RU2269384C2 - Ultrasound generator - Google Patents

Abstract

FIELD: engineering of resonance receiver for technological use.

SUBSTANCE: native frequency of receiver is measured directly in form of frequency of free fading oscillations at input of receiver, disconnected from generator for time, necessary for measurement. This disconnection and connection of receiver to frequency meter is performed by, respectively, high-current and low-current keys, operating inversely. Further generation is performed at measured frequency until moment of appearance of discrepancy signal from amplitude comparator, after that frequency measurement is repeated. Additionally prevented is dependency of discrepancy signal from quality of receiver, exceeding of set limits by generation frequency is also prevented, emergency shutdown of generator is made possible, and also partial digital realization of low-current circuit, necessary to achieve increased stability and resistance to interference.

EFFECT: maintained precise resonance state, and, as a result, achieved maximal efficiency of receiver.

5 cl, 1 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to industrial electronics, mainly to the power supply technology of technological ultrasonic devices (ultrasonic transducers).

BACKGROUND

A feature of technological ultrasonic devices, for example ultrasonic transducers, is a change in the natural frequency due to both the specifics of their device and the operating conditions. The effectiveness of this kind of resonant receivers of electric ultrasonic power is almost completely determined by the accuracy of tuning the generator to the natural frequency of the receiver, that is, by providing resonance.

Known generators for this purpose contain a power (hereinafter referred to as high current) circuit with the possibility of generating and transmitting electric ultrasonic power to the receiver and a control (hereinafter referred to as low current) circuit with the task of providing this resonance.

A high current circuit includes a power amplifier, as a rule, with the ability to work in key mode, having a mode control input. The high current circuit is equipped with a matching circuit with a resonant receiver assembled from reactive elements. A necessary element of a high-current circuit is a signal sensor, by which resonance is adjusted. In the case of a resonant receiver in the form of a parallel resonant circuit, such a sensor is a voltage sensor at the input of the circuit. The generator is an independent device; To connect to the receiver, the high-current circuit is equipped with an appropriate connector.

In addition to the noted common signs, analogues of the claimed invention [1-7] contain in a high-current circuit a controlled high-current key, for example electronic. In most cases [1-6], this key operates at the generation frequency, providing excitation of the receiver. Essentially, in these cases, a high-current switch is an element of a power amplifier with the ability to work in key mode. Its control circuit should fulfill the task of automatically tuning the generation frequency to the natural frequency of the resonant receiver, which is the case in [1-5]. However, the natural frequency of the receiver is not measured directly, which leads to an error in the resonance setting.

In analogue [7], a high-current switch opens a high-current circuit and connects the transducer to an amplitude echo detector. In this case, the task of measuring the natural frequency of the transducer is not posed, and the generation frequency is not tuned to resonance.

The closest analogues are the method [8] and the method and device [9].

According to the method [8], in order to adjust the generation frequency to the resonance, pauses are introduced into the operation of the device, during which the signal is measured in the form of the initial amplitude of the free damped current oscillations of the resonant receiver and the frequency is adjusted to achieve the maximum signal. The described device contains keys in high-current and low-current circuits and a device for storing the mentioned amplitude, the output of which is connected to the input of an extreme regulator that sets the resonant frequency. It is essential that both keys are normally open and, at the same time as the start of the pause, are closed. In this case, the output of the generator and, accordingly, the input of the receiver are short-circuited with a high-current key. This method and its implementing device have disadvantages. This technical solution is applicable only in relation to the receiver, made as a sequential oscillatory circuit, while most of them are performed as parallel oscillatory circuits. It is known that an ideal sequential oscillatory circuit at a resonance frequency has a zero impedance and, therefore, shorts the output of the supply generator. In this case, the generator must be made as a current source, which greatly complicates the device. In addition, when shorting the receiver to the initial amplitude of the current, the energy stored in the reactive elements that are not included in the oscillatory circuit of the receiver contributes to the initial amplitude of the current. The magnitude of this contribution depends on the phase of the generated oscillations corresponding to the moment of shorting, that is, it varies arbitrarily in various pauses. Thus, the signal, at the maximum of which the frequency adjustment is carried out, is not adequate to the task. This gives rise to a tuning error. Finally, the tuning operation itself is carried out as a step-by-step approach with a sequential approach to the resonant frequency. To perform each such operation, a certain number of pauses is required, which reduces the performance of the device.

According to the method and device [9], the oscillation is also periodically stopped at the receiver and its own frequency and amplitude are measured, for which the low-current circuit contains a means for measuring the inherent mechanical vibrations of the converter, an amplitude comparator, and a memory unit. However, the output of the amplitude comparator is connected to the memory block, which is used to adjust the amplitude, control the processing mode of the object, and is not related to the frequency adjustment. To adjust the frequency of the specified means of measurement with its output connected to the input of the automatic frequency control system, the output of which is connected to the input of the generator. In the description, it is noted that automatic frequency adjustment is carried out continuously, according to the known method.

Of the disadvantages of this technical solution, the following is significant. Known methods of automatic frequency adjustment, as already noted, are ineffective, since the problem of generating a signal adequate to the problem has not been solved. In this case, this is due to the fact that the aforementioned measuring tool, upon completion of the automatic tuning procedure, registers the natural frequency of a complex resonant system, which, in addition to the resonant circuit, also includes all other reactive elements of the high-current circuit. This frequency, which obviously differs from the natural frequency of the resonant receiver, for example, the electromechanical oscillatory circuit of the transducer. The resonance of the generator with the receiver is not achieved.

SUMMARY OF THE INVENTION

Ultrasonic transducer as a receiver of high-frequency power has the following specifics. The power consumer is the electromechanical oscillatory circuit of the transducer; the greatest efficiency is achieved when the generated oscillations are resonant with the natural frequency of the electromechanical circuit. However, at the frequency of this resonance, the transducer, as a receiver, is characterized by reactance: capacitive in the case of a piezoelectric transducer and inductive in the case of magnetostrictive. This is a consequence of the fact that only part of the transducer’s own electrical reactive element is involved in the formation of an electromechanical oscillatory circuit. This part is characterized by the corresponding coefficient: the electromechanical coupling coefficient in the first case and the magnetomechanical coupling coefficient in the second. These coefficients are reference values and, depending on the active materials (respectively, piezoceramics or magnetostrictors), lie in the range of 0.2-0.45. It is impossible to isolate this part in order to register its current or voltage drop with subsequent use to determine the resonance frequency.

The problem is exacerbated by the fact that the values of these coefficients are subject to temperature drift and depend on the compression force and, therefore, change uncontrollably during operation. At the same time, the natural frequency of the electromechanical circuit also changes. The mismatch signal (of any kind), if necessary, is formed with the participation of the total magnitude of the electric reactive element of the transducer, so that it does not contain information about these circumstances and is not proportional to the magnitude of the frequency mismatch, that is, it is not adequate to the problem being solved. In the prior art, this problem has not yet found a solution.

The idea of the invention is that they directly measure the natural frequency of a resonant receiver, for example, an electromechanical circuit, and provide power generation precisely at this frequency, without any additional adjustment. The natural frequency is measured in the form of the frequency of free damped oscillations at the input of the receiver, disconnected from the generator for the time required for measurement. Disabling is performed by a signal from an amplitude comparator comparing the signal from a voltage sensor at the input of the transducer with a minimum specified voltage. In this case, the requirement of proportionality of the magnitude of this signal to the frequency mismatch is removed, that is, the signal adequacy requirement. Its purpose is to be the starting signal for making a frequency measurement.

The technical result obtained in all cases consists in achieving accurate resonance of the generator with a resonant receiver, for example, with an electromechanical circuit of the transducer, and, as a result, in achieving the maximum efficiency of the transducer.

1. The idea is implemented in the following device. The generator includes a high-current circuit with the possibility of connecting it to a receiver, for example, to a transducer, using a connector and a control (low-current) circuit.

High current circuit contains a power amplifier with the ability to work in key mode, having a mode control input. It also contains a controlled high-current switch, for example, an electronic one having a control input, and a voltage sensor having a signal output.

The low-current circuit with its input is connected to the output of the voltage sensor signal and contains:

- low-current controlled key, for example, electronic, having inputs for closing and opening;

- device for measuring the frequency of free damped oscillations of the receiver

(frequency counter), consisting of a counter having an input, as well as a timer and a memory device (register-latch), which have their outputs;

- an amplitude comparator having an input with the possibility of receiving a signal at the output when equality is reached between the voltage from the output of the voltage sensor signal and the minimum specified voltage;

- means for controlling the mode of the power amplifier in the form of a voltage controlled oscillator (VCO), which has inputs of frequency modulation and adjustment of the duty cycle and the output of a rectangular voltage.

In this case, the signal output from the voltage sensor is connected to the input of the amplitude comparator, the output of which is connected to the control input of the high-current switch. The output of the voltage sensor is also connected to the input of the counter of the frequency meter, and the output of the register-latch of the frequency meter is connected to the frequency modulation input of the VCO, the rectangular voltage output of which is connected to the control input of the power amplifier, which ends the low-current circuit.

These signs in equivalent form are common with those of the closest analogues [8 and 9] of the claimed invention.

The claimed generator is characterized in that the high-current switch is made as normally closed with the possibility of opening it according to the signal from the amplitude comparator and subsequent closing by the signal from the timer of the frequency meter, the voltage sensor is located between the high-current switch and the connector, and between the output of the voltage sensor and the input of the frequency counter low current key. It is designed as normally open with the possibility of inverse operation relative to the operation of a high-current key. At the same time, the control input of the high-current switch is additionally connected to the output of the timer of the frequency meter, and the control inputs of the low-current switch are connected to the outputs of the amplitude comparator and timer of the frequency meter.

The set of features set forth provides the claimed technical result in all cases.

2. In the particular case, under conditions of a possible decrease in the quality factor of the resonant receiver, for example, due to an increase in the mechanical load of the transducer, a dependence of the voltage amplitude of the first harmonic at the output of the voltage sensor on the quality factor appears without deviating the generation frequency from resonance. In this case, it is necessary to maintain the indicated amplitude in order to fulfill the signal adequacy requirement.

The technical result in this particular case is to eliminate the dependence of the voltage amplitude of the first harmonic at the output of the voltage sensor on the quality factor of the resonant receiver.

This technical result is implemented in the generator described above with the following additions:

- the high-current circuit further comprises a low-pass filter located between the power amplifier and the high-current switch;

- the amplitude comparator is configured to additionally receive at its second output a difference between the maximum predetermined voltage and the voltage from the voltage sensor;

- while the specified second output of the amplitude comparator is connected to the input of the adjustment of the fill factor of the VCO'a.

4. In the particular case of the possible natural frequency of the resonant receiver beyond the specified limits prescribed by the requirements for frequencies allowed in the technology, there is a requirement to stop generation when the specified output occurs.

The technical result in this particular case consists in the termination of generation at a frequency that exceeds the established limits prescribed by the requirements for frequencies allowed in the technology, with the possibility of resuming generation.

This technical result is implemented in the main version of the generator, containing a power source of a high-current circuit, equipped with inputs for operational shutdown and restart, with the following additions. The low-current circuit additionally contains:

- a frequency comparator with the ability to set the set frequency limits;

- re-enable timer;

- in this case, the input of the frequency comparator is connected to the output of the register-latch of the frequency meter, the output of the frequency comparator is connected with the mentioned input of the quick shutdown and with the input of the reclosing timer, and the output of the reclosing timer is connected with the mentioned reclosing input.

4. In the particular case of a possible emergency in a resonant receiver, a requirement arises for emergency shutdown and the issuance of an alarm signal.

According to this proposal, an emergency is identified by the stable exit of the natural frequency of the resonant receiver beyond the set limits. The reaction in the form of this symptom is manifested by all types of damage in the receiver, including breaks, short circuits, destruction of the active element of the electromechanical circuit, transcendental mechanical load.

The technical effect in this particular case consists in turning off the power circuit together with its power source for any type of accident in the resonant receiver.

This technical result is implemented in the described generator, where the power supply of the high-current circuit is equipped with an emergency shutdown input, and the low-current circuit is equipped with an emergency alarm device and differs in that the low-current circuit additionally contains a counter of consecutive consecutive ones without missing coincidence closures of the low-current key and operational shutdown with the possibility of issuing at its output an emergency shutdown signal when a specified number of matches is reached, while the inputs of the hit counter are connected to the input control of the low-current key and with the output of the frequency comparator, and the output of the coincidence counter with the input of the emergency shutdown and the alarm device.

5. In the particular case of increased requirements for stability and noise immunity of the ultrasonic generator, the low-current circuit is partially implemented in the digital version.

The technical result in this particular case is to increase the stability and noise immunity of the generator.

This technical result is achieved in that the low-current circuit contains a microprocessor system, including a microprocessor, RAM and interfaces, in the form of analog-to-digital and digital-to-analog converters. The microprocessor system is programmed with the ability to perform the functions of an amplitude comparator, a low-current key, a frequency meter with a timer and a register-latch, a frequency comparator, a re-enable timer and a coincidence counter. The block diagram of the program is completely similar to the block diagram of the device. The system has analogue inputs and outputs of the signals for performing these functions, with the input connected to the output of the voltage sensor, and the outputs in accordance with the use of these signals. Namely, the output of the signal to achieve the equality of the minimum specified voltage and the amplitude of the voltage from the voltage sensor is connected to the input of the high current switch opening, the output of the measured frequency signal to the frequency modulation input of the VCO, the output of the signal for the end of the counting time interval to the input of the high current switch closure, output a signal of the difference between the minimum specified voltage and the amplitude of the voltage from the voltage sensor - with the input of the fill factor of the VCO, the output of the signal for comparing the measured frequency with the reference frequency limits - with the input of the operative shutdown of the power supply, the output signal of the end of the time interval of the operative shutdown - with the input of the repeated switching on of the power supply, the output of the signal reaching the specified number of matches - with the input of emergency shutdown of the power supply and with the alarm input.

BRIEF DESCRIPTION OF THE DRAWING

The drawing shows a structural diagram of an ultrasonic generator with the notation:

1 - High current circuit power supply with inputs:

A - operational shutdown,

In - re-inclusion,

C - emergency shutdown.

2 - Power amplifier with mode control input D.

3 - Low pass filter.

4 - High current key with inputs:

E - opening,

F - circuit.

5 - Voltage sensor with signal output G.

6 - Connector.

7 - Amplitude comparator with input H and outputs J and K.

8 - Low-current key with switched contacts L-L and inputs M and N.

9 - Frequency counter with the input of the counter O and with the outputs of the P - timer and Q - register-latch.

10 - Voltage-controlled oscillator (VCO) with inputs of R - frequency modulation, S - control of the fill factor and the output T of rectangular voltage.

11 - Frequency comparator with input V and output W.

12 - Restart timer with input Y and output Z.

13 - Coincidence counter with inputs α and β and output γ.

DETAILED DESCRIPTION OF THE INVENTION

A high-current circuit of an ultrasonic generator consists of a power supply 1, a power amplifier 2, a low-pass filter 3, a high-current switch 4, a voltage sensor 5, and a connector 6 for connecting to a resonant receiver.

Power supply 1 has inputs for quick shutdown A, re-enable B and emergency shutdown C. Power amplifier 2 has a mode control input D. High current switch 4 has openings E and shorting F. Voltage sensor 5 has a signal output G.

The low-current circuit consists of an amplitude comparator 7, a low-current key 8, a frequency counter 9, a voltage controlled oscillator (VCO) 10, a frequency comparator 11, a re-enable timer 12, and a hit counter 13.

The amplitude comparator 7 has an input H and outputs J and K. A low-current switch 8 switches the LL contacts and has control inputs M and N. Frequency meter 9 has a counter frequency counter input O, a frequency counter timer output P and a latch register output Q. A VCO 10 has frequency inputs modulation of R and adjustment of the duty cycle S and the output of the rectangular voltage T. The frequency comparator 11 has an input V and an output W. The re-enable timer 12 has an input Y and an output Z. These structural elements are connected with their inputs and outputs in accordance with the diagram given in black hedgehog.

In preparation for work, operational information is entered into a number of structural elements. The technological frequency is entered in the latch register, the counting time interval in the frequency meter timer, the minimum and maximum comparison voltages in the amplitude comparator, the frequency limits in the frequency comparator, the on-time interval in the re-enable timer, the specified number of matches , VCO fill factor adjustment is set to a minimum.

A resonant receiver is connected to the connector. The keys are restored to their initial state: a high-current key - into a closed, low-current key - into an open.

The generation of ultrasonic power occurs at a frequency fixed in the register-latch of the frequency meter. The mismatch of this frequency with the natural frequency of the resonant receiver manifests itself in the form of a decrease in the signal from the voltage sensor at its output G. When the value of this signal coincides with the minimum comparison voltage, the amplitude comparator generates a command signal at the output J. This signal is fed to the opening input of the high-current switch E and the input of the circuit of the low-current switch M. In this case, the voltage G of the free damped oscillations of the resonant receiver arises at the output G of the voltage sensor, in particular, the electromechanical one loop transducer. This voltage is fed to the input O of the counter of the frequency meter while starting the timer of the frequency meter. At the end of the counting time interval, the measured natural frequency of the resonant receiver is sent to the latch register. Simultaneously with the output P of the timer of the frequency meter, a command signal is sent to the input of the circuit F of the high-current switch and to the input of the opening N of the low-current switch; keys are returned to their original state. Counting in the counter of the frequency meter stops, the frequency value is stored in the latch register. This value through the input R of the frequency modulation of the VCO is transmitted to the input D of the power amplifier mode control. From this moment, the generation is carried out at the measured natural frequency of the resonant receiver, thus achieving accurate resonance, which is the technical result achieved in all cases. With a subsequent change in the natural frequency of the resonant receiver, the described procedure is repeated.

As noted above, temperature drifts are a significant cause of changes in the receiver’s natural frequency. With the transition to a stationary temperature regime, this change decreases, along with this, the average frequency of the described procedure decreases, so this practically does not affect the performance of the device.

2. In the particular case of a possible change in the quality factor of the resonant receiver in order to fulfill the signal adequacy requirement for the task of achieving resonance, the dependence of the voltage amplitude of the first harmonic at the output of the voltage sensor on the changing quality factor of the receiver is eliminated. This constitutes a technical result in this particular case, which is achieved as follows.

From the amplitude-frequency spectrum of a rectangular voltage at the output of a power amplifier, using the low-pass filter, only the first harmonic is extracted and fed to the receiver. It is she who is in resonance with the natural frequency of the receiver. Its amplitude increases with an increase in the duty cycle of a rectangular voltage. The corresponding signal for adjusting the duty cycle at the output K of the amplitude comparator is formed as the difference between the maximum specified voltage and the voltage at the input H of the amplitude comparator.

With an increase in the indicated difference, the fill factor of the rectangular voltage at the output W of the VCO and increases, respectively, at the output of the power amplifier. Thus, with a constant amplitude and frequency of a rectangular voltage at the output of a power amplifier, a practically unchanged amplitude of the first harmonic is maintained with a decrease in the quality factor of the resonant receiver. Thus, a technical result is achieved in this particular case.

3. In the particular case of a possible exit of the natural frequency of the resonant receiver beyond the set limits with each next frequency measurement, its value from the output Q of the register-latch is fed to the input V of the frequency comparator. When this value goes beyond the set limits, a signal arises at the output W. According to this signal, which is fed to input A of the power supply on-line shutdown, it is switched off quickly and the restart timer starts from input Y. After the time period of the operational shutdown the source is turned on again powering the signal from output Z of the timer of repeated inclusion. Thus, a technical result is achieved in this particular case.

4. In the particular case of a possible emergency, in the hit counter, the following consecutive counts occur without missing matches of openings of the low-current switch detected at its input N and operational shutdowns recorded at the output W of the frequency comparator. The achievement of a given number of these coincidences indicates a steady exit of the natural frequency of the resonant receiver beyond the established limits, i.e., an accident in the receiver. An alarm signal occurs at the output of the coincidence counter, according to which an emergency shutdown of the power source of the high-current circuit occurs and the alarm starts in the low-current circuit. This is the technical result in this particular case.

5. In the particular case of increased requirements for stability and noise immunity of the generator, the low-current circuit (with the exception of the VCO) is made in the digital version using a microprocessor system. The technical result in this particular case is to increase stability, for example, with respect to temperature drifts and noise immunity of the device.

The microprocessor system includes a microprocessor, RAM and interfaces for converting analog signals to digital codes and vice versa. The microprocessor system is programmed with the ability to perform the functions of all the mentioned blocks of the low-current circuit, except for the VCO, namely, the amplitude comparator, low-current key, a frequency meter with its counter, timer and latch register, frequency comparator, reclosing timer, and coincidence counter. The block diagram of the program is completely similar to the block diagram of the device. The operation of the low-current circuit, partially implemented in the digital version, is also similar to the previously described.

An example implementation of the device.

An ultrasonic generator was manufactured with a technological frequency of 44 kHz with frequency limits of ± 10% with an output power of 100 W to excite a piezoceramic transducer for surgical purposes. The power amplifier is made according to a half-bridge circuit using field-effect transistors. A low-pass filter is applied in the form of a filter plug type m with blocking of all frequencies exceeding the frequency of the first harmonic. High current key is also assembled on field-effect transistors. The voltage sensor represents a voltage divider. As a low-current key, a frequency meter and an amplitude comparator, standard integrated circuits are used. The counting time interval set by the frequency counter timer is 0.1 s. In this case, the error in measuring the frequency is not more than 10 ^-4 . The accuracy of achieving resonance in this device is the same.

INFORMATION SOURCES

1. PCT / SU 81/00013, 02.02.81.

2. SU 1271585 A1, 06/11/85.

3. RU 2180274 C2, 03/27/97.

4. RU 2180275 C2, 03/27/97.

5. RU 2001112845 A, 05.27.2003.

6. RU 2171343 C1, 02.29.2000.

7. WO 9748501 C, 06/18/1996.

8. SU 1500 388 A1, 01/19/87.

9. RU 2031144 C1, 05/11/1990.

Claims (5)

1. An ultrasonic generator including a high-current circuit with the possibility of connecting it to a resonant receiver, for example an ultrasonic transducer, using a connector and a low-current circuit, where the high-current circuit contains a power amplifier with the ability to work in key mode, having a mode control input, a controlled high-current key, for example electronic, having a control input, and a voltage sensor, and a low-current circuit contains an amplitude comparator with the possibility of receiving a signal at its output when equality m I am waiting for voltage from the voltage sensor and the minimum set voltage, a controlled low-current switch, for example, an electronic one having a control input, a frequency meter consisting of a counter input, as well as a timer and a latch register with their outputs, and a voltage controlled generator (VCO), having frequency modulation and duty cycle inputs and a rectangular voltage output, wherein the output of the voltage sensor is connected to the input of the amplitude comparator, the output of which is connected to the control input full-time key, the output of the voltage sensor is also connected to the input of the counter of the frequency meter, and the output of the register-latch of the frequency meter is connected to the frequency modulation input of the VCO, the rectangular voltage output of which is connected to the control input of the power amplifier, characterized in that the high-current key is made as normally closed with the possibility of opening by a signal from the amplitude comparator and subsequent closing by a signal from the timer of the frequency meter, for which the control input of the high-current switch is additionally connected to the output the timer of the frequency meter, a voltage sensor is located between the high-current switch and the connector, and a low-current switch is additionally placed between the output of the voltage sensor and the input of the counter of the frequency meter; connected to the outputs of the amplitude comparator and timer of the frequency meter. 2. The ultrasonic generator according to claim 1, characterized in that in conditions of changing the quality factor of the resonant receiver, for example, due to a change in the mechanical load of the transducer, the high-current circuit further comprises a low-pass filter located between the power amplifier and the high-current switch, and the amplitude comparator is made with the possibility of additional receiving at its second output the difference between the maximum specified voltage and the voltage from the voltage sensor, while the specified second output is connected to the input ohm adjust the fill factor of the VCO. 3. The ultrasonic generator according to claim 1, characterized in that in the case of a possible exit of the natural frequency of the resonant receiver beyond the set limits, the ultrasonic generator contains a power source of a high-current circuit, equipped with outputs for operational shutdown and restart, while the low-current circuit further comprises a frequency comparator with the possibility set frequency limits and a restart timer, the input of the frequency comparator is connected to the output of the register-latch of the frequency meter, the output of the comparator and frequency - to the input of the operational shutdown and restart the timer input and last output - to the input of restart. 4. The ultrasonic generator according to claim 3, characterized in that the power source of the high-current circuit is equipped with an emergency shutdown input, and the low-current circuit is equipped with an alarm device, while the low-current circuit additionally contains a counter of matches following in a row without missing coincidences of opening of the low-current key and operational shutdown with the possibility of issuing an emergency shutdown signal at its output upon reaching a predetermined number of matches, while the inputs of the coincidence counter are connected to the control input weakly on key and a comparator output frequency and the output of the coincidence counter - to the input of the emergency shutdown and alarm device. 5. The ultrasonic generator according to claims 2 to 4, characterized in that under conditions of increased stability requirements, the low-current circuit contains a microprocessor system including a microprocessor, RAM and interfaces, with the ability to perform the functions of an amplitude comparator, low-current key, frequency meter with its timer and a register-latch, a frequency comparator, a re-enable timer and a hit counter having analog inputs and outputs of the signals for performing these functions, the input being connected to the output d tchika voltage, and outputs - in accordance with said signals.