Photocopier Supplies

Laser Photocopier

Laser photocopier is a machine that has the ability to create multiple copies of a required document or an image with the help of a modulated laser. Laser photocopiers and laser printers have lot of things in common. The major difference is the process of image forming. A photocopier uses lens and bright light to focus the image of original on to the drum.

Laser photocopier works in the following way:
Every laser photocopier has light sensitive surface known as a photoreceptor. The light sensitive material is coated with photoconductive material which is applied to a drum. The photoreceptor acts as an insulator when in dark. When it is exposed to light, it acts as a conductor. In the dark, the photoreceptor is charged by applying a DC voltage to its adjacent wires. This DC voltage generates an electric field due to which the air molecules get ionized. Ions that have polarity deposit on photoreceptor's surface which creates an electric field.

In a laser photocopier the image on the photoreceptor is exposed with a modulated laser.
The areas of photoconductor that are exposed to light are discharged selectively which cause reduction in electric field. The darker areas that are not exposed to light retain their charge.

 Developing: Pigmented powder that develops the images is called toner. Toner particles are made of plastic resin that has controlled elastic properties. They are mixed and charged by magnetized beads that transport the toner particles to development zone. The electric field on the photoreceptor applies electrostatic force on charged toner particles that sticks to the image.

Transferring: Powder  image is then transferred from photoreceptor on to the paper by bringing paper in contact with toner particles and then applying charge with a polarity that is opposite of toner particles. The charged should be strong to overcome powder's adhesion to photoreceptor. A second controlled charge now releases the paper which now contains the image

Fuse: In fusing process, toner containing the required image is melted and then bonded to paper. This is done by passing paper through a pair off rollers. A heated roll melts toner particles which then fuse to paper with the help of pressure that is applied from second roll.

Clean: The transfer of toner particles from photoreceptor to paper is not 100 percent. Residual toner still remains and should be removed from photoreceptor before next photocopying cycle starts. Laser photocopiers achieve this cleaning task with the help of a brush cleaner that rotates randomly.