IEEE Spectrum December, 2007 - 50

second spool and capacitor (or third, or fourth)
that can be triggered by a circuit that detects
the projectile emerging from the previous one-
using, say, a bright light, a photoresistor, and
a thin coat of white paint on the slug-I could
get some real velocity. I bet I could get the total
kinetic energy up to well over a joule.
This little toy also points up many of the
reasons that more-powerful gauss rifles
and other electronic projectile throwers still
haven't changed the face of battle. The current
through my circuit peaks somewhere around
10 amperes, which is almost 20 times as much
as the wire in the coil is rated to carry in continuous duty. A real weapon would be discharging hundreds or even thousands of amperes at

hundreds of volts (albeit for only milliseconds
at a time) with corresponding stress on capacitors, coils, and switches. That's fine for a small
electric power substation but not much fun to
carry over your shoulder.
Still, in the back of my mind I have visions
of a Mark II home version. Maybe a huge
bank of capacitors scavenged from defunct
Pc power supplies. or a bicycle wheel,
reinforced and wired into a high-current
generator. The underlying idea is so attractive that there has to be a way....
n

AbouT ThE AuThor
PAuL WALLIch is a science writer who lives
in Montpelier, vt.

ning, and then they ramp up. An applica- sion carries some risk, because you can't
tion filed under the Patent Cooperation always know what you need to know when
Treaty (PCT) can designate numerous you need to know it. For instance, a noncountries for just a few thousand dollars. U.S. filing decision must sometimes be
A year and a half later, however, when the made before a market is clearly defined or
PCT application must be filed in all the a product is actually ready for production.
countries where a patent is desired, the Also, the filing decision must sometimes
cost can run $50 000 or more for only a be made before you know whether the
handful of countries.
effort and cost will bear fruit. Of course,
Third, be very careful where you file, such uncertainty also applies to anyone
considering for each country the level of filing for a patent in his or her home counpatent protection, the total cost, the size try, but there the timing is easier and the
of the market, the number of potential market far more familiar.
licensees, whether your company will
This leads us to one final point: things
manufacture or sell a product incorporat- change. As time marches on, all of the
ing the patented invention in that country, above considerations have to be reevaluand whether competitors will likely do the ated. A patent portfolio needs to be
same. You need to know all these things weeded out from time to time, freeing up
to calculate whether you'll get a return on money that would have gone to mainteyour patent-investment dollars.
nance fees for better use elsewhere, perAlso, consider the quality of the patent. haps even for new non-U.S. filings.
n
Only a small fraction of all patents provide
any real return on investment. Therefore, AbouT ThE AuThor
you must analyze the strength of the pat- kIrk TESkA, adjunct law professor at
ent you are likely to obtain-which may Suffolk university Law School, boston, is
well not be as broad in its coverage as the managing partner of Iandiorio & Teska, an
patent you have in the United States- intellectual-property law firm in Waltham,
and check your analysis with an expert.
Mass. his book Patents for the Too Busy
Suppose, for example, that the deadline Manager is scheduled to be published in the
for international filing is fast approach- spring by Nolo, in berkeley, calif.
ing (remember the one-year rule) and
you have two U.S. applications pend- To ProbE FurThEr
ing. Application A broadly covers the The Web sites of most intellectual-property
core technology underlying your flag- law firms contain helpful tutorials regarding
ship product, but application B narrowly non-u.S. patent filings. The gAo's reports
covers only one functional feature of the mentioned above are free, at http://www.gao.
product. You might file A in numerous gov, appearing under the labels gAo-02-789,
countries, but if competitive products can July 2002, and gAo-03-910, June, 2003.
likely compete using functional features
kirk Teska's own Patent Savvy for
other than yours, then B might be filed in Managers (Nolo, 2007) covers these issues
only a few, if any, non-U.S. countries.
in greater depth; it is available online and at
In the end, the non-U.S. filing deci- most major bookstores.

www.spectrum.ieee.org

http://www.gao http://www.spectrum.ieee.org

Table of Contents for the Digital Edition of IEEE Spectrum December, 2007