Sharp UX-B20 Service Manual page 58

UX-B20U/UX-B20C/B25C
2.6. IC4 (µPD65945) Hardware description
2.6.1 Entire Mechanism Sequence Controller
Depending on data processing of the entire ASIC, this controller man-
ages the following automatic drive sequences:
• Power-on/reset sequence
• CAP position check sequence
• CAP position movement sequence 1
• CAP position movement sequence 2
• Cartridge replacement sequence 1 (movement to replacement
position)
• Cartridge replacement sequence 2 (return to the CAP position)
• Print sequence
• Next page print sequence
• Head failure check sequence
• Cartridge ID check sequence
When Fax Engine sends a motor drive command, this controller acti-
vates the motor control circuit after automatic drive sequences to con-
trol the motor.
2.6.2 Serial Data Receiving Circuit
This circuit stores received serial print data in the input buffer. It
receives data (PDAT) using a 16-bit shift register when the clock
(PCLK) is activated and then writes the data to the buffer by every 16
dots (2 bytes).
Input data is fixed to 216 bytes (1728 dots) per line, and the maximum
serial transfer frequency is 3.3 MHz.
When Fax Engine sends a page break command (Page End register =
1), this circuit adds Flag Word (data indicating the last line of a page)
after to the last piece of data.
2.6.3 Input Buffer
This buffer uses 384 kWord of memory space for receiving serial data.
It is based on a FIFO system and equipped with an address counter.
This buffer also has a determining circuit to show the FIFO status
(FULL, NEARFULL or EMPTY).
2.6.4 Enlargement/Reduction/Resolution Conversion Cir-
cuit
This circuit reads data from the input buffer and enlarges or reduces
image data dot by dot. Based on SHARP's conversion algorithm (over-
sampling technique), this process has made it possible to enlarge/
reduce the length and width individually with the following register set-
ting: horizontal scanning direction KH (15:0) and vertical scanning
direction KV (16:0).
Along the horizontal scanning direction, this circuit removes right and
left dots after enlargement, and fills right and left space with white dots
after reduction to send the center of images (centering).
After conversion, there are 4800 dots (fixed value) along the horizontal
scanning direction. 16 extra white dots are inserted at the right and left
edges for 16-dot long odd and even nozzles of the cartridge head. In
total, 4832 dots are sent per line.
To make voids (margins) at the right and left edges, this circuit masks
dots on both sides individually (in white) according to the register set-
ting from Fax Engine (maximum dots: 255 on the left, and 511 on the
right). After converted in both scanning directions, image data is stored
in the print buffer. When converting a swath of data, this circuit sends a
notification to the entire mechanism sequence controller. It identifies
Flag Word (indicating a page break) on each line. If some sections
have less than a swath (208 lines) of data on the last page, this circuit
fills them with white dots.
In the ink save mode, output data is equivalent to 300 dpi of the verti-
cal scanning.
2.6.5 Split Printing/White Skip Measuring Circuit
This circuit monitors data which is converted by the enlargement/
reduction/resolution conversion circuit to be written to the print buffer
to calculate the number of print dots. 4800 dots for horizontal scanning
are divided into 8 areas (600 dots per each) and the calculation is
made for each area.
This circuit sends the split printing status when detecting an area with
62400 (600 x 208 divided by 2) dots or more, and sends the white skip
status if there are no dots in any areas.
The status is sent to the enlargement/reduction/resolution conversion
circuit and then reflected in Flag Word. This circuit checks Flag Word
when starting the swath printing, and performs the split printing or
white skip operation accordingly using Spitfire controller or the entire
mechanism sequence controller.
2.6.6 Print Buffer
This buffer stores image data which is converted to 600 dpi x 600 dpi
by the enlargement/reduction/resolution conversion circuit. This buffer
sends a notification to notifies the entire mechanism sequence control-
ler when detecting a swath (208 lines) of data. When the entire mech-
anism sequence controller sends a release command, this buffer frees
memory space for a swath of image data.
2.6.7 Spitfire controller
When the entire mechanism sequence controller sends a print start
command, this controller controls Spitfire by reading data dot by dot
from the print buffer and converting the length and width according to
the head alignment.
When receiving a split printing command, this controller masks odd
and even slice data in white to send to the first and second paths
respectively.
Also, it counts dots when sending data to Spitfire to calculate the num-
ber of dots per swath.
2.6.8 Carriage Motor Control Circuit
This circuit drives the carriage motor by controlling Thunderbolt
according to the motor acceleration/deceleration table. The carriage
motor drives by steps specified by the entire mechanism sequence
controller in the order of "Still", "Acceleration", "Constant", and "Decel-
eration".
Moreover, the motor drives by specified steps at a constant speed
when the home position detection sensor is switched ON/OFF, and
then decelerates to stop. The carriage is stopped at a fixed distance
after the sensor is switched, which has made it possible to identify its
position at the time of initialization.
2.6.9 Feeder Motor Control Circuit
This circuit drives the feeder motor by controlling Thunderbolt accord-
ing to the motor acceleration/deceleration table. The feeder motor
drives by steps specified by the entire mechanism sequence controller
in the order of "Still", "Acceleration", "Constant", and "Deceleration".
Moreover, the motor drives by specified steps at a constant speed
when the recording paper detection sensor is switched ON/OFF, and
then decelerates to stop. The motor is stopped at a fixed distance after
the sensor is switched, which has made it possible to locate the begin-
ning of the recording paper.
2.6.10 Thunderbolt Interface Circuit
This circuit receives control signals from the carriage motor control cir-
cuit and the feed motor control circuit, and converts them to serial sig-
nals to send to the motor driver IC (Thunderbolt).
Using its head power circuit, this circuit controls the head power ON/
OFF bit in serial signals (converts to serial signals).
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