Helical actuation

1 Ltd, the UK inventor of an innovative piezoelectric actuator, claims that its product offers designers numerous advantages over conventional electromagnetic transducers.

The company’s Helimorph actuator is made from PZT, a piezoelectric ceramic material that changes shape when a voltage is applied.

Although there’s nothing particularly new about piezoelectric actuators, 1 Ltd’s design stands out thanks to the actuator’s unusual and elegant helical structure.

The actuators are formed from multiple layers of PZT, which are surrounded and separated by conductive electrodes. The resulting ceramic tape is wound into a super-helix – a ‘coiled coil’. When activated with a voltage the actuator deforms and the free end moves parallel to the axis of the major helix.

This geometry, says 1 Ltd’s Simon Longbottom, elevates the device above conventional piezo actuators and ‘means that the Helimorph is able to mechanically amplify a very small displacement to a very large displacement in a very small package.’

The actuator is currently being used in a miniature camera that is also designed by 1Ltd, where its high displacement and neat profile enable it to fit neatly around the lens barrel to enable focussing. The actuator also has very low power requirements. This is because PZT is a capacitative material, and is able to hold its shape without consuming any additional power.

These properties, combined with the fact that the Helimorph is light, frictionless, low maintenance and able to work at temperatures from -50 degrees C to +200 degrees C make it an attractive option for a number of applications.

Indeed, Longbottom says that 1Ltd is in discussion with a number of phone companies who are looking to exploit and improve on the trend for phones with in-built digital cameras.

On the web