Pi Day Patents

Today is Pi Day: March 14th, when written as 3-14 (in the American style), looks like the first 3 digits of pi.  Today is an auspicious Pi Day, as the abbreviated (American) style of writing today’s date is 3-14-16, which is pi rounded to 4 decimal places: 3.1416.  Are there Pi Day patents: patents related to pi?  Or pie?  Of course there are!

The Fascination of Pi

Pi is the ratio between the diameter and circumference of a circle.  It has been known, and studied, for thousands of years.  Pi is an irrational number, meaning that it can be computed to endless precision, and still never be exact: it can’t be represented as a fraction, or when written out in decimal form, will never end and never repeat.  This makes it fascinating and the subject of intense study: the current highest calculation of pi is 13.3 trillion digits, yes, 13,300,000,000,000.  39 digits is enough to calculate just about anything, so this quest is for computation and record-breaking, not a need to know pi – although it is possible that someone will discover that pi does repeat, somewhere after 13.3 trillion digits.  Unlikely, but possible.  The most digits memorized is 70,300 (or 70,000), which make the 16 digits (15 after the decimal point) that I’ve memorized (3.141592653589793) look puny.  Yes, there is a name for the memorization of digits of pi: piphilology.

Patents related to pi

Pi itself is not patent-eligible: it is a law of nature, as a mathematical expression of a ratio.  While roughly 13,000 U.S. patents mention pi, or 3.14, or the Greek letter π, many of those relate to formulas used in describing or carrying out the invention, many other mentions of pi are as a symbol for chemical bonding, or as an abbreviation for a compound or a biological characteristic (such as a protein isoelectric point).

Happily, there are design patents that are appropriate as Pi Day Patents, such as USD531672 for a “Pi illustration display device”, and plant patents such as USPP11719 for an apple tree rootstock.

And no discussion of Pi Day patents could be complete without looking at patents whose patent numbers approximate pi!  For your Pi Day pleasure, in order of decreasing accuracy in approximation of pi, here are:

• US3141592, for an “Apparatus for breaking sheet glass along parallel lines”, issued Jul. 21, 1964.
• US314159, for a “Newspaper binder”, issued Mar. 17, 1885 – very close to Pi Day 1885!
• US31416 (a rounding, not a truncation of pi, but related to today’s date), for an “Improvement in cultivators”, issued Feb. 12, 1861.
• US31415, for a “Truss-bridge”, also issued Feb. 12, 1861.
• US3141, for a “Beehive”, issued Jun 24, 1843.
• US314, for an “Improvement in the manner of constructing and working paddles to be used as ice-breakers”, issued Jul. 29, 1837.
• US31, for the production of fire and light by a combination of liquids”, issued Sep. 22, 1836.
• US3, for “making modern pins” (and a very approximate value of pi), was issued Aug. 1, 1836.

Pi Day Patents

What about patents issued on Pi Days past?  Fear not: I searched, and going back to 1994, there seem to have been only 22 patents issued on March 14th that have the letters “pi”, π, or Π, or 3.14 (that’s out of over 8,500 patents issued on March 14th since 1994).  What about patents filed on March 14th?  Again, going back to 1994, only 54 patent applications filed, out of over 16,000, involve pi, π, Π, or 3.14.  Most of those involve mathematical formulas in describing the invention, and the rest involve chemical groups, or angles (which can be measured in degrees, or in radians with π as a unit) or phase shifts.  Perhaps people are not waiting until the next March 14th to file pi-related patents (which would be a bad patenting strategy).

Pie Patents

And, for puns related to pi, very little can beat a pie with pi in the crust, although pizza (pie) sold for $3.14 per slice is close.  Pie patents?  Oh yes: over 600, 155 of those since 1976 (only those with pie in the title), and of those, 86 are utility patents, 64 are design patents, and 5 are for plant patents, and only about 14 of the 600 were filed or issued on Pi Day (since 1994).  Here are some fun ones:

• D639107, for a “Pie pan having removable pie server”
• US 8172563, for a “Perfect pie crust crimper”
• US 6915949, for a “Multi-layered pizza pie box”
• US 5074777, for an “Apparatus for making a split pie”

Do you have questions?  Interested in knowing more about pi?  Have more digits memorized than I do?  I’d be glad to hear from you in the comments.  Call me at 617-340-9295 or email me at my Contact Me page.  Or, find me on Facebook, Twitter, Google+, LinkedIn, Google Local, or Avvo.