GB2176009A

GB2176009A - Magnetic field intensity meter

Info

Publication number: GB2176009A
Application number: GB08607762A
Authority: GB
Inventors: Nentcho Georgiev Todorov; Dimiter Tzenev Dimitrov; Tihomir Iliev Manev; Georgi Nikolov Dimov; Magdalena Davidkova Stefanova
Original assignee: V M E I LENIN; Vmei Lenin
Current assignee: V M E I LENIN; Vmei Lenin
Priority date: 1985-03-29
Filing date: 1986-03-27
Publication date: 1986-12-10
Also published as: GB2176009B; DE3610474A1; DE3610474C2; HU198250B; JPS61259183A; GB8607762D0; BG41964A1; JPH0439917B2; HUT40519A

Abstract

A magnetic field intensity meter comprises a plurality of local induction transducers (11.....1N) which can be arranged over a patient, a multiplexer (2) having its inputs coupled to the local induction transducers for coupling their outputs in turn to a recording and/or detecting device (8), and a safety device (9) operable to provide an alarm signal if any of the local induction transducers provides an indication of a deviation from a preset mode of therapy. Each transducer may comprise two windings of equal number, their common ends coupled to neutral and the other ends coupled to the inputs of multiplexor (2). <IMAGE>

Description

SPECIFICATION Magnetic field intensity meter The invention relates to a magnetic field intensity meterwhich may be used in medical applications.

A magnetic field intensity meter is known consisting of an induction transducer which is connected to a recording block by means of a block fortransforming alternating voltage into direct current. Thus see USSR patent No.721782.

The disadvantages of the aforementioned meter include the impossibility of obtaining a wide pattern ofthe magnetic field distribution at different points of a patient area or a patient body, as well as the absence of an alarm in the case of a deviation from a preset mode of therapy.

According to the present invention there is provided a magnetic field intensity meter comprising a plurality of local induction transducers which can be arranged over a patient, a multiplexer having its inputs coupled to the local induction transducers for coupling their outputs in turn two a recording and/or detecting device, and a safety device operable to provide an alarm signal if any of the local induction transducers provides an indication of a deviation from a preset mode oftherapy.

A preferred embodiment of the invention may provide a magnetic field intensity meter providing the possibility of getting a full pattern ofthe magnetic field distribution at different points of the patient area orthe patient body, as well as an alarm for magnetotherapy apparatus in the case of deviation from a preset mode oftherapy.

A detailed embodiment provides a magneticfield intensity meter including an induction transducer, a blockfortransforming the alternating voltage into direct current, and a recording block connected to an interlock block input. The interlock block output is connected to the blocking input of magnetotherapy apparatus. The induction transducer consists of local induction transducers, the latter being N in number, each one containing twowindingswiththesame numberofturns,conicallywoundon adielectriccoil with a square cross-section.The joint end of the two windingsofeach local induction transducer is connected to neutral and the othertwo ends ofthe two windings are connected correspondinglyto the N-inputs of a controllable electronic commutatoror multiplexer, to the control input of which the output of a control program block has been connected. The two outputs ofthe controllable electronic commutator are connected to the inputs of two low-frequencyfilters whose outputs are connected correspondingly to the noninverting and inverting inputs of a differentiating or differential amplifier. The amplifier output is connected to the blockfor transforming the alternating voltage into direct current.

The advantage of such a magnetic field intensity meter is the possibility of getting a full pattern of the magneticfield distribution at orto various points of the patient area or patient body, as well as the interlock in the magnetotherapy apparatus in case of deviation from the present mode oftherapy.

An exemplary embodiment of the invention is shown in the drawing, Figure 1 being a block-diagram ofthe meter and Figure 2 being a drawing of one of the local induction transducers.

According to Figure 1 the alternating magneticfield intensity meter comprises of N local induction transducers 11, 1 2,...1 1 N' each transducer having twowindings with the same numberofturns.The joint end of the two windings of each differentiating or differential transducer 1 is connected to neutral, the othertwo ends of the two windings of each transducer being connected to the respective N-inputs of a controllable electronic commutator or multiplexer 2. The output of a control program block3 is connected to the control input ofthe electronic commutator2.

The two outputs ofthe electronic commutator 2 are connected respectively to the inputs of two identical low-frequencyfilters 4 and 5,whose outputs are connected rerspectivelyto the noninverting and inverting inputs of a differentiating or differential amplifier 6. The output of the latter is connected to the input of a block7 fortransforming the alternating voltage into direct current, i.e. an a.c. to d.c.

converter. The block 7 is connected to the input of a recording and/or detecting block 8, which is connected to an interlock block 9 which is itself connected to the interlock or blocking input of magnetotherapy apparatus 10. Figure 2 shows winding 11 of a local induction transducer, the former being conically wound on a dielectric coil with a square cross-section.

The operation ofthe alternating magnetic field intensity meter in a magnetotherapy method is as follows: The local induction transducer 11,12, 1N are to be arranged according to medical requirements in specified points ofthe patient area 1, so thatthe bigger base of winding 11 should be in contact with the patient. This guarantees higher sensitivity of the transducers li, 12 lNtO magnetic signals coming from the patient area, against interfering magnetic signals coming from outside during measuring weak magnetic fields. When stronger magnetic signals are being measured the transducers 11,12,....1Nare turned with their small base to the patient. The second case is applied in magnetic signal control of some organs ofthe human body during magnetotherapy.

The efficient magnetic signals induce in the two windings of each local induction transducer 11, 12,...1N equal and opposite-phased voltages, the latter being proportional tothe degree ofthe measured magnetic intensity and to the frequency ofthe magnetic signals. The frequency ofthe cut-off points of the low-frequency filters 4 and 5 is determined by the choice ofthe filter elements in such a way that it is lowerthan the lowest frequency ofthe efficient magnetic signal applied i n m in magnetotherapy.

Thus, after passing through filters4and 5the information signals sent to both inputs ofthe differentiating amplifier6forfrequencieshigherthan the lowest frequency f0, become frequency-independent. According to the medical requirements a scanning program is set up from the control program block 3 by means ofthe electronic commutator 2. The inputs ofthe local induction transducers 11,12 1N are thereby applied, in accordance with the program, in a fixed order and for à definite period of time to the inputs ofthe low-frequency filters 4 and 5.The intensity ofthe magnetic signals in all N-points ofthe patient area is followedfora certain period oftimewhich is specified forthe therapeutical seance or session. The amp-lified voltage from the output of amplifier6 is fed to block7 for transforming the alternating voltage into direct current whose value is proportional to the mean value of the alternating magneticfield intensity atthe point in which the corresponding transducer1 is located. The output signal from block7 is fed to the recording block 8 which in turn actuates the interlock block 9. If the value allowedforthe alternating - magnetic field is exceeded in any ofthe N-points of the patient area, or in the case of effecting the completion ofthe program for the time ofthe therapeutical seance or session, a blocking signal is fed from block 9 to the magnetotherapy apparatus 10, thus possibly forming or indicating a magneticfield in the patientarea at which the apparatus is switched off.

Claims

1. Amagneticfield intensity meter comprising a plurality of local induction transducers which can be arranged over a patient, a multiplexer having its inputs coupled to the local induction transducers for coupling their outputs in turn to a recording and/or detecting device, and a safety device operable to provide an alarm signal ifany of the local induction Irnhsducers provides an indication of a deviation from a preset mode oftherapy.

2. A meter according to claim 1, wherein the safety device is coupled to detect signalsfrom the recording and/or detecting device.

3; Ameteraccording to-claim 1 or2, wherein each local induction transducer comprises two windings with the same number of turns, the joint end ofthe two windings being coupled to neutral andthe other two winding ends being coupledto inputs ofthe multiplexer.

4. A meter according to claim 3, wherein each local induction transducerthe windings are wound conically on a dielectric coil with a substantially square cross-section.

5. A meter according to any preceding claim, wherein the multiplexerhas a control input coupled to a control program device.

6. A meter according to any peceding claim, wherein the multiplexer has two outputs connected to low-frequency filters, which are themselves coupled to the inverting and noninverting inputs respectively of a differential amplifier.

7. A meter according to any preceding claim, comprising an a.c. to d.c. converter coupled between the transducers and the recording and/or detecting device.

8. A meter according to claim 7 when appended to claim 6, wherein the a.c. to d.c. converter is connected totheoutputofthedifferential amplifier.

9. Amagneticfield intensity meter substantially as herei nbefore described with reference to the accompanying drawing.

10. A meter according to any preceding claim, when coupled to a magnetotherapyapparatusfor blocking the same by said alarm signal.