AMIS-710214 Datasheet, PDF (3/8 Pages) AMI SEMICONDUCTOR – 200dpi Two Level Digital Output Module

AMIS-710214: 200dpi Two Level Digital Output Module
Data Sheet
4.0 Circuit Description and Operation
See Figure 3, which is a simplified block diagram of the analog tracking digitizer. Fundamentally, the tracking digitizer transforms the
signal output from a CIS module existing on the market today.
Figure 3: Analog Signal Reference Generator and a Single-bit Comparator
It takes the analog signal from the CIS section of AMIS-710214 and derives a tracking background reference signal. Then this
reference is compared against the output signals from the CIS section. The resulting signal from comparison produces a two-level
digital signal that is high when the pixel signal is brighter than the background and remains at zero as long as the signal is darker than
the background signal.
Figure 1, AMIS-710214 block diagram depicts the two basic circuits, the CIS (image sensors and video amplifier) and the tracking
digitizer. In the CIS section, the module has 27 serially concatenated PI3004B image sensors, accordingly, the image sensors will span
one scanning-read line width that is 27 sensor times 64 pixel elements/sensor, or 1728 pixel elements.
In operation, the module produces the analog image pixel signals that are proportional to exposure on the corresponding picture
element on the document (the video signal) then passes the signal to the tracking digitizer. In turn, the digitizer processes the analog
image pixels to digital image pixels. The analog image pixels, at test point TV, are separated into two signals. One generates the
reference signal and the other remains unmodified. These unmodified image pixels are applied to one of the input of the comparator.
The reference signal is applied to the second input of the comparator. The results of the comparison are the digital image pixels. This
digital output is produced in two levels, determined by the difference between the background reference signal and the analog image
pixels. A digital pixel output of value “one” represents the analog image pixel that is brighter than the background and digital pixel level
of value “zero” represents the image pixel that is darker than background.
AMI Semiconductor – May 06, M-20539-001
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