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Omron Rings & the EURion Constellation

February 18, 2009

The yellow Omron rings on the front of the 5 Euro note, as seen in the blue channel of an RGB image.

The terms “Omron rings” and “EURion constellation” describe the same object – a pattern of small, usually yellow circles that have lately become popular on many banknotes. Both terms may be used interchangeably in this post.

As there has not yet been a primary source statement of origin or ownership, the official name of the ring pattern is unknown. For the same reason (and certainly security concerns), most information regarding the rings comes from secondary sources, public documents and individuals.

It is virtually certain that the Omron rings are a machine-readable banknote recognition and anti-counterfeiting device.

The relationship of the rings to one-another is defined by a specific mathematical formula. Computer software can check for the presence of the rings in a digital image and compare them to the known formula. Thus, a computer program can be (reasonably) sure that a user has attempted to scan, photograph or reproduce a banknote. Most commercial software that recognizes a banknote image will then attempt to prevent the user from utilizing it.

Publicly available evidence suggests that the Omron rings were developed by the Specialty Products Division of the Japanese electronics company Omron Corporation in 1994. The rings first gained notoriety (and their informal name) in early 2002, when they appeared on the first series of Euro banknotes.

It appears that their first public appearance was on circa 1996 German Marks.

Wikipedia has the most comprehensive public article on the Omron rings that the author is aware of.

See also: the U.S. patent, applied for in 1995. Note that the patent uses, among it’s illustrations, constellations of equilateral triangles.

Omron reference in Moneymakers, 2004, Klaus W. Bender.

Business Week article from 2000.

A quote from Funding Universe: “Omron’s Specialty Products Division … is active in three product areas … highly specialized sensors, such as the bill recognition unit installed in photocopiers to prevent paper currency counterfeiting.”

Reserve Bank of India press release, August 24, 2005. This is the first public linking of the rings to Omron.

A more detailed technical analysis of the Omron rings is outside the scope of this blog.


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