VISUAL TUNING ELECTRONIC DRIVE CIRCUITRY FOR ULTRASONIC DENTAL TOOLS

• US 3,586,936 A
• Filed: 10/16/1969
• Issued: 06/22/1971
• Est. Priority Date: 10/16/1969
• Status: Expired due to Term

• Current Assignee: Robert P. Mcleroy
• Original Assignee: Robert P. Mcleroy
• Inventors: Mcleroy, Robert P.
• Application Number:
  US04/866,984
• Time in Patent Office: 614 Days
• US Class Current: 318/118
• CPC Class Codes: B06B 1/0223 for generating signals continuous in time
• CPC Class Codes: B06B 2201/58 Magnetostrictive transducer
• CPC Class Codes: B06B 2201/76 Medical, dental

Abstract

Solid state electronic circuitry for driving the magnetostrictive transducer of ultrasonic dental tools is described, wherein tuning to resonance is controlled by circuit adjustment to maximum brightness of a tuning indicator lamp. Variation of brightness of the lamp as a function of tuning accuracy is achieved by feeding a reference voltage proportional to the excitation current flowing through the ultrasonic transducer to the input of a differential amplifier stage to compare it with a preset reference voltage. The varying output voltage thus derived is amplified to provide an energization current for the indicator lamp which will be proportional to the transducer excitation current and thus an indication of tuning to resonance.

Claims

1. Electronic drive circuitry for exciting a magnetostrictive transducer used in ultrasonic dental tools and the like comprising, in combination, a source of DC potential, a solid state ultrasonic oscillator energized by said source of DC potential and providing a substantially sawtooth waveform output signal voltage, a power amplifier energized by said source of DC potential and having an input controlled by said output signal voltage, said power amplifier providing a power output signal, an ultrasonic transducer energized as the load of said power output signal, indicator means responsive to current flowing through said transducer to visually indicate tuning to resonance thereof upon variation of said frequency of said sawtooth waveform output, (Electronic drive circuitry for exciting a magnetostrictive transducer, as defined in claim 1, wherein) said indicator means (comprises) comprising a current-responsive visual indicator and a differential amplifier stage having an input transistor and an output transistor, circuit means responsive to load current flowing through said power amplifier and providing a substantially proportional DC reference voltage, said reference voltage being applied to a controlling element of said input transistor, a predetermined comparison DC voltage applied to a controlling element of said second transistor, and a load resistor for said second transistor providing a variable output voltage for energization of said current-responsive visual indicator.

2. Electronic drive circuitry for exciting a magnetostrictive transducer, as defined in claim 1, wherein said oscillator is in the form of an RC relaxation circuit.

3. Electronic drive circuitry for exciting a magnetostrictive transducer, as defined in claim 2, wherein said RC relaxation circuit comprises means for varying the frequency of said sawtooth waveform output.

4. Electronic drive circuitry for exciting a magnetostrictive transducer, as defined in claim 3, wherein said sawtooth waveform output is variable within the frequency range of between 16.5 and 21 kilocycles.

5. Electronic drive circuitry for exciting a magnetostrictive transducer, as defined in claim 1, wherein said visual indicator comprises an incandescent lamp.

6. Electronic drive circuitry for exciting a magnetostrictive transducer used in ultrasonic dental tools and the like comprising, in combination, a source of DC potential, a solid state ultrasonic oscillator energized by said source of DC potential and providing a substantially sawtooth waveform output signal voltage, a transistor power amplifier energized by said source of DC potential and having an input controlled by said output signal voltage, a DC bias circuit including a bias resistor for said power amplifier, said power amplifier providing a power output signal, an ultrasonic transducer energized as the load of said power output signal, and indicator means responsive to current flowing through said bias resistor to visually indicate tuning to resonance of said transducer upon variation of said frequency of said sawtooth waveform output, said bias resistor being operative as a current-limiting resistor with respect to said power amplifier upon accidental short circuiting of said transducer.