Levitron is a brand of levitating toys and gifts in science and educational markets marketed by Creative Gifts Inc. and Fascination Toys & Gifts.[1] The Levitron top device is a commercial toy that displays the phenomenon known as spin stabilized magnetic levitation. This method, with moving permanent magnets, is quite distinct from other versions which use changing electromagnetic fields, levitating various items such as a rotating world globe, model space shuttle or VW Beetle, and picture frame.[2] 750,000 units were sold from 1994 through 1999.[1]
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The toy is essentially a permanent magnetic top and base plate, ring or alternate geometric configuration. Functional parameters, such as the top rotation rate or top weighting, are stringent. Employing principles of the magnetic field and gyroscopic stabilization, the Levitron induces levitation in its top through a series of interactive steps. The levitated top's stabilizing rotation undergoes natural, gradual slowing, so that the levitation phenomenon fails within four minutes unless external power is supplied to sustain rotation.
To levitate the top, a plastic plate is placed on top of the magnetic base, and the top is spun on the plate at between 25-50 rotations per second (1500-3000 rpm). If too slow, the top falls over and slides off sideways; if too fast it does not orient itself to follow magnetic flux as it moves, and slides off. Since it can be difficult to spin the top fast enough by hand, Creative Gifts makes a battery-powered, hand held device to spin the top with an electric motor. Next, the plate is lifted by hand until, if conditions are right, the top rises above it to an equilibrium point. The top must also be weighted with washers of various sizes supplied in the kit. If too heavy it will not rise above the plate; if too light it flies off. [3]
After a few minutes, the top falls when air friction slows it below the critical speed. Air temperature, air currents, ground vibration, and power source interruptions also alter the delicate equilibrium necessary to keep the top stable. More expensive laboratory versions can sustain a levitating top indefinitely by sustaining the top rotation actively compensating for aberrations in rotation. The makers of the Levitron have developed a "Perpetuator", which sits under the Levitron and sends out an additional magnetic pulse. The additional force nudges the spinning top enough to maintain a constant speed. With a constant speed, and with the Levitron perfectly level, the Levitron top can spin for longer periods of time.
The device that was later named Levitron was originally invented (c 1976) and patented (1983) by Vermont inventor Roy Harrigan. A Seattle entrepreneur, Bill Hones, came across the patent in the process of trying to develop a levitating magnet. Hones borrowed the prototype from Harrigan, analyzed its physics with help of his father, who worked at Los Alamos National Laboratory, then filed an "improvement patent" of his own.[4][5]
In the 1990's, Michael and Karen Sherlock formed the company they named "UFO" in New Mexico to market the Levitron under an oral agreement in partnership with Hones' company, Creative Gifts, Inc.[5] Efforts to formalize the agreement in writing fell apart and grew acrimonious[1] after UFO's principals learned about the device's earlier invention by Harrigan, and redesigned their website[6] to incorporate the exposé-style article "THE HIDDEN HISTORY OF THE LEVITRON!", which accused Hones of stealing the invention from Harrigan.[5] Creative Gifts, in turn, filed a trademark infringement suit in United States District Court of New Mexico against UFO and its owners. At trial and on appeal to the Tenth Circuit[7] Creative Gifts' trademark claims were upheld, and all of UFO's counterclaims were rejected after UFO, which had been representing itself as a pro se defendant, was sanctioned by the court for abuse of discovery. The appeals court, noting that UFO had submitted a one-page opening brief with no citations to the record or discussion of the relevant law, commented in its ruling, "they have shot themselves in the foot."[1]