A vibration generating mechanism includes at least first and second permanent magnets spaced from each other with the same magnetic poles opposed to each other. The first permanent magnet is coupled to a link mechanism so that the drive force of a drive source may be transmitted to the first permanent magnet via the link mechanism. A periodic and reciprocating movement of the first permanent magnet relative to the second permanent magnet changes the opposing area thereof, causing vibration of the second permanent magnet.

A damped resonant piezoelectric alerting device (600) includes a motional mass (130), a damping element (136, 156) magnetically coupled to the motional mass (130) and a piezoelectric actuator (100) which is constrained to an actuator mount (132) at a first end and coupled to the motional mass (130) at a second end. The piezoelectric actuator (100) responds to a control signal (108, 110) to generate an alternating out-of-plane movement (812, 814) of the motional mass (130) at an amplitude (412, 414). The alternating out-of-plane movement (812, 814) of the motional mass (130) is transformed into tactile energy to provide a tactile alert about a resonant frequency (608). The amplitude (412, 414) of the out-of-plane movement (812, 814) of the motional mass (130) is controlled by the damping element (136, 156). The alternating out-of-plane movement (812, 814) of the motional mass (130) is also transformed into acoustic energy to provide an audible alert above the resonant frequency (608).

A linear motion electric power generator. A rare earth magnet and a coil are positioned to move linearly back and forth relative to each other. The movement of the coil in the field of the magnet generates a current in the coil. Springless orientation means are provided to maintain a neutral position about which the relative motion occurs.

An oscillatory drive incorporating the invention includes a driven rotor that is mounted on a shaft and includes plural driven permanent magnets disposed thereon. A spring arrangement is coupled to the driven rotor and limits both clock-wise (CW) and counter-clockwise (CCW) rotation thereof. A first driving rotor includes first driving magnets, is mounted for rotation on the shaft and is positioned to a first side of the driven rotor. A second driving rotor includes second driving permanent magnets, is mounted for rotation on the shaft and is positioned to a second side of the driven rotor. The drive mechanism imparts a CW rotation to the first driving rotor and a CCW rotation to the second driving rotor. The first driving permanent magnets coupling to the driven permanent magnets causes a CW rotation of the driven rotor until the spring arrangement terminates the CW rotation and causes a reversal of rotation direction in the CCW direction. The CCW rotation of the second driving rotor and the coupling of its second driving permanent magnets aid the CCW rotation of the driven rotor until that rotation is terminated by the spring arrangement. The reciprocal movement of the driven rotor continues for the duration of energization of the first and second driving rotors.

An electromagnetic vibration generator includes a housing, a U-shaped magnet core disposed in the housing and having parallel-extending legs each terminating in a pole face, and an excitation winding inserted on each core leg. The magnet core is encased in cast resin in the housing. The vibration generator further has an armature adapted to be vibrated by an excitation current flowing through the excitation winding. The armature is separated from the pole faces by an air gap. Arrangements are provided for reducing effects of heat expansion of components of the vibration generator on the air gap width.