Automobile ignition security system using a differential magnetic comparator
US6067824A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 29, 1998 |
| Grant date | May 30, 2000 |
| Priority date | — |
| Expiry date | Oct 29, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T70/7057
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A lock for an automobile ignition system includes a sleeve having a cylindrical inner surface. A lock cylinder is provided which is rotatably mounted within the sleeve and has a cylindrical outer surface defining a cylindrical interface with the inner surface of the sleeve. The cylinder includes a keyway adapted for receiving a key used to rotate the cylinder between an off and start position. A differential magnetic comparator having a pair of magnetically sensitive areas is mounted on the sleeve for detecting when the cylinder is rotated to the start position to generate an ignition signal. A magnet is mounted to the cylinder interface for generating a magnetic flux and for activating the comparator when the cylinder is rotated to the start position. A difference in the magnetic flux density present on the pair of magnetically sensitive areas causes the comparator to generate the ignition signal. However, in the presence of a magnet external to the lock, the magnetically sensitive areas detect no difference in magnetic flux density which prevents the comparator from generating the ignition signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.