05541585 is referenced by 200 patents and cites 13 patents.

The present invention provides a security system for controlling access of persons through a controlled portal. The portal, such as a door, has a lock mechanism for securing the door. A presence detector senses the presence of an object within an approach zone located substantially adjacent the portal. When an object is detected, a fixed transceiver automatically transmits an interrogation signal into the approach zone. A portable transceiver is carried by the person seeking access to the portal. The portable transceiver responds to the interrogation signal by transmitting a response signal. Each portable transceiver or group of transceivers has a unique identification code which is included in the response signal. The fixed transceiver receives the response signal and determines whether the response signal contains a valid access code. If a valid access code is received, the portal is unlocked and other devices may be activated.

Title
Security system for controlling building access
Application Number
8/321256
Publication Number
5541585
Application Date
October 11, 1994
Publication Date
July 30, 1996
Inventor
Daniel V Meyvis
Bloomfield Hills
MI, US
Dean C Duhame
Roseville
MI, US
Agent
Young & Basile
Assignee
Stanley Home Automation
MI, US
IPC
E05B 47/02
G06F 7/04
G08B 13/18
View Original Source