Inkjet printing involves the creation of a digital image by propelling tiny droplets of ink onto the base material such as paper or plastic films. Inkjet printers range from compact, inexpensive printers for personal use to expensive, high-end machines for large business organizations.
Over the last few decades, inkjet printing technologies have evolved a great deal. Different models of inkjets available today cater to the unique needs of users such as graphic designers, students, advertising agencies, small businesses, publishing houses, etc.
Besides the ink formulations and type of printhead used, all inkjet printers can fundamentally be classified according to the printing method deployed. Let’s take a look at the different types of inkjet printers.
1. On-Demand or Drop-on-Demand (DOD) Inkjet
In this printing method, the amount of ink particles necessary for printing something onto a given media are discharged by the vertically aligned nozzles inside the device.
DOD inkjets use three different methods – piezo, thermal, and valve – to apply the required pressure to the ink particles and instantaneously spray them onto the target media.
1.1 On-Demand Piezoelectric Type Printer
These inkjets use a piezoelectric material. This material is placed in an ink-filled container behind the nozzle. When a voltage is applied, this material undergoes volumetric deformation, thus producing the pressure required to discharge the ink particles. Since a piezo element is necessary for every nozzle, the entire structure can be very complex.
A large number of commercial and industrial inkjets use DOD piezoelectric method of printing. Several consumer inkjet printers manufactured by Brother and Epson also use this technology. 10 Pack Epson 200XL Ink Cartridge is one of the most recommended ink for Epson printers.
These printers offer great accuracy as the amount of ink discharged can be precisely manipulated by controlling the voltage. Since there’s no heating involved, this printing method works well regardless of the operating environment. However, air bubble formation inside the nozzles can lead to clogging in such printers; therefore, it is important to get the right ink cartridge for your printer. A low-quality ink cartridge may have the wrong chemical composition, incorrect viscosity or damaged parts that can ultimately lead to printhead failure.
1.2 On-Demand Thermal Type Printer
These inkjets use a heating element alongside the ink-filled chamber. The element is used to heat up tiny droplets of ink which turn into bubbles when heated, and discharge ink particles onto the substrate.
Compared to piezoelectric inkjets, thermal inkjets involve a much simpler process. Therefore, these printers are comparatively easier to miniaturize.
A large number of consumer inkjet printers made by well-known companies such as HP, Canon, and Lexmark use thermal DOD inkjet printing method.
The printhead in a thermal type inkjet is likely to have a shorter service life as compared to a piezo type inkjet.
Nozzles in these printers are more susceptible to clogging when they dry up due to the loss of moisture. Therefore, you must not ignore regular printer maintenance.
1.3 On-Demand Valve Type Printer
These printers use a solenoid valve. The pressurized ink particles are released from the nozzle as soon as the valve is opened. Valve type printing method is generally deployed in industrial printers.
Since pressurized ink is discharged by the solenoid, it allows for greater distance between the nozzle and the target media.
The ink particles are comparatively larger in size. Therefore, the print quality is likely to be less as compared to piezo or thermal inkjet printers.
2. Continuous Type Inkjet (CIJ)
It is one of the oldest inkjet printing technologies in use. This printing method involves a continuous discharge of the ink particles from the nozzle. The ink particles in this case are electrically charged. Electrodes are used to deflect ink particles to spray them onto the substrate in a desired manner.
The ink particles that are not successfully deflected by the electrodes for some reason are collected and returned to the ink chamber. These inkjets are referred to as ‘continuous’ because the ink is continually discharged, even when the device is not in use.
Most industrial printers that are used to print books, magazines, newspapers, business correspondence, transactional marketing material, etc. on a large scale, utilize the continuous inkjet printing method.
In case of continuous type inkjets, the ink particles are discharged at a high pressure. Therefore, it is possible to use highly viscous ink. A high velocity also allows for comparatively greater distance between the printhead and the substrate.
With continuous type inkjet method, it is also possible to use quick-drying ink as the ink particles are continuously discharged. Thus, the ink in continuous inkjets can use volatile solvents such as alcohols or ketones; once the ink particles land on the substrate, they dry up quickly.
This printing method involves a great deal of mechanical/electrical complexity. Therefore, it is pretty hard to miniaturize these inkjets. This is precisely the reason why continuous type inkjets haven’t so far made it to our homes and offices.