Abstract: A tilt switch generates a signal as a function of orientation relative to a force, especially to detect tilting relative to vertical under the influence of gravity. A movable mass is mounted for displacement along a path between preloaded and unloaded positions. In the example of gravity tilt detection, a free-falling weight or an overbalanced inverted pendulum toggles by a mass falling back and forth between the preloaded and unloaded states. The weight is unstable and accelerates from the preloaded position to an unloaded position upon application of the force. A piezoelectric element such as a resilient strip is arranged to be deflected suddenly by the movable mass, and generates an electrical signal. The piezoelectric element can be mounted to obstruct the path of the mass.

Abstract: An air transducer apparatus including a piezoelectric film having a first surface and a second surface opposite said first surface, a first electrode disposed on a first portion of said first surface of said film, the first electrode defining an electrode area for generating a signal in response to acoustic energy incident on said piezoelectric film, and at least one reinforcing area disposed on a second portion of said first surface of said film different from said first portion. The reinforcing area is preferably formed of metal or plastic, and assists in increasing the sensitivity of the apparatus by reinforcing the area adjacent the first electrode.