1 . . . Limited

James Allan

Mark Richard Shepherd

Gareth McKevitt

Richard John Topliss

Anthony Hooley

David Henry Pearce

Ursula Ruth Lenel

Simon Andrew Longbottom

A piezoelectric device comprising a continuous piezoelectric element () extending alternately back and forth to form a plurality of parallel, straight portions () arranged in a stack with intermediate linkage portions () at alternate ends of the straight portions (). Each straight portion () is constructed and arranged with electrodes () to bend, on activation, in the stacking direction in which the straight portions () are stacked with opposite curvature in two halves () of the straight portion () to create displacement between the ends of the straight portion () in the stacking direction adding in series through the stack. The continuous nature of the piezoelectric element () eases manufacture. Devices with two types of construction are disclosed. Firstly, the continuous piezoelectric element () may have a bender construction such as a bimorph bender construction. Secondly, the continuous piezoelectric element () may be a sheet of piezoelectric material having overlapping slits () extending from alternate sides to form the straight portions () between the slits (), with opposed electrodes () arranged on each major surface of the sheet in pairs separated across, and extending along, the straight portions ().

Piezolelectric devices

An example housing that protects a ceramic actuator from excessive and damaging displacement comprises a protective structure arranged to limit the motion of the actuator by contacting at least one section of the actuator between fixed and moving terminals of said actuator. A suspension system for a lens holder of a miniature camera actuated by a ceramic actuator comprises four pivotally connected link elements in form of a parallelogram connected between a housing and the lens holder.

Protective housing for a ceramic actuator

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 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 ().

Growing community of inventors

Suffolk, United Kingdom

James Allan