Mini movers

Zoom lens cameras on mobile phones and vibrating alerts on a range of hand-held devices are becoming standard, but as the demand for smaller models increases, engineers have had to design smaller motors that will drive these features in the same effective way.

US ceramic motor manufacturer New Scale Technologies claims to have developed the world's smallest linear motor — the Squiggle — for use in 3x optical zoom lens modules for phone cameras.

The company worked with photographic lens specialist Tamron to demonstrate the capabilities of the Squiggle, which measures only 10.8 x 18.2 x 16.3mm.

New Scale has also demonstrated a smaller version —measuring 3.4 x 3.4 x 10 mm — for tiny devices such as portable sensors.

While there are many applications for miniature motors, the company is putting a great deal of focus on the mobile phone industry. As it said, the world market for mobile phone cameras is forecast to be nearly one billion by 2009.

Mobile phone companies are moving to produce models with image quality that rivals stand-alone digital cameras by incorporating high-end 3 and 5 megapixel image sensors.

However, achieving that quality also requires high-end precision optics, auto focus and optical zoom capabilities to project sharp and clear images on to the sensors.

'Until now, no-one has delivered a combination automatic focus 3x zoom lens in a module this small,' said New Scale's president and chief technology officer David Henderson.

'The Squiggle has enabled Tamron to deliver high-quality optics in the tiny form that mobile handset designers demand.'

Its motor design consists of piezo- electric ceramics bonded to a threaded nut with a mating screw inside. When electrical signals are applied to the ceramics, it creates ultrasonic vibrations in the nut, causing the screw to rotate and translate with precise linear movement in a very small space.

New Scale claims that while Squiggles are much smaller than conventional electromagnetic motors they are more precise, less expensive and more efficient.

Other companies are also getting in on the miniature motor market.

Precision Microdrives, a UK supplier of precision motion control components and miniature DC motor assemblies, for example, has been rapidly increasing its supply of small vibration motors for mobiles and medical technology applications.

According to the company, it is shrinking the size of its motors to under 10mm in diameter with the use of coreless technology, which allows motors to be designed with rotors without any iron cores.

'We are looking to treble our supply of miniature motors,' said operations director Tsuyoshi Kihara.

Precision has been supplying electric motors for years, he said, but there is a recent trend from customers wanting hand-held devices with vibration functionality.