Non – Impact Printers: Laser printer

Laser printer
Laser printers are an offshoot of photocopying technology. The first commercial laser printer was produced by Canon Cooperation in the 1980’s. It was based on the copier engine called PC-20. The most well know version of this laser printer is HP Laser jet. Laser printers produce s excellent graphics 300-1800 dpi.
Laser printers are rated by two properties, time to first page out which rates how longer the printer processor take to the map an images and print speed which measures rate at which the printer can output pages. The amount of memory available in the printer can affect both ratings.
Laser printers use buffers to store an entire pages at a time and that is why they print very fast at the rate of approximately 21,000 lines or 437 pages per minutes.

Operation of laser printers
Laser printers used a ‘toning’ or development process to product output. The process uses a combination of various electrostatic charges to transfer dry-ink from it storage reservoir, from images with the toner and placed the toner on the paper. The toner is then “fused” to the paper either by heat activated or pressure activated bonding materials mixed in the toner. The process starts when the print job is received from the computer. The printer processes the data and created a digital map where is the images to be printed. The printer pulls a sheet of the paper from the paper tray and begins passing the paper through a charging roller which puts and specific electrostatic charge on the paper to make more receptive to the toner.
At the same time a photoconductor drum located in the printer begins spinning slowly and is charged by primary change roller. As the surface of the drum emerges from the charge process the UV laser begins mapping dots on the drums surface. The dots of the light change the electrostatic proprieties of area of the drum they strike making this sports attractive to the toner. The images surface of the drum then rotates towards the developer roller. The developer roller is a specially designed cylinder made of metal or conductive polymer which carries a thin layer of the toner on its surface. The developer roller rotates to pick-up fresh toner from the toner reservoir and brings it close to photoconductor. When the toner gets very close to the photoconductor, it transfers itself to photoconductors at the points where the laser stuck the photoconductor surface.
At this point the photoconductor has a mirror image of the output on its surface. As the charged surface of the paper passes closely through photoconductor, the toner on the surface of photoconductor is pulled off onto the paper. When the paper passes through the fuser assembly the waxes and bonding agents mixed with the toner which melts and bonds the toner to the papers surface. The paper is then emerged into the output tray.