Mark A Lehman

US Patent:

61509434, Nov 21, 2000

Filed:

Jul 14, 1999

Appl. No.:

9/353162

Inventors:

Mark R. Lehman - Palos Verdes Estates CA
Dan Gechtman - Sherman Oaks CA
Jerome Keith Fuller - Van Nuys CA
Michael A. Hreha - Oceanside CA

Assignee:

American Xtal Technology, Inc. - Fremont CA

International Classification:

G08B 1710

US Classification:

340628

Abstract:

A device for projecting an escape path to direct evacuation from a fire includes a plurality of laser diode projectors secured within a housing and aimed to project successive rays or images along a predetermined escape path. The images may comprise arrow indicators, graphics, or alphanumeric indicators. The laser beams are emitted through the same window in the housing to minimize heat infiltration into the housing. The laser diodes are triggered by an alarm condition, such as direct actuation by a smoke sensor, IR detector, or the like, or secondary actuation in response to the audio alarm signal of a primary fire alarm. For actuation by a primary alarm system, a microphone input is amplified and fed to a microprocessor. The microprocessor is programmed to digitally filter and process the signal to determine the presence of a primary alarm signal, and actuate a fire escape path illuminating module. The audio pickup includes a pair of microphones spaced apart approximately one-half wavelength of the primary alarm signal to avoid acoustic standing wave problems, the microphones switching periodically to acquire the best signal.