Guideline E: Input and output interfaces

E10: Printer duty cycle limitations

Compensating for printer duty cycle limitations

The duty cycle is an engineering term that specifies the ratio of the sum of all on periods to the total period during a specified period of continuous operation. For example, if a motor needs an hour of cooling off for every three hours of continuous operation, the motor duty cycle is rated at 75%.

Duty cycles on some printers require that the mechanisms that generate heat be given time to cool off between printing characters. This is fine for scripts with discrete characters like English, but not for scripts that are cursive, such as, Arabic and Indian Devanagari, that have continuous links. Note that duty cycle limitations are applicable to some printers, such as impact printers that use earlier printing technologies and are not applicable to most newer printing technologies, such as laser and inkjet that support graphics and image printing.


Guideline E10


Provide a mode to print each successive pixel of a character shape matrix.


Example: An inexpensive impact printer can print English text at 100 characters per second (cps). The pause between successive characters printing allows the printer head to cool off. Printing Arabic text at 100 cps quickly overheats the printer head. One solution is to permit the printer speed to vary. The printer automatically slows down when its head temperature reaches a potentially dangerous level.