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:
Mar. 11, 1997
Filed:
Apr. 28, 1995
William P Dye, Indianapolis, IN (US);
Paul J Hoggard, Indianapolis, IN (US);
Von Duprin, Inc., Indianapolis, IN (US);
Abstract
A doorholder for retaining a door in an open position by magnetic interaction with an armature secured to the door has an electromagnetic flux generator which includes a core having a face confronting the armature and a coil of wire surrounding the core. A cup having an inside diameter somewhat greater than the coil outside diameter receives the coil, the core extending from the face to the cup bottom. A power control circuit including a resistor circuit controls electrical power supplied to the coil, the power control circuit being mounted on a circuit board situated between the coil rear surface and the cup bottom. The resistor circuit being situated in sufficiently close proximity to the cup bottom for transfer of heat from the resistor circuit to the cup. The power control circuit may also include a low resistance circuit coupled to the resistor circuit, and including a fusible link selected to carry current when the power input terminals are coupled to a lower voltage power source and to stop carrying current when the power input terminals are coupled to a higher voltage power source.