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.[1] The Levitron top device is a commercial toy under this brand 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 of the top were sold from 1994 through 1999.[1]
The top device
The toy top is essentially a
To levitate the top, a plastic plate is placed on top of the magnetic base, and the top is spun on the plate at 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 produced 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
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, analyzed the physics of the prototype, and then filed for an "improvement patent".[4][5] In 1984, independent of Roy Harrigan, inventor Joseph Chieffo, of Pennsylvania, also discovered spin-stabilized magnetic levitation. Chieffo then developed his own 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[6] and 2014,[7] 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.[7]
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.
See also
- Electromagnetic suspension
- Electrodynamic wheel
- Magnetic bearing
- Electrodynamic bearing
- Spin-stabilized magnetic levitation
References
- ^ a b c Martin B. Paskind (2001-02-26). "Take care not to shoot yourself in the foot". Albuquerque Journal.
- ^ Elizabeth Corcoran (2007-11-27). "Toys Your Techie Friends Will Love". Forbes.
- ^ Michael V. Berry. "Levitron Physics: Frequently Asked Questions About the Levitron". Conversation for Exploration. Archived from the original on 1996-11-09.
- ^ Rod Driver (1999-09-22). "An amazing invention, and a patent failure (Part 1 of 2)". The Providence Journal.[dead link] Alt URL
- ^ a b c Rod Driver (1999-09-23). "The patent that failed its invention (Part 2 of 2)". The Providence Journal.[dead link] Alt URL
- ISSN 0002-9505.
- ^ S2CID 121645252.
- ^ "Levitron Central".
- ^ "THE HIDDEN HISTORY OF THE LEVITRON!".
- ^ Creative Gifts, Inc. v. UFO, 235 F.3d 540 (10th Cir. 2000)(New Mexico)