Assistant Service Manual
OPTIKON 2000
Code 121008S 6-14 Rev. D
6.3.1 U/S DRIVER 347888
CONTROL
LOGIC
DIATHERMY
ADJUSTABLE
POWER SUPPLY
ULTRASOUND
The operating philosophy of the U/S Driver 347888 is shown by the block
diagram above.
The board contains both the U/S driver and the Diathermy driver, they share
the same adjustable power supply and they are both controlled by the same
microprocessor (NEC’s 78F0078).
Sheet 1/2
The U/S driver operates the piezoelectric handpiece, an electromechanical
resonating system, powered by a pair of piezoelectric ceramics that is kept
constantly tuned at its own oscillation frequency.
Ceramics are stressed by a sinusoidal voltage supplied by the u/s amplifier
section. At maximum power, this voltage features a peak amplitude equal to
500 V approx. with a frequency coinciding with the pilot signal supplied by
the Voltage Controlled Oscillator (VCO) section. Tuning accuracy is
measured reading the phase shift between the pilot signal (f) and the power
signal (f’) existing at the ceramic ends: the larger the phase difference, the
better the tuning.
This information is provided to microprocessor by the phase detector
section, that can provide the updated phase shift value at each new cycle of
the pilot signal. This quick response enables the microprocessor, that
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