AMIS-710310 Datasheet, PDF (3/10 Pages) AMI SEMICONDUCTOR – 300dpi Two-Level Digital Output Module

AMIS-710310-DR: 300dpi Two-Level Digital Output Module Data Sheet
4.0 Circuit Description and Operation
Figure 3 is a simplified block diagram of the analog tracking digitizer. Fundamentally, the tracking digitizer transforms the signal output
from an existing CIS module on the market today. It takes the analog signal from the CIS section of AMIS-710310-DR and derives a
tracking background reference signal. Then this reference is compared against the output signals from the CIS section. The resulting
signal from this 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 3: Analog Signal Reference Generator and a Single Bit Comparator
Figure 1 depicts the two basic circuits, the CIS (image sensors and video amplifier) and the tracking digitizer. In the CIS section, the
module has 11 serially concatenated AMIS-7200030 (PI3012A) image sensors, accordingly, the image sensors will span one scanning-
read line width that is 11 sensor times 96 pixel elements/sensor, or 1056 pixel elements.
In operation, the module produces the analog image pixel signals that are proportional to the 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 inputs 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 value of “one” represents the analog image pixel that is brighter than the background and digital pixel level
value of “zero” represents the image pixel that is darker than background.
AMI Semiconductor – May 06, M-20566-001
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