LED printer
From Wikipedia, the free encyclopedia
An LED printer is a recently-developed type of computer printer.
LED technology uses a light-emitting diode (hence the name LED) printhead as a light source within the imaging device. The LED bar pulse-flashes across the entire page width and creates the image on the print drum as it moves down.
LEDs are more efficient mechanically than normal laser printers, since there are fewer moving parts. Depending on design, LED printers can have faster rates of print than some laser based designs, and are generally cheaper to manufacture. Laser systems rely on elaborate combinations of rotating mirrors and lenses that must remain in alignment through use. The laser scans from one end of a line to another, then zig-zags down to the next line. Unlike laser printers, the LED printhead is solid-state and has no moving parts.
There are concerns about the LEDs in the printer experiencing early burnout due to repeated on/off switching as a print is made.[1]
LED printing was invented by Casio.[2]
[edit] Resolution
LED printers have a technical limitation that cannot easily compete with the highest quality laser printers; there are only so many LEDs that can be packed into a linear physical space. A printer having 300 dots-per-inch resolution needs to physically have 300 LEDs per inch, and a printer at 600 dpi needs 600 LEDs per inch.
Many laser printers now commonly print at 1200 dpi, but making LEDs that small is very difficult. It is not uncommon to see LED printers that use a skewed image resolution such as 600x1200 dpi. The horizontal resolution is limited to 600 dpi by the physical size of the LEDs, but the vertical resolution is simply a matter of how fast the LEDs flash as the paper passes by. Image quality depends on the spot shape of each LED. A round pixel/spot will mean that pixels overlap in the vertical direction, while a squashed-oval pixel/spot allows the spots to not overlap and permit a slightly better image quality.
