FR2536924A1 - ELECTRO-SURGERY DEVICE COMPRISING A GENERATOR OF VERY STRAIGHT FRONT RECTANGULAR SLOTS - Google Patents

Abstract

GENERATOR OF RECTANGULAR SIGNALS WITH VERY STRAIGHT FRONTS FOR ELECTRO-SURGERY. A CLOCK3 PROVIDES LOGIC SIGNALS, AT THE FREQUENCY OF 56MHZ, TO COUNTERS20-21 OF PROGRAMMABLE CAPACITY, TRIGGERED AT EACH PERIOD OF A FUNDAMENTAL FREQUENCY OF 875KHZ OBTAINED BY DIVISION IN 40-41 OF THE CLOCK FREQUENCY. THE PROGRAMMING BINARY WORDS ARE PROVIDED, FROM A MICROPROCESSOR, BY FIFO10-11 REGISTERS ARRANGED TO PERIODICALLY RECYCLE THE MODULATION SEQUENCE. A POWER AMPLIFIER, INCLUDING FIELD-EFFECT TRANSISTORS50-51 APPLIES THE OUTPUT SIGNALS TO A TRANSFORMER7.

Description

ELECTRO-SURGERY DEVICE COMPRISING A GENERATOR

  RECTANGULAR SLOTS WITH VERY STRAIGHT FRONTS.

  The invention relates to electro-surgery and, more

  especially the waveform of the signals used to

tissue cutting.

  Current electrosurgical units use, for cutting,

  high frequency currents on the order of several hundred

  ranges from K Hz to a few M Hz (between 250 K Hz and 2 M Hz for example) This is generally a pure maintained wave for cutting and, for coagulation or in mixed mode, possibly a modulated wave , at a rate ranging from 80 to% for example, by signals having a frequency of

  the order of ten or a few tens of K Hz.

  The waveform of the modulation signals is chosen from

  empirically and varies from device to device,

  before going from the square or rectangular signal to the sine wave,

  triangular signal, or other signals, even when

  that they are rectangular, have no steep sides, the electrical circuits used do not transmit

  sufficiently high frequencies for this purpose.

  -2- The powers generated in pure continuous wave regime

  are adjustable between O and 200 watts for the appliance class

  so-called low power reils, from O to 300 watts for so-called medium power devices and from O to 400 watts for high power devices. With such high powers, cutting operation very often produces an area of necrotic tissue in the

  electrode attack region and an inner area under

  more or less burnt * because of this drawback,

  important in practice, electrosurgical units are predominant

  mainly used in coagulation.

  The present invention proposes to remedy this drawback

  deny and make blunt cuts of the kind obtained in microsurgery using a beam

laser.

  It relates to an electro-surgery process characterized by the use of rectangular slots having times

  rise less than a few tens of nanoseconds.

  The invention also relates to a device for generating

  such rectangular slots with very steep sides.

  According to a preferred embodiment of the invention, the adjustment of the power supplied by said generator is obtained by modulation of pulse width by means of a clock pulse counting device at frequency

  equal to several tens of M Hz, programmable by an in-

digital training.

  In a particularly advantageous embodiment,

  digital programming information is provided, from

  shot from a microprocessor, by a storage device and

  periodic recycling, which is advantageously

titled by "FIFO" registers.

  Other particularities, as well as the advantages of the invention

  tion will appear clearly in the light of the description

below. -3-

  The single figure in the accompanying drawing represents a provision

  sitive generator of rectangular signals with very steep sides, modulated in width, conforming to a mode

  preferred embodiment of the invention.

  This device essentially comprises: a microprocessor

  sister, not shown, which provides information words to a

  periodic storage and recycling circuit composed of gold-

  ganes 10 to 14; a modulator composed of organs 20 to 22; a quartz oscillator 3; a frequency divider composed of members 40 and 41, a power amplifier comprising

  two field effect transistors 50-51, preceded by a circuit

  attack baking including three field effect transistors

  -61-62 and an output transformer 7, at the terminals second-

  70-71 which are connected to the user bodies.

  Oscillator 3 provides, in the form of rectangular signals

  amplitude ranges 5 volts for example, a clock frequency

  accommodates C for example equal to 56 M Hz, that the dividers 40-41

  divide by 64 to obtain a frequency of 875 K Hz.

  This is applied to the two stages of programmed counters.

  Mables 20-21 and to the output scale 22 of the modulator.

  At each period of the fundamental frequency A (from 875 K Hz

  in the example considered), the counter assembly 20-21 includes

  starts counting the clock pulses (at 56 M Hz) at the start of the period and sends a pulse to the output flip-flop 22 when it has reached its maximum capacity, which is programmed, between O and a value B, equal to 32 in the example described, by the D output bits of the member 11 (in the example considered o B = 32, D = 5) It follows that the modulator supplies, at its output, a square signal whose width can vary from one period to the next, between 0 and 570 ns, in steps of 1 / B = 1/32, depending on the word compound

of the 5 bits mentioned above.

  This word is provided by two FIFO registers 10 and 11 having a

  content of 16 words of five bits each, arranged for background-

  according to one of the following three modes -4- a loading mode, o the necessary command words

  (in number at most equal to 32) to determine a se-

  full frequency modulation, which are provided by; the microprocessor according to the program put into service, are introduced into the assembly 10-11,

  a looped mode, during which these words circulate conti-

  nuately in the two registers, at frequency A, to produce successive complete sequences; finally, a "transparent V" mode, where everything happens as if the word 31 was permanently applied to the modulator, so that the latter provides unmodulated square signals to the

fundamental frequency -

  The operating mode is determined by the

  terface, itself composed of FIFO registers 12 to 14 and which

  receives a control word from the microprocessors.

  The hardware implementation of this set of storage and sequential reproduction of the width modulation control information provided by the microprocessor does not

will not be described in more detail.

  Those skilled in the art will be able to imagine various variants of this set, its realization with FIFO registers being

however particularly simple.

  Note that the use of FIFO, or equivalent bodies

  slow, allows for modulation sequences as varied and complex as desired, comprising any number of periods of the fundamental frequency A and, optionally, a variation in the width of the slots

  from one time slot to each subsequent time slot.

  As, in practice, the microprocessor used uses

  will be CMOS-type components, which have, among other things, the advantage of being insensitive to the noise generated

  by the power amplifier, words cannot be-

  modified only at a rate of 200 K Hz maximum, that is to say that the modulation speed would be relatively low in the absence of a device for storing and recycling

  information It should also be emphasized that the use of

  sation of such a device considerably simplifies programming and makes the microprocessor -5- available, during modulation, for the execution of other tasks, such as security or power control. The unmodulated square signals will generally be used for cutting. For the mixed mode, a sequence comprising 8 slots of width 570 ns, for example, will be used, followed by 8 slots of width zero or less than 570 ns and, for coagulation, a sequence composed of '16 slots of width 570 ns, followed by 16 slots of width zero or less than 570 ns These examples of modulation sequences

  are in no way limiting, the device described allows-

  as long as you want at will some modulation sequences

  conches. The transistors 60-61-62 and 50-51 are advantageously of the VMOS- type: they work in switches and not in class A, which allows them to substantially maintain the stiffness of the sides of the modulated signals In practice, if the signals at 875 K Hz supplied by flip-flop 22 have for example

  rising edges of the order of 10 ns, the amplified signals

  will have fronts on the order of 20-ns: experience has

  shown that such signals are particularly satisfactory

health for electro-surgery.

  The driver circuit 60-61-62 is of a type known per se The series connection of a resistor 620, an inductor 621 and a diode 622 ensures rapid control of the gate of the transistor 62 by the derivative of the signal applied to the gate of transistor 60 The transistor 62 ensures the discharge of the

  gate capacity of the power VMOS transistor 50.

  In the power amplifier, the transistor 51 fulfills an isolation function and facilitates the gate control.

of transistor 50.

  The assembly consisting of diode 72, in series with the circuit

  composed of capacity 73 and resistance 74 in parallel

  lele, assembly connected to the terminals of the transformer primary

  output mater, fulfills, in a manner known per se, a protective function by recovery, during the times of blocking of the transistors, of the accumulated reactive energy

  in primary during conduction times.

  It goes without saying that various modifications may be made.

  tees to the circuits described and shown, without departing from

the spirit of the invention.

-7-

Claims (4)

Patent claims   1 Electro-surgery device comprising a member generating rectangular slots and, characterized in that said generator member is arranged to generate slots having rise times less than a few tens of nanoseconds. 2 Device according to claim 1-, characterized in that it comprises a clock oscillator   (3) at a frequency equal to several tens of M Hz, one divi-   frequency generator (40-41) generating square signals at a fundamental frequency submultiple of the clock frequency, of the order of several hundred K Hz, means (20-21-22) of counting, at from the start of each period of said fundamental frequency, a variable number   of clock periods programmed by digital information   that and means (22) of generating rectangular slots   areas whose width is determined, at each period of   the fundamental frequency, by the duration of said counting.   3 Device according to claim 2,   characterized in that said digital information is provided   denies, from a microprocessor, by a device (10-   14) for periodic storage and recycling of a sequence of binary words 4 Device according to claim 2, characterized in that said storage and recycling device is composed of FIFO registers (10-14) and arranged and   ordered to perform, ie the loading of said se-   quence, that is to say the circulation in loop of the words of said   quence in the device, i.e. the permanent generation of   word that corresponds to the maximum width of the slots. -8-   Device according to one of Claims 2 to 4,   characterized in that the clock frequency is equal to   56 M Hz and the fundamental frequency is equal to 875 K Hz.   6 Device according to one of claims 2 to 5,   characterized in that it further comprises means for   power multiplication of said rectangular slots, -   comprising field effect transistors (50-51).