| 摘要 |
An ultrasonic oscillator drives a tool at a set frequency. An amplitude control runs the oscillator to set the vibration level. A frequency regulator joins the amplitude and the oscillator. A control feedback loop, in the frequency regulator, keeps handpiece linear dynamics. An operational transconductance amplifier, in the oscillator, governs gain of the loop. A circuit connects to the control to retard the rate of current application over time to the amplifier. The circuit has switching to either retard the rate or reset for start up. The amplifier is a current output device with current directly proportional to the bias current and input voltage with bias as gain change for the loop. The circuit limits the bias to the amplifier to modify frequency response and output current. A capacitor delays application of the bias to the amplifier. Replaceable tools of various lengths or shapes positioned along an axis vibrate for surgery at the frequency and a wave length. Tools longer than one wavelength and of configurations tuned to oscillate around the frequency resonate as a function of their material, length and configuration. A flue surrounds the tool and has a hollow elongate semi rigid central body about an axis with a funnel, at one end thereof and a nozzle, at the other to direct annular irrigant/coolant flow therethrough. The funnel and nozzle are resilient. Reinforcing ridges, inside the nozzle, act to maintain concentricity between the flue and nozzle tip and channel irrigant thereabout.
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