DE1764454A1 - Switching device for an electrical muscle stimulator - Google Patents

Description

PATENT ADVERTISEMENT 176 A4 54

Dr. DIETER LOUIS,

Kino KiIiFKr, 92'5 1;> / re

MURNIiERQ
1

MEDICAL & BIOLOGICAL INSTRUMENTATION LIMITED Wotton Road, Kingsworth Industrial Estate, Ashford, Kent, England

Switching device for an electrical muscle stimulator

Addition to patent ... (patent application P 15 64 529.5)

The subject of the main patent (patent application P 15 64 i? 29.5) is a switching device for an electrical muscle stimulator which, with the help of two generators, one of which generates wave-shaped signals, the other of which generates rectangular pulses of higher frequency, and a mixer or pulse modulation circuit in which the Square-wave pulses are modulated with the wave-shaped signals of lower frequency, pulse series with the frequency of the square-wave pulses is available, the amplitudes of which are determined by the course of the wave-shaped output signal. These pulse trains are supplied to an output stage and are thus available as unipolore excitation pulses for muscle stimulation is available. ■ · ·

The magnitude of the muscle contraction depends to a certain extent on the polarity of the

Stimulation applied impulses. With symmetrical

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Task of such a series of pulses using a pair of electrodes Conditions arise in which the muscle leanings produced are not symmetrical.

In a further embodiment of the inventive concept, the present invention provides the teaching of making the pulse series available in bipolar form, with the successive pulses alternately having opposite polarities. The application of such bipolar series of pulses significantly reduces the likelihood of unbalanced muscle reactions.

Of course, the shape of the impulses is not necessarily rectangular, as is the wave-like output signals of the corresponding generator to a large extent as arbitrary alternating wave or as a chain wave-shaped pulses can be formed.

The circuit solution provides for the pulse modulation of the output signals of both generators with the aid of a Gate circuit »which assumes two different and alternately occurring switching states at the rate of the output pulses of the pulse generator, to be carried out in such a way that the '' pulse series occurring at the output of an output transformer have pulses of alternating polarity.

Two basic circuit arrangements are shown as an example presented, one of which is the uni-

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splits polar Impuleserien in staggered rhythm of the pulse frequency and alternately supplies the formed with the aid Bweier primary windings or einur Priraörwioklunß with Kittelanzapfung two inputs aesAusgangstranjformators and the other of the modulation of the ready alternately applied to two separate switching elements pulses provides that also two inputs aen of Ausgangötraneformators alternately are fed.

Further features of the invention emerge from the following f the description of the embodiments shown in the drawing. Show it

Figure 1 is a block diagram of an embodiment of the invention

must switch device;
FIG. 2 shows the graphical representation of signal forms, v / ie they at different points of the switching device

Figure 1 occur;
Figure> a circuit diagram of part of the switching device

according to Figure 1;
FIG. 4 shows the graphic representation of pulse distances as they are at various points in the circuit diagram

Figure y occur;
Figure 5 is a block diagram of another embodiment of the

switching device according to the invention; Figure 6 is a circuit diagram of the switching device geuäss Fi

gttr 5; '
Figure 7 is a graphical representation of waveforms such as

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at different points of the circuit diagram according to Figure 6 occur;

Figure β the block diagram of a further embodiment the switching device according to the invention.

In Figure 1 is a generator with a wave-shaped output signal 1, the output of which is connected to a micro stage 2 (pulse modulator) via a line 3. The exit a square pulse generator 4 is also connected to this Miecbetufe 2 via a line 5. The output of the Kiech stage is fed to an output stage 7 via a line 6. This switching arrangement corresponds roughly to that of the main patent; the importance of a delay switch arrangement 11 and a Gate switching arrangement 9 is used in connection with FIG described.

In Figure 2, the representation (a) shows the wave-shaped output signal of the generator 1 and (b) the output signal of the square * pulse generators 4 in a significantly enlarged time table. The output signal of level 7 is - as in (c) shown in Figure 2 - a series of unipolar. iMpuleeerien, which in this form when applying eur muscle ~ Stimulation lead to uneymoetriechen Muekelsusaaeneieuungen

In the diagram in FIG. 1, the square-wave pulse generator is present 4 further a line 10 with a delay circuit arrangement

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and the output of which is connected via a line 12 to the input of a gate switching arrangement 9 which simultaneously receives the output signals of the output stage 7 via a line 8. The output of the gate switching arrangement 9 is connected to the input of an output transformer 15 via a line 14. FIG. 3 shows the circuit diagram of the delay switching arrangement 11, the gate switching arrangement 9 and the output transformer 15, the scope of the switching arrangements 11 and 9 being delimited from one another by dashed lines. The "circuit diagram of FIG. 5 is described in the following in connection with the pulse shapes that are shown in FIG. 4 on an exaggeratedly large time scale (compared to FIG. 2 (a)) in order to clarify their relationship to one another. The in (a) The signal form shown here represents the square-wave signal which is fed via line 10 from an output of generator 4 to the input of delay switching arrangement 11. This signal is fed to a differentiating circuit formed from a capacitor 18 and a Y / resistor 19, the negative trailing edge of the differentiated signal over {diode 20 the base of transistor 21 is supplied, which is connected together with a further transistor 22 to a monostable multivibrator. the collector output of transistor 22, and thus the delay circuit provides an output signal in (b) of the figure 4. This graph shows that the output signal of the delay switching arrangement 11 is shifted relative to the output signal of the generator shown in (a).

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The output of the delay switch circuit 11 becomes. The gate switching arrangement 9 is supplied via the line 12, which includes a bistable multivibrator with the transistors 23 and 24 and an electronic switch arrangement with the transistors 26, 28, 50 and 32. The bistable multivibrator is in turn controlled with the trailing edges of the pulses originating from the nonostable multivibrator and the delay switching arrangement in such a way that the transistors are switched through alternately for time intervals which are proportionate to those of the switching periods of the transistors of the monostable multivibrator (distance between the output pulses of the pulse generator 4) The electronic switch arrangement 'has two transistor switches, which are formed on the one hand from the transistor 26, the diode 27 and the transistor 28 and on the other hand from the transistor 30, the diode 31 and the transistor j> 2 and their inputs each with one of the collector outputs of the bistable multivibrator are connected. FIG. 11- gur 4 (c) shows the voltage curve of the signal taken from the collector of transistor 24; It can be seen that the voltage rises as soon as the transistor is switched off at the end of an output pulse of the delay switching device, and that the voltage drops again as soon as the transistor is switched on again at the end of the next pulse of the delay switching device. For the duration of the through-connection of the transistor 24, the transistor 23 is not conductive and vice versa. The transistor 28 j is turned on in the non-conductive state of the transistor 23 and the transistor 32 is in the non-conductive state of the

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Transistor 24 turned on. The emitters of the transistors 28 and 52 aind via line 8 to the output signal of the Output stage 7 connected, which is shown in Figure 2 (o). This signal on line 8 contains pulse series whose of the amplitudes describing envelope is determined by the wave-shaped output signal of the generator 1, which with occurs in phase with the respective output signal of the square-wave pulse generator. The collector output of the transistor 28 is in series with a primary winding 33 of the output trans- j formator 15 and the collector output of transistor 32 is in series with another primary winding 34 of the output transformer 15 switched.

In Figure 4 (d) the voltage pulses are shown that occur at the collector of transistor 32, while in (e) of the same figure the collector voltage pulses of transistor 28 are shown. The signal forms depend on the one hand on the switching state of transistors 28 and 32, the the signals of the bistable multivibrator is determined, and on the other hand by the signal on the line 6, which is fed to the emitters of these two transistors. The switching signals of the bistable HuIt! Vibratorβ reaching the respective bases of the transistors are delayed with regard to the signals passed to the emitters of these transit gates, so that a switching process never occurs during a voltage pulse on the line 8. JDIe two primary windings 33 and 3t of the output transformer 15 are wound in opposite directions, so that βλ the outputs of the secondary windings of the transformer 15

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Series of impulses occur »their successive impulses have opposite polarity, as in Figure 4 (f). You describe the impulse that occurs Bin envelope of the shape of the waveform output signal of the generator 1, as shown in Figure 2 (c), however, this envelope now occurs above and below the zero line. If these bipolar signals obtained in this way are applied to one of the secondary windings via a pair of electrodes When a muscle is laid, symmetrical muscle contractions are achieved.

FIG. 5 shows the block diagram of a further embodiment of the switching device according to the invention has a generator 36 which generates a similar, wave-shaped output signal, as shown in Figure 2 (α). This signal is fed to a gate switch 37 'via a line 40. The output of a square pulse generator i> 8 is via line 41, a bistable multivibrator 39 and a line 42 connected to the gate switch 37, the output of the square-wave pulse generator 38 being connected via a line 43 is also directly connected to the gate switch 37. The output signals of the gate switch 37 are via a Output stage 45 is fed to an output transformer 46.

In Figure 6, the main circuit devices are shown with regard to the block diagram of Figure 5 and marked by corresponding dashed lines. The circuit diagram of FIG. 6 is in connection with the graphic

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BATH ORIGINAL

Signal representations are described in FIG. The generator 36 with a wave-shaped output signal has two freely oscillating interconnected transistors 47 and 48 (astable multivibrator). The conduction and blocking periods of the transistors are determined by the values of the capacitors 49 and 30 and their associated resistances. The output of this generator is fed to a transistor 52, which feeds an amplified current to the gate switch 37 via the line 40. The Rechteckimpulsgeneratqr also has two swinging freely g zuBammengesehaltete transistors 53 and 54; its output signal is fed via a line 41 to a bistable multivibrator with the transistors 55 and 56 for their control (triggering). The course of the output voltage of the square-wave pulse generator 38 on the line 41 is shown in FIG. 7 (a).

The output of the transistor shown in Figure 7 (b)

55 becomes the base of a transistor 57 operating as a gate supplied, on whose base input also the one on the

Line 41 occurring output signal of the square pulse generator " tors via line 43 is switched on.

The output of the transistor shown in Figure 7 (c)

56 becomes the basis of another translator working as a gate 58 is supplied, on whose base input also the output signal of the square-wave generator appearing on line 41 peeled via line 4'3 on 1st.

Those fed to the collectors of transistors 57 and 58

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high voltage describes the amplified, wave-like output signal of generator 36 occurring on line 40.

The resulting output signal at the collector of transistor 57 is shown in FIG. 7 (d) and the output signal is at The collector of transistor 58 is shown in Figure 7 (e). A comparison of the two representations of these output signals shows that the transistors alternately generate the pulses. The amplitude of these impulses is included determined by the simultaneously occurring amplitude of the amplified, wave-shaped output signal of the generator 36.

The collector output of the transistor 57 is via Yeretärkerstufen, which have two transistors 60 and 61, with one Half 62 of a primary winding of the output transformer 46 provided with a central tap. In a similar way Way is the collector output of transistor 58 via amplifier stages, which have two transistors 63 and 64, connected to the other half 65 of the primary winding of the output transformer 46.

The resulting output signal of the secondary winding of the Trans * formator 46 thus has a series of pulses alternating

Polarity, as shown in Figure 7 (f), the amplitude of which depends on the prevailing amplitude of the undulating Output signal of the generator 36 is determined.

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Figure θ attaches the schematic representation of a further embodiment Bform the inventive switching device, the also an output signal with square-wave pulses with alternating opposite polarity is generated, the amplitude of which corresponds to the respective prevailing amplitude of a wave-shaped output signal of a generator. The output of a generator 68 with a wave-like output signal is via a Line 69 connected to the input of a mixer 70 (pulse modulator). There is also an output of a square-wave pulse generator 71 is switched to an input of this mixer stage 70 via a line 72. A second output of the square pulse generator 71 leads via a line 73 to a delay and control circuit stage 74. The output of the mixer stage 70 is via a

Line 7ü connected to an output stage 76, the output of which is switched to the primary winding of an output transformer via a double changeover switch 78. The operation the contacts of the double changeover switch can be made with the aid of a relay controlled by the control switching stage 74 as indicated by the dashed line 79. The | Line 81 is connected to a high voltage; the Output signal, the secondary winding 80 becomes defa output transformer taken.

This switching device shown in Figure 8 operates in in a manner similar to that described with respect to FIGS. 1, 2 and 3. The electronic switch assembly used there is here replaced by a mechanical switch; Instead of the primary coils wound in opposite directions, there is a single primary coil. A Srsatζ of the mechanical switch by equivalent

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BATH ORIGINAL

electronic switch is of course within the scope of the invention. Eb is still not necessary) that the generators Generate 4 »38 and 71 square-wave pulses. Likewise can impulses

be used in wave form or other shape.

It should be expressly noted that, although in these switching devices both generators oscillate freely, the use of such generator types is not mandatory. It can Controlled generators are used, the operation of which depends on the switch position of a switch. Furthermore can a freely oscillating trained generator with wave-shaped Output voltage control a square wave pulse generator of higher frequency.

The generator for wave-shaped output signals is designed in such a way that the leading edge of the output signal is gradual increases as shown in Figure 2 (a). This waveform can be in a known manner with the help of a resistor and a capacitance can be set in the generator circuit. In this way an output signal is achieved which ensures a gradual increase in the impulses applied to the muscle.

The pulse generator is preferably designed so that the ratio of "on" to "off" or the ratio of pulse duration to pulse interval is less than 1.

»
As can be seen from Figure y , the output transform

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mator normally has several secondary windings, the outputs of which are each connected to a pair of electrodes. About this applied to the body of a patient
Electrode pairs, the output signals of the transformer are fed to individual muscles for their stimulation.

The invention is not limited to the following claims
limited. It includes all features from the above description and the drawing that are evidently inventive based on the prior art.

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Claims (1)

Claims Switching device for an electrical muscle stimulator with a generator for wave-shaped signals, a generator for pulse-shaped signals and a pulse modulation and switching device, whose inputs are connected to the outputs of the generators and to their output lines through the wave-shaped signal modulated pulse-shaped signals occur in the form of pulse series, according to patent ... (patent application P 15 64 329.5) characterized in that the pulse modulation and switching device (2, 71 9 »11) (37, 29» 45) (70, 741 76, 78) on the output side with the input or inputs an output transformer (15) (46) (77, 80) connected and for the generation of pulse series from in the temporal Successive pulses of opposite polarity on the or the outputs of the transformer isf, whereby the Pulses occur at the frequency of the generator for pulse-shaped signals. fass 4er Qenera | or | to | »| α | β | ^ | β |||||| e is designed as a feedback pulse generator . 3. Switching device according to one or both of the preceding claims, characterized in that »at least one of the beWen Generators (1) is trained. BATH ORIGINAL 4. Switching device according to one or more of the preceding claims, characterized in that the leading edges the series of pulses occurring on the output side due to the pulses of the transformer (15) (46) (77, 80) described envelopes are formed gradually rising on both sides of the zero line. 5. Switching device according to one or more of the preceding claims, characterized in that the generator for pulse-shaped signals (4) (38) (71) a "On ^tl -" Off "- or a pulse duration-pulse pause ratio less than one " having. 6. Switching device according to one or more of the preceding claims, characterized in that the pulse modulation and switching device (2, 7, 9, 11) (70, 74, 76, 78, ″ has a delay switching arrangement (11) (74). 7. Switching device according to one or more of the preceding claims, characterized in that the Impulsmo- g dulations- and switching means (2, 7, 9, 11) (> 7/3, ■ "]}) an electronic switch means ( 26-28, 30-32) (60, 61, 63, 64.). 8. Switching device according to one or more of the preceding Claims "1 to 6, characterized in that dacc cie Pulse modulation and switching device (70, 74, 76, 78) has a mechanical switch arrangement (78). 009849 / 07S6 176U54 9. Switching device according to one or more of claims 1 to 6, characterized in that the pulse modulation and switching device (2, 7 »9» 11) has a gate switching arrangement (9). ■ ₍ r 10. Switching device according to claim 9, characterized in that the return edge of a pulse originating from the delay circuit is used to control one of the delay switching arrangement (11) downstream of the switching element of the gate switching arrangement (9). 11. Switching device according to one or more of the preceding claims, characterized in that the pulse modulation and switching device (37, 39 _f 4i>) has a bistable switching element (55 »56), at the input of which an output of the generator for pulse-shaped signals ( 36) is connected. j 12. A switching device according to claim 11, characterized in that the Impulsmodulatione- and switching means (37,> 9, 45! has a gate switch (37) whose both Auogangsslgnale depend respectively from three Elngangssignalen. 13 · Switching device according to one or more of the preceding claims, characterized in that the output transformer (15) has two oppositely wound input - 16 - 009849/0755 to original ^ 176U54 tr has windings, H * switching device naoh one or more of the claims 1 to 12, characterized in that the transformer (46) has an input winding (62, 65) with a center tap having. 15 · Switching device according to one or more of the preceding Claims, characterized in that the generators (1, 4) (36, 38) (68, 71) transistors open * point. 16. Switching device according to one or more of the preceding claims, characterized in that the Pulse modulation and switching device (9) (37) has a pair of transistors. 0098 * 9/0755