SU704669A2 - Apparatus for forming ultrasonic field - Google Patents

Description

(54) DEVICE FOR FORMING ULTRASOUND FIELD

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This invention relates to technical acoustics, and can be used to form ultrasonic pulses in delay lines in modulators and other acoustoelectric devices using various types of bulk and surface waves.

A device for forming an ultrasonic field is known according to the ed. No. 447174, containing a piezoelectric element with electrodes connected to a controlled electrical load, the magnitude of the reactive part of which is equal in magnitude and opposite in sign to the resistance of the static capacitance of the piezo element at the operating frequency 1.

The disadvantages of the known device are the low speed, due to the necessity of switching the discrete elements of a controlled / electric load, and the class of generated ultrasonic fields, limited by flat vibrations of the piezoelectric element in thickness.

The aim of the invention is to increase the speed and the expansion of the class of generated ultrasonic fields.

This is achieved by the fact that in the proposed device the reactive part

The electric load of the piezoelectric element is made in the form of a piezoelectric resonator, and the active part is in the form of an electric voltage divider connected to the rectifier input, to the output of which an electronic switch is connected via an RF filter. In the case of surface ultrasonic waves piezoelectric element and the piezoelectric resonator v1ypolneny as a system of interdigitated conductive electrodes deposited on the piezo-active material, and for volumetric ultrasound waves piezoelectric element and the piezoelectric resonator are formed as prodlno oscillating piezoelectric rods or radially vibrating piezoelectric discs with wire electrical covers.

FIG. Figure 1 shows schematically the described device for forming an ultrasonic field with a surface:. nostalgia; see 2 shows a device for forming an ultrasonic field in a longitudinally oscillating rod; in fig. 3 shows a device for generating an ultrasonic field in a radially oscillating disk.

The device (see Figs. 1, 2, 3) contains a piezoelectric element 1 and a piezoelectric resonator 2, electrically connected in parallel through an electric voltage divider 3 to the output of the rectifier 4, the output of which is an RF filter 5 connected to the output of the electronic switch 6 with the input electrodes 7 and 8. In this case, the piezoelectric element 1 and the piezoelectric resonator 2 can be made either as a system of interdigital wires of psng electrodes (Fig. 1) in the case of surface ultrasonic waves, hKGo in the form of longitudinally oscillating piezoelectric FIR rods (Figure 2). radisshno-or vibrating piezoelectric discs (FIG 3) from the conductive & Lectra 1eskimi plates in the case of volumetric ultrasonic waves.

The device works as follows. With the help of the ultrasonic wave incident on the Element 1, periodic electric baths are excited due to the direct piezoelectric effect, which are applied through the voltage divider 3 to the input of the rectifier 4, the electric voltage from the output of the rectifier 4, smoothed by the radio-frequency filter 5 is used to feed the electronic key b.

In the initial position, a negative bias is applied to the control electrodes 7 and 8 of the electronic key 6, therefore the electronic key b is locked and the ultrasonic wave incident on the piezoelectric element 1 is almost fully reflected from the piezoelectric element 1. For changing the ultrasonic field to the control electrodes 7 and 8, a positive the voltage, in which the resistance of the electronic key b decreases sharply, and the incident wave almost completely passes through the piezoelectric element 1.

Thus, when the electrical voltage on the control electrodes 7 and 8 of the electronic key b changes, the ultrasonic field of the piezoelectric element changes almost synchronously and the electronic control of the electrical load of the piezoelectric element allows

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to increase its speed, and the implementation of an inductive load rpysKji of the piezoelectric element in the form of a piezoelectric resonator allows to increase the quality factor of the acoustoelectrical oscillatory system, which increased the efficiency of the entire device. In addition, the implementation of the piezoelectric element and the piezoelectric resonator in various forms allows us to expand the class of formed

ultrasound fields.

Claims (2)

1. Device for the formation of an ultrasonic field according to the ed. No. 447174, characterized in that, in order to increase the speed and expand the class of ultrasonic fields being generated, the reactive part of the electric; the load of the piezoelectric element is made in the form of a piezoelectric resonator, and the active part of the electric load is made in the form of an electric voltage divider connected to the rectifier input, to the output of which an electronic key is connected via an RF filter. 2. Device POP.1, DIFFICULTY with the fact that the piezoelectric. The ment and the piezoelectric resonator are made in the form of a system of oppositely conducting conductors deposited on the piezoactive material. Zo The device according to claim 1, wherein the piezoelectric element and the piezoelectric resonator are made in the form of longitudinally oscillating piezoelectric rods with conductive electrical components. A, a device according to claim 1, 6 tons of l and more so that the piezoelectric element and the piezoelectric resonator are made in the form of radially oscillating piezoelectric disks with conducting electrical plates. Information sources taken into account during the examination 1. USSR author's certificate No. 447174, cl. In About In 1/06, 1972. 7 ., 3