Abstract: A loudspeaker comprises a sound generating element mounted on a support structure, and two rotary actuators I mounted at opposing edges of the sound generating element. The actuators are operable to drive motion of the sound generating element relative to the support structure including a component of rotation. The loudspeaker produces a greater sound output than if driven at one edge only, and is particularly suitable for use in a portable electronic device such as a mobile telephone, in which case the support structure may be a portion of the casing of the, device and the sound generating element maybe a transparent panel covering a display device.

Abstract: 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.

Abstract: 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

Abstract: 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 (11) 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.

Abstract: A loudspeaker system is described including an array of electro-acoustic transducers capable of generating steerable beams of sound and additional transducers adapted to reproduce low frequency sound being placed at the perimeter of said array.

Abstract: There is disclosed a method for setting up a Sound Projector such that it is suitable for a variety of functions, including surround sound. The method allows a semi-automatic or automatic set-up to be accomplished whereby the Sound Projector emits test signals and these are received by one or more microphones in order to detect the position and angles of the major reflecting surfaces in the room. In a preferred embodiment, the room is scanned by a moving directional sound beam and the first reflection of said sound beam is detected at a microphone in order to determine the distance of the reflective surfaces from the Sound Projector for all or most possible angles of sound beams.

Abstract: A camera comprises: a support structure 100; a lens holder 120 holding at least one lens 121; a suspension 130 for mounting said lens holder 120 on the support structure 100 to allow relative movement of the lens holder 120 and the support structure; and an actuator for moving said lens holder 120. The suspension 130 includes two link elements 133, 135 each connected at a first end to the support structure 100 by a pivotal connection and at the other, second end to the lens holder 120 by a pivotal connection, the pivotal connections allowing pivoting of the respective link element 133, 135 around a respective pivot axis, all the pivot axes being parallel, and the extent of the two link elements 133, 135 perpendicular to their respective pivot axes being parallel and of equal length.

Abstract: Various sensors use an electro-active device (11) electrically connected to a detector circuit. The electro-active device (11) comprises an electro-active structure in the form of a continuous electro-active member (12) curving in a helix around a minor axis (13) which is in itself curved for example in a helix around a major axis (14). On activation by relative displacement of the ends (16) of the device (11), the electro-active structure twists around the minor axis due to the fact that the minor axis (13) is curved. The continuous member (12) has a bender construction of a plurality of layers (21) and (22) including at least one layer of electro-active material so that concomitantly with the twisting the continuous member (12) bends generating an electrical signal detected by the detector circuit. The electro-active device (11) is advantageous as a sensing element in a sensor because it has a large displacement, high sensitivity and low compliance.

Abstract: A camera (30) uses an electro-active device (11) to position a movable lens. The electro-active device (11) comprises an electro-active structure in the form of a continuous electro-active member (12) curving in a helix around a minor axis (13) which is in itself curved for example in a helix around a major axis (14). The continuous member (12) has a bender construction of a plurality of layers (21 and 22) including at least one layer of electro-active material so that it bends, on activation, around the minor axis (13). Concomitantly with the bending, the electro-active structure twists around the minor axis. Concomitantly with that twisting, relative displacement of the ends (16) of the device (11) occurs due to the combination of the twisting around the minor axis (13) and the fact that the minor axis (13) is curved. This structure of the electro-active device (11) is compact and provides for linear displacement, thereby making it suitable for positioning the lens of the camera (30).

Abstract: 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

Abstract: A loudspeaker is described with two closely spaced diaphragms simultaneously driven by the two ends of an actuator. By balancing the impedance load of both diaphragms on the actuator both diaphragms radiate in phase and hence improve sound reproduction and efficiency of operation.

Abstract: 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

Abstract: 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.

Abstract: 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 (11) 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.

Abstract: The present invention relates to an electro-active device having an electro-active structure extending along a minor axis (36) which is curved, for example in a helix around a major axis (37). The electro-active structure comprises successive electro-active portions (35) extending around said minor axis and arranged with electrodes to bend, when activated, around the minor axis (36) such that bending of the successive portions (35) is concomitant with rotation of the electro-active structure about the minor axis (36) adding incrementally along the minor axis (36). 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 (35) extending along and curving around the minor axis (35), for example helically to form a helical helix. Alternatively, the electro-active structure may be a plurality of discrete elements (211) connected together.

Abstract: Various sensors use an electro-active device (11) electrically connected to a detector circuit. The electro-active device (11) comprises an electro-active structure in the form of a continuous electro-active member (12) curving in a helix around a minor axis (13) which is in itself curved for example in a helix around a major axis (14). On activation by relative displacement of the ends (16) of the device (11), the electro-active structure twists around the minor axis due to the fact that the minor axis (13) is curved. The continuous member (12) has a bender construction of a plurality of layers (21) and (22) including at least one layer of electro-active material so that concomitantly with the twisting the continuous member (12) bends generating an electrical signal detected by the detector circuit. The electro-active device (11) is advantageous as a sensing element in a sensor because it has a large displacement, high sensitivity and low compliance.

Abstract: A camera (30) uses an electro-active device (11) to position a movable lens. The electro-active device (11) comprises an electro-active structure in the form of a continuous electro-active member (12) curving in a helix around a minor axis (13) which is in itself curved for example in a helix around a major axis (14). The continuous member (12) has a bender construction of a plurality of layers (21 and 22) including at least one layer of electro-active material so that it bends, on activation, around the minor axis (13). Concomitantly with the bending, the electro-active structure twists around the minor axis. Concomitantly with that twisting, relative displacement of the ends (16) of the device (11) occurs due to the combination of the twisting around the minor axis (13) and the fact that the minor axis (13) is curved. This structure of the electro-active device (11) is compact and provides for linear displacement, thereby making it suitable for positioning the lens of the camera (30).

Abstract: 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.

Abstract: A unimorph or bimorph piezoelectric ‘bender’ formed into a flat- (or edge-) wound helix (50,54,55) wherein there is an additional laminate layer of a piezo-resistive material (609,709) the function of which is for sensing and responding to the actual deflection of the bender device. It also discloses a method for making this type of device by co-extrusion of a sinterable paste of the appropriate composition.

Abstract: The present invention relates to an electro-active device having an electro-active structure extending along a minor axis (36) which is curved, for example in a helix around a major axis (37). The electro-active structure comprises successive electro-active portions (35) extending around said minor axis and arranged with electrodes to bend, when activated, around the minor axis (36) such that bending of the successive portions (35) is concomitant with rotation of the electro-active structure about the minor axis (36) adding incrementally along the minor axis (36). The electro-active structure generates displacement out of the local plane in which the minor axis is curved. The electro-active structure may be continuous electro-active member (35) extending along and curving around the minor axis (35), for example helically to form a helical helix. Alternatively, the electro-active structure may be a plurality of discrete elements (211) connected together.