Sharp FO-DC635U, Руководство по обслуживанию

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FO-DC635U
5 – 15
2.8. LCD control block
This block consists of the LCD controller and drive voltage generation
circuit.
2.8.1 SED1374F0A (IC10): pin-80, QFP (LCD Controller)
The LCD controller SED1374F0A (IC10) conducts direct control to dis-
play the bitmap data through the LCD module, which is transferred to
the built-in VRAM by the CPU (IC24).
2.8.2 Drive voltage generation circuit
The drive voltage of the LCD module is generated by the booster cir-
cuit including the switching regulator S-8358J50MC (IC4). The CPU
monitors the ambient temperature of the LCD module using the ther-
mistor, and the temperature adjustment of the LCD’s contrast is per-
formed by controlling the drive voltage.
2.9. Network I/F block
This block establishes interface to the NIC option (FO-LN1) and PCL
board option (FO-NP1) through SUB ASIC mentioned in the above
item 5). The I/F line (DPO-bus) to NIC is shared with the Fax system
on the PCL board, and SUB ASIC assigns a place to connect. The
PCU (laser printer engine) is also shared with the Fax system on the
PCL board, and the printer master is decided by mutual negotiations
via SUB ASIC.
The I/F route is as follows:
1. Fax system to NIC
Makes communication via SUB ASIC.
2. Fax system to PCL board
•
Serial Communication: Clock sync serial communication function
•
Print Request/Acknowledge: Print request from the PCL board
and response to it
3. NIC to PCL board
Makes communication via SUB ASIC.
4. PCL board to PCU
•
Serial Communication: Clock sync serial communication function
•
Other signals: The print vertical sync signal (/TOD) and the print
horizontal sync signal (/HSYNC) are connected directly. Signals
other than these are connected via SUB ASIC.
[3] Circuit description of CIS unit
1. CIS
CIS is an image sensor which puts the original paper in close contact
with the full-size sensor for scanning, being a monochromatic type with
the pixel number of 1,728 dots and the main scanning density of 8
dots/mm.
It is composed of sensor, rod lens, LED light source, control circuit and
so on, and the reading line and focus are previously adjusted as the
unit.
Due to the full-size sensor, the focus distance is so short that the set is
changed from the light weight type to the compact type.
2. Waveform
The following clock is supplied from LC272D0BT-WA6 via 74HCT244
on the control board, and AO is output.
SENSE1
SENSE2 2
13
Set current detection pins.
Connect these pins, fed back through noise filters, to E1, and E2.
E1
E2 3
12
Current control pins by connecting between this pin and GND.
DGND 4,11 Internal diode anode connection
OUT1B
OUT1A
OUT2B
OUT2A 6
7
8
9
Output pins
GND 15 Ground
RC1
RC2 27
16 Used to set the output off time for the switched output signals.
The fixed off times are set by the capacitors and resistors connected to these pins. t off
CR
Vref1
Vref2 26
17 Output current settings
The output current is determined by the voltage (in the range 1.5 to 7.5V) input to these pins.
PHASE1
PHASE2 25
18 Output phase switching inputs.
[H] input: OUT A = high, OUT B = low
[L] input: OUT A = low, OUT B = high
ENABLE1
ENABLE2 24
19 Output on/off settings
[H] input: output OFF
[L] input: output ON
I01, I11
I02, I12
22, 23
21, 20 Digital inputs that set the output current.
The output currents can be set to 1/3, 2/3, or full by setting these pins to appropriate combinations of high
and low levels.
VCC 28 Logic block power supply.
Pin name Pin No. Pin Description
Fig. 7
1.2 ms
0V
1.5 V (TYP)
(White original paper)
Approx. 5 V
CISSI
CISCLK
AO
1.52 MHz
Approx. 5 V
0 V