Circuit Description Of Cis Unit - Sharp AM-900 Service Manual

[5] Circuit description of CIS unit

1. CIS
CIS is an image sensor which scans the original paper in close contact
with the full-size sensor, being a color type with the pixel number of
5,148 dots and the scanning density of 600 dpi. It is composed of sen-
sor, rod lens, LED light source of Red, Green and Blue, Analog mem-
ory circuits and so on.
2. Block diagram
12 9 10 11 8
B G R
NC
C
LED GND
C
VLED
Fig. 20
3. Waveform
3.1. Timing chart 1
1) CLK timing chart
4MHz
CISCLK
(CNCIS 7pin)
CISSP
(CNCIS 6pin)
Ao
(CNCIS 1pin)
Fig. 21
2) Data output timing chart
After turning on the SP pulse, the analog output starts from the set-
ting up point of 64 clock pulse.
1 2 52
CISCLK
CISSP
Ao
VREF Output Perlod(52pixels)
*1
1~52pixels
Fig. 22
CIS UNIT
1 5 4 6 7 3
R
R R
C
C
AO
VDD SP CLK GND
C
VREF GND
Approx. 3.3V
0V
Approx. 1~1.5V
(White level)
Approx. 0.8V
(Offset level)
0V
53 54 64 65 66
Dummy Output Analog Output Period
53~64pixels 65~5212pixels
3.2. Timing chart 2
1) Reading color document
CIS R LED(*)
(Q31-B)
CIS G LED(*)
(Q30-B)
CIS B LED(*)
(Q29-B)
CIS CLK
CIS SP
Ao
2
(*): The pulse width of CIS R LED/CIS G LED/CIS B LED are
adjusted automatically every scan, so it is a change.
2) Reading monochrome document
CIS R LED(*)
CIS G LED(*)
CIS B LED(*)
CIS CLK
CIS SP
Ao
(*): The pulse width of CIS R LED/CIS G LED/CIS B LED are
adjusted automatically every scan, so it is a change.
5 – 22
1.7ms 1.7ms
Fig. 23
1.7ms 1.7ms
Fig. 24
AM-900U
1.7ms
4MHz
1.7ms
4MHz