Note: Descriptions are shown in the official language in which they were submitted.
CA 02359403 2008-08-05
APPARATUS AND METHOD FOR ALTERING GENERATOR
FUNCTIONS IN AN ULTRASONIC SURGICAL SYSTEM
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention generally relates to an apparatus & method for altering
generator functions in an ultrasonic surgical system and, more particularly,
to an ultrasonic system
for providing information to a generator from an ultrasonic surgical
instrument.
2. DESCRIPTION OF THE RELATED ART
It is known that electric scalpels and lasers can be used as a surgical
instrument to
perform the dual function of simultaneously effecting the incision and
hemostatis of soft tissue by
cauterizing tissues and blood vessels. However, such instruments employ very
high temperatures
CA 02359403 2008-08-05
to achieve coagulation, causing vaporization and fumes as well as splattering,
which increases the
risk of spreading infectious diseases to operating, room personnel.
Additionally, the use of such
instruments often results in relatively wide zones of thermal tissue damage.
Cutting and cauterizing of tissue by means of surgical blades vibrated at high
speeds
by ultrasonic drive mechanisms is also well known. One of the problems
associated with such
ultrasonic cutting instruments is uncontrolled or undamped vibrations and the
heat as well as
material fatigue resulting therefrom. In an operaiting room environment
attempts have been made
to control this heating problem by the inclusion of cooling systems with heat
exchangers to cool
the blade. In one known system, for example, the ultrasonic cutting and tissue
fragmentation
system requires a cooling system augmented with a water circulating jacket and
means for
irrigation and aspiration of the cutting site. Another known system requires
the delivery of
cryogenic fluids to the cutting blade.
It is known to limit the current delivered to the transducer as a means for
limiting
the heat generated therein. However, this could result in insufficient power
to the blade at a time
when it is needed for the most effective treatment of the patient. U.S. Patent
No. 5,026,387 to
Thomas discloses a system for controlling the heat in an ultrasonic surgical
cutting and
hemostasis system without the use of a coolant, by controlling the drive
energy supplied to the
.blade. In the system according to this patent an ultrasonic generator is
provided which produces
an electrical signal of a particular voltage, current and frequency, e.g.
55,500 cycles per second.
The generator is connected by a cable to a hand piece which contains
piezoceramic elements
forming an ultrasonic transducer. In response to a switch on the hand piece or
a foot switch
connected to the generator by another cable, the generator signal is applied
to the transducer,
which causes a longitudinal vibration of its elements. A structure connects
the transducer to a
surgical blade, which is thus vibrated at ultrasonic frequencies when the
generator signal is applied
to the transducer. The structure is designed to resonate at the selected
frequency, thus amplifying
the motion initiated by the transducer.
The signal provided to the transducer is controlled so as to provide power on
demand to the transducer in response to the continuous or periodic sensing of
the loading condition
2
CA 02359403 2001-10-17
(tissue contact or withdrawal) of the blade. As a result, the device goes from
a low power, idle
state to a selectable high power, cutting state automatically depending on
whether the scalpel is
or is not in contact with tissue. A third, high power coagulation mode is
manually selectable with
automatic return to an idle power level when the blade is not in contact with
tissue. Since the
ultrasonic power is not continuously supplied to the blade, it generates less
ambient heat, but
imparts sufficient energy to the tissue for incisions and cauterization when
necessary.
The control system in the Thomas patent is of the analog type. A phase lock
loop
that includes a voltage controlled oscillator, a frequency divider, a power
switch, a match net and
a phase detector, stabilizes the frequency applied to the hand piece. A
microprocessor controls
the amount of power by sampling the frequency current and voltage applied to
the hand piece,
because these parameters change with load on the blade.
The power versus load curve in a generator in a typical ultrasonic surgical
system,
such as that described in the Thomas patent has two segments. The first
segment has a positive
slope of increasing power, as the load increases, which indicates constant
current delivery. The
second segment has a negative slope of decreasing power as the load increases,
which indicates
a constant or saturated output voltage. The regulated current for the first
segment is fixed by the
design of the electronic components and the second segment voltage is limited
by the maximum
output voltage of the design. This arrangement is inflexible since the power
versus load
characteristics of the output of such a system can not be optimized to various
types of hand piece
transducers and ultrasonic blades. The performance of traditional analog
ultrasonic power systems
for surgical instruments is affected by the component tolerances and their
variability in the
generator electronics due to changes in operating temperature. In particular,
temperature changes
can cause wide variations in key system parameters such as frequency lock
range, drive signal
level, and other system performance measures.
In order to operate an ultrasonic surgical system in an efficient manner,
during
startup the frequency of the signal supplied to the hand piece transducer is
swept over a range to
locate the resonance frequency. Once it is found, the generator phase lock
loop locks on to the
resonance frequency, keeps monitoring of the transducer current to voltage
phase angle and
maintains the transducer resonating by driving it at the resonance frequency.
A key function of
3
CA 02359403 2008-08-05
such systems is to maintain the transducer resonating across load and
temperature changes that
vary the resonance frequency. However, these traditional ultrasonic drive
systems have little to
no flexibility with regards to adaptive frequency control. Such flexibility is
key to the system's
ability to discriminate undesired resonances. In particular, these systems can
only search for
resonance in one direction, i.e., with increasing or decreasing frequencies
and their search pattern
is fixed. The system cannot hop over other resonance modes or make any
heuristic decisions such
as what resonance/s to skip or lock onto and ensure delivery of power only
when appropriate
frequency lock is achieved.
The prior art ultrasonic generator systems also have little flexibility with
regard to
amplitude control, which would allow the system to employ adaptive control
algorithms and
decision making. For example, these fixed systems lack the ability to make
heuristic decisions
with regards to the output drive, e.g., current or frequency, based on the
load on the blade and/or
the current to voltage phase angle. It also limits the system's ability to set
optimal transducer
drive signal levels for consistent efficient performance, which would increase
the useful life of the
transducer and ensure safe operating conditions for the blade. Further, the
lack of control over
amplitude and frequency control reduces the system's ability to perform
diagnostic tests on the
transducer/blade system and to support troubleshooting in general.
Some limited diagnostic tests performed in the past involve sending a signal
to the
transducer to cause the blade to move and the system to be brought into
resonance or some other
vibration mode. The response of the blade is then determined by measuring the
electrical signal
supplied to the transducer when the system is in one of these modes-. The
ultrasonic system
described in European Patent No. 1 199 047 possesses the ability to sweep the
output drive
frequency, monitor the frequency response of the ultrasonic transducer and
blade, extract
parameters from this response, and use these parameters for system
diagnostics. This
frequency sweep and response measurement mode is achieved via a digital core
such that
the output drive frequency can be stepped with high resolution, accuracy, and
repeatability
not existent in prior art ultrasonic systems.
4
CA 02359403 2001-10-17
However, the prior art systems do not provide for authentication of the use of
the
hand piece with the console. Furthermore, conducting diagnostic and
performance tests in the
prior art systems is cumbersome. Reprogramming or upgrading of the console in
the prior art
systems is also burdensome, since each console needs to be independently
tested and upgraded.
In addition, the prior art system do not allow operation of the console with
varied driving current
and output displacement, depending on the type and output ability of hand
piece in operation with
the console. Therefore, there is a need in the art for an improved system for
implementing
surgical procedures which overcomes these and other disadvantages in the prior
art.
SUMMARY OF THE INVENTION
The present invention provides a system for implementing surgical procedures
which includes an ultrasonic surgical hand piece having an end-effector, a
console having a digital
signal processor (DSP) for controlling the hand piece, an electrical
connection connecting the hand
piece and the console, and a memory device such as an EEPROM (Electrically
Erasable
Programmable Read Only Memory) disposed in the electrical connection or the
hand piece. Data,
in the form of a data string which identifies the hand piece and generator
performance
characteristics, is stored in the memory device. During initialization of the
system, the console
sends an interrogation signal to the hand piece to obtain a readout of the
memory. As the console
reads the memory, the hand piece is authenticated for use with the console if
the proper data is
present. The hand piece is not authenticated for use with the console if the
data is not present or
is not correct. In a particular embodiment of the invention, the data is an
encrypted code, where
the hand piece is authenticated for use with the console by decoding a
corresponding encryption
algorithm resident in the console and providing a responding data pattern.
Moreover, to prevent errors in operating the hand piece, the memory can store
certain diagnostic information which the console can utilize in determining
whether the operation
of the hand piece should be handicapped or disabled. For instance, the memory
can store
information such as limits on the time that the hand piece is active, the
number of activations
within a time period, the number of.defective blades used, operating
temperature, and other limits.
5
CA 02359403 2001-10-17
Those limits stored in the memory can be re-initialized accordingly based on
various operational
conditions of the hand piece.
The memory can also be used to reprogram or upgrade the console, if needed.
For
example, new hand pieces are issued periodically as new system functionality
is achieved. When
such a new hand piece is connected, the system perform diagnostic tests to
determine whether a
reprogram or upgrade of the console is needed. If it is determined that a
reprogram or upgrade
is needed, the console reads the memory located in the electrical connection
or hand piece where
a reprogram or upgrade code is stored. Using the reprogram or upgrade code
read from the
memory, the console is reprogrammed or upgraded accordingly. Therefore, the
consoles in the
field can be upgraded automatically without having to return them to the
manufacturer or to send
a service technician to the console. In a particular embodiment, the memory is
a non-volatile
memory can be plugged into the electrical connection or hand piece.
The memory can also store energy level information and corresponding output
displacement for driving the particular hand piece. By reading the energy
level information, the
console can drive the hand piece according to the output displacement which is
best for that hand
piece.
In addition, the memory can store frequency sweep information including the
nominal resonant frequency, and start and stop sweep points for effecting a
frequency sweep.
Upon reading of the frequency sweep information stored in the memory, the
console effects a
frequency sweep in the indicated frequency range for detecting a resonant
frequency for operating
the hand piece.
In accordance with the invention, a method is provided for implementing
procedures
in a system including an ultrasonic surgical hand piece having an end-
effector, a console having
a digital signal processor (DSP) for controlling the hand piece, an electrical
connection connecting
the hand piece and the console, and a memory disposed in the electrical
connection or hand piece.
The method according to the invention includes reading information stored in
the memory,
determining whether particular or proprietary data are present in the memory,
authenticating use
of the hand piece with the console if the proprietary data are present,
sending a drive current to
drive the hand piece, and imparting ultrasonic movement to the end-effector of
the hand piece
6
CA 02359403 2001-10-17
according to information in the memory. In a particular embodiment, the method
according to the
invention also includes decoding an encryption algorithm in the console, and
providing a
responding data pattern, where the data is an encrypted code.
In a further embodiment, the method according to the invention includes
instructing
the hand piece to operate in a handicap mode if the temperature of the hand
piece exceeds a
handicap limit, and disabling the hand piece if the temperature of the hand
piece exceeds a disable
limit. The method according to the invention can also include instructing the
hand piece to operate
in a handicap mode if the number of defective blades found in a time period of
operating the hand
piece exceeds a handicap limit, and disabling the hand piece if the number of
defective blades
found in the time period exceeds a disable limit. The method according to the
invention can
further include instructing the hand piece to operate in a handicap mode if
the time the hand piece
has been active exceeds a handicap limit, and disabling the hand piece if the
number of defective
blades found in the time the hand piece has been active exceeds a disable
limit. The method
according to the invention can include further steps of operating the hand
piece in a handicap mode
if the number of activations for the hand piece, and/or the number of
activations within a time
period, exceed a handicap limit, and disabling the hand piece if the number of
activations for the
hand piece within the time period exceeds a disable limit. The handicap and
disable limits stored
in the memory can be re-initialized based on varied operational conditions of
the hand piece.
In an additional embodiment, the method according to the invention also
includes
determining whether a reprogramming or upgrade of the console is needed,
reading a reprogram
or upgrade code stored in the memory and reprogramming the console using the
reprogram or
upgrade code, if it is determined that a reprogram or upgrade of the console
is needed.
Moreover, the method according to another embodiment of the invention further
includes reading energy level information stored in the memory, and driving
the hand piece
according to a corresponding output displacement, where the energy level
information stored in
the memory is correlated with corresponding output displacement for driving
the particular hand
piece. In yet another embodiment, the method according to the invention also
includes reading
a nominal resonant frequency, a start sweep point and a stop sweep point
delimiting a frequency
range from the memory, effecting a frequency sweep in the frequency range, and
detecting a
7
CA 02359403 2008-08-05
resonant frequency for operating the hand piece. Alternatively, the frequency
range
information stored in the memory can. be a nominal resonant frequency, a bias
amount
and a margin amount, where the frequency range for the frequency sweep is
calculated
based on the nominal resonant frequency, the bias amount and the margin
amount.
In a further embodiment, there is provided a system for implementing
surgical procedures comprising:
an ultrasonic surgical hand piece having an end-effector;
a console having a digital signal processor (DSP) for controlling the hand
piece;
an electrical connection connecting the hand piece and the console, wherein
the
console sends a drive current to drive the hand piece which imparts ultrasonic
longitudinal movement to the end-effector; and
a memory disposed in a location consisting of one of the electrical
connection,
the housing of the hand piece, and an in-line location in a cable connecting
the electrical
connection with the console and the hand piece, wherein the console reads
information
stored in the memory to authenticate the hand piece for use with the console;
wherein the
memory stores a disable limit and the console disables the hand piece if the
system
exceeds the disable limit;
wherein the memory also stores a handicap limit and the console instructs the
hand piece to operate in a handicap mode if the system exceeds the handicap
limit, the
handicap mode involving one of a) operations below a certain speed or
vibrational
frequency, b) operating below a certain vibrational displacement, and c) a
limited mode.
In a further embodiment, there is provided the system described herein for
use in implementing surgical procedures, comprising:
means for reading information stored in the memory;
means for determining whether particular data is present in the memory;
means for authenticating use of the hand piece with the console if the
particular
data is present; and
means for sending a drive current to drive the hand piece to impart ultrasonic
movement
to the blade.
In a further embodiment, there is provided use of the system described
herein for implementing surgical procedures.
8
CA 02359403 2001-10-17
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other advantages and features of the invention will become
more
apparent from the detailed description of the preferred embodiments of the
invention given below
with reference to the accompanying drawings in which:
FIG. 1 is an illustration of a console for an ultrasonic surgical cutting and
hemostasis system, as well as a hand piece and foot switch in which the method
of the present
invention is implemented;
FIG. 2 is a schematic view of a cross section through the ultrasonic scalpel
hand
piece of the system of FIG. 1;
FIGS. 3A and 3B are block diagrams illustrating the system for the hand piece
according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating the electrical connection between the
generator
console and the ultrasonic surgical hand piece according to the invention in
further detail;
FIG. 5 is a flow diagram illustrating the operation of the non-volatile memory
according to the invention as proprietary lockout for preventing inappropriate
use of the ultrasonic
surgical hand piece;
FIG. 6 and FIG. 7 are flow diagrams illustrating the operation of the non-
volatile
memory according to the invention for error prevention when using the
ultrasonic surgical hand
piece;
FIG. 8 is a flow diagram illustrating the operation of the non-volatile memory
according to the invention for reprogramming or upgrading the console using
the hand piece;
FIG. 9 is a flow diagram illustrating the operation of the ultrasonic surgical
hand
piece at a resonant frequency using information stored in the memory according
to the invention;
and
FIG. 10 is a diagram illustrating an alternative embodiment of the operation
of the
hand piece at a resonant frequency using information stored in the non-
volatile memory according
to the invention.
9
CA 02359403 2008-08-05
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is an illustration of a system for implementing surgical procedures
according
to the invention. By means of a first set of wires in cable 26, electrical
energy, i.e., drive current,
is send from the console 10 to a hand piece 30 where it imparts ultrasonic
longitudinal movement
to a surgical device, such as a sharp end-effector 32. This blade can be used
for generally
simultaneous dissection and cauterization of tissue. The generator in console
10 drives the hand
piece 30 such that the ultrasonically tuned blade 32 mounted on the proximal
end thereof vibrates
and in turn is used for cutting and coagulation in open or laparoscopic
surgical procedures. The
hand piece 30 is a hand-held device that includes an ultrasonic resonator or
transducer that
converts the appropriate electrical signals supplied by the generator in
console 10 into mechanical
vibrations for vibrating the frequency-tuned blade 32. The supply of
ultrasonic current to the hand
piece 30 may be under the control of a switch 34 located on the hand piece 30,
which is connected
to the generator in console 10 by a wire in cable 26 via the electrical
connection 19. The
generator may also be controlled by a foot switch 40, which is connected to
the console 10 by
another cable 50. Thus, in use a surgeon may apply an ultrasonic electrical
signal to the hand
piece 30, causing the blade to vibrate longitudinally at an ultrasonic
frequency, by operating the
switch 34 on the hand with his finger which is activated by pressing button
18, or by operating
the foot switch 40 with his foot.
In a specific embodiment according to the invention, the button 18 is a set of
twin
rocker switches which are generally 180 degrees apart from each other. Each
rocker switch in the
button set 18 can signal to the generator console 10 for delivering power to
the transducer in the
hand piece 30 at a minium or maximum power levels. In addition, the foot
switch 40 includes two
paddles of the press-and-hold activation type, where the paddle on the left
serves as the switch for
activating power delivery at a minimum level, and the paddle on the right
serves as the switch for
activating power delivery at a maximum level.
The generator console 10 includes a liquid crystal display device 12, which
can be
used for indicating the selected cutting power level in various means such as
percentage of
maximum cutting power or numerical power levels associated with cutting power.
The liquid
crystal display device 12 can also be utilized to display other parameters of
the system. A power
1.0
CA 02359403 2001-10-17
switch 11 and power "on" indicator 13 are also provided on the console.
Further, buttons and
switches 16 to 17 control various other functions of the system may be located
on the console
front panel.
When power is applied to the ultrasonic hand piece by operation of either
switch
34 or 40, the assembly will cause the surgical scalpel or blade to vibrate
longitudinally at
approximately 55.5 kHz, and the amount of longitudinal movement will vary
proportionately with
the amount of driving power (current) applied, as adjustably selected by the
user. When relatively
high cutting power is applied, the blade is designed to move longitudinally in
the range of about
40 to 100 microns at the ultrasonic vibrational rate. Such ultrasonic
vibration of the blade will
generate heat as the blade contacts tissue, i.e., the acceleration of the
blade through the tissue
converts the mechanical energy of the moving blade to thermal energy in a very
narrow and
localized area. This localized heat creates a narrow zone of coagulation,
which will reduce or
eliminate bleeding in small vessels, such as those less than one millimeter in
diameter. The
cutting efficiency of the blade, as well as the degree of hemostasis, will
vary with the level of
driving power applied, the cutting rate or force applied by the surgeon to the
blade, the nature of
the tissue type, and the vascularity of the tissue.
As illustrated in more detail in FIG. 2, the ultrasonic hand piece 30 houses a
piezoelectric transducer 36 for converting electrical energy to mechanical
energy that results in
longitudinal vibrational motion of the ends of the transducer. The transducer
36 is in the form of
a stack of ceramic piezoelectric elements having a motion null point at the
center of the stack. It
is mounted between two cylinders 31 and 33. In addition, a cylinder 35 is
attached to cylinder 33,
which is mounted to the housing at another motion null point 37. A horn 38 is
also attached to
the null point on one side and to a coupler 39 on the other side. Blade 32 is
fixed to the coupler
39. As a result, the blade 32 will vibrate in the longitudinal direction at an
ultrasonic frequency
rate with the transducer 36. The ends of the transducer achieve maximum
motion, with the center
of the stack constituting a motionless node, when the transducer is driven at
maximum current at
the transducer's resonant frequency.
The parts of the hand piece are designed such that the combination will
oscillate at
generally the same resonant frequency. In particular, the elements are tuned
such that the resulting
11
CA 02359403 2001-10-17
length of each such element is one-half wavelength. Longitudinal back and
forth motion is
amplified as the diameter closer to the blade 32 of the acoustical mounting
horn 38 decreases.
Thus the horn 38 as well as the blade/coupler are shaped and dimensioned so as
to amplify blade
motion and provide harmonic vibration in resonance with the rest of the
acoustic system, which
produces the maximum back and forth motion of the end of the acoustical
mounting horn 38 close
to the blade 32, preferably from 20 to 25 microns.
The system which creates the ultrasonic electrical signal for driving the
transducer
in the hand piece is illustrated in FIG. 3A and FIG. 3B. This drive system is
flexible and can
create a drive signal at a desired frequency and power level setting. A DSP 60
or microprocessor
in the system is used for monitoring the appropriate power parameters and
vibratory frequency
as well as causing the appropriate power level to be provided in either the
cutting or coagulation
operating modes. The DSP 60 or microprocessor also stores computer programs
which are used
to perform diagnostic tests on components of the system, such as the
transducer/blade.
For example, under the control of a program stored in the DSP or
microprocessor
60, such as a phase correction algorithm, the frequency during startup can be
set to a particular
value, e.g., 50 kHz. It can than be caused to sweep up at a particular rate
until a change in
impedance, indicating the approach to resonance, is detected. Then the sweep
rate can be reduced
so that the system does not overshoot the resonance frequency, e.g., 55 kHz.
The sweep rate can
be achieved by having the frequency change in increments, e.g., 50 cycles. If
a slower rate is
desired, the program can decrease the increment, e.g., to 25 cycles which both
can be based
adaptively on the measured transducer impedance magnitude and phase. Of
course, a faster rate
can be achieved by increasing the size of the increment. Further, the rate of
sweep can be changed
by changing the rate at which the frequency increment is updated.
If it is known that there is an undesired resonant mode , e.g., at say 51 kHz,
the
program can cause the frequency to sweep down, e.g., from 60 kHz, to find
resonance. Also, the
system can sweep up from 50 kHz and hop over 51 kHz where the undesired
resonance is located.
In any event, the system has a great degree of flexibility
In operation, the user sets a particular power level to be used with the
surgical
instrument. This is done with power level selection switch 16 on the front
panel of the console.
12
CA 02359403 2008-08-05
The switch generates signals 150 that are applied to the DSP 60. The DSP 60
then displays the
selected power level by sending a signal on line 152 (FIG. 3B) to the console
front panel display
12.
To actually cause the surgical blade to vibrate, the user activates the foot
switch 40
or the hand piece switch 34. This activation puts a signal on line 154 in FIG.
3A. This signal is
generally effective to cause power to be delivered from push-pull amplifier 78
to the transducer
36. When the DSP or microprocessor 60 has achieved lock on the hand piece
transducer
resonance frequency and power has been successfully applied to the hand piece
transducer, an
audio drive signal is put on line 156. This causes an audio indication in the
system to sound,
which communicates to the user that power is being delivered to the hand piece
and that the scalpel
is active and operational.
As described herein with respect to FIG. 2, FIG. 3A and FIG. 3B and in the
related European Patent No. 1 199 047 the parts of the
hand piece 30 in operational mode are designed, as a whole, to oscillate at
generally the same
resonant frequency, where the elements of the hand piece 30 are tuned so that
the resulting length
of each such element is one-half wavelength or a multiple thereof.
Microprocessor or DSP 60,
using a phase correction algorithm, controls the frequency at which the parts
of the hand piece 30
oscillate. Upon activation of the hand piece 30, the oscillating frequency is
set at a startup value
or nominal resonant frequency such as 50 kHz which is stored in memory. A
sweep of a
frequency range between a start sweep point and a stop sweep point is effected
under the control
of the DSP 60 until the detection of a change in. impedance which indicates
the approach to the
resonant frequency. The change in impedance refers to the impedance of the
hand piece and its
transducers, which may be modeled by a parallel equivalent circuit for
mathematically modeling
the algorithm for controlling the operation of the hand piece 30 as described
in the related U.S.
Application Serial No. 09/693,621. The resonant frequency is the frequency at
a point during the
frequency sweep where the impedance of the equivalent circuit is at its
minimum and the anti-
resonant frequency is the frequency where the impedance is maximum. Phase
margin is the
difference between the resonant frequency and an anti-resonant frequency. A
correlation between
the phase margin and the output displacement of the hand piece 30 exists which
can
1:3
CA 02359403 2001-10-17
advantageously be used to control the displacement so that the hand piece 30
operates at its optimal
performance level.
In order to obtain the impedance measurements and phase measurements, the DSP
60 and the other circuit elements of FIG. 3A and 3B are used. In particular,
push-pull amplifier
78 delivers the ultrasonic signal to a power transformer 86, which in turn
delivers the signal over
a line 85 in cable 26 to the piezoelectric transducers 36 in the hand piece.
The current in line 85
and the voltage on that line are detected by current sense circuit 88 and
voltage sense circuit 92.
The current and voltage sense signals are sent to average voltage circuit 122
and average current
circuit 120, respectively, which take the average values of these signals. The
average voltage is
converted by analog-to-digital converter (ADC) 126 into a digital code that is
input to DSP 60.
Likewise, the current average signal is converted by analog-to-digital
converter (ADC) 124 into
a digital code that is input to DSP 60. In the DSP the ratio of voltage to
current is calculated on
an ongoing basis to give the present impedance values as the frequency is
changed. A significant
change in impedance occurs as resonance is approached.
The signals from current sense 88 and voltage sense 92 are also applied to
respective zero crossing detectors 100, 102. These produce a pulse whenever
the respective
signals cross zero. The pulse from detector 100 is applied to phase detection
logic 104, which can
include a counter that is started by that signal. The pulse from detector 102
is likewise applied
to logic circuit 104 and can be used to stop the counter. As a result, the
count which is reached
by the counter is a digital code on line 140, which represents the difference
in phase between the
current and voltage. The size of this phase difference is also an indication
of how close the system
is operating to the resonant frequency. These signals can be used as part of a
phase lock loop that
cause the generator frequency to lock onto resonance, e.g., by comparing the
phase delta to a
phase set point in the DSP in order to generate a frequency signal to a direct
digital synthesis
(DDS) circuit 128 that drives the push-pull amplifier 78.
Further, the impedance and phase values can be used as indicated above in a
diagnosis phase of operation to detect if the blade is loose. In such a case
the DSP does not seek
to establish phase lock at resonance, but rather drives the hand piece at
particular frequencies and
measures the impedance and phase to determine if the blade is tight.
14
CA 02359403 2001-10-17
FIG. 4 is a diagram that illustrates the electrical connection 19 between the
console
and the hand piece 30 in further detail. According to a specific embodiment of
the invention,
the electrical connection 19, which can be a serial or parallel connection, is
a male-female
electrical connection set. It includes, on one end leading to the hand piece
30 via the cable 26,
5 an electrical connector 19B with pins 401, 402, 403, 404, 405, 406 and 407,
and on the other end
a corresponding connector 19A leading to the console 10 and having receptacles
401A, 402A,
403A, 404A, 405A, 406A and 407A. These receptacles respectively receive pins
401, 402, 403,
404, 405, 406 and 407 of connector 19B. For engaging or disengaging the
electrical connection
19, the connectors 19A and 19B only require simple act of connecting them by
human hands, and
10 need no additional tooling to engage or disengage them. The electrical
connector 19B includes
a memory 400 which is a non-volatile memory device that retains its data for
subsequent usage
even if power is removed therefrom, such as an electrically erasable
programmable read only
memory or EEPROM. The memory 400 is connected to pin 405 for transferring data
to and from
the console 10 at a direct current (DC) of generally 10 mA (milli-amperes).
With respect to the other pins, pin 401 is for delivering the "transducer
high" signal
for operating the transducer 36 in the hand piece 30 at a high power level,
using an alternating
current (AC) of generally 1 A (ampere). Pin 402 is for delivering the
"transducer low" signal for
operating the transducer 36 in the hand piece 30 at a low power level, also
using an alternating
current (AC) of generally 1 A. Pins 403 and 404 are for delivering hand-
activation signals (e.g.,
by pressing button 18) to the hand piece 30, at an alternating current (AC) of
generally 10 mA.
Pin 406 is for delivering a general or common signal to the memory 400, at a
direct current (DC)
of generally 10 mA. Pin 407 is for delivering a signal which indicates the
presence (or lack
thereof) of the hand piece 30, also at a direct current (DC) of generally 10
mA.
The memory 400 is advantageously provided in the electrical connector 19B for
reducing unneeded complexity in electrical isolation configurations which
contribute to increases
in costs, complications in cross-talk noise issues, and adversely affects the
ergonomic performance
of the hand piece 30. By placing the memory 400 in the electrical connector
19B, with adequate
electrical isolation of the memory 400 circuitry, the human operator thereof,
and the patient is
CA 02359403 2001-10-17
readily achieved. Also, the number of wires in cable 26 can be reduced.
However, if desired,
the memory 400 can be located in the hand piece 30, but this is not preferred.
FIG. 5 is a flow diagram that illustrates the operation of the memory 400 as a
proprietary lockout for preventing inappropriate use of the hand piece 30. The
memory 400 can
be utilized to prevent unauthorized, unintentional or inadvertent use of the
hand piece 30 with the
console 10. Inappropriate usage includes hazardous use, poor operational
usage, or non-
compatible use with the console 10.
In step 501, the hand piece 30 is activated, e.g., by pressing the button 18
on
console 10 for hand-activation-enable of the hand piece 30. In step 503,
console 10 then reads the
memory 400 by accessing it via pin 405 in the electrical connection 19 at its
mated position. In
step 505, it is determined whether proprietary data (in the form of a data
string) is present in the
memory 400. The proprietary data, input into the non-volatile memory for all
authorized hand
pieces, are in digital or analog form. The proprietary data can also be a
musical, speech, or sound
effect in either digital or analog format. Having a proper proprietary data
string in the memory
400 means that the use of the hand piece with console 10 is authorized or
authenticated. The
proprietary data can be copyrighted to protect against unlawful or
unauthorized use of the hand
piece. If the proprietary data are present in the memory 400, the hand piece
30 is enabled or
activated by console 10 (step 507). If the proprietary data are not present in
the memory 400 or
an improper data string is present, the hand piece 30 is not enabled (step
509), and an error
message appears on the display device 12 at the console 10 indicating
unauthorized use.
In a specific embodiment according to the invention, when the console 10 reads
the
data in the memory 400, a cyclical redundancy check (CRC) is used to detect
read errors and/or
to authenticate the hand piece. A CRC is a mathematical method that permits
errors in long runs
of data to be detected with a very high degree of accuracy. Before data is
transmitted over a
phone, for example, the sender can compute a 32-bit CRC value from the data's
contents. If the
receiver computes a different CRC value, then the data was corrupted during
transmission.
Matching CRC values confirms with near certainty that the data was transmitted
intact.
According to the CRC authentication technique, the entire block of data is
treated
as a long binary number which is divided by a conveniently small number and
the remainder is
16
CA 02359403 2001-10-17
used as the check value that is tacked onto the end of the data block.
Choosing a prime number
as the divisor provides excellent error detection. The number representing the
complete block
(main data plus CRC value) is always a multiple of the original divisor, so
using the same divisor
always results in a new remainder of zero. This means that the same division
process can be used
to check incoming data as is used to generate the CRC value for outgoing data.
At the transmitter,
the remainder is (usually) non-zero and is sent immediately after the real
data. At the receiver, the
entire data block is checked and if the remainder is zero, then the data
transmission is confirmed.
An 8-bit CRC generator can be implemented in hardware, software or firmware in
the memory 400. Firmware is the controller software for a hardware device,
which can be written
or programmed in a non-volatile memory (e.g., memory 400) such as an EEPROM or
flash ROM
(read only memory). The firmware can be updated with a flash program for
detection and
correction of bugs in the controller software or to improve performance of the
hardware device.
An exemplary EEPROM used in implementing the invention is the 256-bit DS2430A
I wire device
organized as one page of 32 bytes for random access with a 64-bit one-time
programmable
application register, which is a part of the IBUTTONT family of hardware
devices commercially
available from DALLAS SEMICONDUCTOR'.
The following exemplary software code in "C" which is a commonly used
programming language in the art, illustrates how the 8-bit CRC is calculated
when reading the data
in the memory 400 for authenticating use of the hand piece with console 10.
Prior to the
calculation of the CRC of a block of data, the 8-bit CRC is first initialized
to zero. When console
10 reads the 8 bytes of the data in the memory 400, an 8-bit CRC is calculated
for each of the 8
bytes of the data. If the resultant 8-bit CRC is equal to zero, then the use
of the hand piece is with
console 10 is authenticated, and the hand piece is enabled. If the resultant 8-
bit CRC is not equal
to zero, then the use of the hand piece with console 10 is not authenticated,
the hand piece not
enabled, and an error message appears on the display device 12 at console 10
indicating
unauthorized use.
FUNCTION
mlan_CRC8
17
CA 02359403 2001-10-17
PASSED PARAMETERS
`data' - data byte to calculate the 8 bit crc from
`crc8' - the current CRC.
RETURN
the updated 8 bit CRC.
static uchar crc_table[] _
{
0, 94, 188,226, 97, 63,221, 131, 194,156,126, 32,163,253, 31, 65
157,195, 33,127,252,162, 64, 30, 95, 1,227, 189, 62, 96,130,220,
190,224, 2, 92,223,129, 99, 61,124, 34, 192,158, 29, 67,161,255,
70, 24,250,164, 39,121,155,197,132,218 56,102,229,187, 89, 7,
219,133,103,57,186,228, 6, 88, 25, 71, 165,251,120, 38,196,154,
101, 59,217,135, 4, 90,184,230,167,249, 27, 69,198,152,122,36,
248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91, 5,231,185
140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
17, 79,173,243,112, 46,204,146,211, 141,111, 49,178,236, 14, 80,
175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
202,148,118, 40,171,245, 23, 73, 8, 86,180,234,105, 55,213,139,
87, 9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
2 5 233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107,53
uchar mlan CRC8(uchar data, uchar crc8)
{
return crc_ table[crc8 A data];
}
Another exemplary software code is listed below for calculating a 16-bit CRC
for
the memory 400. Similarly, prior to the calculation of the CRC of a block of
data, the 16-bit CRC
18
CA 02359403 2001-10-17
is first initialized to zero. When console 10 reads the 16 bytes of the data
in the memory 400, a
16-bit CRC is calculated for each of bytes I through 30 of the data, and the
results are stored in
bytes 31 and 32. After comparing the results, if the resultant CRC is equal to
zero, then the use
of the hand piece with console 10 is authenticated, and the hand piece is
enabled. If the resultant
CRC is not equal to zero, then the use of the hand piece with console 10 is
not authenticated, the
hand piece is not enabled, and an error message appears on the display device
12 at console 10
indicating unauthorized use.
FUNCTION
mlan_CRC 16
PASSED PARAMETERS
`data' - current word to add into the CRC
4crc16' - the current value of the 16 bit CRC
RETURN
new value of the 16 bit CRC
P
static int oddparity[16] = {0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0};
uint mlan-CRC 16(uint data, uint crc 16)
{
data = (data A (crc 16 & Oxff)) & Oxff;
crc 16>>=8;
if (oddparity[data & 0xf] A oddparity[data >> 4])
crc l 6 A Oxc001;
data <<=6;
crc l 6 A= data;
data <<= 1;
crcl6 A= data;
return crc16;
}
19
CA 02359403 2001-10-17
Furthermore, the data in the memory 400 can be an encrypted code which, when
decoded by a corresponding encryption algorithm resident at console 10,
provides a corresponding
data pattern that serves to authenticate proper usage of the hand piece with
the console.
Encryption is achieved with algorithms that use a computer "key" to encrypt
and decrypt messages
by turning text or other data into an unrecognizable digital form and then by
restoring it to its
original form. The longer the "key, " the more computing is required to crack
the code. To
decipher an encrypted message by brute force, one would need to try every
possible key.
Computer keys are made of "bits" of information of various length. For
instance, an 8-bit key has
256 (2 to the eighth power) possible values. A 56-bit key creates 72
quadrillion possible
combinations. If the key is 128 bits long, or the equivalent of a 16-character
message on a
personal computer, a brute-force attack would be 4.7 sextillion
(4,700,000,000,000,000,000,000)
times more difficult than cracking a 56-bit key. With encryption, unauthorized
use of the hand
piece with console 10 is generally prevented, with a rare possibility of the
encrypted code being
deciphered for unauthenticated use.
A unique identification (ID) number is registered and stored in the memory
(e.g.,
memory 400) for every hand piece manufactured which is compatible for use with
console 10.
In a specific embodiment according to the invention, the memory 400 is the
DS2430A 1 wire
EEPROM device, commercially available from DALLAS SEMICONDUCTOR', which stores
a factory-lasered and tested 64-bit ID number for each hand piece
manufactured. The ID number
can be a model or model family number, in addition to being a unique serial
number ID for each
individual hand piece. This allows the generator console 10 to acknowlege its
compatibility and
useability therewith, without requiring a list of serial numbers for that
model or model family.
Foundry lock data in a hardware format and protocol is stored in the memory
400 to ensure
compatibility with other products of generally the same communications
protocol, e.g., the
products of the MICROLANt protocol commercially available from DALLAS
SEMICONDUCTOR'. This advantageously provides scalability for providing a
system with
additional surgical devices on a local area network (LAN) operating on
generally the same
communications protocol.
CA 02359403 2001-10-17
FIG. 6 and FIG. 7 are flow diagrams that illustrate the operation of the
memory 400
according to the invention for error prevention when using the hand piece 30
with console 10. To
prevent errors in operating the hand piece 30, the memory 400 can store
certain diagnostic
information which console 10 can utilize in determining whether the operation
of the hand piece
30 should be handicapped or disabled. For instance, the memory 400 can store
information such
as limits on the time that the hand piece is active, the number of activations
within a time period,
the number of defective blades used, temperature, and any other performance
characteristics such
as, for example, those listed in Table 1. Those skilled in the art can
appreciate that other error
prevention, diagnostic and performance characteristics can be stored in memory
400. Exemplary
performance characteristics that can be stored in memory 400 (as shown in
Table 1) include
surgical device type information and revision data (row 1 in Table 1), current
set point (row 2),
transducer capacitance (row 3), cable capacitance (row 4), phase margin for
the hand piece
equipped with a test tip or end-effector (row 5), resonant frequency (row 6),
remaining operating
procedures (row 7), lower bound or threshold on operating frequency (row 8),
upper bound or
threshold on operating frequency (row 9), maximum output power (row 10), power
control
information and authorization (row 11), hand piece impedance (row 12), total
on-time information
at specific power levels (rows 13 and 14), hand piece enable/disable
diagnostic information (row
15), hand piece error codes (row 16), temperature range and change data (rows
17, 18 and 19),
current excess load limit (row 20), high impedance fault limit (row 21), and
cyclical redundancy
check (CRC) data (row 22).
Moreover, the memory 400 can store user-specific data such as username,
internal tracking
number, calibration schedule, and custom output performance. The user-specific
data can be
manipulated or programmed through the generator console 10 or initialized at
the time the hand
piece 30 is made at the factory.
21
CA 02359403 2010-02-16
TABLE 1
14 Total on-Time a level < 5
15 Hand piece Diagnostics Enable/Disable
Flags byte no. I
I Bits 1-3: Device Type
Bits 4-8: Revision
2 Current set point
IWPWN
3 Transducer Capacitance
C
4 Cable Capacitance Hand piece Diagnostics Enable/Disable
C, Flags byte no. 2
5 Phase margin with test tip
Pnk
6 Resonance frequency
f
7 Allowed Procedures Remaining
8 Lower bound on seek/lock frequency
(offset from f,,,) 16 Hand piece error code 1 (newest)
f
9 Upper bound on seek/lock frequency Hand piece error code 2
(offset from f,.) Hand piece error code 3
f; Hand piece error code 4
Hand piece error code 5 (oldest)
10 Maximum output power level 5 W 17 AC, Over Tamp Entry
11 Bit 1 Backside power curve control
variable:
Capped Power=1; Descending power = 0
Bit 2; Single cap at all levels =1, 18 AC, Over Temp Exit
Different cap for each power level = 0
19 C,Max Rate of Change
Bit 3: Hand piece Authorized Activation 20 Current Excessive Load Limit
Flag.
Bits 4-8: Unused 21 High Impedance with test tip fault
limit
12 Hand piece Impedance, Re 1Z 1 22 Data CRC
13 Total On-Time @ level 5
22
CA 02359403 2001-10-17
According to a specific embodiment of the invention, once the hand piece 30 is
activated for use, console 10 reads the memory 400 (step 601) for the
diagnostic information.
In step 603, console 10 determines whether the temperature of the hand piece
30 is over the
handicap limit stored in the memory 400. If so, console 10 then instructs the
hand piece 30 to
operate in the handicap mode (step 605), e.g., operating below a certain speed
or vibrational
frequency or in a limited mode such as coagulation or cutting in order to
avoid overheating, or
in a non-limited mode with a specific vibrational annunciation. If not, the
flow control goes to
step 607, where console 10 determines whether the temperature of the hand
piece 30 is over
the disable limit stored in the memory 400. If so, console 10 disables the
hand piece 30 (step
609). If not, the flow control goes to step 611, where console 10 determines
whether the
number of defective blades found within a time period of operating the hand
piece 30 has
exceeded the handicap limit stored in the memory 400. If so, console 10 then
instructs the
hand piece 30 to operate in the handicap mode (step 613), e.g., operating
below a certain speed
or vibrational frequency below the nominal vibrational displacement, or in a
limited mode such
as coagulation or cutting in order to decrease the incidences of blades 32
becoming defective.
The handicap mode in step 613 is not necessarily the same as the handicap mode
in step 605,
depending on the optimal mode for operating the hand piece 30 under the
circumstances with
respect to steps 603 and 611.
If the number of defective blades found has not exceeded the handicap limit,
the
flow control is directed to step 615, where console 10 determines whether the
number of
defective blades found within a time period has exceeded the disable limit
stored in the
memory 400. If so, console 10 disables the hand piece 30 (step 609). If not,
the control flow
is directed, via step A, to step 617, where console 10 determines whether the
time the hand
piece 30 has been active has exceeded the handicap limit stored in memory 400.
If so, console
10 instructs the hand piece 30 to operate in a handicap mode, e.g., operating
below a certain
speed or vibrational frequency, below the nominal vibrational displacement, or
in a limited
mode such as coagulation or cutting. The handicap mode in step 619 is not
necessarily the
same as the handicap mode in steps 605 or 613, depending on the optimal mode
for operating
the hand piece 30 under the circumstances with respect to steps 603, 611 and
617.
23
CA 02359403 2001-10-17
If the time the hand piece 30 has been active has not exceeded the handicap
limit, the flow control is directed to step 621, where console 10 determines
whether the time
the hand piece has been active has exceeded the disable limit stored in the
memory 400. If so,
the control flow is directed, via step B, to step 609 where console 10
disables the hand piece
30. If not, the control flow goes to step 623, where console 10 determines
whether the number
of activations for the hand piece 30 within a time period has exceeded the
handicap limit stored
in memory 400. If so, console 10 instructs the hand piece 30 to operate in a
handicap mode
(step 625), e.g., operating below a certain speed or vibrational frequency,
below the nominal
vibrational displacement, or in a limited mode such as coagulation or cutting.
The handicap
mode in step 625 is not necessarily the same as the handicap mode in steps
605, 613 or 619,
depending on the optimal mode for operating the hand piece 30 under the
circumstances with
respect to steps 603, 611, 617 and 623.
If the number of activations for the hand piece 30 within a time period has
not
exceeded the handicap limit, the flow control is directed to step 627, where
console 10
determines whether the number of activations for the hand piece 30 within a
time period has
exceeded the disable limit stored in the memory 400. If so, the control flow
is directed, via
step B, to step 609 where console 10 disables the hand piece 30. If not, the
control flow is
directed, via step C, to step 601 from which the process steps according to
this particular
embodiment of the invention may be repeated upon subsequent users until the
hand piece 30 is
2 0 caused to be disabled.
The disable limits and the handicap limits described herein with respect to
FIG.
6 and FIG. 7 may be of substantively different criteria for console 10 to
determine the
operational mode of the hand piece 30. The memory 400 may be re-initialized
for different
disable or handicap limits for varied operational conditions of the hand piece
30. Console 10
may likewise be re-initialized to operate on varied criteria for controlling
the operational mode
of the hand piece 30 based on the information stored in the memory 400.
In addition to the disable and handicap modes of operation, an alarm or alert
mode can further be provided when certain criteria are met to alert and allow
a human operator
of the hand piece to take appropriate action to remedy the alerted operating
condition.
24
CA 02359403 2001-10-17
FIG. 8 is a flow diagram that illustrates the operation of the memory 400
according to the invention for reprogramming or upgrading console 10 using the
hand piece
30. In step 801, console 10 performs diagnostic tests on the functions of the
console. It is
determined in step 803 whether any functions are deemed inadequate, e.g.,
functions that need
to be altered, disabled or added. For example, the error prevention functions
described herein
with respect to FIG. 6 and FIG. 7 may need to be added, or the handicap limits
and operational
modes may need to be re-initialized. If it is determined that certain
functions are inadequate,
the flow control is directed to step 807. In step 807, console 10 reads the
memory 400 of the
hand piece 30 where the reprogram code has been stored in step 800. Using the
reprogram
code read from the memory 400, the functions of console 10 are reprogrammed.
If it is determined in step 803 that the functions of console 10 are adequate
or
the memory has a newer version of the program, then the console 10 has, the
flow control
directed to step 805. It is determined in step 805 whether an upgrade is
needed for console 10.
If so, the flow control is directed to step 807. In step 807, console 10 reads
the memory 400
of the hand piece 30 where the reprogram or upgrade code has been stored in
step 800. Using
the reprogram or upgrade code read from the memory 400, the functions of
console 10 are
reprogrammed and upgraded. For example, if console 10 is experiencing
operational
difficulties with a specific generation or version of the hand piece, an
upgrade from the
memory 400 instructs console 10 to allow its use with only newer versions or
generations of
the hand piece. The memory 400 can also store information including the
manufacture date,
design revision, manufacturing code, lot code or other manufacture-related
information for a
specific grouping of hand pieces according to generation or version having
operational
difficulties or defects, from which console 10 can be reprogrammed or upgraded
to refuse
activation for use with such hand pieces.
In an alternative embodiment according to the invention, the reprogram code
can be stored in a non-volatile memory of a device other than the hand piece
30 with the
memory 400. The non-hand piece device with the non-volatile memory can be
plugged
directly into the electrical connection 19 for upgrading or reprogramming
console 10.
CA 02359403 2008-08-05
Moreover, the memory 400 can be utilized in adding an odometer function to
the generator console 10 by keeping track of the number of uses performed for
the hand piece
30 and/or the number of allowable uses remaining.
In addition to storing reprogram or upgrade code, the memory 400 can also
store performance criteria for operating the hand piece 30 with console 10.
For example, the
memory 400 can store energy level information such as a maximum energy level
for driving
the particular hand piece 30, because, e.g., a relatively small hand piece may
not be able to be
driven, in terms of energy levels, as intensely as a relatively large hand
piece for large-scale
surgical procedures. Information correlating the energy levels for driving the
hand piece 30
and the corresponding output displacement can also be stored in the memory
400. The console
10 reads the energy level information stored in the memory 400 and drives the
hand piece 30
according to the corresponding output displacement. In addition to energy
level information,
driving signal characteristics, such as types of amplitude modulation and
resonance frequency,
can be stored in the memory 400. Using the information stored in the memory
400, the
console 10 and the hand piece 30 can perform the error prevention described
herein with
respect to FIG. 6 and FIG. 7, and the reprogramming or upgrade of console 10
described
herein with respect to FIG. 8.
As described herein with respect to FIG. 2 and FIG. 3 and in the related
European Patent No. 1 199 047 the parts of the hand
piece 30 in the operational mode are designed, as a whole, to oscillate at
generally the same
resonant frequency, where the elements of the hand piece 30 are tuned so that
the resulting
length of each such element is one-half wavelength. Microprocessor or DSP 60,
using a phase
correction algorithm, controls the frequency at which the parts of the hand
piece 30 oscillate.
Upon activation of the hand piece 30, the oscillating frequency is set at a
startup value or
nominal resonant frequency such as 50 kHz which is stored in the memory 400 of
the hand
piece 30. A sweep of a frequency range between a start sweep point and a stop
sweep point,
whose values are also stored in the memory 400, is effected under the control
of the DSP 60
until the detection of a change in impedance which indicates the approach to
the resonant
26
CA 02359403 2001-10-17
frequency. Having obtained the resonant frequency, the parts of the hand piece
30 are caused
to oscillate at that frequency.
FIG. 9 is a flow diagram that illustrates the operation of the hand piece 30
according to the invention at a resonant frequency using information stored in
the memory 400.
Once the hand piece 30 is activated (step 901), console 10 reads the memory
400 of the hand
piece 30 (step 903) and retrieves the information needed for operating the
hand piece 30 at the
resonant frequency, including the nominal resonant frequency, a frequency
range delimited by
a start sweep point and a stop sweep point (step 905). A frequency sweep in
that frequency
range is effected under the control of the DSP 60 (step 907). Detection of the
resonant
frequency is effected in step 909. If the resonant frequency has not yet been
detected, the
control flow reverts back to step 907 where the frequency sweep is continued.
Upon detection
of the resonant frequency, the control flow is directed to step 911 where the
parts of the hand
piece 30 are caused to oscillate at that resonant frequency.
FIG. 10 is a diagram that illustrates an alternative embodiment of the
operation
of the hand piece 30 according to the invention at a resonant frequency using
information
stored in the memory 400. Instead of storing the start and stop sweep points
of a frequency
range for the frequency sweep, the memory 400 stores the nominal resonant
frequency and a
bias amount. The console 10 calculates the start and stop sweep points by
subtracting and
adding the bias amount from the nominal resonant frequency, respectively. A
margin, which
is a relatively small amount beyond bias, is tacked on to the bias amount to
respectively reach
the start and stop sweep points of the frequency range in which the frequency
sweep for
seeking a resonant frequency is conducted. Once the resonant frequency is
found, the parts of
the hand piece 30 are caused to oscillate at that resonant frequency.
The memory 400 for an ultrasonic surgical hand piece 30 according to the
invention is located in the electrical connector which is disposed between the
console 10 and
the cable 26. The memory device 400 can also be located in one or more
locations, including
the electrical connector, within the housing of the hand piece 30, or at an in-
line location in the
cable 26.
27
CA 02359403 2001-10-17
In addition to being an EEPROM, the memory 400 can be one or a combination
of a Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM),
Random Access Memory (RAM) or any other volatile memory which is powered by a
cell,
battery, or capacitor, such as a super capacitor. The memory 400 can also be a
Programmable
Array Logic (PAL), Programmable Logic Array (PLA), analog serial storage
device, sound
storage integrated circuit or similar device, or a memory device in
conjunction with a numeric
manipulation device such as a microprocessor for the purpose of encryption.
Although the invention has been particularly shown and described in detail
with
reference to the preferred embodiments thereof, the embodiments are not
intended to be
exhaustive or to limit the invention to the precise forms disclosed herein. It
will be understood
by those skilled in the art that many modifications in form and detail may be
made therein
without departing from the spirit and scope of the invention. Similarly, any
process steps
described herein may be interchangeable with other steps to achieve
substantially the same
result. All such modifications are intended to be encompassed within the scope
of the
invention, which is defined by the following claims and their equivalents.
28
