Sharp UX-177 Service Manual page 26

UX-177H
Last page of document
Back of document
First page of document
Paper feed roller
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)
Document guide ass'y
Lower cabinet
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.
Separation rubber plate
Paper feed
spring
Fig. 4
Paper cover
Fig. 5
5. Optical system
(1) General view
Document
LED Lamp
Glass
Mirror 1
Mirror 3
(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
100%
40%
minimum
Maximum document width, 216mm
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.
3 – 2
CCD
CCD PWB
Rens
Mirror 2
Fig. 6
Peak
Scan line
length
Fig. 7