The fixed head design sees the printer fitted with it's own long life inbuilt print head which is designed to last the life of the printer and never need to be replaced or repaired. Known as a "gaither head" it follows the philosophy that a print head can last longer than the life of the ink in a cartridge and so why should it be replaced with it and bringing it's cost to replacement ink cartridges.
This philosophy drives the price of printer units up but printer cartridges down. Therefore the purchaser of a printer should evaluate the balancing act which should be resolved based on the volume of printing they will require from their printer and the expected life of the printer. As the head is fixed and permanent, more attention to details is applied to it's design and it's production, therefore the head will be more precious than a cheap disposable model and will require little or no calibration.
The flip side of the argument is that if the head becomes damaged or broken then it is an expensive process to repair or replace the print head, in some cases it is not even possible to do this and so an entirely new printer would be required. Fixed head designs are available in printers designed for the home printer but are more commonly noted on high volume printers, the type used in industries such as publication. The consumer space printers utilising fixed heads are primarily Epson, HP and Canon.
The second design for printer heads is the disposable head which is not found as a fixed part in the print unit itself but is provided in each independent printer cartridge that is added to the printer. Each time the ink reservoir in a cartridge is emptied the print head will be disposed of with the cartridge and replaced with a new one.