Sharp FO-1660 Service Manual page 35

Separation rubber
3-5. Documents requiring use of document carrier
1) Documents smaller than B6 (128mm x 182mm).
2) Documents thinner than the thickness of 0.06mm.
3) Documents containing creases, folds, or curls, especially those
whose surface is curled (maximum allowable curl is 5mm).
4) Documents containing tears.
5) Carbon-backed documents. (Insert a white sheet of paper be-
tween the carbon back and the document carrier to avoid transfer
of carbon to the carrier.)
6) Documents containing an easily separable writing material (e.g.,
those written with a lead pencil).
7) Transparent documents.
8) Folded or glued documents.
Document in document carrier should be inserted manually into
the feeder.
4. Document release
4-1. General
To correct a jammed document or to clean the document running
surface, pull the operation panel lock lever under the front center of
the operation panel. To open the upper document guide, the opera-
tion panel must be opened first.
Last page of document
First page of
document
Paper feed spring
Paper feed roller
Fig. 4
5. Optical system
(1) General view
Rear sheet
Reader
glass
Mirror 3
(2) Composition
The optical system is composed of the document feed mechanism,
the LED lamp, the reflecting mirrors, the focusing lens, the CCD
sensor, and the read process circuit.
5-1. LED Lamp/Lens
The LED lamp is used to project light to the document.
NOTE: Take care for the position of the red mark on the lens. (Top
of the light-projected side)
5-2. CCD
The CCD (charge coupled device) image sensor consists of a pho-
todiode array which converts the intensity of light reflected from the
document surface into series of analog voltages which are then
stored in an analog shift register. The series of analog voltages are
then converted into a digital equivalent by a black/white binary logic
circuit.
(Example) Scan signal output waveform
100%
50%
minimum
Maximum document width, 216mm
1) The minimum output from the CCD at the maximum scan width of
document (216mm) must be more than 50% of the peak value.
2) The peak output must be about 0.2 ~ 0.6 under room temperature
to avoid CCD saturation.
3 – 2
UX-600MU/MC
FO-1660U/C
CCD PWB
Document
Red mark
LED lamp
Mirror 2
CCD
Lens
Mirror 1
Fig. 5
Peak
Fig. 6
Scan line
length