SMOOTHER TONER COULD LEAD TO ………

[Anonymous]

Smoother toner could lead to smaller, cheaper color laser printers
June  2007 -The much-trumpeted paperless office was last reported vanishing under a tidal wave of documents back in the early 80s. After extensive investigations, the culprit was found to be the laser printer. These printers had the advantage of being relatively inexpensive with reasonable print quality and were heavy enough that the boss could use it to anchor his fifty-foot yacht. The black-and-white laser printer has continued to improve: small footprint, better quality output at a faster speed, and much, much cheaper. Color laser printers have lagged behind their black-and-white brethren, and the reason, apparently, is in the toner. But Science has a review article that hints at much cheaper and smaller color laser printers in the pipeline.The article in question is a review of electrostatics, which one of my university lecturers described as a necessary evil on the way to electrodynamics. One recent discovery in the field is that, given a certain value of charge and a certain surface area, the strength of the adhesion will vary depending on the number of contact points, even though the charge is still evenly distributed. This is due to the fact that charge comes in fixed units of electrons (and protons, but electrostatics is almost entirely about electrons).Small points of contact act to magnify the effects of charge differences, as even a single electron difference creates a large electric field in its immediate vicinity. Put simply, spiky contacts are held very strongly, while smooth contacts adhere to each other much more weakly. Here’s how it could lead to cheaper laser printers.

Svelte color laser printers
This strong adhesion, when combined with the poor precision control in today’s color laser printers are what make them bulky and expensive. The current generation avoids this problem by using a combination of magnetic particles that have smaller polymeric particles adhering to them as “ink.” The adhesion between the big and small particles is a product of their mutual electrostatic charge, making the whole electrically neutral.The particles are then steered using the magnetic properties of the inner particle to the correct region on a drum, which has been charged in a mirror image of the desired print pattern. This strips off the large inner particle while leaving the toner particles stuck to the correct region of the drum. Finally, the charged polymers are stuck on the paper and cooked. The requirements for both electrostatic and magnetic control systems are what make color laser printers expensive and bulky.To avoid using a magnetic field to control the toner deposition, the researchers have developed a new toner that comes wrapped in its own shell, giving it a very smooth surface that is much less sticky. This much weaker adhesion means that the positioning of the toner can be done using electrostatics alone. In turn, the laser printer can be much smaller using a control system that is very similar to normal laser printer—though with a touch of the three headed ink-jet printer thrown in.It was bad enough to be drowning in black and white copies of rubbish, now we will have to contend with colored bits of paper flying around the office too—if the new toner works out. 

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June 21, 2007 at 2:06 PM