Note: Descriptions are shown in the official language in which they were submitted.
CA 02359426 2001-10-17
10 APPARATUS AND METHOD FOR ALERTING GENERATOR FUNCTIONS
IN AN ULTRASONIC SURGICAL SYSTEM
RELATED APPLICATIONS
The present invention generally relates to, and claims priority of U.S.
Provisional Patent Application 60/241,886 filed on October 20, 2000 and
entitled "BLADE
IDENTIFICATION IN AN ULTRASONIC SURGICAL HANDPIECE", having a common
assignee as the present application, which is incorporated herein by
reference.
CA 02359426 2001-10-17
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an apparatus and method for
alerting generator functions in an ultrasonic surgical system and more
particularly, to an
ultrasonic surgical 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 to achieve coagulation, causing
vaporization and
fumes as well as splattering. 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 operating 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
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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, which is assigned to the assignee of the present
application and
is incorporated herein by reference, 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 (tissue contact or withdrawal) of the blade. As a result, the device
goes from a low
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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
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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 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
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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.
However, the prior art systems do not provide for authentication of the use
of the hand piece with the generator 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
generator console
having a digital signal processor (DSP) for controlling the hand piece, and a
memory device
such as an EEPROM (Electrically Erasable Programmable Read Only Memory)
disposed in
the sheath of the end-effector or in the handle, grip, or mount portion of
shears or scissors
or forceps. A data string, which identifies the hand piece and generator
performance
characteristics, is stored in the memory device. During initialization of the
system and/or
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periodically during standby or ready or while in use, the generator console
sends an
interrogation signal to the hand piece to obtain a readout of the memory. As
the generator
console reads the memory, the hand piece blade or shears is authenticated for
use with the
generator console if the proper data string is present. The hand piece blade
or shears is not
authenticated for use with the console if the data string is not present or is
not correct. In a
particular embodiment of the invention, the data string is an encrypted code,
where the hand
piece or blade or shears is authenticated for use with the generator 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 or blade or shears,
the
memory can store certain diagnostic information which the generator console
can utilize in
determining whether the operation of the hand piece should be handicapped or
disabled or
alert an end user without handicap-or disable-mode operations. 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,
maximum allowable rate of change in temperature, and other limits. 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 generator 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 generator console is
needed. If it is
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determined that a reprogram or upgrade is needed, the generator console reads
the memory
located in the sheath of the end-effector of the hand piece where a reprogram
or upgrade code
is stored. Using the reprogram or upgrade code read from the memory, the
generator console
is reprogrammed or upgraded accordingly. Therefore, the generator consoles in
the field can
be upgraded automatically without having to return them to the manufacturer or
to send a
service technician to the generator console. Alternately, rather than
reprogramming the
generator memory, the blade/shear memory data is utilized by the generator
console as the
basis for operation parameters for the particular blade/shear in use. Default
parameters are
reverted to in operating the hand piece when particular parameters are not
present in
subsequent blades/shears attached to handpiece.
T'he memory can also store energy level information and corresponding output
displacement for driving the particular hand piece. By reading the energy
level information,
the generator console can drive the hand piece according to the output
displacement which
is best for that hand piece and/or blade/shears.
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
generator
console effects a frequency sweep in the indicated frequency range for
detecting a resonant
frequency for operating the hand piece. Ln addition, the memory can store
frequencies or
frequency ranges that should not be swept, such as frequencies that are or
tend to be
transverse-resonant which should be avoided. These stored frequencies can be
in the wider
specified sweep range allowed, which is stored in the blade/shear memory.
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In accordance with the invention, a method is provided for implementing
procedures in a system including an ultrasonic surgical hand piece having a
end-effector, a
console having a digital signal processor (DSP) for controlling the hand
piece, and a memory
disposed in the sheath of the end-effector in or attached to the hand piece.
The method
according to the invention includes reading information stored in the memory,
determining
whether a particular data string is present in the memory, authenticating use
of the hand piece
or blade or shear with the console if the data string is present, sending a
drive current to drive
the hand piece, and imparting ultrasonic movement to the end-effector of the
hand piece
according to information in the memory. In a particular embodiment, the method
according
to the invention also includes decoding an encryption algorithm in the
generator console, and
providing a responding data pattern, where the data string 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
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further steps of instructing the hand piece to operate in a handicap mode if
the number of
activations for the hand piece within a time period exceeds 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 generator
console is
needed, reading a reprogram or upgrade code stored in the memory and
reprogramming the
generator console using the reprogram or upgrade code, if it is determined
that a reprogram
or upgrade of the generator 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 or blade or shears. 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 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 addition, frequencies or frequency bands to be avoided
in the
CA 02359426 2001-10-17
sweeping or driving, or the transverse resonant frequencies, can be stored for
use by the
generator to operate the handpiece or portion diagnostics.
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 (not necessarily drawn
to scale)
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;
FIG. 3A and FIG. 3B are block diagrams illustrating the ultrasonic according
to an embodiment of the invention;
FIG. 4A is a schematic illustration of transducer drive circuitry of a power
transformer 86 of FIG. 3B;
FIG. 4 is a diagram that illustrates a non-volatile memory in the sheath of
the
end-effector in the ultrasonic surgical hand piece according to the invention;
FIG. 4B is a diagram that illustrates a non-volatile memory in the
handle/grip/mount portion (non-sheath portion) of ultrasonic shears according
to the
invention;
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FIG. S 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. SA is a flow diagram illustrating the operation of the non-volatile
memory according to the invention;
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. 6A and FIG. 7A are flow diagrams illustrating the operation of the non-
volatile memory according to the invention;
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;
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;
FIG. l0A is a diagram illustrating an alternative embodiment whereby
frequencies to avoid operating the handpiece are included in the blade/shears
memory.
FIG. 11 is an isometric view of a portion of the ultrasonic surgical hand
piece
with a non-volatile memory in the end-effector in accordance with the
invention;
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FIG. 12 is a side view of a portion of the ultrasonic surgical hand piece with
a non-volatile memory in the end-effector in accordance with the invention;
FIG. 13 is a side section view of a portion of the ultrasonic surgical hand
piece with a non-volatile memory in the end-effector in accordance with the
invention;
FIG. 14 is a diagram illustrating an alternative embodiment utilizing a
handpiece adaptor to bridge the non-volatile memory signal to the handpiece
according to
the invention; and
FIG.15 is an illustration of an electromagnetic coupling means for conveying
memory data to and/or from the non-volatile memory according to the invention.
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 20,
electrical energy, i.e.,
drive current, is sent from the generator console 10 to a handpiece 30 where
it imparts
ultrasonic longitudinal movement to a surgical device, such as a sharp end-
effector 32. This
blade can be used for simultaneous dissection and cauterization.of tissue. The
supply of
ultrasonic current to the hand piece 30 may be under the control of a switch
34 located on
the hand piece, which is connected to the generator in the generator console
10 via wires in
cable 26. The generator may also be controlled by a foot switch 40, which is
connected to
the generator console 10 by another cable 50. Thus, in use a surgeon may apply
an ultrasonic
electrical signal to the hand piece, causing the blade to vibrate
longitudinally at an ultrasonic
frequency, by operating the switch 34 on the hand piece with his finger, or by
operating the
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foot switch 40 with his foot.
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. Power switch 11 is used to turn on the unit. While it is
warming up, the
"standby" light 13 is illuminated. When it is ready for operation, the "ready"
indicator 14
is illuminated and the standby light goes out. If the unit is to supply
maximum power, the
MAX button 15 is depressed. If a lesser power is desired, the MIN button 17 is
activated.
This automatically deactivates the MAX button. The level of power when MIN is
active is
set by button 16.
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
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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 with a motion null point
located at some
point along the stack. The transducer stack is mounted between two cylinders
31 and 33.
In addition a cylinder 35 is attached to cylinder 33, which in turn 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 a portion of the
stack
constituting a motionless node, when the transducer is driven at maximum
current at the
transducer's resonant frequency. However, the current providing the maximum
motion will
vary with each hand piece and is a valve stored in the non-volatile memory of
the hand piece
so the system can use it.
The parts of the hand piece are designed such that the combination will
oscillate at the same resonant frequency. In particular, the elements are
tuned such that the
resulting length of each such element is one-half wavelength or a multiple
thereof.
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
CA 02359426 2001-10-17
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. A
motion from
20 to 25 microns at the transducer stack is amplified by the horn 38 into
blade movement of
about 40 to 100 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
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
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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 a 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 S 1 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. The switch generates signals 1 SO 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 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.
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
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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 I 00, 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 104, which
represents the
difference in phase between the current and voltage. The size of this phase
difference is also
an indication of resonance. 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.
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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.
FIG. 4A is a schematic illustration of transducer drive circuitry of a power
transformer 86 of FIG. 3B. The transducer is represented by an equivalent
electrical circuit
with The components Co, Ls, Cs, and Rs form a transducer equivalent circuit
Tequiv, where
Co is a shunt capacitance and represents the electrical capacitance of the
piezoelectric
elements of the piezoelectric transducer 36 shown in FIG. 2.
Ls, Cs and Rs are an electrical equivalent of the overall mechanical system
and collectively represent the mechanical branch. Ls is the effective mass of
the system, Cs
is the effective compliance and Rs represents mechanical losses associated
with friction,
internal material dissipation and/or the power delivered to the tissue.
Inductor Lt is matched to the shunt capacitance Co at the resonance of the
ultrasonic system, such as approximately 55.5 kHz. Hence, Lt and Co
electrically cancel
each other at the resonant frequency. As a result, all of the drive current
will flow through
the mechanical branch. This helps to ensure that the ultrasonic excursion of
the transducer
is primarily proportional to the drive current.
The two resistors Rp/2 sum in series to a resistance of Rp. This resistance
helps to establish an upper limit of the overall impedance of the output
circuit, and also
establishes an upper limit for the drive voltage. In preferred embodiments, Rp
is a relatively
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large resistance. At resonance, the parallel combination of Rp and Rs is
effectively Rs,
because Rs is much smaller then Rp, even when coagulating and cutting tissue.
The series combination of capacitors Cvl and Cv2 forms a voltage divider.
Together these capacitors reduce the high voltage that typically drives the
transducer to a
level which is appropriate for signal processing by integrated circuits (not
shown). A
transformer Vt couples the reduced voltage to the feedback circuitry (voltage
sense 92 of
FIG. 3B) and also provides isolation between the drive circuitry and the other
circuitry of the
generator.
A small voltage drop is provided across the series combination of resistors
R3 and R4. In the preferred embodiment, the series combination is a relatively
low
resistance in the order of ohms. The voltage drop across R3 and R4 is
proportional to the
drive current. This voltage is provided to the feedback circuitry (current
sense 88 of FIG.
3B) through a transformer IT, which also isolates the drive circuitry from the
rest of the
circuitry of the generator. This signal represents current in the control
algorithms
implemented in the generator.
R1 and R2 are used to establish a minimum impedance level to the control
circuitry for use in the control algorithms. The resistance is divided between
the two output
arms Vout 1, V out2 of the power transformer to help mitigate electromagnetic
radiation and
leakage current.
FIG. 4 is a diagram that illustrates a non-volatile memory 400 in the sheath
of the end-effector according to the invention. The memory 400 is
advantageously provided
in the sheath of the end-effector for reducing unneeded complexity in
electrical isolation
CA 02359426 2001-10-17
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 sheath of the end-effector, adequate electrical
isolation ofthe circuitry
in the memory 400 from the hand piece 30, the human operator thereof, and the
patient is
readily achieved. Also, the number of wires in cable 26 can be reduced.
FIG. 4B is a diagram that illustrates a non-volatile memory 303 in the grip
portion of shears 300 according to the invention. Alternate or additional
locations for
memory are also shown as memory 301 located in the mount portion and/or memory
302 in
the grip portion of shears 300. The shears 300 is attached to handpiece 310.
The contacts
304 and 305 are resident within, outside, or embedded into the shears mount or
grip vicinity
and are wired to the memory. T'hese,contacts make connection with
corresponding contacts
within or on the handpiece to permit generator communications through the
handpiece to the
memory in the shears.
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 end effector
or blade or shears with the generator console 10. Inappropriate usage includes
hazardous
use, poor operational usage, or non-compatible use or unapproved use with the
generator
console 10.
FIG. 5A is another flow diagram that illustrates the operation of the memory
400 or 301, 302, or 303. In this particular embodiment of the method according
to the
invention, the memory in the blade or shears is periodically queried
independent of
21
CA 02359426 2001-10-17
handpiece activation, for example, at intervals of 10 seconds. This particular
embodiment
allows generally immediate detection of blade change and generally immediate
detection of
blade type attached. Such information can contribute to diagnostic
functionalities that
monitor handpiece temperature, temperature rate of change, and other
parameters to adjust
triggers and thresholds and allow the display of blade type and related
parameters in the
generator console in advance of the next activation.
In step SOl, the handpiece 30 is activated, e.g., by pressing the button 18 on
the generator console 10 for hand activation of the handpiece. In step 503,
the generator
console 10 then reads the memory 400. In step 505, it is determined whether a
proprietary
data string is present in the memory 400. The data string, input into the non-
volatile memory
for all authorized hand pieces, is in digital or analog form. The data string
can also be a
musical, speech, or sound effect in either digital or analog format. Having a
proper
proprietary string in the memory 400 means that the use of the hand piece with
the generator
console 10 is authorized or authenticated. If the data string is present in
the memory 400, the
hand piece 30 is enabled or activated by the generator console 10 (step 507).
If the data
string is 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
generator console 10 indicating unauthorized use.
In a specific embodiment according to the invention, when the generator
console 10 reads the data string 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
22
CA 02359426 2001-10-17
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 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 1 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
23
CA 02359426 2001-10-17
the iButtonTM family of hardware devices commercially available from Dallas
SemiconductorTM.
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 string in the memory 400 for authenticating use of the hand piece
with the generator
console 10. Prior to the calculation of the CRC of a block of data, the 8-bit
CRC is first
initialized to zero. When the generator console 10 reads the 8 bytes of the
data string in the
memory 400, an 8-bit CRC is calculated for each of the 8 bytes of the data
string. If the
resultant 8-bit CRC is equal to zero, then the use of the hand piece with the
generator 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 the generator console 10 is not
authenticated, the
hand piece not enabled, and an error message appears on the display device 12
at the
generator console 10 indicating unauthorized use.
/.
FUNCTION
mlan CRC8
PASSED PARAMETERS
'data' - data byte to calculate the 8 bit crc from
'crc8' - the current CRC.
RETURN
the updated 8 bit CRC.
24
CA 02359426 2001-10-17
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,
1 O 1, 59,217, I 35, 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, I 41,11 I , 49,178,236, 14, 80,
1 5 175,241, 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, 9,23 5,18 I , 54,104, I 38,212,149,203, 4 I , I 19,244,170, 72, 22,
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_CRCB(uchar data, uchar crc8)
return crc_ table[crc8 ~ data];
}
CA 02359426 2001-10-17
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 is first initialized to zero. When the generator console 10 reads the
16 bytes of the
data string in the memory 400, an 16-bit CRC is calculated for each of bytes 1
through 30
of the data string, 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 the
generator
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 the generator console 10 is not
authenticated, the
hand piece not enabled, and an error message appears on the display device 12
at the
generator console 10 indicating unauthorized use.
/'
FUNCTION
mlan CRC 16
PASSED PARAMETERS
'data' - current word to add into the CRC
'crc 16' - the current value of the 16 bit CRC
RETURN
new value of the 16 bit CRC
/.
static int oddparity[16] _ {0, 1, l, 0, 1, 0, 0, 1, l, 0, 0, 1, 0, 1, 1, 0};
26
CA 02359426 2001-10-17
uint mlan-CRC 16(uint data, uint crc 16)
data = (data ~ (crc 16 & OxffJ) & Oxff;
crc 16»=8;
if (oddparity[data & OxfJ ~ oddparity[data » 4])
crc 16 ~ =Oxc001;
data «=6;
crc 16 ~= data;
data «= 1;
crc 16 ~= data;
return crc 16;
Furthermore, the data string in the memory 400 can be an encrypted code
which, when decoded by a corresponding encryption algorithm resident at the
generator
console 10, provides a responding 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
27
CA 02359426 2001-10-17
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 the generator
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 or 301 ) for every hand piece and blade and shears
manufactured which
is compatible for use with the generator console 10, where identity is assured
since no two
hand pieces or blades or shears are alike. In a specific embodiment according
to the
invention, the memory 400 is the DS2430A 1 wire EEPROM device, commercially
available
from DALLAS SEMICONDUCTORTM, 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 acknowledge 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 SEMICONDUCTORTM.
This advantageously provides scalability for providing a system with
additional surgical
devices on a local area network (LAN) operated on generally the same
communications
protocol.
28
CA 02359426 2001-10-17
FIG. 6 and FIG. 7 are flow diagrams that illustrate the operation of the
memory 400 or 301 according to the invention for error prevention when using
the sheath
1100 with the generator console 10. To prevent errors in operating the
handpiece 30, the
memory 400 or 301 can store certain diagnostic information which the generator
console 10
can utilize in determining whether the operation of the handpiece 30 should be
handicapped
or disabled. For instance, the memory 400 or 301 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, allowable temperature rate of
change, and
any other performance characteristics such as, e.g., 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 or 301. Exemplary performance characteristics that
can be
stored in memory 400 or 301 (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 handpiece equipped with a
test tip or end-
effector (row S), 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, handpiece impedance (row 12), total on-time information
at specific
power levels (rows 13 and 14), handpiece enable/disable diagnostics
information (row 15),
handpiece 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
29
CA 02359426 2001-10-17
redundancy check (CRC) data (row 22). Other characteristics such as blade
dampening
behavior can also be stored in the memory.
Moreover, the memory 400 can store user-specific data such as user name,
internal tracking number, calibration schedule, and custom output performance
specifications. The user-specific data can be manipulated or programmed
through the
generator console 10 or initialized at the time the end effector is made at
the factory. In
addition, the memory can be used in conjunction of specialized instruments
such as cartery
or self heating devices, homogenizers and liquifiers.
CA 02359426 2001-10-17
TABLE 1
t~" ~a~y '~~i~ i~~~~ 14 Total on-Time @ level
~~ ~~ ~ r ~~~' ~~ <5
P"
~~l~~;'
'~ ~'~
~
,
~
~
r ~3
~~~IC~~~, ~~~~~~~ ~
~~
~
~
r v ~ ~
'~yi.t
4
~ "~ _ ~ i ~' ~ ~~ 1 ~
~i t ~~~" ~~~~~ a~ ~ i~
z'W,~ W h '~~t.F! a y1~
~
~Ae
..iA~,~~y g~
L ~.~i~~~,~ ~ "~ ~ ~"e(
~"~ ~~ iy f 3 ~~
x. ~~~ ~t~
~W~:~b9 '~ ~ i
~
~5
~~~ ~'
R -~ '~~
;
~
t I Hand piece Diagnostics
~ 5 EnabIelDisable
~
~' i n
~
~
F p ~' ~ _ & E ~
:
"
" ' '
~
~~
.
~ Fl
, f b
y ~ ~ ~ ~~
i~i ~~ ~ ~
,
'a
~ ~'
~ ags
=. yte no. 1
1 Bits I-3: Device Type
Bits 4-8: Revision
~ 2 Current set point
Isetpoint
3 Transducer Capacitance
C
4 Cable Capacitance Hand piece Diagnostics
Enable/Disable
C~ Flags byte no. 2
5 Phase margin with test tip
Pm
6 Resonance frequency
f
7 Allowed Procedures Remaining
8 Lower bound on seek/lock
frequency
ff
fr
f
(o
set
om
ro)
16 Hand piece error code
1 (newest)
f
9 Upper bound on seek/lock Hand iece error code 2
frequency
(offset from fro) Hand iece error code 3
f"p~, ~,~a Hand iece error code 4
Hand iece error code 5
oldest
10 Maximum ou ut wer level 17 OCo Over Temp Entry
5 W
11 Bit 1 Backside power curve
control
variable:
Ca ed Power-1; Descendin
ower= U
1 5 Bit 2; Single cap at all 18 ~Co Over Temp Exit
levels =1,
Different cap for each power
level = 0
19 CoMax Rate of Change
Bit 3: Hand piece Authorized20 Current Excessive Load
Activation Limit
Fla .
Bits 4-8: Unused 21 Hi Im edance with test
ti fault limit
12 Hand iece Im edance, Re 22 Data CRC
~ Total On-Time @ level 5 I
-~ l
3
T
31
CA 02359426 2001-10-17
FIG. 6A and FIG. 7A are flow diagrams that illustrate the alerting of an end
user to issues or difficulties triggered by parameters stored in the
blade/shears memory.
Rather than handicapping or reducing functional capabilities, which can
interrupt or degrade
the surgeon's ability to perform the procedure, this particular embodiment of
the method
according to the invention allows the end user to manually halt use at a
convenient point in
context with the nature of the alarm and the surgical work immediately at
hand.
According to a specific embodiment of the invention, once the handpiece 30
is activated for use, the generator console 10 reads the memory 400 or 301
(step 601 ) for the
diagnostic information. In step 603, the generator console 10 determines
whether the
temperature of the handpiece 30 is over the handicap limit stored in the
memory 400. If so,
the generator console 10 then instructs the handpiece 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. If not, the flow
control goes to
step 607, where the generator console 10 determines whether the temperature of
the
handpiece 30 is over the disable limit stored in the memory 400. If so, the
generator console
10 disables the handpiece 30 (step 609). If not, the flow control goes to step
611, where the
generator console 10 determines whether the number of defective blades found
within a time
period of operating the handpiece 30 has exceeded the handicap limit stored in
the memory
400. If so, the generator 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 or
in a limited mode such as coagulation or cutting in order to decrease the
incidence of causing
the blade 32 to become defective. The handicap mode in step 613 is not
necessarily the same
32
CA 02359426 2001-10-17
as the handicap mode in step 605, depending on the optimal mode for operating
the
handpiece 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 the generator 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, the generator console 10 disables the
handpiece 30 (step
609). If not, the control flow is directed, via step A, to step 617, where the
generator console
determines whether the time the handpiece 30 has been active has exceeded the
handicap
limit stored in memory 400. If so, the generator console 10 instructs the
handpiece 30 to
10 operate in a handicap mode, e.g., operating below a certain speed or
vibrational frequency
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 handpiece 30 under the circumstances with respect to
steps 603, 611
and 617.
If the time the handpiece 30 has been active has not exceeded the handicap
limit, the flow control is directed to step 621, where the generator 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
the generator
console 10 disables the handpiece 30. If not, the control flow goes to step
623, where the
generator console 10 determines whether the number of activations for the
handpiece 30
within a time period has exceeded the handicap limit stored in memory 400. If
so, the
generator console 10 instructs the handpiece 30 to operate in a handicap mode
(step 625),
33
CA 02359426 2001-10-17
e.g., operating below a certain speed or vibrational frequency 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
handpiece 30 under the circumstances with respect to steps 603, 611, 617 and
623.
If the number of activations for the handpiece 30 within a time period has not
exceeded the handicap limit, the flow control is directed to step 627, where
the generator
console 10 determines whether the number of activations for the handpiece 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 the generator console 10 disables the
handpiece 30.
If not, the control flow is directed, via step C, to step 601 from which the
process step
according to this particular embodiment of the invention are repeated until
the handpiece 30
is 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 the generator
console 10 to
determine the operational mode of the handpiece 30. The memory 400 may be re-
initialized
for different disable or handicap limits for varied operational conditions of
the handpiece 30.
The generator console 10 may likewise be re-initialized to operate on varied
criteria for
controlling the operational mode of the handpiece 30 based on the information
stored in the
memory 400.
FIG. 8 is a flow diagram that illustrates the operation of the memory 400
according to the invention for reprogramming or upgrading the generator
console 10 using
the handpiece 30. In step 801, the generator console 10 performs diagnostic
tests on the
34
CA 02359426 2001-10-17
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, the generator console 10 reads the memory 400 of the handpiece 30
where the
reprogram code has been stored in step 800. Using the reprogram code read from
the
memory 400, the functions of the generator console 10 is reprogrammed.
If it is determined in step 803 that the functions of the generator console 10
are adequate or the memory has a newer version of the program, then the
generator console
10 has the flow control directed to step 805. It is determined in step 805
whether an upgrade
is needed for the generator console 10. If so, the flow control is directed to
step 807. In step
807, the generator console 10 reads the memory 400 of the handpiece 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 the generator console 10 is
reprogrammed
and upgraded. For example, if the generator console 10 is experiencing
operational
difficulties with a specific generation or version of the hand piece, an
upgrade from the
memory 400 instructs the generator 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
CA 02359426 2001-10-17
operational difficulties or defectiveness, from which the generator console 10
can be
reprogrammed or upgraded to refuse activation for use with such hand pieces.
In addition to storing reprogram or upgrade code, the memory 400 can also
store performance criteria for operating the handpiece 30 with the generator
console 10. For
example, the memory 400 can store energy level information such as a maximum
energy
level for driving the particular handpiece 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 handpiece 30 and the corresponding output displacement can also be
stored in the
memory 400. The generator console 10 reads the energy level information stored
in the
memory 400 and drives the handpiece 30 according to the corresponding output
displacement. In addition to energy level information, driving signal
characteristics, such
as types of amplitude modulation, can be stored in the memory 400. Using the
information
stored in the memory 400, the generator console 10 and the handpiece 3(1 can
perform the
error prevention described herein with respect to FIG. 6 and FIG. 7, and the
reprogramming
or upgrade of the generator console 10 described herein with respect to FIG.
8.
As described herein with respect to FIG. 2 and FIG. 3 and in the related U.S.
Application Serial No. 09/693,621 and incorporated herein by reference, the
parts of the
handpiece 30 in operational mode are designed, as a whole, to oscillate at
generally the same
resonant frequency, where the elements of the handpiece 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
handpiece 30
36
CA 02359426 2001-10-17
oscillate. Upon activation of the handpiece 30, the oscillating frequency is
set at a startup
value or nominal resonant frequency such as SO kHz which is stored in the
memory 400 of
the handpiece 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 frequency. The change in impedance refers to the impedance of,
e.g., a parallel
equivalent circuit for mathematically modeling the algorithm for controlling
the operation
of the handpiece 30 as described in the related U.S. Application Serial No.
09/693,621.
Having obtained the resonant frequency, the parts of the handpiece 30 are
caused to oscillate
at that frequency.
FIG. 9 is a flow diagram that illustrates the operation of the handpiece 30
according to the invention at a resonant frequency using information stored in
the memory
400, Once the handpiece 30 is activated (step 901 ), the generator console 10
reads the
memory 400 of the handpiece 30 (step 903) and retrieves the information needed
for
operating the handpiece 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 handpiece 30 are caused to
oscillate at that
resonant frequency.
37
CA 02359426 2001-10-17
FIG. 10 is a diagram that illustrates an alternative embodiment of the
operation of the handpiece 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 or 301 stores the
nominal
resonant frequency and a bias amount. The generator 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 handpiece 30 are caused to
oscillate at that
resonant frequency.
Using FIG. 9, the operation of the handpiece 30 according to the invention at
a resonant frequency using information stored in the memory 400 or 301 is
illustrated in
accordance with this particular embodiment. Once the handpiece 30 is activated
(step 901 ),
the generator console 10 reads the memory 400 of the handpiece 30 (step 903)
and retrieves
the information needed for operating the handpiece 30 at the resonant
frequency, including
the nominal resonant frequency, the bias amount and the margin amount (step
905), from
which a frequency range is accordingly calculated as described herein with
respect to FIG.
10. The generator console 10 calculates the start and stop sweep points by
subtracting and
adding the bias amount from the nominal resonant frequency, respectively. The
margin
amount, 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
38
CA 02359426 2001-10-17
frequency sweep for seeking a resonant frequency is conducted. The 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 handpiece 30 are caused to oscillate at that resonant frequency.
The memory 400 for an ultrasonic surgical handpiece 30 according to the
invention is located in the sheath of the end-effector. Alternately, the
memory device, 301,
302, or 303, can be located in the grip, mount, or handle portion of a shears
or shears-like
device or other device. The memory device 400 can also be located in one or
more locations,
including the electrical connector, within the housing of the handpiece 30, or
at an in-line
location in the cable 26. In addition to being an EEPROM, the memory 400 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.
Furthermore, the memory 400 can be disposed in a non-hand piece device which
can be
plugged into the handpiece 30 in substitution of the end-effector.
In yet another embodiment, the blade or shears or end-effector communicates
electrically with the switch adaptor or adaptor rather than directly with the
Handpiece. The
39
CA 02359426 2001-10-17
switch adaptor conveys the signal directly or through intermediate processing
to the
handpiece, acting as a bridge. An example is shown in Figure 14 where switch
adaptor 2005
has contact means to the handpiece 2000 and to the blade memory contacts 2004.
This
construction is particularly helpful when the adaptor is a switch adaptor and
there is
insufficient room for passage of wiring from the bade memory directly to the
handpiece
itself.
In another embodiment, the memory communicates with the handpiece or
with the adaptor via electromagnetic coupling instead of a direct electrical
connection. In
this method, the memory and support electronics is connected to a coil, all of
which is
mounted in or on the blade or shears or end-effector. An example is shown in
FIG. 15,
where a coil 1001 is located in the handpiece or the switch adaptor or the
adaptor that is
positioned in relatively close proximity to the memory coil 1002 located on or
in the blade
or shears. A circuit in the generator console drives and reads the coil 1001.
Thereby, the
memory is read and/or written to by the generator console without the use of
direct wire
connections. This method is advantageous over direct electrical contacts since
it reduces
complexity of end-effector fabrication. It also allows for reading and/or
writing to memory
of blades or shears or other end-effectors that are packaged in sterile
packages which cannot
be conveniently opened - yet the data in that memory needs to be known, such
as number of
uses previously encountered or to permit software upgrades in without opening
the sterile
package.
FIGS.11,12 and 13, respectively using an isometric view, side view and side
section view, illustrate a particular embodiment of the ultrasonic surgical
hand piece with a
CA 02359426 2001-10-17
non-volatile memory (such as an EEPROM) in the end-effector in accordance with
the
invention.
The EEPROM 400 is embedded within the plastic handpiece 30 or housing
of the ultrasonic blade 32. The EEPROM 400 has two terminations with the
power/data
contact 1120 and the ground contact 1110. The EEPROM 400 is embedded within
the
handpiece 30 using an insert or second-shot molding process. The EEPROM 400 is
mounted
or positioned so that the ground contact 1110, which is in contact with the
blade 32, can
close the circuit with the transducer 36 (FIG. 4). The other termination via
the power/data
contact 1120 is molded into a position that allows wire communication of power
or data from
the handpiece 30 to the EEPROM 400.
Referring to FIG. 13 in particular, included with the ground contact 1110 is
a metal shim 1140 that is wired to the EEPROM 400. The ground contact 1110, by
manipulating the metal shim 1140, can close the circuit with the external
contact of the blade
32, which is isolated from the transducer 36. Also included with the
power/data contact
1120 is an EEPROM wire 1130 connecting the EEPROM 400 to the contact 1120. The
contact between the EEPROM 40 and the handpiece 30 can be a momentary one that
is long
enough for determining and authenticating the identification of the blade 32.
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 without departing from the spirit and scope of the invention. Similarly,
any process
41
CA 02359426 2001-10-17
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.
42
