Print Driving - Canon WS8400 Service Manual

adjustment values stored in the EEPROM.The SDRAM is used as work memory.
j) The CPU in the system controller manages the overall image processing operations while controlling key operation and message display based on the
adjustment values stored in the EEPROM.The firmware is stored in the FLASH ROM.

2.1.3 Print Driving

In this printer, the print signals and control signals pass through the carriage relay PCB and head relay PCB and are output to the printhead. This allows
the printhead to perform printing operations by discharging ink from the printhead nozzles.
The printhead has six nozzle arrays (Bk, PC, C, PM, M, and Y from the left with the carriage installed).
The print signals received by each printhead include even nozzle data (E_DATA_X X=BK0, BK1, LC0, LC1, C0, C1, LM0, LM1, M0, M1, Y0, Y1) and
odd nozzle data (O_DATAX X=BK0, BK1, LC0, LC1, C0, C1, LM0, LM1, M0, M1, Y0, Y1). These two data types are sent according to the timing
determined by the data transfer clock (HDCLKN, HDCLKP) and data latch pulse (HDLTN, HDLTP).
The drive control signals include heat enable signals (BK_HENB, LC_HENB, C_HENB, LM_HENB, M_HENB, Y_HENB) for ejecting ink from the
printhead nozzle and subheat enable signals (BK_SUBH, LC_SUBH, C_SUBH, LM_SUBH, M_SUBH, Y_SUBH) for maintaining stable ink discharge
rates by raising the temperature of the head when it is lower than the optimum operating temperature.
1.Print drive control
Each nozzle array on a printhead has 1280 nozzles.
The nozzles used for discharging ink are selected by the block enable information in the even nozzle data and odd nozzle data and are separated into 24
blocks. (The 1280th nozzle ends at block number 15.) There are 54 nozzles in blocks 0 to 15, and 52 nozzles in blocks 16 to 23.
In the printhead nozzles in the selected block, heat enable signals and subheat enables signals are applied to adjust the pulse width according to the head
rank, head temperature, internal temperature, and other factors to ensure optimal ink discharge, and then the heat board in the printhead nozzle is driven
so that ink is discharged.
The optimal nozzle block is selected based on the printing pass.
2. Print drive timing
Each printhead has six nozzle arrays (Bk, PC, C, PM, M, Y). These six arrays all use the data transfer clock (HDCLKN, HDCLKP) and data latch pulse
(HDLTN, HDLTP) signals.
The even nozzle data (E_DATA_X X=BK0, BK1, LC0, LC1, C0, C1, LM0, LM1, M0, M1, Y0, Y1), odd nozzle data (O_DATA_X X=BK0, BK1, LC0,
LC1, C0, C1, LM0, LM1, M0, M1, Y0, Y1), heat enable signals (BK_HENB, LC_HENB, C_HENB, LM_HENB, M_HENB, Y_HENB), and subheat
enable signals (BK_SUBH, LC_SUBH, C_SUBH, LM_SUBH, M_SUBH, Y_SUBH) are sent to a specific array as required to control each array
separately.
Printing is performed in both the carriage forward and reverse directions.
The encoder sensor installed on the carriage generates 150-dpi pitch linear scale detection signals (CRENCA) and 120"-phase shift signals (CRENCB).
The carriage recognizes the movement direction by the state of the CRENCB signals with respect to the rising of the CRENCA signals.
The printhead is driven using the 2400-dpi timing signals (internal signal) that divide the CRENCA signals detected by the 150-dpi timing into 16 equal
parts.
Forward printing is based on the rising of the detection signals (CRENCA).
Reverse printing is based on the falling of the detection signals (CRENCA) and is performed in the same manner as forward printing, except that the
transmission order of the even nozzle data and odd nozzle data reverses the heating order of the printhead nozzles.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
1279
The pattern is repeated until 1280 nozzles is reached.
The 1280th nozzle ends at block 15.
F-2-3
Block No.
15 16 17 18 19 20 21 22 23
Chapter 2
0009-1497
2-3