Device for low-frequency electrotherapy

Abstract: Disclosed is a novel device for low-frequency elec­ trotherapy wherein a variable resistor is used to control the output level, comprising a resistive element (4); a sliding member slidable along with said resistive element; a mostureproof container (6) enclosing said resistive element and sliding member; and a guide member (11), attached outside said container, movable magnetically in association with said sliding member, and that the output level is controlled by moving said sliding member.

Description: The present invention relates to a device for low-frequency electrotherapy, specifically, directed to the use in a humid environment such as while having a bath. One major problem in conventional device is how to assure the moistureproof and water-resistance of the power switch and variable resistor that is used as the output controller. Although oscillator and battery can be shut off from moisture by enclosing them in a moistureproof container, protection of movable parts such as those in variable resistor and switch is very difficult. FR-A-2351671 describes a low-frequency treatment apparatus which incorporates certain improved safety features to prevent electric shocks to the person receiving the treatment. The apparatus includes a modulating wave oscillator and a pulse wave generator the outputs of which are combined by a mixer circuit. The low-frequency voltage generated by this apparatus is obtained by the envelope of a triangular wave in which the group of the pulse waves formed only of positive voltage components is gradually increased at predetermined time intervals. This document does not consider the problem identified above of the need for protecting the apparatus against moisture. A device for effecting low-frequency therapy is also described in DE 2262385. The device includes two electrodes, a transistorized multivibrator and an oscillator which generates a signal in the form of an alternating pulse wave having a shape symmetrical with respect to the zero volt axis and having a spike in respective voltage components in positive and negative directions. The present invention aims to overcome the problem identified above. Accordingly, the present invention provides a device to effect low-frequency electrotherapy comprising: an electrode that acts as a dispersive electrode when in use; another electrode that acts as an active electrode when in use; a transistorized multivibrator; and a transistorized oscillator whereby said device is adapted to effect low-frequency electrotherapy in a humid environment; said transistorized multivibrator generates a positive square wave with a pulse interval of 0.1-10 seconds and a pulse width of 0.1-10 seconds when a load is connected between the electrodes; said transistorized oscillator generates a diphasic action potential with a frequency of 10-300 hertz, said diphasic action potential having a spike in respective voltage components in positive and negative directions and said oscillator has an output terminal connected with said active electrode; and whereby said device further comprises a transistorized saturating circuit having an input terminal connected with an output terminal of said multivibrator, and also having an output terminal connected with a base of said transistorized oscillator; a battery means to energise the whole circuit; and a variable resistor connected between the output terminal of said oscillator and said active electrode, said variable resistor comprising; a resistive element; a sliding member slidable along with said resistive element; a moisture proof container enclosing said resistive element and sliding member; and a guide member attached outside said container, said guide member being movable magnetically in association with said sliding member. Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a plan view of an embodiment according to the invention; Fig. 2 is a vertical sectional view of the embodiment; Fig. 3 is a vertical sectional view of another embodiment according to the invention; Figs. 4 and 5 are switch mechanisms of the variable resistors usable in the invention; Fig. 6 is the circuit of a low-frequency oscillator usable in the invention; and Figs. 7 and 8 are the output waveform in the low-frequency oscillator. In the drawings, symbol T designates transistor; R, resistor; C, capacitor; D, diode; H, transformer; and S, power switch. FIGs.1 and 2 illustrate a variable resistor usable in the invention. In this variable resistor, arm member (2) having magnet (1) at its end is fixed about shaft (3) of rotary variable resistor (4) comprising a resistive element and a sliding member that moves in contact with the resistive element when shaft (3) rotates. Arm member (2) and rotary variable resistor (4) are enclosed in moistureproof container (6) having cylindrical projection (5). Stopper (9) is used to rotatably attach L-shaped guide member (11) having magnet (10) to flat surface (8) of projection (5) so that one pole of magnet (10) can face to opposite pole of magnet (6) across cylindrical wall (12) of projection (5). Knob (13) is attached to stopper (9), while dial (14) is provided on flat surface (8) of projection (5). By dialing knob (13) according to dial (14) to move guide member (11), arm member (2) and shaft (3) are rotated magnetically in association with the movement of guide member (11). Thus, a desired level of electric resistance can be attained with variable resistance (4). A desired level of low-frequency voltage can be obtained from a low-frequency oscillator by inserting the variable resistor between the output terminal of the low-frequency oscillator and an electrode, and dialing knob (1) according to dial (14). FIG.3 shows another embodiment according to the invention, wherein moistureproof container (6) is shaped into a cylinder by providing in the embodiment in FIG.1 hearing (15), such as ball or roller bearing, between arm member (2) and the inside wall of moistureproof container (6). This embodiment is characterized in that it can be produced in a smaller size and at a lower cost in comparison with the previous embodiment. Variable resistor (4) enclosed in moistureproof container (6) may be a slide a variable resistor, and should not be restricted to rotary variable resistor as shown in FIGs.1 and 3. In case a slide variable resistor is used, a linear resistive element and a sliding member with magnet are enclosed in moistureproof container (6) in such manner that the sliding member moves in contact with the resistive element, while a guide member having magnet is movably attached outside container (6) at an appropriate distance from the sliding member along with the resistive element. Although either magnet (1) or (10) in FIGs.1 and 3 may be a magnetic piece such as that of iron or nickel, an increased attraction and a stable operation can be attained by making them with magnet. The arm member and/or guide member consists partially or entirely of magnet or a magnetic piece. FIGs.4 and 5 illustrate a switch structure that can be advantageously used in the device according to the invention. In the example as shown in FIG.4, spring arm member (2) and contact (16) are attached around shaft (3) of rotary variable resistor (4) in such manner that they move together and attract each other into conduction when one pole of magnet (1) faces to opposite pole of magnet (10) across side wall (17) of moistureproof container (6). FIG.5 is illustrative of a power switch wherein arm member (2) contacts with contact (18) to separate contacts (18) and (19) when it is at the minimum resistance position. FIG.6 is the circuit of a low-frequency oscillator usable in the invention. In this circuit, the multivibrator comprising transistors T₁ and T₂ oscillates a positive square wave, for example, having a pulse interval of 0.1-10 seconds and a pulse width of 0.1-10 seconds, which is then modified by transistor T₃ and resistor R₅ into a saturated wave voltage as shown in FIG.7. The blocking oscillator including transistor T₄ is to generate a diphasic action potential, and the transistor becomes conductive whenever the saturated wave voltage supplied to the base comes to the positive region. Thus, as shown in FIG.8, the blocking oscillator generates a diphasic action potential at time intervals equal to the pulse width of the square wave. When dispersive electrode E is placed, for example, on a non-affected site of the skin or in bath water and active electrode P comes nearly to or on load Z such as subject's body, the area between dispersive and active electrodes E and P become conductive through load Z. When this occurs, the current from dispersive electrode E charges capacitor C₁₀ through active electrode P, resistor R₁₀, diode D, and resistor R₁₁ and the voltage across capacitor C₇ conducts transistor T₅, transistors T₁ and T₂ receive the emitter current and the multivibrator begins oscillation. The output square wave voltage is modified by transistor T₆ into a saturated wave voltage, and supplied to the base of transistor T₄ through resistor R₅ and the emitter follower circuit including transistor T₃. Transistor T₄ generates diphasic action potential when the voltage supplied to the base is not zero, and the output is controlled with variable resistor VR and then supplied between active and dispersive electrodes P and E. Discharge of battery B never continue if the subject forgets to open power switch S because conduction of transistor T₅ is interrupted and operation of multivibrator and blocking oscillator is stopped when no current flows across dispersive and active electrodes E and P. Since the device according to the invention the variable resistor is not exposed to moisture even when used in a humid environment such as bath, the moisture never disturbs the operation of the device. Since the variable resistor can be immersed in bath water, the subject can control while in bath the dosage of low-frequency voltage. Thus, the device can be advantageously used in the improvement and treatment of blood circulation, muscular strength, muscular fatigue, massage, and haemorrhoids. More particularly, the device equipped with an oscillator circuit, frequency of about 10-300 hertz, exerts a remarkable therapeutic effect when used while taking a bath: At a frequency of 100 hertz or lower, preferably, 10-70 hertz, the device is effective in improvement and treatment of blood circulation, muscular strength, fatigue and haemorrhoids; and at a frequency of 100-300 hertz, in prevention of alopecia as well as in acceleration and regeneration of hair.

Claims: A device to effect low-frequency electrotherapy comprising: an electrode (E) that acts as a dispersive electrode when in use; another electrode (P) that acts as an active electrode when in use; a transistorized multivibrator (T₁,T₂); and a transistorized oscillator (T₄) whereby said device is adapted to effect low-frequency electrotherapy in a humid environment; said transistorized multivibrator generates a positive square wave with a pulse interval of 0.1-10 seconds and a pulse width of 0.1-10 seconds when a load is connected between the electrodes; said transistorized oscillator generates a diphasic action potential with a frequency of 10-300 hertz, said diphasic action potential having a spike in respective voltage components in positive and negative directions and said oscillator (T₄) has an output terminal connected with said active electrode (P); and whereby said device further comprises a transistorized saturating circuit (T₃,R₅,T₆) having an input terminal connected with an output terminal of said multivibrator (T₁,T₂), and also having an output terminal connected with a base of said transistorized oscillator (T₄); a battery means (B) to energise the whole circuit; and a variable resistor connected between the output terminal of said oscillator (T₄) and said active electrode (P), said variable resistor comprising; a resistive element (4); a sliding member (2) slidable along with said resistive element (4); a moisture proof container (6) enclosing said resistive element (4) and sliding member (2); and a guide member (11) attached outside said container, said guide member (11) being movable magnetically in association with said sliding member (2). The device of claim 1 wherein said variable resistor has a switch connection on said variable resistor. The device of claim 1 wherein said variable resistor is a rotary variable resistor. The device of claim 1 wherein said variable resistor is a slide variable resistor. The device of claim 1 wherein at least one of said sliding member and said guide member is at least partially a magnet. The device of claim 5 wherein both said sliding member and said guide member are at least partially a magnet. The device of claim 1 wherein said variable resistor is immersed in bath water during use.

Inventors: MASAKI KAZUMI, MASAKI, KAZUMI
Applicants: HAYASHIBARA KEN, HAYASHIBARA, KEN
Application year: 1987
Main classification: A61N1
IPC codes: H01C1, A61N1, H01C10