LED and LCD Printers
LED stands for Light emitting diode. Light emitting diodes are devices which come in form of tiny bulbs which can be fitted into a lot of electronic devices. They consist of a semiconductor chip. The motion of electrons inside the semiconductor chip makes the LED light up due to the release of photons.
LED printers were first introduced by Casio, which is a Japanese MNC which specializes in a number of electronic equipments such as cameras, PDAs, printers and many more. LED printers are a type of Laser computer printers which use LEDs. The light flashes onto the page being printed allowing the letters and images to form on the drum. The drum has negative charge over it. The light hitting the drum makes that area less charged. This makes the drum attract the toner. The toner is then transferred from the drum to the sheet of paper being printed. This is how the letters or images are formed. The heat produced makes the ink in the form of letters stick properly to the paper.
Because of fewer mobile parts inside an LED printer the reliability and efficiency of this printer is higher than that of a Laser printer. The rate of printing is comparatively faster in LED printers and they have lower manufacturing costs. Unlike LED printers, laser printers have lenses and mirrors which have to be aligned with each other throughout the operation of the printer. This means that even if one of the lenses or mirrors is not aligned the printer can suffer from a malfunction. Laser printers also have several mobile parts compared to LED printers.
There is a drawback of an LED printer, which is the dependence of resolution on the number of LEDs on the print head. This limits the printer in terms of its resolution and quality to a large extent. Only a specific number of LEDs can be accommodated in an area inside the printer. For instance, for an LED printer to have a resolution of 300dpi, there should be 300 LEDs in the print head. Similarly for a 500dpi the number of LEDs required will be 500.
To add LEDs in a printer for making a 1200 dpi printer is difficult as it is almost impossible to make the LEDs small enough so that they fit inside the printer. It is often seen that the horizontal resolution is smaller such as 600 and the vertical resolution is 1200. This makes the resolution as 600×1200 dpi. The vertical resolution is dependent on the rate at which the LEDs produce light while the paper is moving in the printer.