Print Signal - Canon BJ-W3000 Service Manual

2. Print signal

The BJ print head is controlled as follows.
LTCLK
ODATA
DCLK
ODD
EVEN
BENB 0
BENB 1
HSEL 1A,1B
HSEL 2A,2B
HENB 1A,1B
HENB 2A,2B
The image data (ODATA) transmitted to the shift register using the DCLK timing is trans-
ferred to the latch using the LTCLK timing by the signal from the linear encoder.
The BENB0 and BENBI signals are divided into 4 signals by the 2→4 decoder and the
nozzles are controlled in 4 groups.
The HSEL1 and HSEL 2 signals also control the nozzles in 4 groups.
Finally, each block is further divided into 2 by the ODD and EVEN signals and the nozzles
are divided into 8 groups. By dividing the head drive in this way, the power supply load is
reduced and ink filling delays are prevented.
The HENB signals use a pre-pulse to increase the head temperature to a proper value before
the main pulse discharges the ink. The pulse widths are varied according to the head rank and
head temperature sensor for an even ink discharge rate.
These signals are input to the AND gates together with the image data (ODATA) and each
heater is driven by the output.
The HSEL and HENB signals correspord to heaters large and small. By combining these
signals in the various ways, the volume of ink discharged from the nozzles is controlled to form
3 drop sizes as follows:
• Large dot: Both large and small heaters are driven.
• Middle dot: Only large heater is driven.
• Small dot: Only small heater is driven.
Approx. 70µs (14.4kHz)/
Approx. 130µs (7.7kHz)
0 1 2 3 4
1(0) 0(1) 1(0) 0(1) 1(0) 0(1)
1(0) 0(1) 1(0)
1(0)
1(0)
1 block
Figure 2-305
CHAPTER 2. BASIC OPERATION
160
Data transfer to shift register
1(0) 0(1)
Drive of head divided into 8
0(1)
0(1)
0(1)
Variable
Pre-pulse
pulse width
Main pulse
2–45