United States Patent [19J
`Erickson et al.
`
`[75]
`
`[54] DOUBLE-TRANSDUCER SYSTEM FOR
`PEMF THERAPY
`Inventors: John H. Erickson, Plano; John C.
`Tepper, Carrollton, both of Tex.
`[73] Assignee: American Medical Electronics, Inc.,
`Dallas, Tex.
`[21] Appl. No.: 586,505
`[22] Filed:
`Sep. 21, 1990
`Int. Cl.5 ............................................... A61N 1/00
`[51]
`[52] U.S. Cl . ......................................... 600/13; 600/15
`[58] Field of Search ...................................... 600/9-15;
`128/419 F, 802
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,548,208 10/1985 Niemi .................................... 600/14
`4,654,574 3/1987 Thaler ................................... 600/14
`4,850,959 7/1989 Find! ..................................... 600/14
`5,045,050 9/1991 Liboff et al. ............................ 600/9
`5,106,361 4/1992 Liboff et al. .......................... 600/15
`
`I 111111111111111111111 lllll 1111111111111111111111111 lllll 111111111111111111
`US005181902A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,181,902
`Jan. 26, 1993
`
`Primary Examiner-Lee S. Cohen
`Assistant Examiner-John P. Lacyk
`Attorney, Agent, or Firm-Baker & Botts
`
`[57]
`ABSTRACT
`A PEMF double-transducer system (FIG. 1) used for
`PEMF therapy (such as after spinal fusion) uses a two(cid:173)
`transducer configuration for generating flux-aided elec(cid:173)
`tromagnetic fields. The semi-rigid transducers (12, 14)
`are comformable, anatomically contoured and flat(cid:173)
`wound to enhance patient comfort, and incorporated
`with an adjustable belt (16) to provide bracing. The belt
`includes compartments for a drive electronic module
`(22), and a rechargeable battery pack (24), making the
`system portable. The drive electronics (FIG. 3) includes
`a PEMF processor (41) that executes a PEMF program
`for providing pulsing current to the front and back
`transducers at predetermined intervals, thereby activat(cid:173)
`ing the electromagnetic field according to a prescribed
`PEMF regimen.
`
`9 Claims, 2 Drawing Sheets
`
`14
`
`10
`,,'
`
`17
`
`Allergan EX1074
`Page 1
`
`

`

`U.S. Patent
`
`Jan. 26, 1993
`
`Sheet 1 of 2
`
`5,181,902
`
`14
`
`10
`~
`
`16
`
`17
`
`FIG. 1
`
`34
`
`30
`~
`
`32
`
`FIG. 2
`
`Allergan EX1074
`Page 2
`
`

`

`N
`0
`\C
`"""'
`...
`"""' 00
`...
`UI
`
`0 ....
`(t) ....
`00 =(cid:173) (t)
`
`N
`
`N
`
`~
`
`IC w
`IC
`,...
`9'
`N
`~
`
`('D = f"'+-
`~ a.
`•
`• rJ)
`c::
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`I ~
`
`I
`I
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`
`DISPLAY 45
`
`INlERVM.
`
`48
`
`40
`
`1
`
`11
`
`FIG. 3
`
`DOT MATRIX
`16 CHARACTER
`
`CLOO< 44
`AND REAL TIME
`DATA MEMORY
`
`1/0 PORT
`
`49
`
`-=
`-·
`____ _.
`72 I
`COIL:
`BACK•
`!SEC
`:
`----,
`1
`
`I
`
`'82
`
`PRI
`
`-=
`
`-=
`
`-,
`SENSE
`
`I
`I
`I
`I
`I
`I
`
`I _ _.
`
`81
`
`PRII SEC
`
`I COIL
`:FRONT
`:
`,------
`
`I 71 ·-L-----
`
`47
`
`MEMORY !J
`PROGRAM
`PEMF
`
`DECODER 42
`LATCH AND
`ADDRESS
`
`.il
`
`PROCESSOR
`
`MICRO(cid:173)
`PEMF
`
`VOLTAGE
`LOW BATTERY
`
`'--84
`
`RECOVERY
`ENERGY
`
`All lc'S CAPAaTANCEl
`+5V TO
`
`REGULATOR
`VOLTAGE
`S'MTCHING ~52
`
`PRINT PUSHBUTTON
`ALARM BUZZER
`
`THERMOSTAT PROTECTED
`
`BATTERY PACK
`10-CELL NICAD
`
`_
`
`-
`
`~ONNECTO~ I
`I
`I CHARGER
`r BATTERY
`
`-----------------------------,
`
`lL ___________ -=_ ______________ _J
`.
`:
`• I
`I
`.1l 1
`I
`I
`
`Allergan EX1074
`Page 3
`
`

`

`DOUBLE-TRANSDUCER SYSTEM FOR PEMF
`THERAPY
`
`TECHNICAL FIELD OF THE INVENTION
`The invention relates generally to pulsed electromag(cid:173)
`netic field (PEMF) therapy, and more particularly re(cid:173)
`lates to a PEMF system that uses two transducers to
`provide PEMF therapeutic stimulation to a target area
`of the skeletal system (such as the spine), and a method
`of fabricating the system.
`
`15
`
`35
`
`1
`
`5,181,902
`
`2
`circuit. The secondary windings and the energy recov(cid:173)
`ery circuit are active during a deenergization cycle to
`recover energy to conserve battery power-the second(cid:173)
`ary windings are also used to tailor the electromagnetic
`5 field.
`In an exemplary embodiment, the PEMF double(cid:173)
`transducer system is used for spinal PEMF therapy,
`such as for post fusion repair. For both transducers,
`primary, secondary and sense windings are flat wound,
`IO permitting the shell to be formed with a substantially
`flat cross sectional profile. The shell is a semi-rigid
`formable polyurethane elastomer.
`BACKGROUND OF THE INVENTION
`The drive electronics includes a PEMF processor
`Pulsed electromagnetic fields (PEMF) are low(cid:173)
`that executes a PEMF program for controlling the
`energy, time-varying magnetic fields that are used to
`activation of the electromagnetic fields (field strength
`treat therapeutically resistant problems of the musculo(cid:173)
`and duty cycle). In addition to implementing the PEMF
`skeletal system. Those problems include spinal fusion,
`therapy program, the PEMF processor collects appro(cid:173)
`ununited fractures, failed arthrodeses, osteonecrosis,
`priate data in memory to enable the attending health
`and chronic refractory tendonitis, decubitus ulcers and
`20 care professional to monitor the course of the therapy.
`ligament and tendon injuries.
`The transducers are incorporated with a belt that
`The specific problem to which the invention is di(cid:173)
`permits the transducers to be placed around a patient
`rected is an improved PEMF spinal stimulation system
`and secured in place in front and back of the patient.
`for providing PEMF therapeutic stimulation to areas of
`The belt includes compartments for a drive electronics
`the spinal column undergoing fusion or other repair
`25 module and (rechargeable) battery pack.
`(such as treatment to salvage a failed fusion).
`Each transducer is fabricated as follows. Primary,
`For spinal PEMF therapy, an electromagnetic trans(cid:173)
`secondary and sense windings of adhesive coated mag(cid:173)
`ducer is placed on the patient's back such that pulsing
`net wire are wound around a flat mandrel with an ap(cid:173)
`the transducer produces an applied or driving field that
`propriate anatomical shape for the transducer. The
`penetrates to the spinal column. The conventional ap(cid:173)
`30 windings are bonded by heat curing the adhesive to
`proach has been to use a single flexibly packaged trans(cid:173)
`obtain a flat-wound flexible winding bundle. The wind(cid:173)
`ducer of wires coupled to a source of driving current.
`ing bundle is placed in a mold, and encapsulated in a
`The flexible transducer is conformed to the contour of
`semi-rigid shell. A bending fixture is used to configure
`the patient's back, and strapped into place. By control(cid:173)
`the transducer with the selected anatomical contour.
`ling the drive electronics, an appropriate PEMF ther(cid:173)
`The technical advantages of the invention include the
`apy can be administered.
`following. The PEMF double-transducer system in(cid:173)
`Current spinal PEMF systems are disadvantageous in
`at least two respects. To allow a patient to be ambula(cid:173)
`cludes two transducers, a Helmholtz design that is mag(cid:173)
`tory during therapy, additional bracing is usually re(cid:173)
`netic flux-aiding to optimize the electromagnetic field
`quired to prevent bending that might dislodge or stress
`available for stimulating the target area, and to reduce
`the area undergoing treatment. Also, the single trans- 40
`system power consumption. The transducers are config(cid:173)
`ducer configuration fails to take advantage of the flux(cid:173)
`ured with an anatomical contour, and with a substan-
`aiding effect of a two transducer system to maximize
`tially flat cross sectional profile that provides a broad
`field uniformity.
`contact area, thereby enhancing patient comfort. The
`Accordingly, a need exists for an improved PEMF
`transducers are formable with a selected degree of ri(cid:173)
`system that can be used without additional bracing, and 45
`gidity, and with a selected anatomical contour and pro(cid:173)
`provides more uniform active field to the target area
`file, providing a conformable brace without any special
`than available using a single transducer configuration.
`conforming assembly or process (such as heat). The
`transducers can be incorporated into a belt or other
`SUMMARY OF THE INVENTION
`securing means to provide an integrated semi-bracing
`.
`.
`.
`The present mventlon 1s a PEMF double-transducer 50 d
`.
`th PEMF d
`•
`p
`bl d ·
`I
`ti
`system that takes advantage of flux-aiding to achieve
`est~ ~r e
`evice. rogramma e nve e cc-
`improved field uniformity. The semi-rigid transducers
`tromcs ~plement_a P~MF pro~am to control el~tro-
`are contoured and flat-wound to enhance patient com-
`magnetic field ac!1vat1~n accordmg to a predete~ed
`fort while obviating the need for additional bracing.
`PEM:: therapeutic re~m~n, and store and provide ap-
`In one aspect of the invention, the PEMF double- 55 propnate data for momtonng t?e progress oft~e PEMF
`transducer system includes front and back transducers,
`ther~py. The transducers are mcoryorated wi~h a belt
`both including at least a primary winding with a se-
`that mcludes compartments for a dnve electr~mcs J:?od·
`lected number of turns encased in a shell that is at least
`ule and a rechargeable battery pack to provide a mte-
`semi-rigid. The transducers are anatomically contoured,
`grated, portable PEMF system.
`and are physically coupled for releasably securing the 60
`BRIEF DESCRIPTION OF THE DRAWINGS
`transducers on either side of a target area for PEMF
`therapy. Drive electronics are coupled to the primary
`winding of both transducers for selectively generating
`electromagnetic fields, thereby implementing a pre(cid:173)
`scribed PEMF therapy program.
`In more specific aspects of the invention, each trans(cid:173)
`ducer includes both primary and secondary windings,
`and the drive electronics includes an energy recovery
`
`For a more complete understanding of the invention,
`and for further features and advantages, reference is
`now made to the following Detailed Description of an
`65 exemplary embodiment of the invention, taken in con(cid:173)
`junction with the accompanying Drawings, in which:
`FIG. 1 illustrates an exemplary spinal PEMF double(cid:173)
`transducer system according to the invention;
`
`Allergan EX1074
`Page 4
`
`

`

`5,181,902
`
`3
`FIG. 2 is a cross sectional view of a transducer show(cid:173)
`ing the flat-wound bundle of windings, and the encapsu(cid:173)
`lating shell; and
`FIG. 3 is a schematic block diagram of the drive
`electronics.
`
`4
`the patient starts the PEMF program by turning on the
`drive electronics module.
`In accordance with the stored PEMF therapy pro(cid:173)
`gram, the PEMF processor correspondingly control the
`5 activation current supplied to the transducers, thereby
`controlling the electromagnetic fields in terms of ener(cid:173)
`DETAILED DESCRIPTION OF THE
`gization time, deenergization time and duty cycle (repe(cid:173)
`INVENTION
`tition rate). In addition to controlling the PEMF ther-
`apy, the PEMF processor maintains treatment data that
`The Detailed Description of an exemplary embodi-
`ment of the PEMF double-transducer system of the JO is available on request to the patient (through a small
`invention is organized as follows:
`display), and to a health care professional (via an I/O
`I. Spinal PEMF System
`port) for monitoring and analysis.
`2. Transducer Fabrication
`2. Transducer Fabrication. For an exemplary em-
`3. Drive Electronics Module
`bodiment, the front and back flat-wound contoured
`4. Conclusion
`15 transducers are fabricated as follows.
`The exemplary embodiment is a self-contained porta-
`FIG. 2 is a cross sectional view of a transducer (front
`ble PEMF system for providing PEMF therapy to
`or back) 30 that includes primary, secondary and sense
`windings 32 encapsulated in a semi-rigid shell 34. The
`the spinal column, such as for fusion repair.
`I. Spinal PEMF System. FIGURE illustrates an ex-
`primary, secondary and sense windings are not shown
`emplary spinal PEMF double-transducer system 10. 20 differentiated in the FIG., nor is the total number of
`The system includes front and back transducers 12 and
`windings shown meant to be accurate-the FIG. is
`14 incorporated with an adjustable belt 16.
`illustrative only.
`Transducers 12 and 14 are anatomically contoured to
`For the exemplary embodiment, a transducer in-
`enhance patient comfort, with a substantially flat cross
`eludes two parallel primary windings of about 7 turns
`sectional profile that provides a broad contact area, 25 each, a secondary winding of about 35 turns, and a sense
`thereby enhancing patient comfort . The transducers
`winding of at least 1 turn. For the primary and second-
`ary windings, 18 gauge wire can be used, while 22
`are semi-rigid to maintain the selected contour and
`profile, and to provide bracing support as a fully inte-
`gauge wire can be used for the sense winding. The
`grated PEMF system. As described in Section 2, the
`approximate dimensions of the winding bundle are 0.75
`transducers include flat-wound primary, secondary and 30 by 0.12 inches, while the approximate dimensions of the
`sense windings encapsulated in a shell of a plasticized
`shell are 1.50 by 0.31 inches.
`elastomer material (such as polyurethane) with a se-
`The winding material is a commercially available
`lected degree of rigidity.
`magnet wire that includes an overcoat of an adhesive,
`The transducers include both primary and secondary
`such as polyurethane adhesive coated wire. The shell is
`windings, with the secondary windings being used to 35 a polyurethane-type elastomer material, also available
`provide energy recovery, and as a collateral function, to
`commercially. Other shell materials can be used to pro-
`assist in tailoring the electromagnetic field output from
`vide different degrees of transducer-shell rigidity,
`the transducers. Alternatively, the advantages of the
`thereby providing different bracing rigidity characteris-
`PEMF double-transducer system of the invention for
`tics.
`implementing a PEMF therapy could be obtained using 40
`The adhesive-coated primary, secondary and sense
`a pair of transducers, each with only a primary winding
`windings are wound simultaneously in a winding ma-
`(i.e., with no energy recovery windings, but preferably
`chine around a flat mandrel of the appropriate shape for
`with an alternative efficient programmed energy for-
`the transducer. The windings are maintained in the
`mat).
`flat-wound position shown in the FIG. by parallel side-
`Adjustable belt 16 can be fastened by means of a 45 plates. Once wound, the start and finish wire ends for
`buckle 17. The belt includes compartments for a drive
`each winding are cut to provide leads for coupling to
`electronics module 22, and a rechargeable battery pack
`the drive electronics, and the winding assembly-wind-
`24.
`ing bundle, mandrel and sideplates-is removed from
`The drive electronics module includes a PEMF pro-
`the winding machine.
`cessor for providing pulsing current to the front and 50
`The winding assembly is then placed in an oven for
`back transducers at predetermined intervals, thereby
`heat curing at the appropriate curing temperature. Heat
`activating the electromagnetic field according to a pre-
`curing activates the adhesive coating, and the windings
`scribed preprogrammed PEMF regimen. The drive
`are bonded together to form the winding bundle 32.
`electronics is coupled to the back transducer 14 by a
`The winding assembly is removed from the oven and,
`cord 26.
`55 after cooling, a sideplate is removed, allowing the
`The battery pack can be recharged using an AC
`bonded winding bundle to be removed. The winding
`adapter 28.
`bundle is now in a flexible, bonded unit.
`The winding bundle 32 is placed in a substantially flat
`In operation, a health care professional determines a
`PEMF therapy that includes a regimen of PEMF stimu-
`mold of the appropriate shape, with the winding leads
`lation of a target area of the spine. The prescribed 60 running out of the mold fill slot. The polyurethane type
`PEMF therapy regimen is translated into a PEMF pro-
`elastomer material is then introduced into the mold to
`form the shell 34.
`gram, which is programmed into a PEMF memory in
`the drive electronics, either during manufacture or sub-
`For the exemplary embodiment, a two component
`sequently.
`polyurethane elastomer is used: an isocyanate and a
`To commence a PEMF therapy session, the patient 65 polyol. In a vacuum, the two components are mixed,
`arranges the contoured front and back transducers for
`and then poured into the mold, covering the winding
`comfort, and engages the buckle (adjusting the belt to
`bundle. These steps are performed in a vacuum to elimi-
`control snugness). Once the PEMF system is in place,
`nate entrapped air which can cause voids that reduce
`
`Allergan EX1074
`Page 5
`
`

`

`5,181,902
`
`5
`structural integrity and are cosmetically undesirable.
`The mold is placed in an oven for heat curing the poly(cid:173)
`urethane type elastomer material to form the encapsu(cid:173)
`lating shell 34.
`After cooling, the potted transducer is removed from 5
`the mold. The transducer is cleaned of mold release, and
`any flash is trimmed off.
`Finally, the transducer is placed in a bending fixture,
`and bent into the desired anatomical contour. The com(cid:173)
`pleted semi-rigid transducer is now ready to be incorpo- 10
`tated into the belt, and coupled to the drive electronics.
`3. Drive Electronics Module. The drive electronics
`module includes the PEMF processor and the associ(cid:173)
`ated PEMF memory for storing a PEMF therapy pro(cid:173)
`gram.
`FIG. 3 is a schematic block diagram of drive elec(cid:173)
`tronics 40, which includes a PEMF processor 41, with
`associated IC (integrated circuit) components: an ad(cid:173)
`dress latch and decoder circuit 42, a PEMF program
`memory 43, a data memory and real time clock circuit 20
`44, a 16 character dot matrix display module 45 and an
`interval timer/pulse counter 46. The PEMF processor
`is coupled to these components by an address bus 47 and
`a data bus 48.
`A PEMF program can be loaded into an EPROM or 25
`other memory and installed as PEMF program memory
`43; alternatively, the PEMF program can be read into
`the PEMF program memory via an I/O port 49. Data
`co11ected during execution of the programmable PEMF
`program parameters- such as start time, stop time, 30
`duration, and daily average -is stored in the data mem(cid:173)
`ory 44, and can be read out to a printer (or over a com(cid:173)
`munications link) via the I/O port 49.
`The PEMF processor 41 receives power from a
`power source, such as a 12 volt NICAD battery pack 35
`50, through a switching voltage regulator 52 (which
`also provides +5 volts power to the other IC compo(cid:173)
`nents).
`PEMF processor 41, and the supporting IC TTL
`logic chips and display module, function conventionally 40
`and are commercial1y available. For the exemplary
`embodiment, PEMF processor 41 is an Intel 80C51
`processor. The address latch and decoder IC 42 is actu(cid:173)
`ally two chips, a 74HC573 and 74HC138. The PEMF
`program memory is a 2864 8 Kbyte EEPROM that is 45
`loaded with a PEMF program during manufacture, but
`that can be altered electrical1y while in use. The data
`memory and real time clock IC 44 is a Mostek
`MK48T02, used to store representative data about the
`patient's use of the PEMF system based on the inter- 50
`nal1y maintained clock and calendar. The 16-character
`dot matrix display module 45 is a standard integrated
`display module package.
`The interval timer/pulse counter IC 46 is an Intel
`82C54 that includes two general purpose counters con- 55
`trol1ed by the PEMF processor, executing the PEMF
`program, to establish the duty cycle of the pulse output.
`The pulse output, in turn, controls the energization and
`deenergization of the transducers, and thereby deter(cid:173)
`mines the activation of the magnetic fields used in the 60
`PEMF therapy.
`For the exemplary embodiment, the PEMF program
`causes the interval timer/pulse counter IC 46 to output
`a variable programmed train of, for example, 99 pulses
`lasting 25,740 microseconds, with a pulse period of 65 65
`microseconds on and 195 microseconds off. That is, for
`each pulse, the transducers are energized for 65 micro(cid:173)
`seconds and then deenergized (recovery phase) for 195
`
`6
`microseconds. A pulse train is output to the transducers
`every 667,000 microseconds (every 667 milliseconds or
`one third of a second).
`timer/pulse
`the interval
`The pulse
`trains from
`counter 46 are input to a transducer drive amplifier 62,
`which control FET switches 64 and 65. The FET
`switches control the activation current through the
`primary windings of the front and back windings 71 and
`72, thereby controlling the energization and deenergiza-
`tion of the transducers. When switched on (during a 65
`microsecond on pulse), activation current from the
`battery 50 flows through the primary windings, energiz(cid:173)
`ing the transducer. When switched off (during the 195
`microsecond off period), current flows through the
`15 secondary windings as the transducer is deenergized.
`The other ends of the primary windings for the front
`and back transducers are coupled to the battery 50, as
`are the corresponding ends of the secondary windings
`through diodes 81 and 82 (the other ends of the second(cid:173)
`ary windings are grounded). A group of four energy
`recovery capacitors 84 release energy during trans-
`ducer energization, and store energy during transducer
`deenergization. Thus, the energy recovery capacitors
`84 and the diodes 81 and 82 for an energy recovery
`circuit that operates in conjunction with the secondary
`winding to provide energy recovery, thereby conserv-
`ing battery power.
`The sense winding for each of the transducers is cou(cid:173)
`pled through a field sense amplifier 90 to the PEMF
`processor 41. The field sense amplifier senses the elec(cid:173)
`tromagnetic fields generated during transducer activa-
`tion, and provides feedback to the PEMF processor for
`monitoring the PEMF operation. The PEMF processor
`causes appropriate monitori"1g data to be stored in the
`data memory 44, and will cause an alarm signal in the
`case of malfunction.
`4. Conclusion. Although the invention has been de-
`scribed with respect to a specific, exemplary embodi(cid:173)
`ment, various changes and modifications may be sug(cid:173)
`gested to one skilled in the art. For example, while the
`exemplary embodiment is described in relation to a
`spinal PEMF system, the PEMF double-transducer
`system can be used to provide PEMF therapy for other
`areas of the musculoskeletal system, such as the hip or
`collar bone, with the transducers being being anatomi(cid:173)
`cal1y contoured positioning on either side of the target
`area. Also, the exemplary PEMF system is completely
`portable, while the advantages of the invention can be
`obtained from a system designed to be non-portable.
`Therefore, it is intended that the invention encompass
`all changes and modifications that fal1 within the scope
`of the appended claims.
`What is claimed is:
`1. A PEMF double-transducer system for providing
`PEMF therapeutic stimulation to the spine of a patient's
`body, comprising:
`front and back transducers, both including at least a
`primary winding with a selected number of turns
`encapsulated in a shel1, said shells being at least
`semi-rigid for providing support to the patient, said
`she11s being anatomically contoured for situating
`on either side of a target area of the spine for
`PEMF therapy and physically coupled for releas(cid:173)
`ably securing said transducers in place;
`drive electronics coupled to said primary winding of
`both said front and back transducers for selectively
`activating an electromagnetic field, thereby imple(cid:173)
`menting a prescribed PEMF therapy;
`
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`
`

`

`5,181,902
`
`7
`said drive electronics including a PEMF processor
`and a PEMF program for controlling said proces(cid:173)
`sor to energize and deenergize said transducers to
`implement a predetermined PEMF therapy pro(cid:173)
`gram for the patient's spine;
`said drive electronics also including circuitry for
`monitoring the patient's use of the PEMF system
`and the course of the PEMF therapy; and
`a battery pack electrically connected to said drive
`electronics
`a belt supporting the front and back transducers and
`having compartments containing the drive elec(cid:173)
`tronics, the battery pack, and a buckle for releas(cid:173)
`ably securing the transducers in place such that the
`PEMF double transducer system is portable.
`2. The PEMF double-transducer system of claim 1,
`wherein:
`both front and back transducers further include a
`secondary winding with a selected number of
`turns;
`said drive electronics including an energy recovery
`circuit coupled to said secondary winding for re(cid:173)
`covering energy during each activation of said
`transducers.
`3. The PEMF double-transducer system of claim 2 25
`wherein said energy recovery circuit includes an en-
`
`8
`ergy recovery capacitance coupled in parallel with said
`primary and secondary windings.
`4. The PEMF double-transducer system of claim 1,
`wherein both front and back transducers further include
`5 a sense winding with a selected number of sense turns,
`said sense winding being coupled to said drive electron(cid:173)
`ics for providing a feedback indication of the PEMF
`output from said transducers.
`S. The PEMF double-transducer system of claim 1,
`JO wherein the transducers have a substantially flat cross
`sectional profile.
`6. The PEMF double-transducer system of claim S,
`wherein, for both the front and back transducers, the
`primary and secondary windings are flat wound.
`7. The PEMF double-transducer system of claim 6,
`wherein the windings are adhesive coated magnet wire,
`bonded into a winding bundle prior to encapsulation.
`8. The PEMF double-transducer system of claim 1,
`wherein said encapsulating shell is a polyurethane elas(cid:173)
`tomer.
`9. The PEMF double-transducer system of claim 1,
`wherein said drive electronics generates clock and cal(cid:173)
`endar data, and wherein said PEMF program collects
`clock and calendar data representative of the patient's
`use of the PEMF system.
`• • • • •
`
`15
`
`20
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`Allergan EX1074
`Page 7
`
`

`

`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`5,181,902
`January 26, 1993
`John H. Erickson et al.
`
`PATENT NO.
`DATED
`INVENTOR{$) :
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`Column 3, line 19, underline "l. Spinal PEMF System".
`
`Column 3, line 19, after "FIGURE" insert -- 1 --.
`
`Column 4, line 13, underline "2. Transducer Fabrication":
`
`Column 5, line 12, underline "3. Drive Electronics Module".
`
`Column 6, line 37, underline "4. Conclusion".
`Column 7, line 8, delete "and".
`Column 7, line 10, insert --;and --after "electronics".
`In abstract, sentence 8, delete "electronic" and insert --electronics--.
`
`·
`
`Signed and Sealed this
`
`Eleventh Day of April, 1995
`
`Attest:
`
`Attesting Officer
`
`Commissioner of Patents and Trademarks
`
`BRUCE LEHMAN
`
`Allergan EX1074
`Page 8
`
`