US 4,690,066 AGranted

Electromagnetically floated carrier system with stopping unit

AssigneeKabushiki Kaisha Toshiba

InventorsMimpei Morishita, Teruo Azukizawa

Life of this patent

Estimating the term…

Loading patent…

Abstract

A carrier which transports semiconductor chips or the like can run along two rails made of a ferromagnetic material and extending along a running path. The carrier has four supports projecting from its bottom. Four magnets units are supported by the supports, respectively, and each magnet unit includes a permanent magnet and a pair of electromagnets such that the magnet units face the rails. The carrier is held floated with respect to the rails by electromagnetic forces acting between the magnet units and rails. The supports support four gap sensors which detect the gap between the magnet units and rails and produce an output signal corresponding to the gap. Magnetic flux control unit is provided on the underside of the carrier to control the current supplied to the electromagnets in accordance with the outputs of the gap sensors to maintain the gap constant within a predetermined range. A stopping unit is provided at a station at which the carrier is to be stopped, and stops the carrier by means of a electromagnetic forces of attraction acting between the stopping unit and one of the magnet units provided on the carrier.

Claims19

Dependent claims

A system for transporting cargo to a predetermined position, comprising:

a carrier for carrying cargo;
at least one rail extending along the travelling path of said carrier, at least the lower portion of said rail being made of a ferromagnetic material;
means including a plurality of magnet units each having at least one permanent magnet and at least one electromagnet, provided on said carrier and facing said rail, for generating electromagnetic force that floats said carrier with respect to said rail, a gap being provided between each magnet unit and said rail;
gap sensor means provided on said carrier for sensing the gap between each magnet unit and said rail and generating an output signal representing this gap;
means for energizing said electromagnets with an excitation current in accordance with the output signal of said gap sensor means to make the gap fall within a predetermined range;
means provided on said carrier for supplying power to said gap sensor means and said energizing means;
and
a station, at which said carrier is to be stopped, and at least a stopping unit provided at said station such that it faces one of said magnet units when said carrier is stopped at said station, said carrier being stopped upon arrival at said station by electromagnetic forces of attraction acting between said stopping unit and magnet unit.

5 more elements

Dependencies are inferred from the claim text.