Intermec ColorCoder V4 Service Manual page 37

2.2 Image Formation System, cont'd.
2.2:B BJ Line Head, cont'd.
1
Ejection
face
2
Bubbles
Main heater
3
4
5
6
7
Bubble volume
(relative value)
Heater drive pulse
(main heat section)
1
2 3 4 5
Figure 2-19
Intermec ColorCoder V4 – Service Manual Ed. 1
Principle of Ink Ejection
The BJ method takes advantage of the bubbles generated by the
heater element. The generation of bubbles causes the pressure in the
nozzle to change, causing the ink to be ejected.
1. Normal condition
At the ejection face, the surface tension of the ink balances the
outside pressure.
2. Heaters are heated
The ink adjacent to the main heater is heated to form fine bubbles.
3. Boiling
The ink adjacent to the main heater vaporizes abruptly to have the
bubbles grow.
4. Expansion of bubbles
When the bubbles grow to the maximum, the ink is ejected out of
the ejection face.
5. Contraction of bubbles
The bubbles are cooled down with the ink to contract. The ink at the
tip of the nozzle rushes out at the speed at which it is ejected.
6. Destruction of bubbles
The ink comes in contact with the heater surface to be abruptly
cooled down.
7. Supply of ink
The ink is again supplied to the nozzle by the capillary tube
phenomenon.
6 7
Chapter 2 Operation and Timing
36