HOW THEY WORK : “How a Photocopying Machine Works”

Have you ever wondered as to how the image of your Identity card, certificate, form, document, name it, moves from the original image to what we may call a carbon (black) copy of it? The machine works seamlessly easy but the technology behind it is not all that hard to figure out. First and foremost, there is the reading process, then the image transfer process and the printing process. In brief, the machine comprises of a scanner of a sort, this scanner is then linked to the printer which gives you an output. With increased sophistication, they have developed a number of devices that combine the functions of copying, scanning and printing; of course, these wonder machines may come with a facsimile (what you call a fax) function as well. By the way, the fax functionality is a sort of copier that does the scanning, printing and transmitting the image through either a phone line or via internet connectivity. In this article, I will try to restrict the subject matter to the copier though I may discuss the other devices as an elaboration. In a nut shell, we should understand that, photocopying may simply be termed as “the copying employing light (photo)”. There are two main types of copying viz, xerographic (maybe the reason XEROX machines were named so) and electrostatic. Both of these employ the same process to make a copy but they each do it in a slightly different way. When you place a page on a copier and press the start button, the copier runs by using a series of mirrors and lenses to reflect an image of the subject onto the side of a rotating tube. In a xerographic copier this tube is light sensitive. The picture that is projected onto the tube creates an electrostatic charge that accumulates on the tube creating a pattern that matches the image of the page being copied. In turn, the tube attracts the ink (toner) powder which sticks to the charged parts of the tube. A piece of paper is then pressed against the tube and the toner is transferred to the paper. The paper now has an image picked from the tube; this represents the image of the subject matter being copied. The paper is then heated to infuse the toner in a bid to make a more permanent impression. Basically, the electrostatic copier uses a similar process except that instead, of a light sensitive tube, light sensitive paper is used. In this case, the image is projected directly onto the paper which produces a pattern of charge, this coated paper is then passed between a heating device (like a flat iron) to create a final copy. The majority of photocopying machines work as more or less as follows:- The image being copied is imaged onto the drum in a positive charge. The image from the original copy illuminates the charged drum and a latent image is formed.Static electricity attracts toner to the drum surface and a visible image is formed. Toner on the drum is transferred to paper by positive charging. After the image transfer process is completed, the paper is separated from the drum surface. Toner on the copy paper is firmly fixed when the paper runs between heat and pressure rollers. A cleaning blade wipes off excess toner. The drum is exposed by a neon lamp to erase remaining static charge. The photocopying machines have been enhanced to make it easy for the users in such a way that, the user gets as many services from the same device. It is possible to enlarge or shrink the image such that it can fit onto a given paper size or as may be desired by the final end user. Collating is another very important feature on a copier, here; the machine arranges the pages in a predetermined manner. This is useful if one is copying several booklets with a number of pages, it sorts the pages in a predetermined manner. Some machines like the Document Centres come complete with a stapler. This makes the machine truly an all in one. As children, we used to rub plastic pens or foot rulers in our hair and then pass them over particles of paper, the charged rulers or pens attached such particles onto them; in a similar manner, the copier applies a similar technology. Much as we were doing it rudimentarily, the photocopier does it scientifically. Inside a copier there is a special drum. The drum acts a lot like the pen you can charge it with a form of static electricity. Inside the copier there is also a very fine black powder known as toner. The drum, charged with static electricity, can attract the toner particles. There are three things about the drum and the toner that let a copier tick. eddie@afrowebs.com