•
Low Voltage Transformer: produces low voltage AC that is later rectified, filtered, and regulated to produce
+5 VDC, +12 VDC, and -12 VDC. It also provides an important safety barrier. The voltage generated on the
secondary of the transformer is isolated - i.e. the voltage is not referenced to earth ground.
•
High Voltage Transformer: produces high voltage AC (250 VAC) that is later rectified, filtered and regulated
to produce a variable DC level used in driving the Hand Piece. It also provides an important safety barrier. The
voltage generated on the secondary of the transformer is isolated - i.e. the voltage is not referenced to
earth ground.
•
Generator PCB: produces power at ultrasonic frequencies to drive the Hand Piece. This is accomplished
as follows:
-
An SCR switching circuit, filter, and software regulate power rectified from the high voltage transformer
to a predefined level, determined by the user-selected power level. Additionally, a zero crossing detection
circuit informs the software when the AC line voltage swings through zero volts. This allows the software
to schedule SCR firings.
-
The DC voltage is then converted into a 55 kilohertz (+/-2 KHz) square wave by means of a
FET switching circuit.
-
The 55 kilohertz square wave is then filtered by a resonant LC network to produce the sinusoidal wave
form that drives the hand piece.
In addition, the generator PCB contains a phase lock loop circuit that monitors the resonant frequency of
the Hand Piece and adjusts the 55 kilohertz up or down to stay at resonance, which changes with
temperature and load.
A secondary function of the Generator PCB is to provide a central point of connectivity for the other PCBs and
modules in the Generator.
The third function is to rectify, filter, and regulate the low voltage AC to generate the logic voltages. These
voltages are +5 VDC, +12 VDC, and -12 VDC. Logic voltage is also inverted to supply power for the
LCD back light.
•
Keyboard/Interlock PCB: The Keyboard portion of this PCB informs the user of the operative state of the
U
LTRA
C
ISION
H
ARMONIC
S
CALPEL
System using LED indicators. It also allows the user to change the default
settings as described in Chapter 3 of this manual and in the Generator Manual.
The interlock portion of this assembly acts as a shunt, placing a resistive load across the output to the blade
whenever it is not activated at the VAR or FULL power levels. The interlock is used to quickly stop the blade
motion once the Foot Switch pedal is released.
•
Microprocessor PCB: The microprocessor PCB contains the software program that drives the U
LTRA
C
ISION
H
ARMONIC
S
CALPEL
System. The software monitors zero crossings, regulates DC voltage, processes button
and pedal activations, and drives the liquid crystal display. It also monitors performance of the generator PCB
and the acoustic drive train.
•
Liquid Crystal Display: The liquid crystal display reports the operative mode of the ULTRACISION System.
It is driven by the microprocessor PCB via the generator PCB.
•
Foot Switch: The Foot Switch module allows the user to activate the system in either variable or full mode
based on which foot pedal is being pressed. Pedal activations are communicated with the microprocessor via the
keyboard/interlock and generator PCB.
4
2.2
Generator and
Foot Switch
continued
Chapter 2 - Principles of Operation
continued
