How a Digital Photocopier Works

The digital photocopier technology has replaced the analog photocopier in the workplace. Staff are no longer queuing in the copy room to reproduce their documents, they request a lot of their copying and printing from the comfort of their office chair! The advanced digital technology is better for the environment than old, analog machines and they are easier to maintain and repair. Combining the functions of a photocopier, laser printer, a scanner and a fax machine the digital photocopier has claimed a valuable place in the office where one machine has replaced several. A digital photocopier is a wise investment for any workplace.



Old school, or analog (Xerography), photocopiers work by combining a positively charged drum and negatively charged substance called toner to reproduce the image of the original document. The original document would have to be rescanned for each copy required. Digital photocopiers scan the original document once and store the data as a file on its hard drive so the document can be reprinted easily and it can even be changed.



The printing function of the digital photocopier is very like a modern laser printer. The printer efficiently memorises the document scanned and creates the page in the raster memory. Through lenses and mirrors, a laser reproduces the image on paper, which is then made visible through toner with an opposite charge.

Image quality is usually considerably higher on a digital copier than an analog model. The advanced scanning technology means that duplicates can be indistinguishable from the original document. If the original document is not clear or faded, digital copiers have facilities that enable you to change the intensity for the copies resulting in your duplicates being of a far more superior quality than your original document.



The Technical Stuff



Inside your digital photocopier is a photoreceptor, this is a light sensitive surface consisting of a layer of photoconductive material that is attached to a drum. In the dark the photoreceptor in insulating but expose it to light and it becomes conducting. High voltage produces an electrical field near adjacent wires causing ionisation and create an electric field across the photoreceptor.



The image is scanned by a laser or a diode image bar, the areas of the photoreceptor that are exposed to the light are discharged causing a reduction in the electric field. The darker areas retain charge.



Toner is the powder used to develop the image. Toner is composed of colourant and plastic resin, the particles have electrostatic properties. Magnetised carrier beads transport the toner to the development area where they are charged by static electricity (triboelectricity). The photoreceptor sends a electrostatic force to the charged toner, this causes the toner to 'stick' to the image.



The image is transferred to paper by the toner coming in contact with paper and applying a polar charge opposite to that of the toner. A second charge releases the paper from the photoreceptor, the image is now on the paper.



To fuse the image the toner comprising the image is melted and stuck to the paper. This is achieved by passing the paper through rollers. A heated roll melts the toner, which is fused to the paper with the assistance of pressure from the second roller.



The advanced capabilities of a digital photocopier make them faster, quieter and produce better quality reproductions than traditional, analog photocopiers.