Table of Contents
Advertisement
(2) Image process section
The image process section is composed of gate array A and gate
array B, the SRAM for peripheral table, and the FIFO.
The image signal flow is shown as follows.
The image signals which was A/D converted according to the shading
data from the image process section are converted into data which
were subjected to the visible sensitivity (inverse function) correction
and the auto exposure process. If the zooming mode is selected,
electronic zooming is performed. Zooming in the sub scanning direc-
tion in this machine is performed by changing the moving speed of
the optical system. In the main scanning direction, image data are
electronically interpolated for zooming. Then the data are divided into
the photo area, the hatched area, the character area, and the other
area by the characteristics amount of the converted data and the
peripheral pixels.
After that, the density conversion is performed to obtain the suitable
density for each mode.
If the density conversion mode is the photo mode, lines are aligned to
provide higher gradation before sending to the laser control section.
(3) Laser control section
G/A
FIFO
FIFO
Basic function
Image digital signal → Laser drive PWM signal exchange
1
2
PWM calibration control on starting printing
TTL → ECL conversion
3
4
Lim FIFO R/W control
Printer
I/F
TTL/
VIDEO
PWM
EC L
IC
VIDEO\
conversion
-5.2V
Operational description
Image signals processed in the image process section are stored in
the FIFO as the line image signals and inputted to the LCU G/A. The
first print position signal (BD signal) from the LSU and the CKX4 are
synchronized to align the image line positions. The line data are read
from the FIFO and converted into the PWM width corresponding to
the data by the IC and delivered to the LSU unit at the ECL level.
The LCU G/A takes the following four states with the PLAY, the
LDON, and the image data signal to control the timing of laser con-
trol.
Laser state
LDONB
Stop
Forcibly ON
Image write
Void formation
The LDONB signal forcibly turns on laser. It is driven LOW when the
rotation ready signal of the polygon motor is sensed. Since the laser
power is automatically performed by the LDONB, the LDONB re-
quires LOW signal of 10ms or more. When the LDONB is LOW, the
PLAYB signal is driven LOW to allow the LSU to operate.
[LSU GA and peripheral circuit]
The LSU GA functions are classified as follows.
•
Control to write image data from the ICU to two FIFO's alternative-
ly for every line.
Input:
GCK
Output:
F1WB, F2WB, FWCK, RSTWB
(Image data themselves from the ICU are supplied to the FIFO
directly.)
•
Control to read image data from the FIFO to which data are not
written.
Output:
F1RB, F2RB, FRCK, RSTRB, DIM [0..7]
•
Generates the sync signal (BDB) for image clock and the ICU in
synchronization with the sync signal (/SYNC) from the LSU.
Input:
CKX4, HSB
Output:
CLK, BDB
•
According to instructions from the ICU, etc., control of the effective
area in the main scanning direction and forcibly turning on the
laser are performed.
Input:
SLAT, LSCK, LSIN, LDCNB, PALYB, CAL0
Output:
D0 [0..7]
•
PWM ICU calibration is performed at the start of turning on the
laser.
Input:
LDBON, PLAYB, CAL0
Output:
CALIN
9 – 5
PLAYB
Image data
1
1
0
1
0
Image data
1
0
White data
Advertisement
Table of Contents
