Maintaining spring loaded or automatically closing door open during time delay or lighting period by a time controlled electromagnet fixed to wall and attracting ferrous plate fixed to door frame

摘要

A spring loaded or similar door may be kept open for a predetermined period by fixing a ferrous plate to a vertical interior member of the door frame on the lock side and using the attraction to an electromagnet which is fixed to a second plate attached to the wall. The second plate also bears a shock absorbing spring and a contact which initiates a time controlled electricity supply to the electromagnet