RU2113248C1 - Signal former for low-frequency physiotherapy device - Google Patents

Abstract

FIELD: medical engineering; physiotherapy; measuring and computer engineering. SUBSTANCE: signal former has controller, digital indication unit, keyboard unit, digital-to-analog converter, low-pass filter, audio signalling unit, synchronization signal output, and terminal for connection of fixed, reference DC voltage source. Digital indication unit is made as register unit and display. One of digital-to-analog converters serves for multiplication. EFFECT: higher reliability and electrical safety, extended functional capabilities. 2 dwg

Description

 The invention relates to medical equipment, where it can be used in devices intended for physiotherapy. In addition, it can be used in measuring, computing and automation as sources of intermittent low-frequency signals with variable parameters.

 Known shaper signals used in the equipment of low-frequency (LF) physiotherapy "Amplipulse-4" [1].

 Its fundamental disadvantages are as follows: it does not provide a smooth decrease in the amplitude of the patient’s current at the end of the treatment procedure; does not provide for a medical procedure in an automatic mode; It does not provide a “soft” and unambiguous effect on the patient in intermittent mode. All this significantly reduces the effectiveness of the therapeutic effect of the device in which the aforementioned signal shaper is used.

 In another apparatus for the low-frequency physiotherapy Amplipuls-6 [2], the disadvantages that occur in the signal shaper of the Amplipuls-4 device have been eliminated. But at the same time, the signal generator of the Amplipuls-6 apparatus has other, no less significant drawbacks, which are discussed below.

 1. To increase (positive or negative) patient current at the output of the physiotherapy low-frequency device, the operator uses a potentiometer in the signal conditioner. In this case, the increment may be coarse or the current may disappear altogether due to loss of contact in the potentiometer. On the other hand, in intermittent modes (with a pause), it is important to increase the current only out of pause. Otherwise, the patient may receive an unacceptable current.

 The operator controls the increment of the patient’s current by a pointer instrument with a continuously oscillating arrow (at AM), and therefore it is extremely difficult to establish the required current increment. The described principle of implementing the current increment and its indication leads to subjective errors, fast fatigue of the operator and, most importantly, violates the electrical safety of the treatment procedure and reduces the reliability of the equipment.

 2. The technical implementation of the shaper is based on the use of a cumbersome hardware solution, as a result of which its power consumption and overall dimensions are quite large.

 3. The functionality of the signal conditioner is strictly limited, since neither the form nor the parameters of its output signals can be changed if necessary without the circuit design of the signal conditioner.

 The closest prototype of the claimed device is a signal conditioner used in the device [3]. It contains a controller (microcomputer), the input of which is connected to the output of the keyboard unit, the first output - with the digital display unit (LCD), and the second - with the input of the DAC, the output of which is the output of the signal conditioner.

 However, the signal shaper - the prototype has significant drawbacks, the essence of which is as follows.

 1. The output signal has a rectangular or “modified rectangular” shape. The output signal of such a shaper does not provide the required signal at the output of modern low-frequency physiotherapy devices, i.e., AM series of sinusoidal current signals with specified values of series and pause durations, current rise and fall times in a series with several AM frequency and depth.

 These are the requirements for the output signals of low-frequency physiotherapy devices, presented, in particular, by the Russian Ministry of Health.

 2. There is no possibility of automatic and safe correction of the patient’s current directly during the treatment procedure (in the entire range of currents).

 3. There is no sound indication during the set of parameters and correction of the patient’s current during the treatment procedure, and there is no sound alarm after the specified time of the procedure.

 All this (Section 2.3) creates operational inconvenience when using the device for low-frequency physiotherapy and causes operator fatigue.

 The aim of the invention is to increase the reliability and electrical safety of devices for low-frequency physiotherapy due to the automatic uniform increment outside the pauses of the output current of the signal conditioner while expanding the functionality.

 The goal is achieved by the fact that a second DAC, a low-pass filter, an audio signaling block, an output of synchronization signals and a terminal for connecting a source of a fixed reference DC voltage are introduced into the signal shaper for low-frequency physiotherapy devices containing a controller, digital display unit, keyboard block, DAC , the digital display unit is made in the form of a block of registers and display, while the first output of the controller is connected to the first input of the display, the second input of which is connected to the output via the first information bus the house of the block of registers, the input of which through the second information bus is connected to the second output of the controller, the third output of which through the third information bus is connected to the input of the keyboard block, the output of which through the fourth information bus is connected to the input of the controller, the fourth output of which is connected to the input of the sound alarm unit, the fifth controller output through the fifth information bus is connected to the second input of the second DAC, the first input of which is connected to a terminal for connecting a source of a fixed reference voltage DC output of the second DAC, being the source of a variable reference DC voltage for the first (multiplying) DAC, is connected to the first input of the first DAC, the second input of which is connected through the sixth information bus to the sixth output of the controller, the seventh output of which is connected to the seventh information bus with the output of the synchronization signals, the output of the first DAC is connected to the input of the low-pass filter, the output of which is the main output of the signal conditioner.

 A comparative analysis with the prototype shows that in the inventive signal shaper new blocks and new functional connections are used. New units include a second DAC, a low-pass filter, an audible alarm unit. Six information buses were used, including two for dialogue communication between the controller and the keyboard block. An output of synchronization signals and a terminal for connecting a source of a fixed reference DC voltage are introduced.

 Thus, the claimed device meets the criterion of "novelty."

 The newly introduced set of features is essential, as it allows to increase the reliability and electrical safety of the device in which the signal conditioner is used due to the automatic uniform increment outside the pauses of the output current of the signal conditioner. On the other hand, the claimed device provides an extension of the functionality of the signal shaper due to the formation of a series of sinusoidal signals with adjustable parameters. Finally, the inventive device provides maximum comfort during operation due to the presence of sound indications and audible alarms, as well as due to the automatic installation of the output current. This allows us to conclude that the claimed device meets the criterion of "significant differences".

 The claimed technical solution meets the criterion of "inventive step", since it is for specialists explicitly not follows from the level of medical technology.

 At the same time, the claimed technical solution is “industrially applicable”, since it is the main unit of low-frequency physiotherapy devices widely used in surgery, traumatology, neuropathology, sports medicine and in everyday medical practice.

 The inventive signal shaper is scheduled for mass production as part of devices for low-frequency physiotherapy.

 In FIG. 1 shows a structural diagram of the inventive device; in FIG. 2 - in General terms, the signal at the main output of the inventive signal conditioner.

In FIG. 1 the following designations are adopted: 1 - digital display unit, 2 - keyboard unit, 3 - controller, 4 - sound alarm unit, 5 - second DAC, 6 - first DAC, 7 - low-pass filter (LPF), 8 - display, 9 - a block of registers, 10 - the main output, 11 - the output of the synchronization signals, 12 - terminal for connecting a source of fixed reference DC voltage ("U _op = const"). "U _op = var" is a variable reference DC voltage, I-VII is the first and seventh information buses.

In FIG. 2, the following notation is used: U _post is the constant component of the output signal, U _syn is the amplitude of the sinusoidal component of the output signal, T1 _mode is the period of the sinusoidal component of the first series, T2 _mode is the period of the sinusoidal component of the second series, T1 is the duration of the first series, T2 is the duration of the second series, T _f - the rise time of the output signal, T _cn the decay time of the output signal, T3 - the duration of the pause.

 The following describes the practical implementation of the inventive signal shaper.

 Block 1 digital display contains a display 8 and block 9 registers. The first of them is made on a liquid crystal indicator of the type IZhTS14-4 / 7, and the second - on microcircuits of the type K561IR2.

 The keyboard block 2 is made in the form of a standard 3x4 monoblock (N 709840 in the German Conrad catalog for 1995) and a separate start / stop button of the Pkn150-1 type.

 The controller 3 is made on a microcomputer of type P87C51.

 The sound alarm unit 4 is made on the basis of a chip type KR1544LN1 and a piezoceramic bell of tin ZP-1.

 The first and second DACs are 6 and 5. Each of these two DACs is made on two microcircuits: type KR572PA1A (directly DAC) and type KR140UD1408A (operational amplifier).

 The low-pass filter 7 is made according to the scheme of the L-shaped two-link RC filter.

 The proposed signal shaper for low-frequency physiotherapy devices works as follows.

The controller 3 provides the polling pulses of the keyboard block 2 on the four-wire data bus III and reads information about the pressed key on one of the conductors of the three-wire data bus IV. Information read from the keyboard is recorded in block 9 registers on a five-wire bus II containing four data conductors and one clock signal. From the output of block 9, the data on bus I goes to the second input of the display 8. The first input of the display 8 from the first output of the controller 3 continuously receives a pulse signal in the form of a meander with a frequency of 50 Hz, which is necessary for the normal operation of the liquid crystal display. Information corresponding to the instantaneous value of the signal at the main output 10 is fed to the second (information) inputs of both DACs via eight-bit V and VI data buses. Through terminal 12, a fixed DC voltage is supplied to the first input of the DAC 5. The period of the input code signals for DAC 5 and DAC 6 is 200 μs (f = 5 kHz). The DAC 5 output variable in value, fed to the first input (reference voltage input) of the DAC 6, at each instant corresponds to the value of the patient current at the output of the low-frequency physiotherapy device. Before the start of the procedure (until the start / stop button is pressed after a set of parameters or during the forced stop of the procedure by the same button), a zero value is transmitted to the second input of the DAC 5 from the controller 3, that is, the reference voltage equal to the DAC 6 is to zero. In this case, the same voltage is at the main output 10. At the end of the DAC 6, at the end of the parameter set, the code corresponding to the instantaneous value of the generated sinusoidal signal is continuously transmitted from the controller 3. Its frequency is equal to the modulation frequency set on display 8, and the amplitude is determined by the amplitude modulation coefficient set there. Thus, the operation of the signal conditioner is carried out in real time. During the procedure, in the signal shaper it is possible to change the constant component of the main output signal corresponding to the patient current. This change can be done in one of two ways:
a) when the procedure is forcibly stopped, the numeric keys of the keyboard set a new value for the patient’s current and after restarting the procedure (using the "start / stop" button), the code corresponding to the new value of the patient’s current is received from the controller 3 on the DAC 5;
b) Without interrupting the procedure, they correct (increase or decrease) the constant component of the signal at the main output 10 by pressing the function button "more" or "less" of the keyboard and holding it pressed until the current value is reached. In this case, the code change at the input of the DAC 5 is carried out automatically by a unit of the least significant bit every 0.5 s only during the exposure of the patient to the current, i.e. out of pauses.

 The controller 3 gives a signal to the acoustic signaling unit 4 when any of the keyboard buttons is pressed and at the end of the procedure, focusing the attention of the operator. Block 7 provides filtering of the output analog signal, "clearing" it from a quantization frequency of 5 kHz. In accordance with the information supplied to the controller 3 from the keyboard unit 2, an output signal is generated at the main output 10, a general view of which is shown in FIG. 2. Among the parameters of the output signal, set using block 2 of the keyboard and block 1 of the digital display, include: type of work (type of output signal); modulation factor (KM); modulation frequency (FM); the duration of two different series and pause (T1, T2 and T3 in Fig. 2); value of the DC component of the output signal. In intermittent modes of operation, the duration of the pause is usually selected from the relation T3 = 1.5 (T1 + T2), where T1, T2 T3 are explained in figure 2 ..

 With the inclusion of the supply voltage to the signal shaper, controller 3 outputs several synchronization signals to output 11 for collaboration with other blocks of physiotherapy low frequency devices. These signals include two pulse signals with a repetition rate of 5 kHz and one pulse signal with a repetition rate of 2 MHz. In the future, I use the first two signals (f = 5 kHz) to generate a sinusoidal carrier signal from them for the output signal of the low-frequency physiotherapy device, and a signal with a frequency of 2 MHz is used to synchronize the power supplies of other blocks of the low-frequency physiotherapy device.

 The technical and economic efficiency of the claimed device consists in increasing the reliability and electrical safety of low-frequency physiotherapy devices due to the automatic uniform increment outside the pauses of the output current of the signal shaper; in expanding the functionality of the signal conditioner; in creating maximum comfort during the use of physiotherapy low frequency devices and in reducing operator fatigue due to the presence of sound indications and audible alarms, as well as due to the automatic increment of the output current of the signal conditioner.

 Sources of information.

 1. Amplipulse-4 low-frequency physiotherapy apparatus. Passport V / O "Medexport", M. (typographical publication), 1990.

 2. Amplipulse-6 low-frequency physiotherapy apparatus. Passport UIVR 941519 001PS 1995.

 3. UK patent N 2181059, Merns Technology Incorporated, cl. A 61 N 1/32, 04/15/88.

Claims (1)

 A signal generator for low-frequency physiotherapy devices, comprising a controller, a digital display unit, a keyboard unit, a DAC, characterized in that a second DAC, a low-pass filter, an audio signal unit, a synchronization signal output, and a terminal for connecting a fixed DC voltage reference are inserted into it , the digital display unit is made in the form of a block of registers and display, while the first output of the controller is connected to the first input of the display, the second input of which is through the first information bus connected to the output of the register block, the input of which through the information bus is connected to the second output of the controller, the third output of which through the third information bus is connected to the input of the keyboard block, the output of which through the fourth information bus is connected to the input of the controller, the fourth output of which is connected to the input of the sound signaling unit , the fifth controller output through the fifth information bus is connected to the second input of the second DAC, the first input of which is connected to the terminal for connecting the source of the fixed reference voltage DC voltage, the output of the second DAC, being the source of a variable reference DC voltage for the first (multiplying) DAC, is connected to the first input of the first DAC, the second input of which is connected through the sixth information bus to the sixth output of the controller, the seventh output of which is connected through the seventh information bus with the output of the synchronization signals, the output of the first DAC is connected to the input of the low-pass filter, the output of which is the main output of the signal conditioner.

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