Levitron
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Levitron is a brand of levitating toys and gifts in science and educational markets marketed by Creative Gifts Inc. and Fascination Toys & Gifts. The ''Levitron''
top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...
device is a commercial toy under this brand that displays the phenomenon known as
spin-stabilized magnetic levitation Spin-stabilized magnetic levitation is a phenomenon of magnetic levitation whereby a spinning magnet or array of magnets (typically as a top) is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic e ...
. 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. 750,000 units of the top were sold from 1994 through 1999.


The top device

The toy top is essentially a
permanent magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...
ic ring and corresponding magnetic base plate with a ring or alternate geometric configuration. Functional parameters, such as the top
rotation Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...
rate or top weighting, are stringent. Employing principles of the magnetic field and
gyroscopic A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotat ...
stabilization, the Levitron top induces levitation 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 An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
. 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. After a few minutes, the top falls when
air friction In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...
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.


Company history


Invention and patents

The first spin-stabilized permanent magnet levitation device was invented (c 1976) and patented (1983) by inventor Roy Harrigan, of Vermont. In the mid-1990s, Seattle entrepreneur Bill Hones, who was himself exploring the possibility of permanent magnet levitation, discovered Harrigan's patent. Hones subsequently contacted Harrigan and later met with him. Upon Hones' request, Harrigan permitted him to borrow his prototype with the understanding that they were entering into a business arrangement. Hones, with the help of his father, a Physicist and employee at
Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...
, analyzed the physics of the prototype, and then filed for an "improvement patent".Alt URL
/ref>
/ref> In 1984, independent of Roy Harrigan, inventor Joseph Chieffo, of Pennsylvania, also discovered spin-stabilized magnetic levitation. Chieffo then developed his ow
spin-stabilized magnetic levitation device
and attempted to obtain a patent thereon. Employing an attorney to conduct a U.S. Patent and Trademark records search, Chieffo was informed of the existence of the Harrigan patent; he thus concluded his efforts to secure a patent. In a final assessment, Chieffo's attorney noted that his device, although apparently unpatentable, could be marketed without infringing upon the Harrigan patent. In 1988, Chieffo marketed his device in kit form. Contrasting with the dished supporting magnet of the Harrigan invention, the base magnet of this latter device was rectangular and planar of upper surface, not unlike the base magnet of Hones' later-patented device, the now-popular Physics toy known as the Levitron. In 2012 and 2014, Levitrons were operated at an angle of 45° as well as with their spin axis horizontal. This inclined and horizontal operation was obtained with the help of additional magnetic “V”s. The horizontal Levitron is particularly stable which gives it educational potential.


Trademark litigation

In the 1990s, the then husband and wife partners 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. Efforts to formalize the agreement in writing fell apart and grew acrimonious after UFO's principals learned about the device's earlier invention by Harrigan, and redesigned their website to incorporate the exposé-style article "THE HIDDEN HISTORY OF THE LEVITRON!", which accused Hones of stealing the invention from Harrigan. Creative Gifts, in turn, filed a
trademark infringement Trademark infringement is a violation of the exclusive rights attached to a trademark without the authorization of the trademark owner or any licensees (provided that such authorization was within the scope of the licence). Infringement may o ...
suit in United States District Court of New Mexico against UFO and its owners. At trial and on appeal to the Tenth Circuit''Creative Gifts, Inc. v. UFO,'' 235 F.3d 540 (10th Cir. 2000)(New Mexico) 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 ''Pro se'' legal representation ( or ) comes from Latin ''pro se'', meaning "for oneself" or "on behalf of themselves" which, in modern law, means to argue on one's own behalf in a legal proceeding, as a defendant or plaintiff in civil cases, o ...
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."


See also

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Electromagnetic suspension Electromagnetic suspension (EMS) is the magnetic levitation of an object achieved by constantly altering the strength of a magnetic field produced by electromagnets using a feedback loop. In most cases the levitation effect is mostly due to perman ...
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Electrodynamic wheel An electrodynamic wheel is a type of wheel proposed for use in electrodynamic levitation of the maglev train transport system. Unlike a conventional wheel, an electrodynamic wheel has a rim studded with magnets of alternating poles. As the wheel ...
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Magnetic bearing A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with ve ...
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Electrodynamic bearing A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with ve ...
*
Spin-stabilized magnetic levitation Spin-stabilized magnetic levitation is a phenomenon of magnetic levitation whereby a spinning magnet or array of magnets (typically as a top) is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic e ...


References

{{Reflist, 30em


External links


Levitron home page

Spin stabilized magnetic levitation

Online simulation of the Levitron (Java applet)
American brands Magnetic levitation Magnetic devices Educational toys Articles containing video clips Tops