WO2014139486A1

WO2014139486A1 - Regulation device preventing electrical shock in devices using electrotherapy for treatment and the method of prevention of electric shock

Info

Publication number: WO2014139486A1
Application number: PCT/CZ2014/000025
Authority: WO
Inventors: Jiri KARES
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-03-09
Filing date: 2014-03-06
Publication date: 2014-09-18
Anticipated expiration: 2015-09-09
Also published as: CZ304552B6; DE112014001207T5; GB2530421A; WO2014139486A4; CZ2013175A3; GB201517424D0; PL413855A1; SK500592015A3; SK288395B6

Abstract

The regulation device, preventing electrical shock in devices using electrotherapy for treatment, consists of a starting circuit (5) which is connected to the circuit (6) for gradual regulation of output current, which is further connected to an amplifier (8) of regulation deviation, which is interconnected to a stabilizer (7) of output current with a delay element, and a switch (9) of a stand-by and operation mode of the device. To prevent electrical shock in devices using electrotherapy for treatment, the device must meet the following conditions between the time delay Treg of the output current from the regulator block (4), the time Tvyp for quick switching of the device from operation mode to stand-by mode, and the time Trun of gradual regulation of the amplitude set-up of the output current: Treg > Tvyp Treg « Trun A device using electrotherapy for treatment consisting of a power supply block (1), an indication block (2), and a switched-mode power supply block with feedback (3) connected to a regulator block (4) of output current with the delay Treg does not cause electric shock to patients in case of accidental disruption of medical therapy when the device is in operation mode.

Description

Regulation device preventing electrical shock in devices using electrotherapy for treatment and the method of prevention of electric shock

Technical Field:

The invention relates to the field of health care, particularly to medical devices using electrotherapy as a physical medicine treatment method.

Prior State of Art:

Electrotherapy is a medical procedure used to treat a variety of diseases and health problems. The treatment employing the beneficial effects of electric energy uses direct or pulsating current. The devices are powered by batteries or from the power mains. The devices provide a high degree of safety in terms of their interaction with the power mains.

In the treatment procedure, the patient is connected to the circuit, in which some type of electrotherapy takes place. The current intensity and the length of procedures are individual. After a certain time of the procedure, the polarity of current is switched over and the procedure is repeated with the reversed polarity.

The used devices, such as in WO 97/15348 and KR 20120111708, have a built-in solution called

"soft-start" or "re-soft-start", which regulates the gradual regulation of input voltage.

Procedures are ended by switching the device from the operating mode to the stand-by mode and subsequent disconnection of the patient from the circuit, to which he was connected.

Even weak current - around 5 mA - is high enough to cause electric shock to the patient during the procedure in case of accidental or emergency disconnection of the patient from the circuit, to which he was connected, before the device was switched from operation to stand-by mode. To someone, this electric shock may cause certain inconvenience.

Currently available devices, which use electrotherapy as a physical method of treatment, do not provide any protection against electrical shock that could occur when the patient is suddenly disconnected from the circuit during the medical procedure - before switching the device from operation to stand-by mode. The existing devices, which use electrotherapy, operate with a common output current regulator, which responds to changing load of the patient, when this patient is connected or disconnected from the circuit during the procedure, by an abrupt voltage variation; thus, the patient cannot avoid electric shock. If the circuit between the patient and the device is broken, the patient usually suffers electric shock. Subject of the Invention

The above disadvantages are overcome by installing a regulation device to prevent electric shock in devices using electrotherapy for physical method of treatment and the method of avoiding of electric shock.

The purpose of the invention was to develop a regulation device for devices that use electrotherapy as a physical method of treatment so, that they would not cause electric shock to patients in case of accidental interruption of procedure.

As already mentioned above, devices using electrotherapy are safe against the electrical mains; they are powered via a power pack or by batteries. Electrotherapy uses direct current or pulsating current.

However, even weak current - around 5 niA - is high enough to cause electric shock to the patient during the procedure in the moment of accidental or emergency disconnection of the patient from the circuit before the device was switched off - put from operation to stand-by mode. To someone, this electric shock may cause certain inconvenience.

This invention aims to ensure the patient does not suffer electric shock during the procedure in the event of accidental interruption of the procedure, such as taking out the hands from the water with electrodes when the device is in operation mode. The subject of the invention is a new design of the regulation device to prevent electric shock in devices using electrotherapy as physical method of treatment.

The cause of given positive function of the device, that it does not cause electric shock, is its ability to adapt, as an electric power source, to change of load impedance of the patient's body exactly when the patient removes the hands from the water with electrodes. The power source is a regulable source of direct current.

For removal of electric shock, the key factor is the relationship between the regulator and the regulated system - the loading impedance of the patient's body enjoying the treatment therapy.

The parameters of the regulator, which need to be adjusted in order to regulate the regulated system with zero or negligible regulation deviation, are the following: speed, reaction, response time, and inertia

The load impedance of the patient's body, enjoying the treatment therapy as the regulated system, has the following characteristics:

the direct current creates only ohmic resistance;

in the course of therapy, the amount of the ohmic resistance varies in the range of about ±5%, i.e., relatively little and slowly

at the beginning and end of the procedure, the ohmic resistance changes several times within max. 1 sec, as a response to connection or disconnection of the patient from/to the circuit. The regulator of output current with the delay Treg consists of an output current stabilizer with a delay element, an amplifier of regulation deviation, a starting circuit, a circuit of gradual regulation of output current, and a switch of stand-by and operation modes of the device.

The output current regulator with the delay Treg - type PI - proportional integral regulator, where the derivative component is, suppressed regulates with zero regulation deviation only in the course of the procedure when the changes of ohmic resistance of the load - by the patient's body are small, of several percent and change very slowly in units of seconds. Great and relatively rapid changes in resistance of the load - by patient's body at starting and finishing of the procedure the regulator solves as follows:

After turning on the device - before the start of the procedure - the value of the output voltage is about 10V. With this voltage value - in stand-by mode - the patient connects to the circuit. After the patient is connected to the circuit, the load - the patient's body is exposed to the current of about 2 mA, and the device switches to operation mode automatically. After reaching this value of the current, the voltage in the circuit further decreases to approximately 3V, and the current starts to rise slowly until it reaches the preset amplitude value. The current increase time is about 0 to 60 sec, depending on the pre-set amplitude value of current, i.e., shorter time for lower value and longer time for higher value.

After the pre-set current value is regulated, the medical procedure itself starts. After completing the procedure, the patient is disconnected from the circuit and the device automatically switches to standby mode. When the patient suddenly interrupts the procedure, i.e., unexpectedly pulls his hands from the water while the device is on, there will be a rapid rise in the current up to its nominal value, while regulator will respond to the rapid change by withholding its current value with the delay Treg. During this time, the device manages to switch to standby mode. Standby mode is identical to the state of the device after switching on. The device is ready to start further medical procedures.

The regulator by its function completely eliminates electrical shock at the beginning and end of the procedure under meeting the following conditions between the delay Treg of the output current from the regulator block (4), the time Tvyp for quick switching of the device from operation mode to stand-by mode, and the time Trim of gradual regulation of the amplitude of the output current:

Treg > Tvyp

Treg « Trun Devices using electrotherapy as a physical method of treatment completely eliminate electrical shock in case of accidental interruption of the medical procedure by connecting to the regulator block of output current (4) with the delay Treg.

This feature allows the patient to discontinue the procedure therapy at any time and resume it again without having to switch the device from operation mode to stand-by mode and vice versa.

Explanation of Drawings

The invention is illustrated in the attached drawings. Figure 1 contains the block diagram of the medical device in which occurrence of electric shock is prevented during the procedure using electrotherapy. Figure 2 shows the block diagram of the regulator of output current with the delay. Figure 3 shows the electrical diagram of the regulator of output current with the delay.

Example of Embodiment of the Invention

The regulation device for preventing electric shock in devices utilizing electrotherapy for treatment, as illustrated in the attached drawings in Figure 2 and Figure 3, consists of stabilizer 7 of output current with a delay element, of amplifier 8 of regulation deviation, of starting circuit 5, of circuit 6 of gradual regulation of output current, and of switch 9 of operation and stand-by modes of the device.

Stabilizer 7 of output current with a delay element allows to set a certain value of output current and to maintain that value independently on actual load parameters exactly at the time the patient removes the hands from the water with electrodes. The delay element "instantaneously" cancels this and creates a delay of response of the stabilizer in tenths of seconds. In term of circuit design, stabilizer 7 of output current with the delay Treg used transistor T2 connected to a common base. The voltage drop caused by the output current in resistors Rll and R26 and Schottky diode D18 is compared on base transition with the preset voltage of potentiometer JPl. The regulation deviation is conducted through resistor R16 to the input of the regulation deviation amplifier. Diode D15 linearizes the setting process by the potentiometer, and Zener diode D8 along with resistor R22 are used to stabilize it. Capacitors C12 and C13, together with fault circuit Rl 1, R26, and D18, determine the length of the time delay of the stabilizer of output current (7). In stand-by mode and during gradual regulation of output current, stabilizer 7 of output current with delay element is balanced, and on resistor R26, there occurs residual voltage dependent on the current setting of potentiometer JPl. This voltage causes a measurement error of output current and slows the switching of the source to stand-by mode. Measurement error in standby mode is eliminated by the presence of emitter follower T13 and of input V2, which bridges diode D8 and produces zero bias of the base of transistor T2. After switching to operation mode, residual voltage is removed by Schottky diode D18 connected for the voltage in the reverse direction.

Amplifier 8 of regulation deviation is made up of transistors T4 and T5. Amplifier 8 of regulation deviation is controlled by N-FET transistor T7, which limits its activity to operation mode of the source. In stand-by mode, amplifier 8 of regulation deviation is switched off by high resistance of channel T7. Using the input from the electrode, amplifier 8 of regulation deviation limits the maximum output voltage in electrodes of the device.

Starting circuit 5 serves to switch the source from stand-by mode to operation mode and vice versa. It is formed by transistor T6 with a scanner circuit of output current with diodes D9 and D17 and resistors R12 and R25. Resistor R25 sets the amount of the switching current of both function modes. The Zener diode connected in the forward direction reduces the voltage drop on resistor R25 to about 0.6 V. Schottky diode D17 separates the base circuit of transistor T6 from delay element C12, C13, Rll. Output VI controls indication functions of the device.

Circuit 6 of gradual regulation of output current is a charging RC member formed by high-capacity ceramic capacitors CIO, Cll and resistor R18. The time of gradual regulation of output current is roughly given by the RC constant of this circuit and here is approx. 60 sec. This time depends on the value of the set output current. N-FET transistor T7 with high input resistance, which does not load the recharging RC element, directly controls amplification of the amplifier 8 of regulation deviation.

The discharge circuit of capacitors CIO and Cl l is transistor T8, together with resistor R19. The start of regulation of output current is determined by closing transistor T8 by signal from the starting circuit. Switch (9) of stand-by and operation modes directly controls the control circuit of the switched-mode power source (3) of the device. This above given wiring is analogous to the regulation solution for the elimination of electric shock used in electrotherapy devices in case of accidental interruption of the procedure.

It is also possible to use a digital solution.

The device using electrotherapy for treatment consisting of a power supply block (1), an indication block (2), and a switched-mode power supply block with feedback (3) connected to a regulator block (4) of output current with the delay Treg does not cause electric shock to patients in case of accidental disruption of the medical procedure. Industrial Applicability

The presented regulation device is applicable in all devices or instruments, which use any kind of electrotherapy.

Claims

Patent Claims

1. The regulation device preventing the electrical shock in devices using electrotherapy for treatment, characterized in that it consists of a starting circuit (5) which is connected to the circuit (6) for gradual regulation of output current which is further connected to an amplifier (8) of regulation deviation which is interconnected to a stabilizer (7) of output current with a delay element and a switch (9) of stand-by and operation modes of the device.

2. The method of using the regulation device which prevents electric shock in devices according to claim 1 is characterized in that the regulation device prevents electric shock in the event of sudden interruption of the procedure by the fact that the time delay Treg of output current from the regulator block (4) is greater than the time Tv p for rapid switching the device into stand-by mode and that the time delay Treg of output current from the regulator block (4) is significantly less than the time Tmn of gradual regulation of the amplitude of the output current of the device; therefore the following applies:

Treg > Tvyp

Treg « Trim