Position Control; Exposure Logic; Power Supply - KaVo ORTHOPANTOMOGRAPH OP 3D Service Manual

4 Device description
For further information on the boards, see the relevant sections in this document.

4.3.3 Position control

Positioning of the device is done by stepper- and DC-motors, using feedback from
optical, resistive and Hall sensors. The control chain per actuator is described below.
Upper shelf linear and pivot movement, rotator movement
The movement is driven by a stepper motor. A resistive sensor determines the
approximate position of the actuator. A number of exact positions is determine by
matching the approximate position with feedback from an optical sensor changing state
at regular intervals. Positioning between these points is based on by counting steps fed
to the stepper motor.
Lasers and collimator movement
The movement is driven by a stepper motor. An optical sensor is used to determine the
Home position. Driving to wanted position is done by first finding the Home position, and
then counting steps fed to the stepper motor.
Z-movement
The movement is driven by a DC motor. An optical sensor is used to determine the Home
position. The Z-position is determined by using the home position as reference and
counting pulses generated by a Hall sensor connected to the motor.
Imaging chain overview / Image data transfer
Image capturing is handled by the i2000 Image Capture Board. This board is responsible
for both triggering the sensor and capturing image data. The data is stored in the i2000
Image Capture Board until transferred through the I3000 board to the image capturing
workstation.

4.3.4 Exposure logic

Exposure logic is solely controlled by i4000 board. The i4000 board includes power
supply, inverter and filament power supply that are responsible for supplying the X-ray
tube head.
Filament pre-heat
Prior the high voltage generation at the tube head the filament is pre-heated. The pre-
heating process is controlled and monitored by the i4000 board.
Exposure
After the filament pre-heat, the exposure is enabled. Exposure is monitored by the i4000
board by utilizing the KVFB and MAFB signals and comparing them against the selected
reference signals.
Backup timer
The exposure timing is controlled by the firmware. In the event of malfunction there
is an added safety timer implemented in hardware, which will cut the exposure in case
EXPENA-signal is active too long.

4.3.5 Power supply

The mains power supply comes from the wall socket through the back panel to the i4100
board. For further information, see
Power distribution +24Vdc
Mains power configuration
Detach the indicated screw on the back panel cover and lift it off to access the device
back panel.
20
i4100 back panel board
en la página 48.
en la página 42. See also
ORTHOPANTOMOGRAPH
™
OP 3D