Ultrasonic wave generating apparatus with voltage-controlled filter

• US 4,277,758 A
• Filed: 08/09/1979
• Issued: 07/07/1981
• Est. Priority Date: 08/09/1979
• Status: Expired due to Term

• Current Assignee: TAGA Electric Company Limited
• Original Assignee: TAGA Electric Company Limited
• Inventors: Mishiro, Shoji
• Primary Examiner(s): Moore, David K.
• Application Number:
  US06/065,161
• Time in Patent Office: 698 Days
• Field of Search: 331/1 R, 331/26, 331/116 R, 331/116 M, 331/4, 331/25, 310/316, 310/116, 310/311
• US Class Current: 331/1.00R
• CPC Class Codes: B06B 1/0253 taken directly from the generator circuit
• CPC Class Codes: B06B 2201/57 Electrostrictive transducer
• CPC Class Codes: H03B 5/323 the resonator having more than two terminals H03B5/326 takes precedence
• CPC Class Codes: H03L 7/02 using a frequency discriminator comprising a passive frequency-determining element

Abstract

The present invention deals with an ultrasonic wave generating apparatus with voltage controlled filter, comprising a phase comparator which detects a shifted value from a predetermined phase difference between a driving voltage or a driving current of an ultrasonic transducer and a vibratory velocity signal, and a voltage-controlled band-pass filter which is controlled by the output of the phase comparator and which is provided in a feedback loop from the vibratory velocity signal to an input of a driving amplifier of the ultrasonic transducer, wherein the oscillating frequency is changed while following the resonant frequency of the ultrasonic transducer, so that stable operation is materialized without developing abnormal oscillation in subresonant frequencies and permitting very small following error.

Claims

1. An ultrasonic wave generating apparatus comprising:

ultrasonic transducer means for producing ultrasonic waves and a vibratory velocity signal;

driving amplifier means for driving said ultrasonic transducer means;

phase comparator means for comparing the output of said driving amplifier means with the said vibratory velocity signal for detecting a shifted value from a predetermined phase difference and producing a phase difference signal in response thereto;

a voltage controlled band-pass filter means, said phase difference signal controlling said voltage controlled band-pass filter means;

said voltage controlled band-pass filter means being directly connected to said vibratory velocity signal in a feedback loop.

2. An ultrasonic wave generating apparatus according to claim 1, wherein said voltage controlled band-pass filter means is a bridged T filter.

3. An ultrasonic wave generating apparatus comprising:

ultrasonic transducer means for producing ultrasonic waves and a vibratory velocity signal;

driving amplifier means for driving said ultrasonic transducer means;

a voltage to current converter inserted between said ultrasonic transducer means and said driving amplifier means;

phase comparator means for comparing the output of said driving amplifier means with the said vibratory velocity signal for detecting a shifted value from a predetermined phase difference and producing a phase difference signal in response thereto;

a voltage controlled band-pass filter means, said phase difference signal controlling said voltage controlled band-pass filter means;

said voltage controlled band-pass filter means being directly connected to said vibratory velocity signal in a feedback loop.

4. An ultrasonic wave generating apparatus according to claim 3, wherein said voltage-controlled band-pass filter means is a bridged T filter.

5. An ultrasonic wave generating apparatus according to claim 3 or 4, wherein said ultrasonic transducer is an electro-strictive transducer.