Electromagnetic lock having a self-adjusting switch assembly for door-movement alert
US4915431A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1989 |
| Grant date | Apr 10, 1990 |
| Priority date | — |
| Expiry date | Feb 27, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T292/11
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An electromagnetic lock including an armature and an electromagnet with the armature adapted for floating attachment to a door by a plunger-bolt assembly fixed to the door, and an electromagnet adapted for fixed attachment to a door frame. A door-movement alert switch structure comprising a pushbutton switch supported on the electromagnet, a plunger supported on the plunger-bolt assembly, and a spring force-biasing the plunger into mating contact with the switch when the door is electromagnetically locked to establish a first switch-actuation state. The force-biased spring maintains the switch in its first state while the armature is magnetically restrained. When the door is opened a door-movement distance slightly less than the armature float distance, the plunger is partially drawn into a plunger housing fixed on the plunger-bolt assembly. The switch responds by transferring to a second switch actuation state indicating an attempt to open the magnetically locked door.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.