Lsu Drive Circuit - Toshiba e-STUDIO170F Service Manual

7.3.3

LSU Drive Circuit

Main PBA
X1
PTCCK1
230
41.716
MHz
X2
PTCCK2
231
47.234 IC15
MHz
ASIC
( Engine controller )
SDD0-15
IC1
SDRAM
The LSU (Laser Scanner Unit) drive circuit consists of the Engine-CPU (IC37), ASIC (Engine controller:
IC15) and other peripheral devices. It drives the LSU connected to CN3 and CN8 on the Main PBA to
apply a laser beam to the drum.
The ASIC sends a printing command to the Engine-CPU by the CMD signal. This allows the Engine-
CPU to drive the polygonal motor in the LSU to make the polygonal mirror rotate. When the printing is
ready, the Engine-CPU sends a TOD signal and a UFEX signal to the ASIC.
The ASIC reads the raster data accumulated in the SDRAM (IC1) and serially converts them to a
LDATA signal. Then the ASIC detects the clock signal (OSC1 or OSC2) outputted from the facsimile
oscillator (X1) or the printer oscillator (X2) according to the timing of the TOD signal and the UFEX sig-
nal, and sends the LDATA signal to the LSU according to the timing of the clock signal.
The LSU radiates a laser beam according to the input LDATA signal to make a latent image latent on
the drum.
Signal Name Type
CMD
TOD
UFEX
LDATA
PTCCK1
PTCCK2
January 2005 © TOSHIBA TEC
CMD
33
TOD
236
UFEX
234
LDATA
235
Fig.7-21
Active
O - Serial communication command signal
I L Top of data signal
I L Horizontal synchronizing signal
O - Print data
I - 16 dots/mm clock
I - 300/600 dpi clock
7 - 27
34
Control signal
IC37
40
Engine-CPU
Control signal
25
19 25, 26
2
8 1
10 3
9
IC14
IC14
Description
e-STUDIO170F Circuit Description
LSU
2
Destination
Engine-CPU
Engine-CPU
Engine-CPU
IC14
X1
X2
7