Eco-Friendly Roller Gives Greener Copies
Charge Roller Replaces Corona Wire in Commercial Digital Printers
Jan 30, 2009
A patent for the bias charge roller (USPTO #6807389) was issued in 2004 to Xerox Corporation, so this particular product is far from new. Nevertheless, Fenner Precision of Buffalo, NY recently announced a new bias charge roller that they claim offers an alternative to current technology that is more ecologically friendly.
"Fenner Precision's bias charge rollers are the first to operate in production digital presses," explained Susan Matson, Account Manager for Fenner's marketing partner (personal communication).
According to a report in the Jan 8, 2009 edition of Machine Design magazine and materials on Fenner Precision's web site (unless otherwise cited, quotes are from the Fenner site), the new bias charge roller product uses less electricity, generates less ozone and nitrogen oxide, lasts longer, and is easier to replace when it finally does wear out.
Background: How Digital Printing Works
In standard xerography, developed from an idea by Chester Carlson in 1938, a photoconductive drum is charged using either a conductive roller or a corona wire. Light reflected off the document to be copied then exposes portions of the drum, which become conductive and attract charged particles of toner.
Parts that were black on the original become charged and attract toner; parts that were white are uncharged, do not attract toner, and so remain white. The toner is then transferred to the copy paper and heat-fused in place. The rollers are cleaned, the drum is discharged, and the machine is ready for the next copy.
Photoconductive technology of this or a similar type is used in a variety of printer engines ranging from small office laser printers to large commercial models that can handle paper several feet wide.
Problems With Corona Wire Technology
Corona wires have the following technological characteristics:
- they use a high voltage to charge the photoconductive surface of the copy drum; in consequence, they use "great amounts of electricity"
- they are prone to breakage
- they also generate ozone, which presents a health risk, especially in small photocopy rooms.
- in addition, they create nitrogen oxides (NOx), which are known pollutants
Any new technology that doesn't come with these drawbacks, then, is to be welcomed.
What's New about Fenner's BCR?
According to the manufacturer, their new product made of semiconductive polyurethane (PU):
- lasts up to ten times longer than similar products made from conventional rubber, PU foam, or PU elastomeric charging systems
- is more resistant to breakdown than other PU rollers
- uses an "exclusive liquid cast manufacturing process" that provides uniform charge distribution to the "organic photoconductors" on the roller
- is made of non-sparking material
- resists imaging oil in liquid-toner applications
So, it has several key advantages over corona wire.
Advantages of the BCR over Corona Wire
The advantages are not just technological, as they translate into real advantages for the consumer:
- Uses less electricity
- Enables faster printing
- Has a far longer useful life
- Is easier to replace
- Will permit smaller printer development
"This is a breakthrough for the digital xerographic industry," claims Krishna Chaurasia, Manager of Research and Development, Digital Products for Fenner Precision on the corporate site. "The Bias Charge Roller has a longer life, enables faster printing, lowers electricity requirements and is easier to replace. All together, this reduces the cost per page" for large commercial print runs.
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