Dentistry – Apparatus – Having motor or means to transmit motion from motor to tool
Reexamination Certificate
2000-02-15
2003-09-16
Lucchesi, Nicholas D. (Department: 3764)
Dentistry
Apparatus
Having motor or means to transmit motion from motor to tool
Reexamination Certificate
active
06619957
ABSTRACT:
The invention relates to ultrasonic scalar hand-pieces. More specifically the invention provides ultrasonic scalar hand-pieces having a circuit to modify an electrical signals and conducting the modified electrical signals to a coil enclosed by a hand-piece housing.
BACKGROUND OF THE INVENTION
An ultrasonic scalar converts electrical energy to mechanical energy, primarily in the ultrasonic frequency range, and this mechanical energy is used to remove tooth scale. Takeshita in U.S. pat. No. 4,453,919 discloses an air driven dental scaler the disclosure of which is incorporated herein by reference in its entirety. Dentsply International Inc manufactures a Densonic TM sonic scaler which is driven by air pressure. The system operates in the ultrasonic frequency range, frequencies greater than 18K. Hertz, but is not be specifically limited to this frequency range. Operating in the ultrasonic frequency range provides beneficial scaling performance, and provides higher patient comfort in comparison to lower frequency units. The magnetostrictive actuator utilized in the system of the invention requires less power consumption than prior art systems.
Pinkerton et al disclose magnetostrictive material in U.S. Pat. No. 5,993,565 the disclosure of which is incorporated herein by reference in its entirety. Magnetostriction occurs when a material on exposure to a magnetic field develops significant strain: at room temperature, sample dimensions can change by as much as fractions of a percent. Conversely, the straining of a magnetostrictive material changes its magnetization state. Magnetostrictive materials have been used with electromagnetic actuators to form transducers which serve as, for example, ultrasonic generators or fine control valves for the metering of fluids. In these applications, variation of the magnetic field is employed to produce varying strains in the magnetostrictive material to produce a mechanical output. Conversely, a suitable magnetostrictive material might be employed as a torque or force sensor. Maximizing device performance suggests using materials having large saturation magnetostriction, .lambda..sub.s, which is a dimensionless measure of the field-induced strain frequently expressed in units of parts per million (ppm). Extremely high values of .lambda..sub.s are found in rare earth-iron compounds such as the terbium-iron compound, TbFe.sub.2, where .lambda..sub.s equals 1750 ppm for a polycrystalline sample. Unfortunately, the rare earth-iron compounds are very brittle materials having little tensile strength, an unpropitious characteristic for automotive applications requiring good mechanical properties. On the other hand, stronger and tougher materials such as steels have very limited magnetostriction: T250 maraging steel, which is currently being evaluated in torque sensors, has a .lambda..sub.s of only .about.30 ppm. The wide gulf between these two extremes offers ample opportunity and challenge for developing new magnetostrictors combining good magnetostriction with satisfactory mechanical properties. The prospect of embedding magnetostrictive powder in a strengthening matrix has been sporadically explored as follows. The Clark and Belson patent, U.S. Pat. No. 4,378,258, entitled “Conversion Between Magnetic Energy and Mechanical Energy,” reported sintering cold-pressed pellets of ErFe.sub.2 with nickel and TbFe.sub.2 with iron. Few details of the properties of these materials were provided. They retain some magnetostriction, but as it turns out, the sintered bodies are brittle and of insufficient strength for many applications such as automotive sensor applications. Clark and Belson also produced resin-bonded composites of the RE-Fe.sub.2 (RE=rare earth) magnetostrictive compounds. Peters and Huston of the International Nickel Company attempted to prepare composites of SmFe.sub.2 in nickel by sintering, by extrusion and by hot pressing, but they obtained values of magnetostriction which were only modestly larger than that of the nickel alone and did not recommend the practices. See D. T. Peters and E. L. Huston, “Nickel Composite Magnetostrictive Material Research for Ultrasonic Transducer,” January 1977, Naval Electronic Systems Command Contract No. N0003976-C-0017, US Department of Commerce National Technical Information Service, ADA 040336; and D. T. Peters, “Production and Evaluation of ReF(2)-Nickel Composite Magnetostrictive Materials,” Final Report, January 1979, Naval Electronic Systems Command Contract No. 0003977-C-0108, US Department of Commerce National Technical Information Service, ADA 066947. Others have also made magnetostrictive composites of RE-Fe.sub.2 materials in epoxy binders.
The prior art does not disclose a hand held scaler ultrasonic, comprising a hand-piece housing, and an air driven electrical current generator, as provided by the present invention.
The prior art does not disclose a hand held scaler ultrasonic, comprising: a hand-piece housing, and a frequency control circuit, as provided by the present invention.
The problems low tip oscillation frequency of prior art hand held scalers is overcome by the present invention.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an ultrasonic scaler, comprising a hand-piece housing, and an air driven electrical current generator, wherein the air driven electrical current generator is enclosed by the hand-piece housing.
It is an object of the invention to provide an ultrasonic scaler, comprising: a hand-piece housing, and a frequency control circuit, wherein the frequency control circuit is enclosed by the hand-piece housing.
REFERENCES:
patent: 4378258 (1983-03-01), Clark et al.
patent: 4453919 (1984-06-01), Takeshita
patent: 5460593 (1995-10-01), Mersky et al.
patent: 5754016 (1998-05-01), Jovanovic et al.
patent: 5900690 (1999-05-01), Gipson et al.
patent: 5993565 (1999-11-01), Pinkerton et al.
patent: 6106289 (2000-08-01), Rainey et al.
Hecht Robert F.
Hoube Allen G.
Mosch James G.
Werner Peter H.
Bieber James R.
Dentsply Research & Development Corp.
Lovercheck Dale R.
Lucchesi Nicholas D.
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