Oki OKIOFFICE84, Maintenance Manual

Page: 263 / 519

SIGNAL FLOW
A2 - 1 40672201TH Rev. 4
A2.1 Explanation of Signal Flow
(1) Copy Mode
Figure A2.1 shows the picture signal route in local copy mode
One-line picture data is transferred to A/D converter (analog/digital) via operational
amplifier from the scanning unit (CIS: contact image sensor) as an analog data. After
conversion from analog data to 6-bit digital data by A/D converter, the picture data is sent
to IEXSEED (image processing LSI) and SRAM. Here, the picture data undergoes
various kinds of picture processings (IEXSEED and SRAM), converted to two-level binary
data (black and white) and then sent to IOGA4 (scanning control). The one-line binary
picture data from IOGA4 is stored into DRAM. When the data for one page has been
stored in the DRAM, the data is read out from the DRAM and sent to IOGA4. The data is
converted into a serial data by the picture control of IOGA4 and transferred to the LED
print head for printing as HDATA0. Writing of data into the page memory is also possible
during the printing operation.
(2) G3 Send Mode
Figure A2.2 shows the G3 send picture signal route
In the G3 mode, the data transfer route from the scan unit up to the DRAM is the same
as in the copy mode described in (1).
The picture data for one-line is transferred from DRAM to IOGA4 (CPU). The IOGA4
(CPU) performs the picture data processing (encode) for this picture data (FILLER, fill
bits are inserted etc.) and again stores into the DRAM. The stored encoded data is
output from DRAM to the MODEM under the control of IOGA4 (CPU). After modulation,
the picture signal “S” is sent to the NCU board as the transmission data. The transmis-
sion data “S” goes through the amplifier and is sent to the telephone line L1 and L2 via
the transformer T1 as high speed signal.
(3) G3 Receive Mode
Figure A2.3 shows the G3 receive picture signal route
In the G3 mode, the high-speed picture signal arriving from the telephone line at L1 and
L2 of NCU passes through the transformer T1 and the amplifier and is input to the
MODEM as “R” signal. After demodulation by modem, the picture data is sent to IOGA4
(CPU). The IOGA4 (CPU) performs the picture data processing (decode) for this picture
data and stores into the DRAM. Then, the stored picture data is again written into DRAM
(as a page memory) by the picture processing control of IOGA4 (CPU). When the data
for one page has been stored in the DRAM, the data is read out from the DRAM and sent
to IOGA4. The picture data is converted into a signal data by the printer control of
IOGA4 and transferred to the LED print head for printing as HDATA 0.
(4) 300bps Send Mode
Figure A2.4 shows 300bps send protocol signal route
In G3 communication, this is the route of the procedural control signals (pre-message,
post-message phases etc.) at 300bps.
The protocol send data is read into DRAM in the sequence the contents of varrious data
stored in the FLASH memory area in advance under the control of IOGA4 (CPU). The
contents of the frame has been edited on the DRAM by IOGA4 (CPU) and sent to
MODEM via IOGA4 (CPU). HDLC (high level data link control) frame of the data is
structured by the modem and converted to serial data in synchrony with the modem’s
DCLK (data clock). After modulation, the protocol signal is output from “S” of the modem
and sent to the telephone line L1 and L2 via the transformer T1 of NCU.