Patent ID: 7532118
Filing Date: 2009-05-12
Classification: G08B

Abstract:
1. In a security fence, a vibration sensor unit comprising a sensor housing consisting of an essentially hemispherical top section and an essentially hemispherical bottom section fastened together by fasteners and having a channel therethrough, through which a signal cable may be run; the sensor housing being supported by a back plate having a concave socket thereon that engages the essentially spherical housing, allowing accurate positioning of sensors therein, with respect to the horizontal; the essentially spherical housing being held against the socket by a clasp that encircles the sensor housing therearound, and being attached to the back plate by fixing means; the back plate including attaching means for attaching it to an installation, wherein the sensor unit comprises six sensors connected in parallel, each sensor comprising a conductive ball supported on electrical contacts, wherein each of said electrical contacts being three miniature spheres, each supported in a cup, thereby as vibrations disturb said conductive ball, said miniature spheres jiggle around and rotate slightly, resulting in contact of new areas of said ball with each of said miniature spheres, thereby prolonging the lifetime of said sensor.