpiece The drive signal is adjusted to apply a current level at or near a desired target for can be.

[0115] This version of the invention can be understood by reference to the flow diagram of Figures 15A and 15B. In this version of the invention, steps 140, 142, 144, 148 and 154 is implemented as described above with respect to the process illustrated in the flow chart of FIGS. 6A and 6B. In this version of the invention, the handpiece is actuated first. When the above-described step 150A is an alternative to step 150, This is performed the first time the handpiece is turned on. In step 150A, the processor The VOLTAGE_SET signal 96 represents the highest voltage that should be applied to the handpiece. The processor 96 also generates and outputs a FREQUENCY_SET signal. In step 150, the initial FREQUENCY_SET signal is determined. The same process used in step 150A is used to The same signal can be output at

[0116] After step 154 ​​is performed, the method of the present invention includes, in step 252: The processor calculates through the driver 40 the equivalent current through the mechanical components of the handpiece. In step 254, the ratio of the currents is calculated. The ratio of the handover time is compared to the target ratio (TF). Initially, the target ratio is is a scalar value representing the desired target frequency of the drive signal for the mechanical components of the handpiece. For example, it may be desirable to drive a mechanical component of a handpiece at a resonant frequency. In this case, the initial target ratio is 0 (zero). If it is desired to drive the active component, the initial target ratio is unity. The target ratio may be between these values ​​because the mechanical components of the handpiece A frequency having a response characteristic between the response at the resonant frequency and the response at the anti-resonant frequency. This is the case when it is desirable to drive the tip in numerical order.

[0117] Based on this comparison, if necessary, the frequency of the drive signal is selected in step 256. This analysis and resetting of the FREQUENCY_SET signal is The analysis and frequency reconfiguration operations of steps 164 and 166 are similar.

[0118] After step 254 and, if necessary, step 256 are performed, step 25 At 8, the processor calculates the equivalent current through the mechanical components of the handpiece, i.e. current

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[0119] If the calculated current is relatively close to the target current, the processor 96 determines whether the system is The signal has a frequency substantially equal to a desired target frequency for the mechanical components of the handpiece. and the equivalent current through these components is substantially equal to the target of this equivalent component of the current. If the system is in this state, the processor The controller loops back to step 144. This loopback can be done by step 164 or step This is similar to the loop back to step 144 that is executed after step 166 is executed. .

[0120] As a result of performing step 260, there is a significant difference between the calculated current and the target current. In many situations, this is because the calculated current is greater than the target current. If the system of the present invention is in this state, then in step 262 Then, the processor adjusts the value of the target ratio. This new ratio is TRADJ This is the goal As a result of the subsequent resetting of the drive frequency away from the drive frequency, the mechanical This is because a similar reduction occurs in the equivalent component of the current applied to the objective component.

[0121] In step 264, the equivalent components of the current through the mechanical components of the handpiece are calculated. The ratio of the currents through the drivers is compared to a regulated target ratio. This will show that the actual ratio is significantly different from the adjusted target ratio. The processor then adjusts the FREQUENCY_SET signal in step 266. The FREQUENCY_SET signal controls the current applied to the mechanical components of the handpiece. is needed to reset the equivalent component of The initial target current and the adjusted target current are reset so that the new drive signal is closer to the If the difference from the target current is small, step 266 may not be performed.

[0122] After performing step 264, and often after performing step 262 Then, processor 96 loops back to execution of step 144.

[0123] This version of the invention allows for a frequency that is close to the desired target frequency for the handpiece. and the equivalent component of the current applied to the mechanical components of the handpiece is this current The result is a drive signal that is close to the target for the drive signal without the need to set the potential of the drive signal. The blood is delivered to the handpiece without any need for a special device.

[0124] VII. ALTERNATIVE OR ADDITIONAL MEANS OF OBTAINING DRIVER CAPACITANCE In another version of the invention, the control console 64 includes at least one piezoelectric actuator. Driver capacitance C O There are circuits that can measure the The capacitance is obtained by outputting a drive signal that is swept over a wide range. During this period, the V S and i S Based on these data, the processor 96 determines the driver capacity. Citans C O is mathematically calculated.

[0125] The system 30 of the present invention handles a memory having data representative of the driver capacitance. A process is carried out to determine this capacitance so that it is not necessary to provide a In these versions of the invention, the system may be configured to As part of the initial setup of the system, driver capacitance is determined. .

[0126] The system associates data representing the capacitance value of the driver with the handpiece. Even if the driver capacitance can be obtained from the memory, the system 30 There is also a reason to have this function of asking for One reason it is desirable to have the stem perform this process is because Specifically, the system performs this step and determines the state of the process. The determined value of the driver capacitor generated by the sensor and the value obtained from the handpiece memory The capacitance value thus obtained is compared with the capacitance value obtained in step 142. If these capacitance values ​​are not substantially equal, The processor interprets this difference as an indication that the handpiece may be in a malfunction. This malfunction is caused by some type of damage to the driver. In that case, the processor may detect that the handpiece is not functioning properly. The practitioner can use this information to determine whether this particular handler is It is possible to determine whether it is appropriate to proceed with the procedure using the dope piece.

[0127] In any configuration of the present invention, the system may be configured to automatically detect and report the presence of a driver, even after the procedure has begun. As mentioned above, the driver capacitance can be determined. , the driver capacitance is, for the purpose of providing a drive signal in accordance with the present invention, Nevertheless, during the procedure, the dry Situations may arise where the capacitance may change, for example over a long period of time, i.e. In addition, if the handpiece is used for more than 10 minutes, the handpiece including the driver 40 The handpiece may be subject to friction-induced heating. This heating may occur when the driver This is the result of the repeated expansion and contraction of the 0. The dry Therefore, the initial capacitance may change. Even when reading from the dope memory 58, the system The organization may periodically conduct a process to request a review.

[0128] In this configuration of the present invention, the determined driver capacitance is If it is within the set range, the processor 96 selects the newly determined driver capacity. The capacitance of the variable driver C O It is used to set the characteristics of the drive signal. However, the new driver capacitance may be different from the previous driver capacitance setting. There may also be a situation where the system is out of range. Set to interpret 0 as an indication that handpiece 32 is in a malfunctioning state. If processor 96 makes this determination, the processor Display a message indicating that the piece may be in this state.

[0129] VIII. Alternative Models of Impedance of Handpiece Mechanical Components In an alternative configuration of the present invention, the current applied to the driver 40 and the mechanical structure of the handpiece The model of the equivalent components of the current applied to the components is the resistance, inductance, and The method may be based on alternative models of impedance and capacitance.

[0130] FIG. 14 illustrates the components of the handpiece that provide impedance to the current and the equivalent applied current. This represents an alternative model for the arrangement of the The components of the capacitance, i.e., the combined capacitance C A and mixed capacitors Blended Capacitance C X Each of these capacitances has the formula ( As represented by equations (14) and (15), the dynamics of the mechanical components of the handpiece 40 are It is a function of both the driver capacitance and the equivalent capacitance.

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[0131] This is due to the impedance of the handpiece and the applied current to the mechanical components of the handpiece. The real component of the ratio of the equivalent current flowing through the mechanical components of the handpiece to the equivalent component of the current flowing through the This means that the formula used to calculate

[0132] In addition, although not shown, the equivalent impedance of the mechanical components of the handpiece, etc. In this model, there are three components that contribute to the impedance: resistance, inductance, It is understood that two of the impedances or capacitances may be in parallel with each other. In this model, a third component exists in series with the two parallel components.

[0133] [IX ADDITIONAL ALTERNATIVE VERSIONS] The above relates to specific versions of the invention. Some versions of the invention are For example, different versions of the invention may have different mechanisms than those described. The above mechanisms can be combined.

[0134] The structural features of the invention may also differ from those described. For example, The post to be placed can be machined using a horn. Other means can be used to measure the voltage applied to the handpiece and the current through the handpiece. Therefore, it is better to use resistors rather than inductors to perform this signal sensing. In some versions of the invention, an isolation disk is provided between adjacent drivers. There may be no gap between the nearest driver and the mass 36 or between the driver and the ho There may be an isolation element between the driver and the driver. The number of drivers may be greater than the number of drivers disclosed. Sometimes it's less, sometimes it's more.

[0135] In some versions of the invention, a signal foot pedal or hand switch is It controls both the on / off state of the source and the magnitude of the drive signal applied to the handpiece. It is a control member used to

[0136] Similarly, the electrical components of the system may differ from those described. For example, some versions of the control console may not include a Class D amplifier. In one alternative version, the signal output from the power supply is output to a class A amplifier. In one embodiment of this version of the invention, the processor 96 determines the peak voltage of the drive signal. The VOLTAGE_SET signal is still output to the power supply 68 to reset the The processor 68 outputs a variable frequency positive input to the amplifier as the FREQUENCY_SET signal. The amplifier outputs a sine wave signal based on the FREQUENCY_SET signal. The signal from the power supply is selectively amplified to provide a drive signal having a frequency of In yet another embodiment of this version of the invention, the power supply outputs a DC signal of a fixed potential. The processor outputs a sine wave that varies in both frequency and peak-to-peak voltage. In this way, this signal is the combined VOLTAGE_SET signal and the FREQ This sine wave is applied to the amplifier. The amplifier selectively amplifies a constant signal from the power signal to generate a selected drive signal. In these versions of the invention, the signal is amplified before being fed to the handpiece 32. In some cases, it may not be necessary to filter the drive signal output by the device.

[0137] Steps in a process may be performed in a different sequence than described. Thus, the version of the invention described with respect to the flow charts of Figures 6A and 6B For this embodiment, the system adjusts the frequency of the drive signal before adjusting the voltage of the drive signal. The version of the invention described with respect to Figures 15A-15C can be constructed as follows. In the embodiment, the current through the driver 40 and the mechanical configuration of the handpiece are adjusted to the target frequency. One of the comparisons of the ratios with the equivalent components of the current applied to the elements can be omitted. In this version of the invention, the result of performing steps 260 and 262 is that It will be appreciated that the ratio is compared to a target ratio which in most cases is being adjusted.

[0138] Similarly, the control algorithm may be modified. The ratio between the current delivered and the equivalent component of the current applied to the mechanical components of the handpiece. The algorithmic components used to change the target frequency and the actual frequency are not necessarily In some versions of the invention, this Second or higher order differences between these frequencies are used to generate components that modify the fundamental ratio. In another version of the invention, within a first range of difference in frequency: The components are based on the order of difference for these frequencies. Within the second range, the components are based on a second order of difference in frequency. In some versions of the invention, components over a range of frequency differences are In this version of the invention, the modification components are calculated using The coefficients used may differ depending on the difference in frequency.

[0139] Therefore, the appended claims are to be construed as including all such modifications as fall within the true spirit and scope of this invention. This document is intended to cover such modifications and variations.

Claims

1. A control console for vibrating a tip of an ultrasonic instrument, the ultrasonic instrument comprising at least one driver to which an AC drive signal is applied for vibrating the tip, and at least one memory device having stored thereon data indicative of a maximum value of an equivalent component of current to be applied to a mechanical component of the ultrasonic instrument, an assembly for generating the AC drive signal applied to the at least one driver of the ultrasonic device; Foot pedal and a processor connected to the assembly and to the foot pedal; Equipped with The processor, reading data of a maximum value of the current equivalent component from the at least one memory device of the ultrasound device; When the foot pedal is depressed, the amount of depression of the foot pedal is calculated; Calculating a target value of a current equivalent component to be applied to a mechanical component of the ultrasonic device based on the maximum value data of the current equivalent component read out and the depression amount of the foot pedal; setting a voltage level of the AC drive signal based on the calculated target value of the current equivalent component; Control console.

2. the at least one memory device of the ultrasound instrument stores data indicative of a capacitance of the at least one driver; The processor, reading data indicative of a capacitance of the at least one driver from at least one memory device of the ultrasound instrument; setting a voltage level of the AC drive signal based on retrieved data indicative of a capacitance of the at least one driver and a calculated target value of the current equivalent component at least upon initial start-up of the ultrasonic device. The control console of claim 1 .

3. 3. The control console of claim 2, wherein the processor sets a frequency of the AC drive signal based on data indicative of a capacitance of the at least one driver retrieved at least upon initial power-up of the ultrasound device.

4. The processor, determining a second capacitance of the at least one driver by setting a voltage level of the AC drive signal based on the retrieved data indicating the capacitance of the at least one driver and the calculated target value of the current equivalent component, and then determining a second capacitance of the at least one driver by setting a frequency and a voltage of the AC drive signal; setting a voltage level of the AC drive signal based on the determined second capacitance and the calculated target value of the current equivalent component; A control console according to claim 2 or 3.

5. A transformer having a primary winding and a secondary winding in which the AC drive signal is induced by a signal applied to the primary winding, the transformer further comprising a coil for measuring the voltage of the AC drive signal; the processor sets a voltage level of the AC drive signal applied to the at least one driver of the ultrasonic device based on the measured voltage of the AC drive signal, the calculated target value of the current equivalent component, and data indicative of a capacitance of the at least one driver. A control console according to claim 2 or 3.

6. the control console includes a conductor extending from the secondary winding for providing the AC drive signal to the ultrasonic device, and a coil disposed adjacent the conductor for measuring a current of the AC drive signal; the control console sets a voltage level of the AC drive signal applied to the at least one driver of the ultrasonic device based on the measured voltage of the AC drive signal, the measured current of the AC drive signal, the calculated target value of the current equivalent component, and data indicative of a capacitance of the at least one driver.

6. The control console of claim 5.

7. the at least one memory device of the ultrasonic instrument stores data indicative of PID coefficients for adjusting the AC drive signal; The control console includes: reading the PID coefficient data from the at least one memory device of the ultrasound machine; setting a voltage level of the AC drive signal based on the read data of the PID coefficients and the calculated target value of the current equivalent component; The control console of claim 1 .

8. 8. The control console of claim 7, wherein the control console sets a frequency of the AC drive signal based on the retrieved PID coefficient data.

9. 1. A method for adjusting an AC drive signal provided from a control console to an ultrasonic instrument to vibrate a tip of the ultrasonic instrument, comprising: The ultrasonic instrument comprises at least one driver to which an AC drive signal is applied to vibrate the tip, and at least one memory device having stored therein data indicative of a maximum value of an equivalent component of a current to be applied to a mechanical component of the ultrasonic instrument, a foot pedal connected to the control console; the control console reading data of the maximum value of the current equivalent component from the at least one memory device of the ultrasound machine; the control console determining depression of the foot pedal to determine a depression amount; The control console calculates a target value of a current equivalent component to be applied to a mechanical component of the ultrasonic device based on the maximum value data of the current equivalent component read out and the depression amount of the foot pedal; the control console setting a voltage level of the AC drive signal based on the calculated target value of the current equivalent component; The method includes:

10. the at least one memory device of the ultrasound instrument storing data indicative of a capacitance of the at least one driver; the control console reading data indicative of a capacitance of the at least one driver from the at least one memory device of the ultrasound machine; the control console setting a voltage level of the AC drive signal based on at least retrieved data indicative of the capacitance of the at least one driver and the calculated target value of the current equivalent component at an initial power-up of the ultrasonic device; 10. The method of claim 9, comprising:

11. determining a second capacitance of the at least one driver by setting a frequency and a voltage of the AC drive signal after setting a voltage level of the AC drive signal based on the retrieved data indicating the capacitance of the at least one driver and the calculated target value of the current equivalent component; setting a voltage level of the AC drive signal based on the determined second capacitance and the calculated target value of the current equivalent component; 11. The method of claim 10, comprising:

12. The ultrasonic device includes a handpiece and a sleeve provided to cover the tip portion, the handpiece having the at least one driver and a handpiece memory storing data indicative of a capacitance of the at least one driver; the sleeve having an open distal end, a conduit and a tip memory storing data of a maximum value of the current equivalent component, the tip extending through the open distal end, the conduit for allowing irrigation liquid to flow along the sleeve and out the open distal end when the ultrasonic device is activated and the tip vibrates; the control console retrieving data from the handpiece memory indicative of a capacitance of the at least one driver; the control console reading data of the maximum value of the current equivalent component from the tip memory; 12. The method according to claim 10 or 11, comprising:

13. the at least one memory device of the ultrasonic instrument stores data indicative of PID coefficients for adjusting the AC drive signal; the control console reading the PID coefficient data from the at least one memory device of the ultrasound machine; the control console setting a voltage level of the AC drive signal based on the retrieved PID coefficient data and the calculated target value of the current equivalent component; 10. The method of claim 9, comprising:

14. The method of claim 13 including the step of the control console setting the frequency of the AC drive signal based on the retrieved PID coefficient data.

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