Abstract:
A power supply apparatus for operation supplies a drive signal of a resonant frequency to a surgical instrument to drive the instrument. A recognition section recognizes a surgical instrument connected to the power supply apparatus. A setting section sets a frequency scanning condition according to the surgical instrument recognized by the recognition section. A scanning section scans for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set by the setting section.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a power supply apparatus for operation and a resonant frequency searching method. 
     2. Description of the Related Art 
     In Jpn. Pat. Appln. KOKAI Publication No. 2002-45368, an ulltrasonic coagulation/incision apparatus provided with resonant frequency follow-up means for following up a resonant frequency for driving an ultrasonic vibrator is disclosed. In Jpn. Pat. Appln. KOKAI Publication No. 2004-216107, an ultrasonic operation apparatus provided with frequency control means for controlling an oscillating frequency on the basis of phase information on a drive signal supplied to an ultrasonic vibrator is disclosed. In Jpn. Pat. Appln. KOKAI Publication No. 2005-253874, an ultrasonic surgical instrument provided with a gripping section, insertion section, vibrator mounting section, and vibrator is disclosed. In Jpn. Pat. Appln. KOKAI Publication No. 2006-231084, a control method of an ultrasonic operation system in which a hand-piece including an ultrasonic vibrator, and an apparatus main body including oscillation means for generating a drive signal for driving the ultrasonic vibrator are detachably connected to each other is disclosed. Further, in U.S. Pat. No. 6,898,536, a method of improving a start-up of an ultrasonic system in a zero-load state is disclosed. In U.S. Pat. No. 6,662,127, a method of detecting existence of a blade in an ultrasonic system is disclosed. 
     BRIEF SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, there is provided a power supply apparatus for operation for supplying a drive signal of a resonant frequency to a surgical instrument to drive the instrument comprising: 
     a recognition section for recognizing a surgical instrument connected to the power supply apparatus; 
     a setting section for setting a frequency scanning condition according to the surgical instrument recognized by the recognition section; and 
     a scanning section for scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set by the setting section. 
     According to a second aspect of the present invention, there is provided a power supply apparatus for operation for supplying a drive signal of a resonant frequency to a surgical instrument to drive the instrument comprising: 
     a count section for counting the number of times the resonant frequency of the surgical instrument is scanned for; 
     a setting section for setting a frequency scanning condition according to the number of times of the scanning counted by the count section; and 
     a scanning section for scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set by the setting section. 
     According to a third aspect of the present invention, there is provided a power supply apparatus for operation for supplying a drive signal of a resonant frequency to a surgical instrument to drive the instrument comprising: 
     a measurement section for measuring a capacitance component of the surgical instrument on the basis of a voltage, a current, and impedance detected from the drive signal supplied to the surgical instrument; 
     a setting section for setting a frequency scanning condition according to the capacitance component measured by the measurement section; and 
     a scanning section for scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set by the setting section. 
     According to a fourth aspect of the present invention, there is provided a method of scanning for a resonant frequency of a surgical instrument, comprising: 
     a recognition step of recognizing the surgical instrument; 
     a setting step of setting a frequency scanning condition according to the surgical instrument recognized in the recognition step; and 
     a scanning step of scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set in the setting step. 
     According to a fifth aspect of the present invention, there is provided a method of scanning for a resonant frequency of a surgical instrument, comprising: 
     a counting step of counting the number of times the resonant frequency of the surgical instrument is scanned for; 
     a setting step of setting a frequency scanning condition according to the number of times of the scanning counted in the counting step; and 
     a scanning step of scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set in the setting step. 
     According to a sixth aspect of the present invention, there is provided a method of scanning for a resonant frequency of a surgical instrument, comprising: 
     a measurement step of measuring a capacitance component of the surgical instrument on the basis of a voltage, a current, and impedance detected from a drive signal supplied to the surgical instrument; 
     a setting step of setting a frequency scanning condition according to the capacitance component measured in the measurement step; and 
     a scanning step of scanning for the resonant frequency of the surgical instrument on the basis of the frequency scanning condition set in the setting step. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  is an external perspective view of an ultrasonic operation system. 
         FIG. 2  is a view showing a schematic configuration of the ultrasonic operation system. 
         FIG. 3  is a functional block diagram for explaining a function of each unit in an ultrasonic power source unit in an ultrasonic operation system. 
         FIG. 4  is a view showing a state where a drive current generated in an ultrasonic power source unit flows to the hand-piece side. 
         FIG. 5  is a view showing a relationship between a voltage phase and a current phase. 
         FIG. 6  is a view for explaining a procedure for scanning for a resonant frequency fr. 
         FIG. 7  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece according to a first embodiment of the present invention. 
         FIG. 8  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece according to a second embodiment of the present invention. 
         FIG. 9  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece according to a third embodiment of the present invention. 
       (A) and (B) in  FIG. 10  are views showing two phase frequency characteristics corresponding to amounts of capacitance components of ultrasonic vibrators. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. An endoscopic surgical operation for performing medical treatment of a diseased part to be performed by using a scope for observing a state in an abdominal cavity of a patient is known.  FIG. 1  is an external perspective view of an ultrasonic operation system used as an example of a system for such an endoscopic surgical operation. The ultrasonic operation system is constituted of an ultrasonic power source unit  1  serving as a power supply apparatus for operation for generating an ultrasonic output for driving an ultrasonic vibrator, a hand-piece  2  serving as an ultrasonic surgical instrument for performing treatment by using an ultrasonic output supplied from the ultrasonic power source unit  1  through a cable  5 , and a foot switch  3  connected to the ultrasonic power source unit  1  through a cable  4 , for controlling the ultrasonic output from the ultrasonic power source unit  1 . 
       FIG. 2  is a view showing a schematic configuration of the ultrasonic operation system. The hand-piece  2  is constituted of a hand-piece main body section  2   a  which includes handles  4 , and in which an ultrasonic vibrator (not shown) is incorporated, and a probe  2   b  for transmitting vibration of the ultrasonic vibrator to a treatment section  5 . The ultrasonic power source unit  1  is provided with an ultrasonic oscillator circuit  1   a  for generating electric energy for vibrating the ultrasonic vibrator. An electric signal output from the ultrasonic power source unit  1  is converted into mechanical vibration (ultrasonic vibration) by the ultrasonic vibrator inside the hand-piece main body section  2   a , and thereafter the vibration is transmitted by the probe  2   b  to the treatment section  5 . The treatment section  5  is provided with a grasping section  6  called a jaw driven to be opened or closed with respect to the distal end of the probe  2   b . When the handles  4  are operated, the grasping section  6  is driven to be opened or closed with respect to the distal end of the probe  2   b , and coagulation or incision of living tissue is performed by utilizing frictional heat generated by holding the living tissue between the distal end of the probe  2   b  and the grasping section  6  and applying the ultrasonic vibration thereto. 
       FIG. 3  is a functional block diagram for explaining a function of each unit in an ultrasonic power source unit in an ultrasonic operation system. The hand-piece  2  is connected to the ultrasonic power source unit  1  through a connector  1   e . In the ultrasonic power source unit  1 , an ultrasonic oscillator circuit  1   a , voltage/current detection circuit  1   f , resonant frequency detection circuit  1   g , phase difference detection circuit  1   h , foot switch detection circuit  1   d , recognition section  1   b , and control circuit  1   c  are provided. The ultrasonic oscillator circuit  1   a  is a part for generating a drive signal for driving the ultrasonic vibrator inside the hand-piece  2 . The voltage/current detection circuit  1   f  is a part for detecting a voltage phase signal θV, a current phase signal θI corresponding to the vibration, and the impedance Z from the drive signal supplied to the ultrasonic vibrator. The phase difference detection circuit  1   h  is a part for detecting a phase difference between the detected phase of the voltage V and the detected phase of the current I. The resonant frequency detection circuit  1   g  is a part for detecting the resonant frequency of the ultrasonic vibrator on the basis of the voltage phase signal θV, the current phase signal θI, and the impedance Z which are output from the voltage/current detection circuit  1   f . The foot switch detection circuit  1   d  is a part for detecting that the foot switch  3  has been operated by the operator. The recognition section  1   b  is a part for, when the hand-piece  2  is connected to the ultrasonic power source unit  1 , reading a resistance value of a resistor incorporated in the hand-piece  2 , and recognizing the type of the hand-piece  2 . Examples of the hand-piece are an ultrasonic coagulation incision hand-piece, ultrasonic suction hand-piece, and the like. 
       FIGS. 4 to 6  are views for explaining a control method of the ultrasonic drive in an ultrasonic operation system. In  FIG. 4 , in the ultrasonic oscillator circuit  1   a , a sinusoidal drive voltage VSIN is generated. When a sinusoidal drive current ISIN corresponding to the voltage VSIN flows through the ultrasonic vibrator inside the hand-piece main body section  2   a , the ultrasonic vibrator converts the electric signal into mechanical vibration, and transmits the vibration to the distal end of the probe  2   b.    
     In the ultrasonic drive described above, when the ultrasonic wave is output at a constant oscillating frequency, a phase difference is produced between the voltage V and the current I as shown in  FIG. 5(A) , and hence the drive efficiency is lowered. Thus, the control circuit  1   c  in  FIG. 3  drives the ultrasonic vibrator while searching for a resonance point at which the phase difference between the voltage V and the current I becomes 0 ( FIG. 5(B) ). 
     For example, in  FIG. 6 , the abscissa indicates frequency f, and the ordinate indicates impedance Z, current I, and phase difference (θV−θI). The part (θVθθI) indicates the phase difference. In this embodiment, a point at which the impedance Z is minimized is scanned for while the frequency is successively changed so as to detect the resonant frequency fr at which the phase difference (θV−θI) becomes zero. The control circuit  1   c  starts to drive the ultrasonic vibrator at the detected resonant frequency fr. 
     FIRST EMBODIMENT 
       FIG. 7  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece according to a first embodiment of the present invention. First, a control circuit  1   c  judges whether or not a hand-piece  2  is connected to an ultrasonic power source unit  1  (step S 1 ). When the hand-piece  2  is not connected to the ultrasonic power source unit  1 , the control circuit  1   c  waits till the judgment result becomes YES. When the connection of the hand-piece to the power source unit  1  is confirmed, a recognition section  1   b  in  FIG. 3  reads a resistance value of a resistor incorporated in the hand-piece  2 , recognizes the type of the hand-piece  2  (step S 2 ), and sends the recognition result to the control circuit  1   c . The control circuit  1   c  includes therein a table in which the type of the hand-piece, scan start frequency, scan end frequency, and scan frequency width are made to correspond to each other. The control circuit  1   c  refers to this table to set at least one of (1) the scan start frequency and scan end frequency, and (2) the scan frequency width as a new frequency scanning condition (step S 3 ). In terms of the example of  FIG. 6 , fs is the scan start frequency, fe is the scan end frequency, and fw is the scan frequency width. Here, fw is the interval between two sampling points. 
     The control circuit  1   c  starts to scan for the resonant frequency on the set frequency scanning condition (step S 4 ). According to the first embodiment described above, the frequency scanning condition is changed according to the type of the device, and hence it is possible to shorten the time needed for the resonant frequency scanning, and thus finally shorten the operation time needed to treat the living tissue. 
     SECOND EMBODIMENT 
       FIG. 8  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece  2  according to a second embodiment of the present invention. First, a control circuit  1   c  judges whether or not a drive output for driving the hand-piece  2  is in the ON state (step S 10 ). If the judgment result is NO, the control circuit  1   c  waits till the judgment result becomes YES. When it is confirmed that the drive output is in the ON state, the control circuit  1   c  executes the scanning in search of the resonant frequency on a preset frequency scanning condition (step S 11 ). If the resonant frequency cannot be scanned for by one time scanning, the scanning is further executed. At this time, the number of times of the scanning operation is counted, and the counted result is stored in the internal memory of the control circuit  1   c  as the number of times of the scanning. If the resonant frequency cannot be scanned for after the scanning is executed the predetermined number of times, the control circuit  1   c  reads the number of times of the scanning from the memory (step S 12 ). The control circuit  1   c  includes therein a table in which the number of times of the scanning, scan start frequency, scan end frequency, and scan frequency width are made to correspond to each other. The control circuit  1   c  refers to this table to set at least one of (1) the scan start frequency and scan end frequency, and (2) the scan frequency width as a new frequency scanning condition (step S 13 ). In terms of the example of  FIG. 6 , fs is the scan start frequency, fe is the scan end frequency, and fw is the scan frequency width. Here, fw is the interval between two sampling points. 
     Then, the control circuit  1   c  returns to step S 10 , repeats the above steps until the resonant frequency is detected, and stops the scanning operation when the resonant frequency is detected. Incidentally, the number of times of the scanning is determined in advance, and the scanning may be stopped irrespective of whether or not the resonant frequency has been detected. 
     According to the second embodiment described above, the frequency scanning condition is changed according to the number of times of the scanning, and thus it is possible to improve the oscillating capability of the device, shorten the time needed to scan for the resonant frequency, and finally shorten the time needed to treat the living tissue. 
     THIRD EMBODIMENT 
       FIG. 9  is a flowchart for explaining a method of scanning for a resonant frequency of a hand-piece according to a third embodiment of the present invention. The capacitance component of the hand-piece  2 , specifically, the ultrasonic vibrator is varied depending on the type of the device and the use environment. If the capacitance component is varied, the characteristic curve of the impedance Z and the phase frequency characteristics of the voltage and the current described in connection with  FIG. 6  are also varied. For example, when the capacitance component is large, fr and f 2  become close to each other in the phase frequency characteristic as shown in  FIG. 10(A) . On the other hand, when the capacitance component is small, f 1  and fr become close to each other in the phase frequency characteristic as shown in  FIG. 10(B) . 
     When fr and f 2  are close to each other, if the scanning is started in search of the resonant frequency from the higher frequency side, the phase is abruptly changed between f 2  and fr. Hence, if the scanning is performed in search of the resonant frequency slowly between f 2  and fr, fr can be detected easier. On the other hand, even if the scanning is performed in search of the resonant frequency at a high speed between fr and f 1 , the oscillation capability of the device is not deteriorated. Conversely, when f 1  and fr are close to each other, if the scanning is performed at a high speed from the start of the scanning on the higher frequency side to fr, and is performed slowly between fr and f 1 , the oscillation capability of the device is improved. That is, by changing the frequency scanning condition according to the capacitance component of the ultrasonic vibrator, the oscillation capability of the device can be improved. 
     First, the control circuit  1   c  measures the capacitance component of the ultrasonic vibrator (step S 20 ). This capacitance component is measured by a known method on the basis of, for example, the phases of the voltage and the current detected from the drive signal supplied to the hand-piece  2 , and the impedance. The control circuit  1   c  includes therein a table in which the capacitance component, scan start frequency, scan end frequency, and scan frequency width are made to correspond to each other. The control circuit  1   c  refers to this table to set at least one of (1) the scan start frequency and scan end frequency, and (2) the scan frequency width as a new frequency scanning condition (step S 21 ). In terms of the example of  FIG. 6 , fs is the scan start frequency, fe is the scan end frequency, and fw is the scan frequency width. Here, fw is the interval between two sampling points. 
     Then, the control circuit  1   c  starts to scan for the resonant frequency on the set frequency scanning condition (step S 22 ). 
     According to the third embodiment described above, the frequency scanning condition is changed according to the capacitance component of the hand-piece  2 , specifically, the ultrasonic vibrator, and hence it is possible to perform frequency scanning suited for the type of the device or a change in the use environment, improve the oscillation capability of the device, shorten the time needed to scan for the resonant frequency, and ultimately shorten the time needed to treat the living tissue.