Abstract: A method of generating a keyboard switch haptic sensation in a coupled system comprising a touch-sensitive surface and a force exciter or actuator coupled to the touch-sensitive surface, the method comprising generating a carrier wave signal at frequencies within the frequency bandwidth of the coupled system, modulating the carrier wave signal with a modulation envelope so that the modulated carrier wave signal has a closely spaced pair of peaks, and driving the exciter or actuator with the modulated carrier wave signal to excite the touch-sensitive surface to provide a closely spaced pair of impulses whereby the keyboard switch haptic sensation is simulated to a user touching the touch-sensitive surface.

Abstract: The invention relates to a method of making an actuator comprising a plurality of force elements and an actuator made according to the method. The method comprises providing a coupler for coupling force from the force elements to a load; calculating a transfer function for each force element wherein the transfer functions allow the force provided to the load to be predicted; determining an error functional which is indicative of any undesired dips in the predicted force; calculating the parameters of the force elements which minimise the error functional, and coupling force elements having the calculated parameters to the coupler to make the actuator.

Abstract: Apparatus for providing different audio signals in a plurality of zones of a single enclosed space, comprising loudspeakers associated with, and positioned in, each zone to radiate an audio output, means capable of supplying a different audio signal to the loudspeakers in each zone, signal processing means comprising means for dividing the audio frequency spectrum of each audio signal into higher and lower parts, means for directing the higher frequencies radiated in their respective zones, and means for varying the phase, and delay of the lower frequencies to tend to cancel sound radiation outside their respective zones.

Abstract: A touch sensitive device comprising a touch surface, a force exciter coupled to the touch surface to excite vibration in the surface in response to a signal sent to the exciter, with the touch surface and exciter together forming a coupled system and a signal generator to generate the signal, with the signal generator generating a carrier wave signal at frequencies within the frequency bandwidth of the coupled system and modulating the carrier wave signal with a complex modulation where the modulated carrier wave signal has a time response comparable to that of a low frequency signal which produces a desired haptic sensation whereby a user touching the touch surface excited by the exciter in response to the modulated carrier wave signal experiences the desired haptic sensation which is perceived at a frequency below the frequency bandwidth of the coupled system.

Abstract: A method of calibrating a touch sensitive device comprising a touch-sensitive screen; a plurality of transducers mounted to the screen and a processor, the method comprising inputting a signal into the screen at a test position on the screen whereby the screen is excited into vibration; detecting vibration in the screen using the plurality of transducers; and processing, in the processor of the touch-sensitive device, the detected vibration to generate an output signal for each of the plurality of transducers whereby when the transducers are driven by the output signals the screen is excited to generate a desired haptics sensation at the test position.

Abstract: An apparatus including a touch sensitive screen having a face adapted to receive a user's hand-writing via a hand-held stylus. The screen includes means exciting the screen to vibrate so as to transmit the vibration to the stylus to simulate the sensation of a writing implement writing on paper as the stylus is moved over the face of the screen. The apparatus may include means for period modulating the electrical signal applied to the exciting means and means for amplitude modulating the electrical signal. The apparatus may include means for sensing the velocity of movement of the stylus over the screen face and means for modulating the vibration according to the sensed velocity.

Abstract: A touch sensitive device comprising a panel capable of supporting bending waves, a user-accessible touch sensitive screen on or forming part of a face of the panel, the touch sensitive screen having a plurality of different sensing areas, a plurality of vibration exciters coupled to the panel to apply bending waves to the panel to provide tactile feedback at the plurality of sensing areas in response to the user touching a sensing area, and signal processing means arranged to apply signals to the vibration exciters so as to steer bending waves applied to the panel by the plurality of vibration exciters whereby the amplitude of the applied bending waves is maximised at the sensing area touched by the user and reduced or minimised at each other sensing area.

Abstract: An inertial vibration transducer for exciting bending waves in a sound-radiating member has a motor coil assembly with a tubular member adapted to be rigidly mounted directly to the sound-radiating member by adhesive means. The transducer has a magnet assembly supported on a resilient suspension, and the magnet of the magnet assembly may be disposed within the tubular member of the motor coil assembly. Loudspeakers incorporating such transducers also are disclosed.

Abstract: A panel-form loudspeaker having a member capable of sustaining and propagating input vibrational energy by bending waves, and a transducer mounted on the member for applying a local couple to the member. The motor coil assembly of the transducer has a surrounding attachment portion rigidly attached to one face of the member in spaced relation to the central attachment portion of the magnet assembly of the transducer. When the transducer is energized, the motor coil assembly and the magnet assembly move in opposite directions to apply a couple to the member through their respective spaced attachment portions to launch bending waves into the member.

Abstract: An electronic musical instrument having a keyboard and a loudspeaker, wherein the loudspeaker comprises a resonant distributed mode acoustic radiator having a stiff lightweight member having capability to sustain and propagate input vibrational energy by bending waves in at least one operative area extending transversely of thickness, and a transducer mounted wholly and exclusively on the member at a predetermined location or site within the operative area.

Abstract: A greetings or the like card (144), characterised by a board (2) forming at least part of the card and in that the board is a distributed mode acoustic radiator having a transducer (9) mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate.

Abstract: A loudspeaker (81) comprises an enclosure, an acoustic radiator (2) in the enclosure, a compliant suspension (3) mounting the radiator in the enclosure for pistonic movement relative thereto, and a first transducer (9) for driving the radiator pistonically. The radiator is also excited by a bending wave transducer mounted on the radiator which vibrates the radiator to cause it to resonate. The first transducer varies the air pressure in the enclosure to cause the radiator to move pistonically.

Abstract: Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Abstract: A panel-form microphone characterised by a distributed mode acoustic member (12) and a transducer (63) coupled wholly and exclusively to the member to produce a signal in response to resonance of the member due to incident acoustic energy.

Abstract: A panel-form loudspeaker (81) comprising a resonant distributed mode acoustic radiator having a periphery, a transducer (9) mounted to the radiator to excite distributed mode resonance in the radiator, and a frame (1) supporting the radiator, the transducer being coupled between the radiator and the frame to vibrate the panel to cause it to resonate to produce an acoustic output, characterized in that frame supports the radiator round its periphery and by resilient suspension means coupled between the frame and the radiator periphery.

Abstract: A loudspeaker (81) comprising an enclosure, an acoustic radiator (2) in the enclosure, a compliant suspension (3) mounting the radiator in the enclosure for pistonic movement relative thereto, and transducer means (9) for driving the radiator pistonically, characterized in that the radiator is a panel-form distributed mode acoustic radiator, by a first transducer mounted wholly and exclusively on the radiator to vibrate the radiator to cause it to resonate, and by means (11) for varying the air pressure in the enclosure to cause the radiator to move pistonically.

Abstract: A visual display unit having a display screen, a housing in which the display screen is mounted, and a loudspeaker in the housing comprising a member capable of sustaining and propagating input vibrational energy by a plurality of resonant bending wave modes in an operative area, the frequencies of the resonant bending wave modes being interleaved so that resonant bending wave modes are evenly distributed. A transducer is mounted wholly and exclusively on the operative area of the member at a preferential location which substantially maximizes acoustic coupling to the resonant bending wave modes in the member, the resonant bending wave modes in turn producing an acoustic output.

Abstract: A ceiling tile adapted to be supported in an overhead opening and function as a loudspeaker. The tile is in the form of a distributed mode acoustic radiator with a transducer mounted wholly and exclusively on the radiator at a location for coupling to resonant bending wave modes so as to vibrate the radiator and cause it to resonate.

Abstract: A portable compact-disc player (41), characterized by an opposed pair of loudspeakers (81) attached to the player, and in that each loudspeaker comprises a distributed mode acoustic radiator having a transducer (9) wholly and exclusively mounted thereon to vibrate the radiator to cause it to resonate.

Abstract: An inertial vibration transducer (9) characterised by a motor coil assembly comprising a tubular member (18) and a coil (13) rigidly fixed to the tubular member, and by a magnet assembly (15) disposed concentrically within the motor coil, and resilient means (19) supporting the magnet assembly for axial movement relative to the motor coil, the motor coil and tubular member being adapted to be rigidly mounted to a distributed mode radiator (2).