JP3600862B2 - Electrical stimulator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrical stimulator suitable for assisting motor function or recovering motor function of a drop foot patient.
[0002]
[Prior art]
One of the sequelae of hemiplegia due to cerebrovascular disease is what is called a drop foot. In patients with drop foot, dorsiflexion of the ankle joint becomes difficult due to relaxation of the dorsiflexor muscle group of the ankle joint and enhancement of the plantar flexor muscle group. For this reason, while walking, the ankle joint dorsiflexes due to contraction of the dorsiflexor muscles and the leg swings smoothly in a healthy person, whereas in a drop foot patient, the ankle joint does not dorsiflex and the toe touches the ground. . This “dragging walking” makes it difficult for the patient to walk.
[0003]
FIG. 8 is a diagram illustrating a configuration of an electric stimulator that has been conventionally studied. The electrodes E21 and E22 are arranged on the muscle belly of the muscle whose muscle activity is to be picked up, and the electrode E23 is arranged at an arbitrary position. Even if the patient tries to move the muscle, minute voluntary myoelectricity is generated, and the electrodes E21 and E22 are for detecting the voluntary myoelectricity. Using the electrode E23 as a ground electrode, the voluntary myoelectric signal of the target muscle detected by the electrodes E21 and E22 is input to the measurement amplifier 61 via the input protection resistors R11 and R12. The diodes D11 and D12 limit the voltage to about ± 0.5 V so that the measurement amplifier 61 does not saturate. Thereafter, the signal is amplified by a multistage amplifier 62 having a band of 300 to 450 Hz to a size that can be recognized by the microcomputer 63, and is taken in from the A / D conversion input PIN of the microcomputer 63 at a sampling frequency of 1 KHz. The microcomputer 63 controls the stimulating means 64 by outputting a pulse having a width proportional to the amplitude of the voluntary myoelectric potential. The stimulation pulse is a bipolar pulse, and the anode pulse and the cathode pulse have the same pulse width and amplitude. The stimulus pulse amplitude is about 100 V and the pulse width is adjusted between 50 μs-1 ms, the larger the width, the stronger the stimulus. The stimulation pulse cycle is 50 ms, and at the timing when the pulse is applied, the photo MOS relays SW1 and SW2 are turned on, and the stimulation pulse is conducted to the electrodes E21 and E22. When the stimulus pulse is not applied, the photo MOS relays SW1 and SW2 are turned off, thereby preventing the noise from the stimulating means 64 from being mixed and also preventing the short circuit between the electrodes E21 and E22. The microcomputer 63 controls ON / OFF timing of the photo MOS relays SW1 and SW2. A transformer is suitable as the stimulating means 64 as means for simultaneously realizing the amplitude of 100 V and the isolation. However, it is also possible to use an H bridge circuit using a charge pump booster circuit. In that case, if a phototransistor or a photo MOS relay is used for the transistor portion, the transistor may be isolated.
[0004]
[Problems to be solved by the invention]
However, the above-described related art has the following problems.
In order to detect voluntary myoelectricity, it is desirable to arrange both electrodes on the muscle abdomen, but one of the electrodes must be arranged on the nerve in consideration of the efficiency of electrical stimulation. For this reason, the distance between the electrodes that detect voluntary myoelectricity that should not be separated by more than a few centimeters is large, so that voluntary myoelectricity from not only the target muscle but also other muscles with large involuntary activity is detected. Would.
FIG. 9 is a diagram showing a configuration of a conventional multi-channel type electric stimulator. It is also possible to obtain more stimulus outputs from the circuits described so far. As a conventional technique, in the case of electrical stimulation of an implanted electrode having a small stimulation pulse voltage, the output of an amplifier or the like can be used directly as a stimulation pulse, and it is easy to increase the number of channels. In the electrical stimulation from the surface, as shown in FIG. 9, the stimulation means 71 connected to the electrodes E31 and E32, the stimulation means 72 connected to the electrodes E33 and E34, and the stimulation means 73 connected to the electrodes E35 and E36. As described above, a booster circuit using a transformer is necessary for each channel, and the increase in the size and weight of the apparatus main body was unavoidable.
[0005]
In view of the above problems, an object of the present invention is to provide an electric stimulator capable of independently applying a stimulus signal to three or more electrodes with one transformer for applying a stimulus signal.
[0006]
[0007]
[0008]
[0009]
[0010]
[0011]
[0012]
[Means for Solving the Problems]
Electrostimulation device of the present invention includes a control means for controlling the stimulation signal based on the signal between the two first electrodes of the three or more electrodes and, the three or more electrodes placed on the skin surface, the three Stimulating means for outputting a signal controlled by the control means, the stimulating means having an output having one terminal connected to one second electrode other than the first electrode among the above electrodes, and an output of the stimulating means And a plurality of relays for sequentially connecting the other terminal of the third electrode and the electrodes other than the second electrode among the three or more electrodes .
[0013]
The electrical stimulating device of the present invention further includes a control unit that controls a stimulus signal based on signals between five or more electrodes disposed on the skin surface and a plurality of sets of third electrodes among the five or more electrodes. Stimulating means having an output having one terminal connected to one fourth electrode of the five or more electrodes other than the third electrode, and outputting a signal controlled by the control means; and a plurality of relays end to the other terminal of the output means you sequentially connected to the other end is connected, is connected to the other end of the relay, and a set of the third electrode to at least one relay and a set of switches connected. Thereby, it is reduced in size and weight, and it is made to be worn on the body on a daily basis.
In addition, since the switch is a diac, passive switching becomes possible.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0015]
FIG. 1 is a diagram showing a configuration of an electrical stimulating device on which the present invention is based . This electrical stimulator, mainly electrodes E1, E2, E3, input protection resistors R1, R2, instrumentation amplifier 11, the multi-stage amplifier 12, microcomputer 13, the stimulation means 14, consisting of a diac D1, D2. The weak voluntary electromyogram detected by the electrodes E1 and E2 is input to the measurement amplifier 11 via the input protection resistors R1 and R2 and amplified, and further amplified by the multistage amplifier 12 to such an extent that the microcomputer 13 can recognize it. It is taken into the microcomputer 13 from the D conversion input PIN. The microcomputer 13 performs signal processing to calculate the voluntary electromyogram, and outputs a pulse having a width corresponding to the magnitude to control the stimulating means 14. The stimulating means 14 applies a stimulus to the electrodes E1 and E2 via the diacs D1 and D2, and further directly applies a stimulus to the electrode E3.
[0016]
The electrodes E1 and E2 are arranged on the skin surface of the muscular abdomen of the muscle to acquire muscle activity, detect weak voluntary myoelectricity generated when the patient tries to move the muscle, and apply a stimulation signal from the skin to the muscle. It functions as an electrode for giving.
[0017]
The electrode E3 is disposed on the skin surface above the muscle belly or nerve of the muscle to be stimulated, and functions as a ground electrode and as an electrode for applying a stimulation signal from the skin to the muscle or nerve.
[0018]
The input protection resistors R1 and R2 protect the measurement amplifier 11 when applying a stimulus signal to the electrodes E1 and E2.
[0019]
The measurement amplifier 11 receives the voluntary electromyogram acquired by the electrodes E1 and E2 via the input protection resistors R1 and R2, and amplifies the weak voluntary electromyogram.
[0020]
The multi-stage amplifier 12 receives the optional myoelectric signal amplified by the measurement amplifier 11 and amplifies it to such an extent that the microcomputer 13 can recognize it.
[0021]
FIG. 2 is a waveform diagram illustrating signal processing of the microcomputer. The first stage is a stimulus pulse signal. Two stimulus pulse waveforms applied every 60 ms constitute one set, and the two stimulus waveforms are the same. Therefore, the stimulus waveform is updated every 120 ms. At the input of the microcomputer 13, voluntary myoelectricity is taken in from the A / D conversion input PIN, sampled at a sampling period of 1 ms, and converted into a digital signal. As shown in the second row, the waveform is a signal in which a myoelectric signal including an M wave is superimposed on the stimulus signal and the artifact. The stimulus signal is input at the beginning of the 60 ms cycle, and its amplitude is extremely large compared to the voluntary myoelectricity, and is a signal that is not necessary for subsequent signal processing. Limited by two diacs. Since the two stimulus waveforms every 60 ms are the same, the corresponding two artifacts and the M wave every 60 ms are also the same, and by taking the difference between them, the artifact and the M wave are canceled out and only the component due to voluntary myoelectricity is removed. Can be extracted. However, since it is unstable for a while (approximately 20 ms) from the beginning of the 60 ms period, it is stable by selecting near the end of the period (15 ms in the following example, but it can be made wider) and taking the difference. A component due to voluntary myoelectricity can be extracted. At that time, the period is set to 60 ms, that is, an integral multiple of 20 ms, so that hum noise of 20 ms (50 Hz) can be removed. The sampling period is 1 ms, and the time when the stimulus waveform of this signal is updated is 1, and the signal of the first cycle is a (1), a (2)... A (60), and the signal of the second cycle is a ( 61), a (62) ・ ・ ・ a (120)
b (n) = a (n) -a (n-60); 104 ≦ n ≦ 119
b (n) = 0; 1 ≦ n ≦ 103, n = 120
Is the waveform after the third-stage signal processing. The reason why the data of n = 120 is not used is that the microcomputer 14 performs the calculation of the next stimulus intensity and cannot be reflected as a value in the calculation process. By this signal processing, stimuli other than voluntary myoelectricity, artifacts caused by the stimuli, hum noise having a period of 20 ms, and M waves are removed. Thereafter, the microcomputer 13 calculates the maximum value-minimum value of b (n), outputs a pulse having a width corresponding to the magnitude, and controls the stimulating means 14. This determines the intensity of the next stimulus. The stimulation cycle is not limited to 60 ms as long as the signal processing method is the same.
[0022]
The stimulating means 14 applies a stimulating signal to the electrodes E1, E2, E3. A stimulus signal is directly applied to the electrodes E1 and E2 via the diacs D1 and D2 and to the electrode E3. The electrode at the timing to which the negative charge pulse is applied is the related electrode (electrode for contracting muscle), and the other is the unrelated electrode, and the stimulation pulse amplitude is about 100V. The pulse width can be adjusted between 0 and 1 ms, but is adjusted between 50 μs and 1 ms to actually apply a stimulus to the muscle, and the larger the width, the stronger the stimulus.
[0023]
The diacs D1 and D2 separate the electrodes E1 and E2 from the stimulating means 14 when the myoelectricity is detected, thereby preventing the noise from the stimulating means 14 from being mixed and the short circuit between the electrodes E1, E2 and E3. Plays. In other words, when the voltage between the terminals of the diacs D1 and D2 becomes a drop voltage (about 0.5 V or more), the terminals are electrically connected. The diacs D1 and D2 are limited to about ± 1 V (two serial diacs = 2 × 0.5 V) so that the differential input of the measurement amplifier 11 does not become excessive. For this reason, the diodes D11 and D12 shown in FIG. 8 which were conventionally required can be omitted.
[0024]
[0025]
FIG. 3 is a diagram showing a configuration of the electrical stimulation device according to the first embodiment of the present invention. The electrodes E4, E5 and E6 are connected to the stimulating means 31 via the relays SWa1, SWa2 and SWa3 with the electrode E7 as a ground electrode. By sequentially switching the output (secondary side) of one transformer of the stimulating means 31 with relays SWa1, SWa2, and SWa3 such as a photo MOS relay capable of high voltage switching, it is possible to obtain a stimulus output of multiple channels with one transformer. it can.
[0026]
FIG. 4 is a waveform diagram for explaining a relay switching method according to the first embodiment. First, the relay SWa1 is turned on for 3 ms, conduction of a stimulus pulse from the transformer to the ground electrode E7 and the electrode E4 is performed, and then the relays SWa2, SWa3,... Are sequentially switched every 1.5 ms, during which the electrodes E5, E6,.・ ・ Stimulate the stimulation pulse. After conducting the stimulus to all the channels, all the relays are turned ON, all the electrodes E4, E5, E6,... Are short-circuited, and the electric charges remaining on the electrodes E4, E5, E6,. To discharge.
[0027]
FIG. 5 is a diagram showing a configuration of the electrical stimulation device according to the second embodiment of the present invention. Diacs D5 and D6 are connected to stimulating means 53 via relay SWb1 using electrode E15 as a ground electrode, and electrodes E11 and E12 are further connected. The measurement amplifier 51 is connected via input protection resistors R5 and R6 connected in parallel with the electrodes E11 and E12. Similarly, the relay SWb2, the diacs D7 and D8, the electrodes E13 and E14, the input protection resistors R7 and R8, and the measurement amplifier 52 are connected to multiple channels. Thus, first, by connecting the plurality of electrodes E11, E12, E13,... To one relay SWb1, SWb2,. Furthermore, if the detection and stimulation circuit developed this time is connected as a stimulus channel output by using the relays SWb1, SWb2,... And the diacs D5, D6, D7. Also, the number of myoelectric detection channels can be increased. In the case of the conventional method, it was considered that the number of relays became enormous and control became difficult. However, the adoption of the diac enables passive switching, and facilitates multichanneling of the myoelectric detection site.
[0028]
FIG. 6 is a diagram showing the configuration of the electric stimulator according to the third embodiment of the present invention. The present embodiment uses a charge pump booster circuit as the stimulating means of the first embodiment. The electrode E44 is arranged on the anode of the stimulating means 81 as a ground electrode. The relay SWc1 is arranged on the cathode of the stimulating means 81, and the ground electrode E44 and the electrodes E41, E42, E43,... Are connected therefrom via the relays SWc2, SWc3, SWc4, SWc5.
[0029]
FIG. 7 is a waveform diagram illustrating a relay switching method according to the third embodiment. When the stimulus is applied, the relay SWc1 is turned on and the relay SWc2 is turned off, and the relays SWc3, SWc4,... After applying the stimulus to all the channels, all the relays E41 and E42 are turned on while all the other relays SWc2, SWc3, SWc4, SWc5. , E43, E44,... Are short-circuited, and electric charges remaining on all the electrodes E41, E42, E43, E44,.
[0030]
Note that the present invention is not limited to the above embodiment.
[0031]
In configurations where Ru shown in FIG. 1, the diac D1, D2 is the ON to the microcomputer 13 may be a relay OFF is controlled.
[0032]
The present invention is not limited to a patient with a drop foot and can be used as an upper limb or other muscle exercise aid.
[0033]
[0034]
[0035]
[0036]
【The invention's effect】
As described above, according to the first aspect of the present invention, the myoelectricity of a target muscle is detected with a small number of electrodes, and the electrodes are arranged at positions suitable for stimulating the target muscle or nerve. Then, the stimulation signal can be independently applied to three or more electrodes by one transformer or the like for applying the stimulation signal.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electric stimulating device on which the present invention is based .
FIG. 2 is a waveform diagram illustrating signal processing of a microcomputer.
FIG. 3 is a diagram showing a configuration of the electrical stimulation device according to the first embodiment of the present invention.
FIG. 4 is a waveform diagram illustrating a method for switching a relay according to the first embodiment.
FIG. 5 is a diagram showing a configuration of an electric stimulator according to a second embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of an electric stimulator according to a third embodiment of the present invention.
FIG. 7 is a waveform diagram illustrating a relay switching method according to a third embodiment.
FIG. 8 is a diagram illustrating a configuration of an electric stimulator that has been studied in the past.
FIG. 9 is a diagram showing a configuration of a conventional multi-channel type electric stimulator.
[Explanation of symbols]
11, 51, 52, 61 Measurement amplifier 12, 62 Multistage amplifier 13, 63 Microcomputer 14, 31, 53, 64, 71, 72, 73, 81 Stimulation means D1, D2, D5, D6, D7, D8 Diac D11, D12 Diodes E1, E2, E3, E4, E7, E11, E12, E13, E14, E21, E22, E23, E31, E32, E33, E34, E35, E36, E41, E42, E43, E44 Electrodes R1, R2, R5 , R6, R7, R8, R11, R12 Input protection resistors SW1, SW2, SWa1, SWa2, SWa3, SWb1, SWb2, SWc1, SWc2, SWc3, SWc4, SWc5 Relay

Claims (3)

Three or more electrodes placed on the skin surface;
Control means for controlling a stimulation signal based on a signal between two first electrodes of the three or more electrodes ;
A stimulating unit that has an output whose one terminal is connected to one second electrode other than the first electrode among the three or more electrodes, and outputs a signal controlled by the control unit;
An electric stimulating apparatus comprising: a plurality of relays for sequentially connecting the other terminal of the output of the stimulating means and an electrode other than the second electrode among the three or more electrodes . Five or more electrodes placed on the skin surface,
Control means for controlling a stimulation signal based on a signal between a plurality of sets of third electrodes among the five or more electrodes ;
Stimulating means for outputting a signal controlled by the control means, the stimulating means having an output of which one terminal is connected to one fourth electrode other than the third electrode among the five or more electrodes ,
A plurality of relays you turn connected to the other end one end connected to the other terminal of the output of the stimulus means,
Connected to the other end of the relay, and the electrical stimulation device, characterized in that it comprises a <br/> a set of switches connected to a set of the third electrode to at least one relay. The electrical stimulator according to claim 2, wherein the switch is a diac.

Images