NOM03A6--AY17G
http://onsemi.com
6
DESCRIPTION OF OPERATION
Functional Description
The NOM03A6--AY17G module consists of 13 contact
image sensors, each with 96 pixel elements, that are
cascaded to provide 1248 photo--detectors with their
associated multiplex switches and double--buffered digital
shift register that controls its sequential readout. A buffer
amplifies the video pixels from the image sensors and output
the analog video signal of the module as shown in Figure 2.
In operation, the sensors produce an analog image pixel
signal (or video signal) proportional to the exposure on the
corresponding picture elements on the document. The
VOUT signal outputs 1248 pixels for each scan line. The
first bit shifted out from VOUT during each scan represents
the first pixel on the connector end of the module.
A pictorial of the NOM03A6--AY17G cross section view
is shown in Figure 4. Mounted in the module isa one--to--one
graded--index micro lens array that focuses the scanned
document image onto the sensing plane. Illumination is
accomplished by means of an integrated LED light source.
An internal reflector helps illuminate the document more
completely, eliminating shadows caused by wrinkles in the
paper. All components are housed in a small plastic housing,
which has a glass cover. The top surface of the glass acts as
the focal point for the object being scanned and protects the
imaging array, micro lens assembly and LED light source
from dust.
PCB
Sensors
Rod
Lens
LED BarModule Housing
Document Surface
Glass Window
Light Path
Figure 4. Module Cross Section View
Connector Pin Out Description
Connections to the module are via a 2.4x14.50mm 10--pin
connector (ECE part number EBW--PK23--P010L2--3Z)
located at one end of the module as shown in the package
drawing on page 8. The location of pin number 1 is
indicated on the package drawing.
Scanner Applications
A typical use of the NOM03A6--AY17G module in
scanner applications is shown in Figure 6. The document to
be digitized is fed into the scanner where a sensor detects its
presence. The scanner then operates the motor to move the
paper under the contact image sensor module. The module
illuminates the paper with internal LEDs and the image
sensor pixel array detects the amount of reflected light and
simultaneously measures a full line of pixels which are
sampled and transferred to a FIFO for storage and
conversion to a parallel output format. Once the pixel line is
processed, the motor advances the paper and the next scan
line is captured.
Initialization
Document
Detected?
Start Scan
SP= , CP= CTR=0
Transfer Scan Line Data
Done
CTR++ == 1248
no
no
yes
Document
Detected?
CP=
Initialization
Document
Detected?
Start Scan
SP= , CP= CTR=0
Read Pixel into Memory
Transfer Scan Line Data
Done
no
no
yes
Document
Detected?
CP=
Figure 5. Typical Scanner Algorithm
Figure 5 outlines the basic steps in the scanner control
sequence. First the circuits are initialized and the scanner
waits for a document to be detected, usually by a paper
sensing switch. Then a start pulse and clock pulse are
supplied to capture a line image. At the next clock pulse the
first pixel value appears on the output. The pixel can be
stored in a local line buffer m emory. Subsequent clocks
cause the remaining pixels to be shifted out and stored in the
line buffer. Once the complete line has been shifted out it can
be transferred to the host application and the system
advances the paper and the line scan process repeats until the
paper sensing switch indicates the document has passed
completely through the scanner.
Device Marking and Barcode Description
Each module is marked with a tag that contains the part
number, a number combining the manufacturing date code
and serial number and a barcode. The barcode presents the
date code and serial number in Interleave 2 of 5 barcode
format as follows
YYMMSSSSSS
where YY is the year,
MM is the month, and
SSSSSS is the serial number.
Glass Lens Care
Precautions should be taken to avoid scratching or
touching the glass lens. The glass lens may be cleaned with
alcohol.
