Process and circuit for exciting an ultrasonic generator and its use for atomizing a liquid

#The present invention relates to a process and a circuit for exciting an ultrasonic generator, and to the use of the circuit with the ultrasonic generator for atomizing a liquid.

#The possibility of atomizing liquids with the aid of piezoelectric ultrasonic generators is known. For example, the article by W.D. Drews "Flussigkeitszerstaubung durch Ultraschall" in Elektronik, 1979, No. 10, pp. 83 to 90, briefly describes the principle of this process, in which an ultrasonic generator or vibrator is provided with an atomizer disk or plate and a circuit for exciting the ultrasonic generator.

#However, several problems are encountered in technically bringing about the atomization of a liquid with the aid of an ultrasonic generator.

#In the drawings:

#FIG. 1 is a block circuit diagram of a circuit for exciting an ultrasonic generator according to the present invention;

#FIG. 2 is a schematic view of an embodiment of the final or output stage of the circuit according to FIG. 1; and

#FIG. 1 shows a circuit for exciting an ultrasonic generator or vibrator 1, whose per se known atomizer disk or plate (cf. e.g. DE-3534853) is not shown. The ultrasonic generator 1 is excited by means of a final or output stage 2, shown in detail in FIG. 2. The output stage 2 is supplied with current I from a direct current voltage source U. The output stage 2 is controlled by a driver stage 3, which in turn receives a signal of frequency f from a voltage-controlled oscillator 4.

#The voltage-controlled oscillator (VCO) 4 is known per se and constructed of commercially available components. The permitted voltage swing at its control input is predetermined, whilst the corresponding frequency swing at its signal output can be adjusted in a known per se manner by the value of the frequency-determining components, which are known and for the sake of clarity not shown in FIG. 1 and which are connectable to the oscillator 4 and which, when using analog technology, can be resistors and/or capacitors, whilst, when using digital technology, they can comprise a crystal oscillator and signal inputs on corresponding programming inputs.

#The control input of oscillator 4 receives a signal from a triangular wave generator 5, so that the frequency f is swept or wobbled as a function of the output voltage of generator 5. In accordance with the sweep direction the triangular wave generator 5 increases or decreases its output voltage and oscillator 4 its frequency f.