Sharper shooters

Sensor technology first developed for the automotive sector could improve the performance of digital cameras by removing motion blurring from images, researchers claim.

Engineers at Germany’s Fraunhofer Institute for Silicon Technology said their sensor-based system automatically detects and removes blur caused by slight movements as the shutter is pressed.

Rapid advances in digital technology have created a mass market for compact cameras, but blurred pictures still remain a hazard.

The Fraunhofer team, working with German MEMS specialist SiliconDynamics, has designed a super-compact motion sensor which can be made small and cheaply enough to be installed even in a mobile phone camera.

Based on minute gyroscopes machined out of 10µm thick polycrystalline silicon, the sensor is incorporated into a package just 200µm across.

The gyroscopes are made from silicon, said lead researcher Oliver Schwarzelbach, and work on the capacitance principle. Comb-like structures are arranged so that the teeth of one fixed comb are interlinked with the teeth of another that is free to move.

Any rotation of the sensor makes the teeth of the moving comb slide into the fixed one, increasing the electrical capacitance of the system.

‘With three gyroscopes for each direction we can detect any rotation,’ said Schwarzelbach.

The sensor is surrounded by advanced electronics systems which process the signal from the gyroscopes and allow it to test itself, detect and recognise faults and compensate for wear.

The extremely compact size is possible because of the way the sensor is packaged, said Schwarzelbach. ‘These sensors have to be encapsulated under a high vacuum,’ he explained. ‘We’ve managed to increase the vacuum a hundred-fold over currently-available sensors, to 0.1mbar, and that means we can make the capsule much smaller.’

The sensors are currently optimised for the automotive market, where they are designed to be used as part of an active suspension system, to trigger airbags if the car overturns, and to improve the accuracy of GPS co-ordinates.

For these safety-critical applications, the in-built failsafes are crucial, said Schwarzelbach, but for general consumer products they could be scaled back to reduce the cost of the sensor.

Installed in a digital camera, the sensors would be able to track minute movements of the camera as the shutter is pressed, and automatically process the signal from the imaging sensor to remove the blurring.

‘We’re working on massproduction of the automotive version of the sensor now,’ said Schwarzelbach, ‘and we can have the consumer version ready for production in a year.’