14 June 2007

Vibration-compensated mini projectors

Projector technology has improved considerably in the last few years, but although brightness, contrast, and color are better than ever, size still remains an issue for those looking for a truly portable device.

Miniature projectors embedded in our cell phones, handheld game consoles and other personal electronics appear very likely to play a major role in the future of information display.

Projecting a large screen display on a wall appears the most effective way we can currently envisage having a large screen inside a small form factor. One of the problems will of course be that a handheld device projecting a large screen might not lead to a stable, vibration-free and easily readable display.

Now German scientists from the Institute for Photonic Microsystems in Dresden have combined a compact laser projector system with inertia and yaw rate sensors to project vibration-compensated images. The sensor system detects the slightest motion and rotates the image to compensate for it, ensuring a steady picture, even in a moving vehicle. The system could be commercially available within two years.

The new development from the Fraunhofer Institute for Photonic Microsystems IPMS can be integrated into any mobile handheld device and used to project the display onto any flat surface in A3 format. And the great thing is, the image always remains steady – even if the user holding the device is shaking or the whole car is vibrating.

The car journey has been going on for hours, and back-seat passengers often have nothing better than the view from the window to divert them. Playing ‘sudoku’ on the cell phone gets tiring after a while, as the display is too small and keeps shaking with the motion of the car. A new development by the Fraunhofer Institute for Photonic Microsystems IPMS in Dresden could soon help: A novel miniature laser projector can be integrated into any mobile handheld device and used to project the display onto any flat surface in A3 format. And the great thing is, the image always remains steady – even if the user holding the device is shaking or the whole car is vibrating.

Even images from cell phones can be shown without vibration on a flat surface.

Researchers at the IPMS, who developed the miniature projector jointly with their colleagues at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF, have now succeeded in making it insensitive to small movements. “We have combined our compact laser projector system with inertia and yaw rate sensors,” explains Dr Michael Scholles, business unit manager at the IPMS. “This sensor system is capable of detecting any kind of motion. The information is then sent to the image processing unit, which rotates the image to compensate for the motion and ensures a steady picture.” In future handheld devices, which could for instance combine a cell phone, a PDA and a games console, the system can be used for projecting a conveniently sized, vibration-compensated image of any application. “The system could be commercially available a year or two,” estimates Scholles.

The developers of the system would also like to see it used as an active control, instead of a mouse or a joystick for instance. This would be especially useful for mobile devices such as PDAs or mobile phones, devices for which a mouse is not really suitable. The researchers have constructed a demonstrator for computer games from a commercially available steering wheel that has been equipped with a mini projector. The projector, which is mounted on the axle of the steering wheel, projects the image of the computer game onto the wall. The sensor system simultaneously detects the motion of the wheel and thus controls the movements of the figures in the game – rather like a joystick.

The projection system is fitted with a micromechanical scanning mirror, also developed by the IPMS, that constructs the image by deflecting the light beam into rows and columns. The projector has a size of only 17 x 7 x 5 millimeters. The researchers achieved this level of miniaturization by employing laser diodes instead of conventional lamps.