Classification of Inkjet Printing Technologies
Inkjet printing technology is mainly divided into two major categories:
- Continuous Inkjet (CIJ)
- Drop-on-Demand (DOD)
Among them, Drop-on-Demand (DOD) is further subdivided into:
- Thermal Inkjet
- Piezoelectric Inkjet
The following analysis focuses on the droplet formation stage and practical importance, along with their advantages and disadvantages.
1. Continuous Inkjet (CIJ)
Continuous Inkjet (CIJ)
Continuous droplet generation, switched for printing
- Binary: Kodak, Domino, VideoJet
- Multi-level deflection: Domino, Imaje, Hitachi, Linx, VideoJet
Droplet Formation Stage:
Ink is continuously ejected from the nozzle under high pressure to form a continuous ink stream. This stream is broken into uniform droplets by piezoelectric crystal vibration.
The droplets are electrically charged via a charging electrode, and their landing positions are controlled by deflection plates. Unused droplets are collected and recirculated.
Importance:
High-speed jetting (industrial speeds up to 100 m/s) makes it suitable for production lines such as packaging and label printing.
Advantages and Disadvantages:
Advantages:
- High printing speed, suitable for mass production
- Ink recycling system reduces waste
Disadvantages:
- Complex structure, high maintenance cost
- Requires conductive ink, limiting ink type selection
2. Drop-on-Demand (DOD)
Drop-on-Demand (DOD)
Droplets are generated only when needed
- Thermal inkjet: Canon, HP, Kodak, Lexmark, Funai, Memjet, Olivetti
- Piezoelectric inkjet: Brother, Epson, Fujifilm Dimatix, HP, Konica Minolta, Kyocera, Oce, Panasonic, Ricoh, SII, TTEC, Trident, Xaar, Xerox
- Micro-voltage: Seiko Epson, Tonejet
2.1 Thermal Inkjet
Droplet Formation Stage:
A heating element rapidly vaporizes the ink to form a bubble. The expansion of the bubble ejects the ink droplet, and after cooling, the bubble collapses, drawing in fresh ink.
Importance:
Mature technology with low cost, widely used in consumer printers (e.g., HP, Canon).
Advantages and Disadvantages:
Advantages:
- Simple structure, high printhead integration, suitable for low-cost devices
- Smooth color transitions in color printing
Disadvantages:
- High temperature may alter ink chemistry; prone to clogging if unused for long periods
- Shorter printhead lifespan (requires periodic replacement)
2.2 Piezoelectric Inkjet
Droplet Formation Stage:
A piezoelectric crystal deforms under applied voltage, compressing the ink chamber and directly ejecting droplets without heating.
Importance:
High-precision droplet control (as small as 1 pL), suitable for high-resolution printing (e.g., Epson).
Advantages and Disadvantages:
Advantages:
- Wide ink compatibility (water-based and solvent-based inks)
- Long printhead lifespan, lower maintenance cost
Disadvantages:
- High equipment cost, complex printhead manufacturing process
- Slightly lower jetting speed compared to thermal inkjet
Technology Comparison Summary
| Technology Type | Droplet Formation Mechanism | Core Advantages | Main Limitations |
| Continuous Inkjet | High-pressure breakup + electrostatic deflection | High speed, industrial stability | Complex structure, limited ink types |
| Thermal Inkjet | Bubble-driven (thermal) | Low cost, smooth color transition | Clogging risk, short printhead life |
| Piezoelectric Inkjet | Piezo crystal deformation | High precision, broad ink compatibility | High cost, slower speed |
Application Recommendations
- Industrial applications: Prefer Continuous Inkjet (CIJ) or Piezoelectric Inkjet (DOD)
- Consumer printing: Thermal Inkjet offers better cost-performance but requires regular maintenance
This classification provides a clear framework for selecting appropriate inkjet technologies based on application requirements, performance expectations, and cost considerations.