Kodak DirectView CR 825 Theory Manual page 67

THEORY GUIDE
10DEC05
3. The corrected signals are added together in the SUMMING AMPLIFIER. An offset
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Page adjustment signal is added to adjust for any other offset error. The offset signal is provided
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by 2 D/A CONVERTERS that allow large and small adjustments. The offset adjustment
signal causes the signal to be 0 when no light hits the PMTs.
4. The adjusted signal is sent through a LOW PASS FILTER for noise reduction.
5. The filtered signal is sent to the 16-BIT A/D CONVERTER for measurement of the
brightness of the blue light emitted by the SCREEN. The intensity of the blue light is
proportional to the charge stored by the PHOSPHOR and the intensity of the laser beam
that hit the PHOSPHOR. To construct the original image again, it is necessary to know
the strength of the laser beam when the blue light was measured.
6. The PMT/DAS BOARD A5 includes logic circuits that interface with the DIGITIZER
BOARD A3. This serial data interface allows the DIGITIZER BOARD A3 to adjust the A/D
CONVERTERS on the PMT/DAS BOARD A5. The PIXEL CLOCK on the DIGITIZER
BOARD connects to the A/D CONVERTER and sends a command to make a
measurement. The A/D CONVERTER makes a 16-bit value for each measurement. The
16-bit values are sent to a DATA MULTIPLEXER that breaks the 16-bit value into 2 8-bit
bytes.
7. The image is sent to the DIGITIZER BOARD A3 one pixel at a time. The data is stored in
a FIFO BUFFER until a complete line of data is received. The raw image data is sent from
the DIGITIZER BOARD A3 to the MCPU BOARD A2. In the MCPU BOARD A2 the data is
stored in a BUFFER. When all the data for a given image is in the BUFFER, the MCPU
BOARD A2 sends the full raw image to the INTERNAL PC for processing and distribution
to the hospital network.
Optical