9.2.2 Inversion and Amplification
The analog signal (OS) from the CCD is output to the A/D conversion PCB. It
is sent in the minus direction under the dc bias voltage (approximate 6 volts).
For every line scanned, 14 dummy pixels produce the black limit level data,
while at the same time the DC reset signal (DCREST) is turned on. The DC
reset signal turns on the switch [A]. Thus, the CCD output (black limit level)
activates Q601, and C657 is charged with the Q601 output. When the switch
[A] is turned off, the CCD output (the image data) is sent to IC629-pin 2 while
the charged voltage in C657 is applied to IC629-pin 3. Therefore, the
difference in voltage between the image data and the black limit level is
inverted and output from IC629-pin 6 above the base voltage of 1.7 volts.
The IC640 amplifies the output of IC629-pin 6 above the base voltage of 1.7
volts. The amplification ratio can be changed by VR601. This signal (V0) can
be observed through TP603 in the A/D conversion PCB.
+12V
OS
Q601
-12V
C657
+12V
DCREST
IC636
1.7V
1.7V
CN602-4
_
+
+
_
V0
TP603
VR601
IC640
IC629
6.8K
2
3
6
2.2K
_
+
+5V
1.7V
[A]
14 pixels
One Scanning Line
SH
Approx. 6V
OS
IC629-6
V0 (TP603)
Approx. 1.7V
1.7V
DCREST
1 December 1993
2-95
Содержание VT3500
Страница 8: ...2 6 USER CODE MODE 4 27 2 6 1 User Codes 4 27 2 6 2 How To Use a User Code 4 27...
Страница 15: ...SECTION 1 OVERALL MACHINE INFORMATION...
Страница 19: ...2 GUIDETOCOMPONENTSANDTHEIRFUNCTION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 December 1993 1 5...
Страница 21: ...16 17 18 19 20 21 22 23 24 25 26 27 28 1 December 1993 1 7...
Страница 37: ...SECTION 2 SECTIONAL DESCRIPTION...
Страница 89: ...E H D G F D C A B C I J K 1 December 1993 2 53...
Страница 123: ...1 December 1993 2 87...
Страница 127: ...1 December 1993 2 91...
Страница 161: ...Background Patterns The 40 background patterns shown below can be selected 1 2 3 4 5 6 7 8 9 1 December 1993 2 125...
Страница 162: ...13 14 15 16 17 18 10 11 12 1 December 1993 2 126...
Страница 163: ...19 20 21 22 23 24 25 26 27 1 December 1993 2 127...
Страница 164: ...28 29 30 31 32 33 34 35 36 1 December 1993 2 128...
Страница 165: ...37 38 39 40 1 December 1993 2 129...
Страница 192: ...SECTION 3 INSTALLATION...
Страница 206: ...SECTION 4 SERVICE TABLES...
Страница 209: ...Q Fig 4 R S Fig 5 T U Fig 6 V Fig 7 1 December 1993 4 3...
Страница 234: ...SECTION 5 REPLACEMENT AND ADJUSTMENT...
Страница 317: ...SECTION 6 TROUBLESHOOTING...