|
Whenever I walk around, travel from a city to another, I see a lot of colorful billboards, banners, tarpaulins, and sometimes photos of known politicians on a signage. These collaterals are made possible by digital printing. Well I used to own a HP LaserJet printer. School projects, researches, reports, I even made thesis with it. So I wonder, how did all these start? Who is the brilliant mind behind the scene? It was in 1938, that Chester Carlson invented a dry printing process called the electro photography commonly called a Xerox (xerography). Xerox is the combination of electrostatic printing with photography. The original process was unwieldy, needing many manual processing steps with flat plates. It took him almost 18 years to automate the whole process. He was then awarded a patent for his work, the foundation of technology employed with LaserJet printers today. How it really works? 1.Charging - An electrostatic charge of 600 volts is uniformly distributed over the surface of the drum. The output is limited by a control grid or a screen. 2. Exposure – The document to be copied is illuminated by flash lamps on the plate and is scanned by moving light and lenses, such that its image is projected onto and synchronized with the moving drum surface. 3. Development – the drum is presented with a slowly turbulent mixture of toner particles and larger iron, reusable carrier particles. 4. Transfer – paper is passed between the drum and the transfer corona, which has a polarity that is the opposite of the charge of the toner. 5. Separation – electric charges on the paper are partially neutralized by AC from a second corona, usually constructed in tandem with the transfer corona and immediately after it. 6. Fusing – the toner image is permanently fixed to the paper using either a heat and pressure mechanism (Hot Roll Fuser) to melt and bond the toner particles into the medium (usually paper) being printed on. 7. Cleaning – the drum, being partially discharged during separation, is further discharged by light. Any remaining toner that did not transfer in fusing, is removed from the drum surface by a rotating brush under suction, or a squeegee known as the cleaning blade. Carlson spent so much time on this, creating a way for LaserJet printers and many more to exist and evolve. Many if not most of the people today know about digital printing, although most do not know who created it. Enjoy the wonders that the printer and HP CC364x toner provides.
Related Articles -
toner, digital printing, laserjet printer,
| 
