Inertia switch for sensing vibration forces

Claim 1

In a security monitoring vibration sensor, the combination of: a metal ball; an axial metallic electrode means providing a tangential supporting contact with said ball from beneath, the area of said contact being concentrated approximately at the nadir of the vertical axis of said ball, said axial electrode means thus making a constantly good electrical connection with said ball, while shifting slideably horizontally relative to said ball, in responding rapidly to external vibrations, without substantially overcoming the inertia of said ball as to disturb its position of rest in which it is slideably supported on said axial electrode means by said contact; a tubular metallic electrode means insulated from but rigidly attached to said axial electrode means and closely surrounding said ball to limit movements of said ball laterally, in any direction within said tubular metallic electrode means, to a relatively minute distance thereby producing, in response to minute lateral external vibration forces being imposed on said axial and tubular electrode means, a rapid oscillation of said ball with the latter rebounding from opposite sides of said tubular metallic electrode means, to produce a strong warning electric signal at each terminal point of said oscillation; means providing opposite phase terminals leading respectively from said axial and tubular electrode means; means providing an insulating enclosing structure for said sensor; and means for securing the sensor in vertical position on a building the security of which is being monitored.