Abstract: A drumhead assembly comprising a drumhead membrane fixed within an annular ring and a tensioning ring for tensioning the membrane, located within the annular ring and against the drumhead membrane, comprising a cylindrical rod formed in a circular, flat configuration and a tensioning member for maintaining the tensioning ring in a pre-tensioned configuration. The tensioning member can be adjustable, as in the form of a turnbuckle, so as to vary the diameter of the tensioning ring, or fixed, as in the form of a spacer, so as to maintain the tensioning ring at a predetermined diameter.

Abstract: A drumhead assembly comprising a drumhead membrane fixed within an annular ring and a tensioning ring for tensioning the membrane, located within the annular ring and against the drumhead membrane, comprising a cylindrical rod formed in a circular, flat configuration and a tensioning member for maintaining the tensioning ring in a pre-tensioned configuration. The tensioning member can be adjustable, as in the form of a turnbuckle, so as to vary the diameter of the tensioning ring, or fixed, as in the form of a spacer, so as to maintain the tensioning ring at a predetermined diameter.

Abstract: A practice drumhead assembly including a mesh membrane held in substantially fixed relation to an acoustic membrane. The assembly preferably includes an annular tensioning ring for tensioning the mesh membrane, and an engagement member for substantially fixing the mesh membrane relative to the acoustic membrane. The tensioning ring includes a cylindrical rod with a turnbuckle that is rotated to increase the diameter of the tensioning ring.

Abstract: A device for determining which zone on a target has been struck by an object. The device is made of a frame, and a flexible support means which is mounted on the frame, and is disposed in the path of a moving object. A transducer made of piezoelectric film, coated with a conductive coating on each of its surfaces to form electrodes, is mounted on the flexible surface. Attached to the electrodes of the transducer are leads which transmit electrical pulses to a signal processing unit. An object striking the target produces an electrical pulse which is translated by the signal processing unit and which determines the zone on the target which was struck by the object.

Abstract: A piezo film switch comprises a cantilever with a pair of layers, including a piezo film layer and a flexible, backing layer laminated thereto. The piezo film layer produces a positive or negative output pulse, depending upon a direction of deflection of the cantilever. Interface circuitry coupled to the piezo film layer is powered by the output pulses and provides "pseudo contact closures" which emulate the operation of a mechanical switch.

Abstract: An amusement device is disclosed which contains a signal generator attached to a flexible member. When the flexible member is repeatedly waved, an oscillatory electrical signal is produced by the signal generator and supplied to a sound generator which produces sound which synchronously varies with the repeated flexure of the member caused by the waving action. The sound generator produces a first tone with respect to the oscillatory electrical signal and a second tone when the frequency of the oscillatory electrical signal exceeds a predetermined value.

Abstract: A sensing device is disclosed which produces a response when the point of impact between an object and a member occurs at a preselected location on the member. When the member vibrates after being impacted by the object, an oscillatory electrical signal is produced by a piezoelectric sensor. Appropriate circuitry is provided for analyzing the oscillatory electrical signal and for producing a response if the object impacted the member at the preselected location. The sensing apparatus is particularly useful in athletics for determining whether a game object contacted the athletic instrument at its "sweet spot".

Abstract: A structural member having a piezoelectric transmitter film and a piezoelectric receiver film adhered thereto. The transmitter film produces a vibration upon activation by a voltage controlled oscillator which forms part of a phase-lock loop circuit. The vibrations of the structural member generate electric signals on the receiver film, which feed into a phase comparator. The other input of the phase comparator is the output signal of the voltage controlled oscillator. The phase comparator will output a dc signal proportional to the difference in phase between the two signals. When the structural member becomes damped, the phase comparator will go into saturation, thereby producing a voltage which can activate an alarm signal or other device.

Abstract: A practice drumhead assembly including a mesh membrane held in substantially fixed relation to an acoustic membrane. The assembly preferably includes an annular tensioning ring for tensioning the mesh membrane, and an engagement member for substantially fixing the mesh membrane relative to the acoustic membrane. The tensioning ring includes a cylindrical rod with a turnbuckle that is rotated to increase the diameter of the tensioning ring.