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: A touch sensitive device comprising a touch sensitive display member capable of supporting bending wave vibration and having a user accessible display surface, an array of transducers coupled to the display member with the array of transducers comprising at least some transducers which are configured to both detect physical touching of the input surface by the user and to input impulses into the display member to produce a haptics sensation to the user in response to said detected touching of the display surface, and a signal processor to receive signals from at least some of transducers in the array of transducers and adapted to analyze the signals to determine the location of the physical touch on the display surface.

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: A user/machine interface comprising a panel having a surface, the panel being capable of supporting bending waves, a touch-sensitive input device associated with the surface, and means including a force transducer for providing force feedback to the input device. The force is in the form of pulses to the panel, the pulses being in the form of a modulated signal shaped as a damped sinusoid whereby a button click sensation is provided to the user's finger tip. The modulated signal may be produced by a narrow-band sine wave having a carrier frequency in the range 150 to 750 Hz and being of a duration of at least 10 ms.

Abstract: An inertial vibration exciter having a magnet assembly defining an annular gap, a coil assembly disposed in the annular gap, suspension means mounting the coil assembly for reciprocating movement in the gap, means coupling the coil assembly to a member to be vibrated, and a hermetically sealed housing in which the magnet assembly, the coil assembly, the suspension means and the coupling means are disposed. The housing may comprise a heat sink thermally coupled to the magnet assembly and the heat sink may be resiliently coupled to the housing. The coupling means may comprise a plate-like member to which the coil is rigidly attached and of a size substantially greater than the diameter of the coil. The plate-like member may be resiliently coupled to the housing.

Abstract: An acoustic device and method of making said acoustic device. The acoustic device comprises a diaphragm having resonant bending wave modes in the operating frequency range, and a plurality of electromechanical transducers coupled to the diaphragm. The positioning and mechanical impedance of the transducers are such that at least a selected number of the resonant bending wave modes are balanced so that the net transverse modal velocity over the area of the diaphragm tends to zero with the balancing of the resonant bending wave modes being achieved substantially by the positioning and mechanical impedance of the transducers. The parameters of the diaphragm may be such that there are a plurality of nodal grouped locations at or around which the nodal lines of a selected number of resonant modes are clustered. Each transducer may be mounted at one of the plurality of nodal grouped locations.

Abstract: A contact sensitive device (10) comprising a member (12) capable of supporting bending waves, a first sensor (16) mounted on the member for measuring bending wave vibration in the member, the sensor (16) determining a first measured bending wave signal and a processor which calculates information relating to a contact on the member (12) from the measured bending wave signal, the processor applying a correction based on the dispersion relation of the material of the member (12) supporting the bending waves, characterized in that the device (10) comprises a second sensor (16) to determine a second measured bending wave signal which is measured simultaneously with the first measured bending wave signal and the processor calculates a dispersion corrected function of the two measured bending wave signals which is selected from the group consisting of a dispersion corrected correlation function, a dispersion corrected convolution function, a dispersion corrected coherence function and other phase equivalent functio

Abstract: Audio apparatus comprising a housing and a piezoelectric transducer (12) mounted in the housing (10) so that the transducer is adjacent a user's pinna whereby the transducer excites vibration in the pinna to cause it to transmit an acoustic signal from the transducer to a user's inner ear characterised by comprising a coupler (14) coupling the transducer (12) to the housing (10) with the coupler (14) approximating to a simple support for the transducer (12).

Abstract: A touch sensitive device comprising a touch sensitive display member capable of supporting bending wave vibration and having a user accessible display surface, an array of transducers coupled to the display member with the array of transducers comprising at least some transducers which are configured to both detect physical touching of the input surface by the user and to input impulses into the display member to produce a haptics sensation to the user in response to said detected touching of the display surface, and a signal processor to receive signals from at least some of transducers in the array of transducers and adapted to analyse the signals to determine the location of the physical touch on the display surface.

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: An assembly (38) comprises a vibration transducer (50) coupled to a substrate (58) which incorporates a circuit (62) electrically connected to the transducer (50). The substrate (58) is adapted to be coupled to a bending wave member (30) for converting actuator vibration into acoustic radiation or vice versa and has sufficient flexibility to allow bending wave coupling between the substrate (58) and the member (30).

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: A method of making a touch-sensitive data entry screen of the kind arranged to provide haptic response to a user via at least one electromechanical exciter coupled to the screen, comprising analysing the mechanical and electromechanical coupled system represented by the data entry screen and the at least one exciter, and selecting values of parameters of the coupled system to provide a required displacement and acceleration of the screen at low frequency in response to human touch.

Abstract: An inertial vibration exciter having a magnet assembly defining an annular gap, a coil assembly disposed in the annular gap, suspension means mounting the coil assembly for reciprocating movement in the gap, means coupling the coil assembly to a member to be vibrated, and a hermetically sealed housing in which the magnet assembly, the coil assembly, the suspension means and the coupling means are disposed. The housing may comprise a heat sink thermally coupled to the magnet assembly and the heat sink may be resiliently coupled to the housing. The coupling means may comprise a plate-like member to which the coil is rigidly attached and of a size substantially greater than the diameter of the coil. The plate-like member may be resiliently coupled to the housing.

Abstract: An acoustic device intended to operate pistonically and in bending comprising a panel-form acoustic radiator, a magnetic drive system including a voice coil on a tubular bobbin, the bobbin being directly coupled to the radiator to drive the radiator directly; and a coupling device connected to the bobbin, and to the radiator at a position at or near to the first nodal line of bending resonance of the radiator. A method of improving the on-axis response of a loudspeaker having a panel-form radiator and intended to operate both pistonically and in bending, comprising driving the radiator by a directly connected tubular bobbin, and substantially suppressing the lowest natural frequency of the radiator by providing a coupler connected from the bobbin to the radiator at or near to its first nodal line.

Abstract: A switching amplifier includes a modulator, which includes a pulse generator. The pulse generator generates positive and negative pulses, in response to an input signal, and the frequency of the negative pulses can be controlled independently of the frequency of the positive pulses. The positive pulses and negative pulses are combined to form a composite pulse stream, which can be low-pass filtered such that the filter output is an amplified version of the input signal.

Abstract: An acoustic device comprising a diaphragm (10) having an area and having an operating frequency range and the diaphragm (10) being such that it has resonant modes in the operating frequency range, an electromechanical transducer having a drive part coupled to the diaphragm (10) and adapted to exchange energy with the diaphragm, and at least one mechanical impedance means (20,22,24) coupled to or integral with the diaphragm, the positioning and mass of the drive part (26) of the transducer and of the at least one mechanical impedance means (20,22,24) being such that the net transverse modal velocity over the area of the diaphragm (10) tends to zero.