1 . . . Limited

Cambridge Mechatronics Limited

Yamaha Corporation

Anthony Hooley

Gareth McKevitt

Paul Thomas Troughton

David Henry Pearce

Mark Richard Shepherd

Ursula Ruth Lenel

Angus Gavin Goudie

Richard John Topliss

Paul Raymond Windle

Irving Alexander Bienek

Dominic George Webber

David Charles William Richards

James Allan

Thomas M Gregory

Robert John Leedham

Mark Easton

Andrew Matheson

David Livingstone

Simon Andrew Longbottom

Damon Thomas Ryan

Shinichi Makino

Luc Forest

David Christopher Turner

David Charles Wilson Richards

Gareth Mckevitt

An example set-up method for a loudspeaker system capable of generating at least one directed beam of audio sound includes emitting directional beams of set-up sound signals from the loudspeaker system into a room, registering at least one reflection of the emitted signals at one or more locations within the room, and evaluating the registered reflected signals to obtain data for use in configuring the surround sound system.

Set-up method for array-type sound system

A miniature camera lens actuation apparatus comprises a support structure, a camera lens element supported on the support structure by a suspension system; and an SMA actuator connected between the support structure and the movable element to drive movement of the camera lens element. The control circuit may include a drive circuit and a sensor circuit which have separate electrical connections to the SMA actuator to reduce the impact of the resistance of the electrical connections on the sensing. The control circuit may vary the drive signal in response to a temperature signal indicative of the ambient temperature. An endstop limits movement to prevent extension of the SMA actuator in its unheated state beyond a maximum length which is at or below the length corresponding the local maximum resistance of the resistance-length curve. Control of position is effected using resistance of the SMA actuator as a measure of position. The control employs a 'ratcheting' method to prevent a failure condition and an initial calibration step to derive a range of target resistance values. In manufacture, the position of a lens holder is adjusted relative to a carrier to provide focussing on the image sensor of an image of an object at a distance in the range from infinity to the hyperfocal distance when the SMA actuator is heated to a predetermined temperature greater than ambient temperature.

Shape memory alloy actuation apparatus

The invention relates to sonic steerable antennae and their use to achieve a variety of effects. The invention comprises a method and apparatus for taking an input signal, replicating it a number of times and modifying each of the replicas before routing them to respective output transducers such that a desired sound field is created. This sound field may comprise a directed beam, focus beam or a simulated origin. Further, 'anti-sound' may be directed so as to create nulls (quiet spots) in an already existing sound field. The input signal replicas may also be modified in way which changes their amplitude or they may be filtered to provide the desired delaying. Reflective or resonant surfaces may be used to achieve a surround sound effect, a microphone may be located in front of an array of loudspeakers, beams of light may be used to identify the present focal position, a limiting device may be used to ensure that clipping or distortion is reduced when more than one input signal is output by the same device and the concept of beam directivity may be used to achieve input nulls or beams in a microphone made up of an array of input transducers. Further, sound field shaping information may be associated with an audio signal to be broadcast.

Method and apparatus to shape sound

A miniature camera lens actuation apparatus provides an auto-macro function in which a camera lens element has two focus positions. In one type of apparatus, a shape memory alloy actuator arranged to drive movement of the camera lens element relative to a support structure against an end-stop arranged to limit the movement. The shape memory alloy actuator is connected to one of the movable element and the support structure by a compliant connector. This limits the stresses on the shape memory alloy actuator and therefore increases its lifetime. In another type of apparatus, the suspension system supporting the movable element on the support structure provides the movable element with two stable positions along the movement direction.

Method and apparatus to direct sound

The invention generally relates to a method and apparatus for taking an input signal, replicating it a number of times and modifying each of the replicas before routing them to respective output transducers such that a desired sound field is created. This sound field may comprise a directed beam, focussed beam or a simulated origin. In a first aspect, delays are added to sound channels to remove the effects of different travelling distances. In a second aspect, a delay is added to a video signal to account for the delays added to the sound channels. In a third aspect, different window functions are applied to each channel to give improved flexibility of use. In a fourth aspect, a smaller extent of transducers is used top output high frequencies than are used to output low frequencies. An array having a larger density of transducers near the centre is also provided. In a fifth aspect, a line of elongate transducers is provided to give good directivity in a plane. In a sixth aspect, sound beams are focussed in front or behind surfaces to give different beam widths and simulated origins. In a seventh aspect, a camera is used to indicate where sound is directed.

Method and apparatus to create a sound field

The invention provides transducer arrays which are capable of outputting sound beams having a relatively constant width, and with minimal sidelobes, across a range of frequencies. This is achieved by utilising one or more digital signal modifiers within the signal path between the input sound signal and the array of transducers. Variable window functions are also disclosed.

Signal processing device for acoustic transducer array

A loudspeaker comprising: a support, a sound-generating element mounted to the support for vibration to generate sound; and an electro-active device coupled between the support and the sound-generating element for vibrating the sound-generating element in response to an electrical signal. The electro-active device comprises a structure extending along a minor axis which extends in a curve around a major axis parallel to the vibration direction of the sound-generating element, the structure comprising successive electro-active portions arranged with electrodes to bend around the minor axis on activation in response to application of the electrical signal to the electrodes, and coupled together such that bending of successive portions causes concomitant rotation of adjacent portions around the minor axis adding incrementally along the minor axis, which rotation causes concomitant change of the axial length of the structure along the major axis.

Loudspeaker using an electro-active device

A digital pulse-width-modulation (PWM) generator comprising: an n bit digital magnitude comparator having first and second n bit inputs and an output indicative of the relative values of the signals applied at the first and second inputs; a first n bit digital up/down counter having a count direction input coupled to receive a sign bit of a digital unary input signal, an n bit parallel binary count output connected to the first n bit input of the magnitude comparator, and a clock input; a second n bit counter having a clock input coupled to receive a constant rate clock signal and an n bit parallel binary count output connected to the second n bit input of the magnitude comparator; an AND gate having a first input coupled to receive the constant rate clock signal in frequency divided form and a second input coupled to receive a magnitude portion of the digital unary input signal, and further having an output connected to the clock input of the first counter; and wherein the comparator continually generates an output signal indicative of the relative magnitudes of the counts of the first and second counters, whereby said output signal is a PWM output signal with an average value representing a ramp voltage having a slope determined by magnitude portion of the digital unary input signal with a direction of a slope of the output signal being determined by the polarity of the sign bit.

Digital loudspeaker

An equivalent to the spatial separation either side of a nominal median plane that is inherent in a bimorph (with one piezoelectric layer on one side, and the second on the other side of the plane) is attained by structurally shaping the cross-section of a simple, single piezoelectric layer () such that it has a multiplicity of piezoelectric portions arranged in two generally-planar groups one either side of a median plane, so that any dimension change undergone by a portion on one side of that plane will tend to bend the whole device in the opposite direction to the same sense dimension change undergone by a portion on the other side of that plane. The simple, single layer acts as though it were a bimorph if elongate and beam-like, bending along its length, one end moving up/down, or back/forth, relative to the other but with any need for an internal, electrode.

Piezoelectric structures

Various sensors use an electro-active device () electrically connected to a detector circuit. The electro-active device () comprises an electro-active structure in the form of a continuous electro-active member () curving in a helix around a minor axis () which is in itself curved for example in a helix around a major axis (). On activation by relative displacement of the ends () of the device (), the electro-active structure twists around the minor axis due to the fact that the minor axis () is curved. The continuous member () has a bender construction of a plurality of layers () and () including at least one layer of electro-active material so that concomitantly with the twisting the continuous member () bends generating an electrical signal detected by the detector circuit. The electro-active device () is advantageous as a sensing element in a sensor because it has a large displacement, high sensitivity and low compliance.

Sensor using electro active curved helix and double helix

A camera () uses an electro-active device () to position a movable lens. The electro-active device () comprises an electro-active structure in the form of a continuous electro-active member () curving in a helix around a minor axis () which is in itself curved for example in a helix around a major axis (). The continuous member () has a bender construction of a plurality of layers (and) including at least one layer of electro-active material so that it bends, on activation, around the minor axis (). Concomitantly with the bending, the electro-active structure twists around the minor axis. Concomitantly with that twisting, relative displacement of the ends () of the device () occurs due to the combination of the twisting around the minor axis () and the fact that the minor axis () is curved. This structure of the electro-active device () is compact and provides for linear displacement, thereby making it suitable for positioning the lens of the camera ().

Camera lens positioning using a electro-active device

A digital pulse-width-modulation (PWM) generator comprising:

Digital pulse-width-modulation generator

The present invention relates to an electro-active device having an electro-active structure extending along a minor axis ( ) which is curved, for example in a helix around a major axis ( ). The electro-active structure comprises successive electro-active portions ( ) extending around said minor axis and arranged with electrodes to bend, when activated, around the minor axis ( ) such that bending of the successive portions ( ) is concomitant with rotation of the electro-active structure about the minor axis ( ) adding incrementally along the minor axis ( ). The electro-active structure generates displacement out of the local plane in which the minor axis is curved. The electra-active structure may be continuous electro-active member ( ) extending along and curving around the minor axis ( ), for example helically to form a helical helix. Alternatively, the electro-active structure may be a plurality of discrete elements ( ) connected together. The electro-active portions preferably have a bender structure formed from a plurality of layers. The device may be used as a driver, a sensor or a generator.

Electro active devices

In its first aspect the invention provides an electromechanical acoustic transducer ( ) which is resistively terminated at the rear with a closely-coupled sound absorber ( ) made from an aerogel with good acoustic absorption at low frequencies. The invention also provides an aerogel suitable for this use and which is a conglomerate of small particles packed so that there are spaces left therebetween to allow the passage of sound. Moreover, the invention provides an aerogel suitable for this use and comprised of multiple layers ( etc.) of materials of graded properties, or comprised of material of continuously varying properties throughout the thickness of the absorbing structure, in the principal direction of sound from the source.

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Cambridge, United Kingdom

Anthony Hooley