The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 15, 2002
Filed:
Jul. 06, 2000
Bengt-Allan Bergvall, Huskvarna, SE;
Ulf Petersson, Tollered, SE;
Aktiebolaget Electrolux, Stockholm, SE;
Abstract
A search system for a tool. A border cable separates inner and outer areas. A generator feeds the border cable with current, whose magnetic field affects a sensing unit on the tool, and the sensing unit emits signals to a control unit that directs the tool's motion. The current contains at least two components of different frequency. A search cable is placed within the inner area so that it separates a search area, and is fed by a signal generator with an adapted current (e.g., the current direction alternates to be either in phase or out of phase in relation to the current direction in the border cable) so that the magnetic fields in the different areas provide at least three patterns. Accordingly, the control unit can separate the inner, outer, and search areas.