Sharp FO-165, Service Manual

Page: 38 / 112

Fig. 4
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. Cross section view
(RIGHT SIDE)
Fig. 5
4-2. General
When the release lever is pulled by hand in the direction of arrow A,
the latch is released and the upper document guide moves on its axis
in the direction of the arrow. The feed rollers, the separation rubber
plate, and the pinch rollers become free to make it possible to remove
the document.
5. Optical system
(1) General view
Fig. 6
(2) Composition
The optical system is composed of the document feed mechanism,
the lamp, the reflecting mirrors, the focusing lens, the CCD sensor,
and the read process circuit.
5-1. LED Lamp
The LED lamp is used to expose the document.
5-2. Lens
The lens is used to focus the light reflected from the document on the
CCD elements.
5-3. 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
Fig. 7
1) The minimum output from the CCD at the maximum scan width of
document (216mm) must be more than 40% of the peak value.
2) The peak output must be about 200mV under room temperature
to avoid CCD saturation.
Paper feed roller
Back of document
Last page of document
First page of document
Separation rubber plate
Paper feed
spring
CCD
CCD PWB
Document
LED Lamp
Glass
Mirror 2
Rens
Mirror 1
Mirror 3
Peak
40%
minimum
Maximum document width, 216mm
Scan line
length
100%
Document guide ass'y
Lower cabinet
Paper cover
UX-177H
3 – 2