Sonic transducer and drive circuit

• US 4,056,761 A
• Filed: 09/11/1975
• Issued: 11/01/1977
• Est. Priority Date: 09/11/1975
• Status: Expired due to Term

• Current Assignee: Quintron, Inc.
• Original Assignee: Quintron, Inc.
• Inventors: Monroe, Marvin E., Jacoby, Benjamin Franklin
• Primary Examiner(s): Duggan, Donovan F.
• Application Number:
  US05/612,358
• Time in Patent Office: 782 Days
• Field of Search: 310/8.1, 310/26, 318/116, 318/118, 323/8
• US Class Current: 318/116
• CPC Class Codes: B06B 1/0261 taken from a transducer or electrode connected to the driving transducer

Abstract

A sonic transducer, having a drive electromechanical transducing element and a pickup electromechanical transducing element or a single transducing element electronically operating as both, is excited through suitable power amplifiers by a voltage controlled oscillator. A phase comparator connected to these transducing elements detects the phase difference between stress and strain in the transducer. Its output is connected to an integrator circuit means which integrates the phase difference signal and applies the integrated signal to control the voltage controlled oscillator. The maximum and minimum values of the voltage which is applied to control the oscillator are independently limited by a pair of diodes connected to sources of two different voltages. An adjustably fixable phase shift circuit is interposed between the pickup transducing element and the phase comparator to permit calibration of the system for optimal operation. Amplifier and clipper circuitry interposed between the phase shift circuit and the phase comparator circuit make the oscillator output signal independent of the amplitude of the vibrations of the sonic transducer.

Claims

1. A sonic tool comprising:

a. a sonic transducer including electromechanical transducing means for the application of a periodic electronic drive signal thereto to produce a mechanical stress for driving said transducer and for generating an electronic pickup signal which is proportional to mechanical strain;

b. a phase comparator having an output signal proportional to the phase difference of a pair of periodic signals at a pair of inputs, one input connected to receive the electronic drive signal applied to said transducing means and the other input connected to receive the electronic pickup signal from said transducing means;

c. integrator circuit means having its input connected to the output of said phase comparator;

d. an electronic signal controlled oscillator having its input control terminal connected for control by the output of said integrator circuit means and its output connected for exciting said transducing means with said drive signal;

e. limiter circuit means connected to the input control terminal of said oscillator for limiting the escursions of the control signal to confine it within a selected range; and

f. an adjustable phase shift network means and amplitude limiting circuit means electrically interposed in cascade between said transducing means and said phase comparator for introducing a selected phase shift in said pickup signal and for making the input pickup signal applied to said phase detector independent of the amplitude of the pickup signal from said transducing means.

2. A sonic tool according to claim 1 wherein a power amplifier is interposed and connected between the output of said oscillator and said drive transducing element.

3. A tool according to claim 2 wherein said oscillator is a voltage controlled oscillator.

4. A tool according to claim 3 wherein said limiter circuit means comprises a pair of diodes having an unlike terminal of each connected to said control terminal and the other terminal of each connected to sources of two different voltage levels.

5. A sonic tool according to claim 1 wherein said transducing means comprises a drive electromechanical transducing element connected for the application thereto of said drive signal and a pickup transducing element connected to the pickup signal input of said comparator.

6. A sonic tool comprising:

a. a sonic transducer including electromechanical transducing means for the application of a periodic electronic drive signal thereto to produce a mechanical stress for driving said transducer and for generating an electronic pickup signal which is proportional to mechanical strain;

b. a phase comparator having an output signal proportional to the phase difference of a pair of periodic signals at a pair of inputs, one input connected to receive the electronic drive signal applied to said transducing means and the other input connected to receive the electronic pickup signal from said transducing means;

c. integrator circuit means having its input connected to the output of said phase comparator;

d. an electronic signal controlled oscillator having its input control terminal connected for control by the output of said integrator circuit means and its output connected for exciting said transducing means with said drive signal;

wherein said transducing means comprises a transducing element and time sharing means for applying a driving signal from said oscillator during a minor part of each cycle and for applying said pickup signal from said transducing element to said phase comparator during another part of each cycle.

7. A sonic tool according to claim 6 wherein said time sharing means includes a transformer with a pair of windings having relatively fewer turns one for the application of said signal and the other for the pickup of said pickup signal and having a winding with relatively more terms connected to said transducing element.

8. A sonic tool according to claim 6 further comprising:

a. a limiter circuit means connected to the input control terminal of said oscillator for limiting the excursions of the control signal to confine it within a selected range; and

b. an adjustable phase shift network means and amplitude limiting means electrically interposed in cascade between said pickup winding element and said phase comparator for introducing a selected phase shift in said pickup signal and for making the input pickup signal applied to said phase detector independent of the amplitude of the pickup signal from said pickup transducing element.

9. A sonic tool comprising:

a. a sonic transducer including electromechanical transducing means for the application of a periodic electronic drive signal thereto to produce a mechanical stress for driving said transducer and for generating an electronic pickup signal which is proportional to mechanical strain;

b. a phase comparator having an output signal proportional to the phase difference of a pair of periodic signals at a pair of inputs, one input connected to receive the electronic drive signal applied to said transducing means and the other input connected to receive the electronic pickup signal from said transducing means;

c. integrator circuit means having its input connected to the output of said phase comparator;

d. an electronic signal controlled oscillator having its input control terminal connected for control by the output of said integrator circuit means and its output connected for exciting said transducing means with said drive signal;

wherein said transducing means comprises a transducing element and balancing means connected to said transducing element, the output of said oscillator and the pickup signal input of said phase comparator for coupling said drive signal to said transducing means and for coupling said pickup signal to said phase comparator.

10. A sonic tool according to claim 9 wherein said balancing means comprising a bridge circuit.

11. A sonic tool according to claim 9 wherein said balancing means comprises a hybrid transformer.

12. A method for exciting a sonic transducer, the method comprising:

a. exciting said sonic transducer by a signal controlled oscillator operable over a limit frequency range including the desired resonant frequencies of said transducer;

b. detecting a signal which is proportional to mechanical strain;

c. shifting the phase of said strain signal;

d. clipping said strain signal to eliminate amplitude variations;

e. detecting the phase difference between the excitation signal from said controlled oscillator and the clipped and phase shifted strain signal to obtain a signal proportional to said phase difference;

f. integrating said phase difference signal about a selected phase difference; and

g. controlling said oscllator with said integrated phase difference signal.

13. A method according to claim 12 further comprising the step of limiting said frequency range by limiting the excursions of said integrated phase difference signal to within selected limits.